[{"PlanS_conform":"1","publisher":"EDP Sciences","scopus_import":"1","fulldoi":"https://doi.org/10.1051/0004-6361/202556597","_id":"21341","publication_identifier":{"eissn":["1432-0746"],"issn":["0004-6361"]},"publication":"Astronomy & Astrophysics","arxiv":1,"OA_place":"publisher","project":[{"_id":"bd9b2118-d553-11ed-ba76-db24564edfea","grant_number":"101076224","name":"Young galaxies as tracers and agents of cosmic reionization"}],"has_accepted_license":"1","oa":1,"department":[{"_id":"JoMa"},{"_id":"GradSch"}],"article_processing_charge":"No","citation":{"ama":"Kotiwale G, Matthee JJ, Kashino D, et al. Rapid, out-of-equilibrium metal enrichment indicated by a flat mass-metallicity relation at z ∼ 6 from NIRCam grism spectroscopy. <i>Astronomy &#38; Astrophysics</i>. 2026;706. doi:<a href=\"https://doi.org/10.1051/0004-6361/202556597\">10.1051/0004-6361/202556597</a>","chicago":"Kotiwale, Gauri, Jorryt J Matthee, Daichi Kashino, Aswin P. Vijayan, Alberto Torralba Torregrosa, Claudia Di Cesare, Edoardo Iani, et al. “Rapid, out-of-Equilibrium Metal Enrichment Indicated by a Flat Mass-Metallicity Relation at z ∼ 6 from NIRCam Grism Spectroscopy.” <i>Astronomy &#38; Astrophysics</i>. EDP Sciences, 2026. <a href=\"https://doi.org/10.1051/0004-6361/202556597\">https://doi.org/10.1051/0004-6361/202556597</a>.","ieee":"G. Kotiwale <i>et al.</i>, “Rapid, out-of-equilibrium metal enrichment indicated by a flat mass-metallicity relation at z ∼ 6 from NIRCam grism spectroscopy,” <i>Astronomy &#38; Astrophysics</i>, vol. 706. EDP Sciences, 2026.","ista":"Kotiwale G, Matthee JJ, Kashino D, Vijayan AP, Torralba Torregrosa A, Di Cesare C, Iani E, Bordoloi R, Leja J, Maseda MV, Tacchella S, Shivaei I, Heintz KE, Danhaive AL, Mascia S, Kramarenko I, Navarrete B, Mackenzie R, Naidu RP, Sobral D. 2026. Rapid, out-of-equilibrium metal enrichment indicated by a flat mass-metallicity relation at z ∼ 6 from NIRCam grism spectroscopy. Astronomy &#38; Astrophysics. 706, A165.","mla":"Kotiwale, Gauri, et al. “Rapid, out-of-Equilibrium Metal Enrichment Indicated by a Flat Mass-Metallicity Relation at z ∼ 6 from NIRCam Grism Spectroscopy.” <i>Astronomy &#38; Astrophysics</i>, vol. 706, A165, EDP Sciences, 2026, doi:<a href=\"https://doi.org/10.1051/0004-6361/202556597\">10.1051/0004-6361/202556597</a>.","apa":"Kotiwale, G., Matthee, J. J., Kashino, D., Vijayan, A. P., Torralba Torregrosa, A., Di Cesare, C., … Sobral, D. (2026). Rapid, out-of-equilibrium metal enrichment indicated by a flat mass-metallicity relation at z ∼ 6 from NIRCam grism spectroscopy. <i>Astronomy &#38; Astrophysics</i>. EDP Sciences. <a href=\"https://doi.org/10.1051/0004-6361/202556597\">https://doi.org/10.1051/0004-6361/202556597</a>","short":"G. Kotiwale, J.J. Matthee, D. Kashino, A.P. Vijayan, A. Torralba Torregrosa, C. Di Cesare, E. Iani, R. Bordoloi, J. Leja, M.V. Maseda, S. Tacchella, I. Shivaei, K.E. Heintz, A.L. Danhaive, S. Mascia, I. Kramarenko, B. Navarrete, R. Mackenzie, R.P. Naidu, D. Sobral, Astronomy &#38; Astrophysics 706 (2026)."},"volume":706,"month":"02","date_published":"2026-02-01T00:00:00Z","publication_status":"published","article_type":"original","user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","corr_author":"1","tmp":{"short":"CC BY (4.0)","image":"/images/cc_by.png","name":"Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)","legal_code_url":"https://creativecommons.org/licenses/by/4.0/legalcode"},"author":[{"id":"1438afc8-1ff6-11ee-9fa6-cd4a75d66875","first_name":"Gauri","last_name":"Kotiwale","full_name":"Kotiwale, Gauri"},{"full_name":"Matthee, Jorryt J","orcid":"0000-0003-2871-127X","last_name":"Matthee","first_name":"Jorryt J","id":"7439a258-f3c0-11ec-9501-9df22fe06720"},{"first_name":"Daichi","last_name":"Kashino","full_name":"Kashino, Daichi"},{"full_name":"Vijayan, Aswin P.","first_name":"Aswin P.","last_name":"Vijayan"},{"full_name":"Torralba Torregrosa, Alberto","orcid":"0000-0001-5586-6950","last_name":"Torralba Torregrosa","id":"018f0249-0e87-11f0-b167-cbce08fbd541","first_name":"Alberto"},{"full_name":"Di Cesare, Claudia","first_name":"Claudia","id":"2d002343-372f-11ef-98ec-a164d20427cb","last_name":"Di Cesare"},{"full_name":"Iani, Edoardo","id":"4053390a-6b68-11ef-9828-a3b8adef8d0a","first_name":"Edoardo","last_name":"Iani","orcid":"0000-0001-8386-3546"},{"full_name":"Bordoloi, Rongmon","first_name":"Rongmon","last_name":"Bordoloi"},{"full_name":"Leja, Joel","last_name":"Leja","first_name":"Joel"},{"full_name":"Maseda, Michael V.","last_name":"Maseda","first_name":"Michael V."},{"last_name":"Tacchella","first_name":"Sandro","full_name":"Tacchella, Sandro"},{"last_name":"Shivaei","first_name":"Irene","full_name":"Shivaei, Irene"},{"first_name":"Kasper E.","last_name":"Heintz","full_name":"Heintz, Kasper E."},{"full_name":"Danhaive, A. Lola","first_name":"A. Lola","last_name":"Danhaive"},{"full_name":"Mascia, Sara","first_name":"Sara","id":"edaf889c-c7cd-11ef-ab1b-bb28c431bd29","last_name":"Mascia"},{"full_name":"Kramarenko, Ivan","first_name":"Ivan","id":"9a9394cb-3200-11ee-973b-f5ba2a8b16e4","last_name":"Kramarenko","orcid":"0000-0001-5346-6048"},{"full_name":"Navarrete, Benjamín","last_name":"Navarrete","first_name":"Benjamín","id":"aa14a535-50c9-11ef-b52e-e0c373d10148"},{"full_name":"Mackenzie, Ruari","last_name":"Mackenzie","first_name":"Ruari"},{"full_name":"Naidu, Rohan P.","last_name":"Naidu","first_name":"Rohan P."},{"full_name":"Sobral, David","last_name":"Sobral","first_name":"David"}],"ddc":["520"],"acknowledgement":"We thank the anonymous referee for the insightful comments that helped improving this paper. This work is based on observations made with the NASA/ESA/CSA James Webb Space Telescope. The data were obtained from the Mikulski Archive for Space Telescopes at the Space Telescope Science Institute, which is operated by the Associations of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-03127 for JWST. These observations were taken under programmes # 1243, # 1933 and # 3516. Funded by the European Union (ERC, AGENTS, 101076224). Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or the European Research Council. Neither the European Union nor the granting authority can be held responsible for them. GK acknowledges support from the Foundation MERAC. APV acknowledge support from the Sussex Astronomy Centre STFC Consolidated Grant (ST/X001040/1).","date_created":"2026-02-22T23:01:35Z","OA_type":"diamond","file_date_updated":"2026-02-24T07:46:47Z","status":"public","doi":"10.1051/0004-6361/202556597","type":"journal_article","language":[{"iso":"eng"}],"oa_version":"Published Version","day":"01","date_updated":"2026-02-24T07:49:42Z","title":"Rapid, out-of-equilibrium metal enrichment indicated by a flat mass-metallicity relation at z ∼ 6 from NIRCam grism spectroscopy","article_number":"A165","abstract":[{"lang":"eng","text":"We aim to characterise the mass-metallicity relation (MZR) and the 3D correlation between the stellar mass, metallicity, and star formation rate (SFR) known as the fundamental metallicity relation (FMR) for galaxies at 5 < z < 7. Using ∼800 [O III] selected galaxies from deep NIRCam grism surveys, we present our stacked measurements of direct-Te metallicities, which we used to test recent strong-line metallicity calibrations. Our measured direct-Te metallicities (0.1–0.2 Z⊙ for M★ ≈ 5 × 107 − 9 M⊙, respectively) match recent JWST/NIRSpec-based results. However, there are significant inconsistencies between observations and hydrodynamical simulations. We observe a flatter MZR slope than the SPHINX20 and FLARES simulations, which cannot be attributed to selection effects. With simple models, we show that the effect of an [O III] flux-limited sample on the observed shape of the MZR is strongly dependent on the FMR. If the FMR is similar to the one in the local Universe, the intrinsic high-redshift MZR should be even flatter than is observed. In turn, a 3D relation where SFR correlates positively with metallicity at fixed mass would imply an intrinsically steeper MZR. Our measurements indicate that metallicity variations at fixed mass show little dependence on the SFR, suggesting a flat intrinsic MZR. This could indicate that the low-mass galaxies at these redshifts are out of equilibrium and that metal enrichment occurs rapidly in low-mass galaxies. However, being limited by our stacking analysis, we are yet to probe the scatter in the MZR and its dependence on SFR. Large carefully selected samples of galaxies with robust metallicity measurements can put tight constraints on the high-redshift FMR and help us to understand the interplay between gas flows, star formation, and feedback in early galaxies."}],"DOAJ_listed":"1","file":[{"date_updated":"2026-02-24T07:46:47Z","file_name":"2026_AstronomyAstrophysics_Kotiwale.pdf","access_level":"open_access","date_created":"2026-02-24T07:46:47Z","file_id":"21355","content_type":"application/pdf","creator":"dernst","checksum":"6f5849d29ad43bee32f90152f6fc0294","success":1,"file_size":6531719,"relation":"main_file"}],"intvolume":"       706","year":"2026","external_id":{"arxiv":["2510.19959"]},"quality_controlled":"1"},{"DOAJ_listed":"1","file":[{"access_level":"open_access","file_name":"2026_AstronomyAstrophysics_Torralba2.pdf","date_updated":"2026-03-16T10:57:49Z","content_type":"application/pdf","creator":"dernst","checksum":"fcab9cb3dcf1d68612e1fdc8191643c1","success":1,"file_id":"21460","date_created":"2026-03-16T10:57:49Z","file_size":2510157,"relation":"main_file"}],"article_number":"A75","abstract":[{"text":"The population of the little red dots (LRDs) may represent a key phase of supermassive black hole (SMBH) growth. A cocoon of dense excited gas is emerging as a key component to explain the most striking properties of LRDs, such as strong Balmer breaks and Balmer absorption, as well as the weak IR emission. To dissect the structure of LRDs, we analyzed new deep JWST/NIRSpec PRISM and G395H spectra of FRESCO-GN-9771, one of the most luminous known LRDs at z = 5.5. These spectra reveal a strong Balmer break, broad Balmer lines, and very narrow [O III] emission. We revealed a forest of optical [Fe II] lines, which we argue are emerging from a dense (nH = 109 − 10 cm−3) warm layer with electron temperature Te ≈ 7000 K. The broad wings of Hα and Hβ have an exponential profile due to electron scattering in this same layer. The high Hα : Hβ : Hγ flux ratio of ≈10.4 : 1 : 0.14 is an indicator of collisional excitation and resonant scattering dominating the Balmer line emission. A narrow Hγ component, unseen in the other two Balmer lines due to outshining by the broad components, could trace the ISM of a normal host galaxy with a star formation rate of ∼5 M⊙ yr−1. The warm layer is mostly opaque to Balmer transitions, producing a characteristic P Cygni profile in the line centers suggesting outflowing motions. This same layer is responsible for shaping the Balmer break. The broadband spectrum can be reasonably matched by a simple photoionized slab model that dominates the λ > 1500 Å continuum and a low-mass (∼108 M⊙) galaxy that could explain the narrow [O III], with only a subdominant contribution to the UV continuum. Our findings indicate that Balmer lines are not directly tracing the gas kinematics near the SMBH and that the BH mass scale is likely much lower than virial indicators suggest.","lang":"eng"}],"intvolume":"       707","language":[{"iso":"eng"}],"oa_version":"Published Version","date_updated":"2026-03-16T10:59:16Z","title":"The warm outer layer of a little red dot as the source of [Fe ii] and collisional Balmer lines with scattering wings","day":"01","quality_controlled":"1","year":"2026","external_id":{"arxiv":["2510.00103"]},"acknowledgement":"We thank the scientific referee for useful and constructive comments. We thank Ylva Götberg and Zoltan Haiman for insightful discussions about the physics of gaseous envelopes and accretion into black holes. Funded by the European Union (ERC, AGENTS, 101076224). Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or the European Research Council. Neither the European Union nor the granting authority can be held responsible for them. This work is based in part on observations made with the NASA/ESA/CSA James Webb Space Telescope. The data were obtained from the Mikulski Archive for Space Telescopes at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-03127 for JWST. These observations are associated with program #5664. This work has received funding from the Swiss State Secretariat for Education, Research and Innovation (SERI) under contract number MB22.00072, as well as from the Swiss National Science Foundation (SNSF) through project grant 200020_207349.","date_created":"2026-03-15T23:01:36Z","tmp":{"short":"CC BY (4.0)","image":"/images/cc_by.png","name":"Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)","legal_code_url":"https://creativecommons.org/licenses/by/4.0/legalcode"},"corr_author":"1","ddc":["520"],"author":[{"id":"018f0249-0e87-11f0-b167-cbce08fbd541","first_name":"Alberto","last_name":"Torralba Torregrosa","orcid":"0000-0001-5586-6950","full_name":"Torralba Torregrosa, Alberto"},{"full_name":"Matthee, Jorryt J","last_name":"Matthee","orcid":"0000-0003-2871-127X","id":"7439a258-f3c0-11ec-9501-9df22fe06720","first_name":"Jorryt J"},{"full_name":"Pezzulli, Gabriele","first_name":"Gabriele","last_name":"Pezzulli"},{"full_name":"Naidu, Rohan P.","last_name":"Naidu","first_name":"Rohan P."},{"full_name":"Ishikawa, Yuzo","last_name":"Ishikawa","first_name":"Yuzo"},{"last_name":"Brammer","first_name":"Gabriel B.","full_name":"Brammer, Gabriel B."},{"full_name":"Chang, Seok Jun","first_name":"Seok Jun","last_name":"Chang"},{"last_name":"Chisholm","first_name":"John","full_name":"Chisholm, John"},{"last_name":"De Graaff","first_name":"Anna","full_name":"De Graaff, Anna"},{"first_name":"Francesco","last_name":"D’Eugenio","full_name":"D’Eugenio, Francesco"},{"last_name":"Di Cesare","first_name":"Claudia","id":"2d002343-372f-11ef-98ec-a164d20427cb","full_name":"Di Cesare, Claudia"},{"full_name":"Eilers, Anna Christina","first_name":"Anna Christina","last_name":"Eilers"},{"first_name":"Jenny E.","last_name":"Greene","full_name":"Greene, Jenny E."},{"full_name":"Gronke, Max","first_name":"Max","last_name":"Gronke"},{"full_name":"Iani, Edoardo","id":"4053390a-6b68-11ef-9828-a3b8adef8d0a","first_name":"Edoardo","orcid":"0000-0001-8386-3546","last_name":"Iani"},{"last_name":"Kokorev","first_name":"Vasily","full_name":"Kokorev, Vasily"},{"last_name":"Kotiwale","id":"1438afc8-1ff6-11ee-9fa6-cd4a75d66875","first_name":"Gauri","full_name":"Kotiwale, Gauri"},{"last_name":"Kramarenko","orcid":"0000-0001-5346-6048","first_name":"Ivan","id":"9a9394cb-3200-11ee-973b-f5ba2a8b16e4","full_name":"Kramarenko, Ivan"},{"full_name":"Ma, Yilun","first_name":"Yilun","last_name":"Ma"},{"full_name":"Mascia, Sara","last_name":"Mascia","first_name":"Sara","id":"edaf889c-c7cd-11ef-ab1b-bb28c431bd29"},{"full_name":"Navarrete, Benjamín","id":"aa14a535-50c9-11ef-b52e-e0c373d10148","first_name":"Benjamín","last_name":"Navarrete"},{"first_name":"Erica","last_name":"Nelson","full_name":"Nelson, Erica"},{"last_name":"Oesch","first_name":"Pascal","full_name":"Oesch, Pascal"},{"full_name":"Simcoe, Robert A.","last_name":"Simcoe","first_name":"Robert A."},{"full_name":"Wuyts, Stijn","last_name":"Wuyts","first_name":"Stijn"}],"status":"public","file_date_updated":"2026-03-16T10:57:49Z","doi":"10.1051/0004-6361/202557537","OA_type":"diamond","type":"journal_article","citation":{"chicago":"Torralba Torregrosa, Alberto, Jorryt J Matthee, Gabriele Pezzulli, Rohan P. Naidu, Yuzo Ishikawa, Gabriel B. Brammer, Seok Jun Chang, et al. “The Warm Outer Layer of a Little Red Dot as the Source of [Fe Ii] and Collisional Balmer Lines with Scattering Wings.” <i>Astronomy &#38; Astrophysics</i>. EDP Sciences, 2026. <a href=\"https://doi.org/10.1051/0004-6361/202557537\">https://doi.org/10.1051/0004-6361/202557537</a>.","ama":"Torralba Torregrosa A, Matthee JJ, Pezzulli G, et al. The warm outer layer of a little red dot as the source of [Fe ii] and collisional Balmer lines with scattering wings. <i>Astronomy &#38; Astrophysics</i>. 2026;707. doi:<a href=\"https://doi.org/10.1051/0004-6361/202557537\">10.1051/0004-6361/202557537</a>","short":"A. Torralba Torregrosa, J.J. Matthee, G. Pezzulli, R.P. Naidu, Y. Ishikawa, G.B. Brammer, S.J. Chang, J. Chisholm, A. De Graaff, F. D’Eugenio, C. Di Cesare, A.C. Eilers, J.E. Greene, M. Gronke, E. Iani, V. Kokorev, G. Kotiwale, I. Kramarenko, Y. Ma, S. Mascia, B. Navarrete, E. Nelson, P. Oesch, R.A. Simcoe, S. Wuyts, Astronomy &#38; Astrophysics 707 (2026).","ista":"Torralba Torregrosa A, Matthee JJ, Pezzulli G, Naidu RP, Ishikawa Y, Brammer GB, Chang SJ, Chisholm J, De Graaff A, D’Eugenio F, Di Cesare C, Eilers AC, Greene JE, Gronke M, Iani E, Kokorev V, Kotiwale G, Kramarenko I, Ma Y, Mascia S, Navarrete B, Nelson E, Oesch P, Simcoe RA, Wuyts S. 2026. The warm outer layer of a little red dot as the source of [Fe ii] and collisional Balmer lines with scattering wings. Astronomy &#38; Astrophysics. 707, A75.","apa":"Torralba Torregrosa, A., Matthee, J. J., Pezzulli, G., Naidu, R. P., Ishikawa, Y., Brammer, G. B., … Wuyts, S. (2026). The warm outer layer of a little red dot as the source of [Fe ii] and collisional Balmer lines with scattering wings. <i>Astronomy &#38; Astrophysics</i>. EDP Sciences. <a href=\"https://doi.org/10.1051/0004-6361/202557537\">https://doi.org/10.1051/0004-6361/202557537</a>","mla":"Torralba Torregrosa, Alberto, et al. “The Warm Outer Layer of a Little Red Dot as the Source of [Fe Ii] and Collisional Balmer Lines with Scattering Wings.” <i>Astronomy &#38; Astrophysics</i>, vol. 707, A75, EDP Sciences, 2026, doi:<a href=\"https://doi.org/10.1051/0004-6361/202557537\">10.1051/0004-6361/202557537</a>.","ieee":"A. Torralba Torregrosa <i>et al.</i>, “The warm outer layer of a little red dot as the source of [Fe ii] and collisional Balmer lines with scattering wings,” <i>Astronomy &#38; Astrophysics</i>, vol. 707. EDP Sciences, 2026."},"volume":707,"article_processing_charge":"No","department":[{"_id":"JoMa"}],"article_type":"original","user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","month":"03","publication_status":"published","date_published":"2026-03-01T00:00:00Z","_id":"21451","publication_identifier":{"eissn":["1432-0746"],"issn":["0004-6361"]},"publication":"Astronomy & Astrophysics","scopus_import":"1","publisher":"EDP Sciences","PlanS_conform":"1","fulldoi":"https://doi.org/10.1051/0004-6361/202557537","has_accepted_license":"1","oa":1,"arxiv":1,"OA_place":"publisher","project":[{"_id":"bd9b2118-d553-11ed-ba76-db24564edfea","grant_number":"101076224","name":"Young galaxies as tracers and agents of cosmic reionization"}]},{"article_processing_charge":"No","department":[{"_id":"JoMa"},{"_id":"GradSch"}],"volume":707,"citation":{"ama":"Di Cesare C, Matthee JJ, Naidu RP, et al. The slope and scatter of the star-forming main sequence at z ∼ 5: Reconciling observations with simulations. <i>Astronomy &#38; Astrophysics</i>. 2026;707. doi:<a href=\"https://doi.org/10.1051/0004-6361/202557790\">10.1051/0004-6361/202557790</a>","chicago":"Di Cesare, Claudia, Jorryt J Matthee, Rohan P. Naidu, Alberto Torralba, Gauri Kotiwale, Ivan Kramarenko, Jeremy Blaizot, et al. “The Slope and Scatter of the Star-Forming Main Sequence at z ∼ 5: Reconciling Observations with Simulations.” <i>Astronomy &#38; Astrophysics</i>. EDP Sciences, 2026. <a href=\"https://doi.org/10.1051/0004-6361/202557790\">https://doi.org/10.1051/0004-6361/202557790</a>.","apa":"Di Cesare, C., Matthee, J. J., Naidu, R. P., Torralba, A., Kotiwale, G., Kramarenko, I., … Tacchella, S. (2026). The slope and scatter of the star-forming main sequence at z ∼ 5: Reconciling observations with simulations. <i>Astronomy &#38; Astrophysics</i>. EDP Sciences. <a href=\"https://doi.org/10.1051/0004-6361/202557790\">https://doi.org/10.1051/0004-6361/202557790</a>","mla":"Di Cesare, Claudia, et al. “The Slope and Scatter of the Star-Forming Main Sequence at z ∼ 5: Reconciling Observations with Simulations.” <i>Astronomy &#38; Astrophysics</i>, vol. 707, A129, EDP Sciences, 2026, doi:<a href=\"https://doi.org/10.1051/0004-6361/202557790\">10.1051/0004-6361/202557790</a>.","ista":"Di Cesare C, Matthee JJ, Naidu RP, Torralba A, Kotiwale G, Kramarenko I, Blaizot J, Rosdahl J, Leja J, Iani E, Adamo A, Covelo-Paz A, Furtak LJ, Heintz KE, Mascia S, Navarrete B, Oesch PA, Romano M, Shivaei I, Tacchella S. 2026. The slope and scatter of the star-forming main sequence at z ∼ 5: Reconciling observations with simulations. Astronomy &#38; Astrophysics. 707, A129.","short":"C. Di Cesare, J.J. Matthee, R.P. Naidu, A. Torralba, G. Kotiwale, I. Kramarenko, J. Blaizot, J. Rosdahl, J. Leja, E. Iani, A. Adamo, A. Covelo-Paz, L.J. Furtak, K.E. Heintz, S. Mascia, B. Navarrete, P.A. Oesch, M. Romano, I. Shivaei, S. Tacchella, Astronomy &#38; Astrophysics 707 (2026).","ieee":"C. Di Cesare <i>et al.</i>, “The slope and scatter of the star-forming main sequence at z ∼ 5: Reconciling observations with simulations,” <i>Astronomy &#38; Astrophysics</i>, vol. 707. EDP Sciences, 2026."},"publication_status":"published","date_published":"2026-03-01T00:00:00Z","month":"03","user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","article_type":"original","fulldoi":"https://doi.org/10.1051/0004-6361/202557790","publisher":"EDP Sciences","PlanS_conform":"1","scopus_import":"1","publication":"Astronomy & Astrophysics","_id":"21452","publication_identifier":{"eissn":["1432-0746"],"issn":["0004-6361"]},"project":[{"_id":"bd9b2118-d553-11ed-ba76-db24564edfea","name":"Young galaxies as tracers and agents of cosmic reionization","grant_number":"101076224"}],"arxiv":1,"OA_place":"publisher","oa":1,"has_accepted_license":"1","day":"01","date_updated":"2026-03-16T10:52:44Z","title":"The slope and scatter of the star-forming main sequence at z ∼ 5: Reconciling observations with simulations","oa_version":"Published Version","language":[{"iso":"eng"}],"intvolume":"       707","article_number":"A129","abstract":[{"text":"Galaxies exhibit a tight correlation between their star formation rate (SFR) and stellar mass over a wide redshift range known as the star-forming main sequence (SFMS). With JWST, the SFMS can now be investigated at high redshifts down to masses of ∼106 M⊙, using sensitive star formation rate tracers such as the Hα emission, which allow us to probe the variability in the star formation histories. We present inferences of the SFMS based on 316 Hα-selected galaxies at z ∼ 4 − 5 with log(M★/M⊙) = 6.4 − 10.6. These galaxies were identified behind the Abell 2744 lensing cluster with NIRCam grism spectroscopy from the survey All the Little Things (ALT). At face value, our data suggest a shallow slope in the SFMS (SFR ∝ M★α, with α = 0.45). After we corrected this for the Hα-flux limited nature of our survey using a Bayesian framework, the slope steepened to α = 0.59+0.10−0.09, whereas current data on their own are inconclusive on the mass dependence of the scatter. These slopes differ significantly from the slope of ∼1 that is expected from the observed evolution of the galaxy stellar mass function and from simulations. When we fixed the slope to α = 1, we found evidence for a decreasing intrinsic scatter with stellar mass (from ∼0.5 dex at M★ = 108 M⊙ to 0.4 dex at M★ = 1010 M⊙). This difference might be explained by a (combination of) luminosity-dependent SFR(Hα) calibration, a population of (mini)-quenched low-mass galaxies, or underestimated dust attenuation in high-mass galaxies. Future deep observations with different facilities can quantify these processes, which will enable us to achieve better insights into the variability of the star formation histories.","lang":"eng"}],"file":[{"file_name":"2026_AstronomyAstrophysics_DiCesare.pdf","date_updated":"2026-03-16T10:48:07Z","access_level":"open_access","date_created":"2026-03-16T10:48:07Z","file_id":"21459","content_type":"application/pdf","creator":"dernst","checksum":"c056b00ce7324849754521fde10fb7ca","success":1,"file_size":1821411,"relation":"main_file"}],"DOAJ_listed":"1","external_id":{"arxiv":["2510.19044"]},"year":"2026","quality_controlled":"1","author":[{"last_name":"Di Cesare","first_name":"Claudia","id":"2d002343-372f-11ef-98ec-a164d20427cb","full_name":"Di Cesare, Claudia"},{"orcid":"0000-0003-2871-127X","last_name":"Matthee","id":"7439a258-f3c0-11ec-9501-9df22fe06720","first_name":"Jorryt J","full_name":"Matthee, Jorryt J"},{"full_name":"Naidu, Rohan P.","first_name":"Rohan P.","last_name":"Naidu"},{"full_name":"Torralba, Alberto","last_name":"Torralba","first_name":"Alberto"},{"full_name":"Kotiwale, Gauri","first_name":"Gauri","id":"1438afc8-1ff6-11ee-9fa6-cd4a75d66875","last_name":"Kotiwale"},{"orcid":"0000-0001-5346-6048","last_name":"Kramarenko","id":"9a9394cb-3200-11ee-973b-f5ba2a8b16e4","first_name":"Ivan","full_name":"Kramarenko, Ivan"},{"full_name":"Blaizot, Jeremy","last_name":"Blaizot","first_name":"Jeremy"},{"full_name":"Rosdahl, Joakim","first_name":"Joakim","last_name":"Rosdahl"},{"full_name":"Leja, Joel","last_name":"Leja","first_name":"Joel"},{"id":"4053390a-6b68-11ef-9828-a3b8adef8d0a","first_name":"Edoardo","last_name":"Iani","orcid":"0000-0001-8386-3546","full_name":"Iani, Edoardo"},{"full_name":"Adamo, Angela","first_name":"Angela","last_name":"Adamo"},{"last_name":"Covelo-Paz","first_name":"Alba","full_name":"Covelo-Paz, Alba"},{"last_name":"Furtak","first_name":"Lukas J.","full_name":"Furtak, Lukas J."},{"full_name":"Heintz, Kasper E.","first_name":"Kasper E.","last_name":"Heintz"},{"id":"edaf889c-c7cd-11ef-ab1b-bb28c431bd29","first_name":"Sara","last_name":"Mascia","full_name":"Mascia, Sara"},{"full_name":"Navarrete, Benjamín","id":"aa14a535-50c9-11ef-b52e-e0c373d10148","first_name":"Benjamín","last_name":"Navarrete"},{"last_name":"Oesch","first_name":"Pascal A.","full_name":"Oesch, Pascal A."},{"full_name":"Romano, Michael","first_name":"Michael","last_name":"Romano"},{"full_name":"Shivaei, Irene","last_name":"Shivaei","first_name":"Irene"},{"full_name":"Tacchella, Sandro","last_name":"Tacchella","first_name":"Sandro"}],"ddc":["520"],"corr_author":"1","tmp":{"short":"CC BY (4.0)","image":"/images/cc_by.png","name":"Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)","legal_code_url":"https://creativecommons.org/licenses/by/4.0/legalcode"},"date_created":"2026-03-15T23:01:36Z","acknowledgement":"We thank the anonymous referee for the insightful comments that helped improving the manuscript. We thank Romain. A. Meyer for valuable discussion, Pierluigi Rinaldi for his help with data handling and Luca Graziani and William McClymont for providing the dustyGadget and\r\nTHESAN-ZOOM data, respectively. Funded by the European Union (ERC, AGENTS, 101076224). Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or the European Research Council. Neither the European Union nor the granting authority can be held responsible for them. This work is based on observations made with the NASA/ESA/CSA James Webb Space Telescope. The data were obtained from the Mikulski Archive for Space Telescopes at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-03127 for JWST. These observations are associated with program # 3516. We acknowledge funding from JWST program GO-3516. Software used in developing this work includes: matplotlib (Hunter 2007), numpy (Oliphant 2007), scipy (Virtanen et al. 2020), TOPCAT (Taylor 2005), and Astropy (Astropy Collaboration 2013).","type":"journal_article","OA_type":"diamond","doi":"10.1051/0004-6361/202557790","status":"public","file_date_updated":"2026-03-16T10:48:07Z"},{"type":"journal_article","OA_type":"gold","status":"public","doi":"10.3847/1538-4357/ae3b25","file_date_updated":"2026-05-04T10:40:07Z","date_created":"2026-04-12T22:01:49Z","acknowledgement":"We wish to thank our colleagues in the CEERS collaboration for their hard work and valuable contributions on this project. We extend our sincerest thanks to the anonymous referee whose critical and constructive report improved the quality of this manuscript. We also thank the JADES team for providing an excellent dataset for science. We with to thank colleagues for valuable discussions, feedback, and suggestions, including John Chisholm, Kevin Huffenberger, Jessica\r\nMeh, Julian Muñoz, Irene Shivaei, Justin Spilker, Aaron Smith, and Romain Teyssier.\r\nPortions of this research were conducted with the advanced computing resources provided by Texas A&M High Performance Research Computing (HPRC, http://hprc.tamu.edu). This work benefited from support from the George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy at Texas A&M University. CP thanks Marsha and Ralph Schilling for generous support of this research. This work was partially support by the Future Investigators in NASA Earth and Space Science and Technology (FINESST) program grant No. 80NSSC23K1487. R.A. acknowledges support of grant PID2023-147386NB-I00 funded by MICIU/AEI/10.13039/501100011033 and by ERDF/EU, and the Severo Ochoa grant CEX2021-001131-S funded by MCIN/AEI/10.13039/50110001103. A.C.C. acknowledges support from a UKRI Frontier Research Guarantee Grant (PI Carnall; grant reference EP/Y037065/1) This work acknowledges support from the NASA/ESA/CSA James Webb Space Telescope through the\r\nSpace Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Incorporated, under NASA contract NAS5-03127. Support for program JWST-ERS-01345.009-A, JWST-GO-02079.013-A, JWST-GO-06368.011-A, and JWST-GO-01837.030-A, was provided by NASA through a grant from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-03127. This work made use of v2.2 of the Binary Population\r\nand Spectral Synthesis (BPASS) models as described in E. R. Stanway & J. J. Eldridge (2018).","issue":"1","author":[{"last_name":"Papovich","first_name":"Casey","full_name":"Papovich, Casey"},{"full_name":"Cole, Justin W.","first_name":"Justin W.","last_name":"Cole"},{"full_name":"Hu, Weida","last_name":"Hu","first_name":"Weida"},{"full_name":"Finkelstein, Steven L.","first_name":"Steven L.","last_name":"Finkelstein"},{"first_name":"Lu","last_name":"Shen","full_name":"Shen, Lu"},{"first_name":"Pablo","last_name":"Arrabal Haro","full_name":"Arrabal Haro, Pablo"},{"first_name":"Ricardo O.","last_name":"Amorín","full_name":"Amorín, Ricardo O."},{"full_name":"Backhaus, Bren E.","first_name":"Bren E.","last_name":"Backhaus"},{"last_name":"Bagley","first_name":"Micaela B.","full_name":"Bagley, Micaela B."},{"full_name":"Bhatawdekar, Rachana","first_name":"Rachana","last_name":"Bhatawdekar"},{"last_name":"Calabrò","first_name":"Antonello","full_name":"Calabrò, Antonello"},{"first_name":"Adam C.","last_name":"Carnall","full_name":"Carnall, Adam C."},{"full_name":"Cleri, Nikko J.","last_name":"Cleri","first_name":"Nikko J."},{"full_name":"Daddi, Emanuele","first_name":"Emanuele","last_name":"Daddi"},{"last_name":"Dickinson","first_name":"Mark","full_name":"Dickinson, Mark"},{"last_name":"Grogin","first_name":"Norman A.","full_name":"Grogin, Norman A."},{"full_name":"Holwerda, Benne W.","last_name":"Holwerda","first_name":"Benne W."},{"first_name":"Anne E.","last_name":"Jaskot","full_name":"Jaskot, Anne E."},{"full_name":"Koekemoer, Anton M.","last_name":"Koekemoer","first_name":"Anton M."},{"full_name":"Llerena, Mario","first_name":"Mario","last_name":"Llerena"},{"last_name":"Lucas","first_name":"Ray A.","full_name":"Lucas, Ray A."},{"first_name":"Sara","id":"edaf889c-c7cd-11ef-ab1b-bb28c431bd29","last_name":"Mascia","full_name":"Mascia, Sara"},{"full_name":"Pacucci, Fabio","first_name":"Fabio","last_name":"Pacucci"},{"full_name":"Pentericci, Laura","last_name":"Pentericci","first_name":"Laura"},{"last_name":"Pérez-González","first_name":"Pablo G.","full_name":"Pérez-González, Pablo G."},{"full_name":"Pirzkal, Nor","first_name":"Nor","last_name":"Pirzkal"},{"full_name":"Raghunathan, Srinivasan","last_name":"Raghunathan","first_name":"Srinivasan"},{"first_name":"Lise Marie","last_name":"Seillé","full_name":"Seillé, Lise Marie"},{"full_name":"Somerville, Rachel S.","first_name":"Rachel S.","last_name":"Somerville"},{"first_name":"L. Y.Aaron","last_name":"Yung","full_name":"Yung, L. Y.Aaron"}],"ddc":["520"],"tmp":{"short":"CC BY (4.0)","image":"/images/cc_by.png","name":"Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)","legal_code_url":"https://creativecommons.org/licenses/by/4.0/legalcode"},"quality_controlled":"1","external_id":{"arxiv":["2505.08870"]},"year":"2026","intvolume":"      1000","article_number":"111","abstract":[{"lang":"eng","text":"Early results from JWST suggest that Epoch of Reionization (EoR) galaxies produce copious ionizing photons, which, if they escape efficiently, could cause reionization to occur too early. We study this problem using JWST imaging and prism spectroscopy for 412 galaxies at 4.5 < z < 9.0. We fit these data simultaneously with stellar population and nebular emission models that include a parameter for the fraction of ionizing photons that escape the galaxy, fesc. We find that the ionization production efficiency, ξion = Q(H0)/LUV, increases with redshift and decreasing UV luminosity, but shows significant scatter, (log ion z, MUV) 0.3 dex. The inferred escape fractions averaged over the population are low, ranging from〈fesc〉 ≃ 2.6% ± 1.4% at 6 < z < 9 to 6.5% ± 2.2% at 4.5 < z < 6, with weak or no indication of evolution with redshift. This implies that in our models most of the ionizing photons need to be absorbed to account for the nebular emission. We compute the impact of our results on reionization, including the distributions for ξion and fesc, and the evolution and uncertainty of the UV luminosity function. Considering galaxies brighter than MUV < −16 mag would produce an intergalactic medium hydrogen-ionized fraction of xe = 0.5 at 5.3 < z < 5.8, possibly too late compared to constraints from from quasistellar\r\nobject (QSO) sight lines. Including fainter galaxies, MUV < −14 mag, we obtain xe = 0.5 at 6.0 < z < 8.1, fully consistent with QSO and cosmic microwave background data. This implies that EoR galaxies produce plenty of ionizing photons, but that these do not efficiently escape. This may be a result of high gas column densities combined with burstier star formation histories, which limit the time massive stars are able to clear channels through the gas for ionizing photons to escape."}],"file":[{"file_id":"21791","success":1,"checksum":"0031a6f197a3fa8c2845de10b6bdc696","creator":"dernst","content_type":"application/pdf","date_created":"2026-05-04T10:40:07Z","date_updated":"2026-05-04T10:40:07Z","file_name":"2026_AstrophysicalJour_Papovich.pdf","access_level":"open_access","relation":"main_file","file_size":6670398}],"day":"20","title":"Galaxies in the epoch of reionization are all bark and no bite-plenty of ionizing photons, low escape fractions","date_updated":"2026-05-04T10:44:57Z","language":[{"iso":"eng"}],"oa_version":"Published Version","oa":1,"has_accepted_license":"1","OA_place":"publisher","arxiv":1,"publication":"The Astrophysical Journal","_id":"21710","publication_identifier":{"issn":["0004-637X"],"eissn":["1538-4357"]},"fulldoi":"https://doi.org/10.3847/1538-4357/ae3b25","publisher":"IOP Publishing","scopus_import":"1","user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","article_type":"original","publication_status":"published","date_published":"2026-03-20T00:00:00Z","month":"03","volume":1000,"citation":{"chicago":"Papovich, Casey, Justin W. Cole, Weida Hu, Steven L. Finkelstein, Lu Shen, Pablo Arrabal Haro, Ricardo O. Amorín, et al. “Galaxies in the Epoch of Reionization Are All Bark and No Bite-Plenty of Ionizing Photons, Low Escape Fractions.” <i>The Astrophysical Journal</i>. IOP Publishing, 2026. <a href=\"https://doi.org/10.3847/1538-4357/ae3b25\">https://doi.org/10.3847/1538-4357/ae3b25</a>.","ama":"Papovich C, Cole JW, Hu W, et al. Galaxies in the epoch of reionization are all bark and no bite-plenty of ionizing photons, low escape fractions. <i>The Astrophysical Journal</i>. 2026;1000(1). doi:<a href=\"https://doi.org/10.3847/1538-4357/ae3b25\">10.3847/1538-4357/ae3b25</a>","apa":"Papovich, C., Cole, J. W., Hu, W., Finkelstein, S. L., Shen, L., Arrabal Haro, P., … Yung, L. Y. A. (2026). Galaxies in the epoch of reionization are all bark and no bite-plenty of ionizing photons, low escape fractions. <i>The Astrophysical Journal</i>. IOP Publishing. <a href=\"https://doi.org/10.3847/1538-4357/ae3b25\">https://doi.org/10.3847/1538-4357/ae3b25</a>","mla":"Papovich, Casey, et al. “Galaxies in the Epoch of Reionization Are All Bark and No Bite-Plenty of Ionizing Photons, Low Escape Fractions.” <i>The Astrophysical Journal</i>, vol. 1000, no. 1, 111, IOP Publishing, 2026, doi:<a href=\"https://doi.org/10.3847/1538-4357/ae3b25\">10.3847/1538-4357/ae3b25</a>.","ista":"Papovich C, Cole JW, Hu W, Finkelstein SL, Shen L, Arrabal Haro P, Amorín RO, Backhaus BE, Bagley MB, Bhatawdekar R, Calabrò A, Carnall AC, Cleri NJ, Daddi E, Dickinson M, Grogin NA, Holwerda BW, Jaskot AE, Koekemoer AM, Llerena M, Lucas RA, Mascia S, Pacucci F, Pentericci L, Pérez-González PG, Pirzkal N, Raghunathan S, Seillé LM, Somerville RS, Yung LYA. 2026. Galaxies in the epoch of reionization are all bark and no bite-plenty of ionizing photons, low escape fractions. The Astrophysical Journal. 1000(1), 111.","short":"C. Papovich, J.W. Cole, W. Hu, S.L. Finkelstein, L. Shen, P. Arrabal Haro, R.O. Amorín, B.E. Backhaus, M.B. Bagley, R. Bhatawdekar, A. Calabrò, A.C. Carnall, N.J. Cleri, E. Daddi, M. Dickinson, N.A. Grogin, B.W. Holwerda, A.E. Jaskot, A.M. Koekemoer, M. Llerena, R.A. Lucas, S. Mascia, F. Pacucci, L. Pentericci, P.G. Pérez-González, N. Pirzkal, S. Raghunathan, L.M. Seillé, R.S. Somerville, L.Y.A. Yung, The Astrophysical Journal 1000 (2026).","ieee":"C. Papovich <i>et al.</i>, “Galaxies in the epoch of reionization are all bark and no bite-plenty of ionizing photons, low escape fractions,” <i>The Astrophysical Journal</i>, vol. 1000, no. 1. IOP Publishing, 2026."},"article_processing_charge":"Yes","department":[{"_id":"JoMa"}]},{"year":"2026","external_id":{"arxiv":["2512.08490"]},"quality_controlled":"1","oa_version":"Published Version","language":[{"iso":"eng"}],"day":"09","date_updated":"2026-06-02T06:39:53Z","title":"Investigating ionising sources and the complex interstellar medium of GHZ2 at z=12.3","abstract":[{"lang":"eng","text":"An accurate characterisation of the physical properties of galaxies at cosmic dawn is key to understanding\r\nthe origin of the high abundance of UV-bright galaxies at z≳10. We exploit deep (9.1-hour exposure time)\r\nNIRSpec PRISM observations of GHZ2 to constrain the sources of ionising radiation and the properties of the\r\ninterstellar medium (ISM) in this bright, compact, and highly ionising galaxy at z=12.3. We measure with\r\nhigh significance the prominent N IV, C IV, He II, O III, C III, O II, and Ne III emission features previously\r\ndetected in shallower observations, and confirm the detection of the N III] λ1750 multiplet, yielding tight\r\nconstraints on the N/O ratio, which is found to be ≃2 times the solar value. We also detect the Mg II λ2800,\r\n[Fe IV] λ2833 and Si II λ1812 doublets, the H8+HeI λλ3889 blend, and the Si IV+O IV] λλ1400 absorption\r\ncomplex. The O III λ3133 fluorescence line is only detected in the first observing epoch, implying variability\r\non a rest-frame time span of 19 days, strongly suggesting the presence of an active nucleus. Combining the\r\nNIRSpec dataset with available optical and far-infrared constraints from MIRI and ALMA, we show that the\r\nemission spectrum of GHZ2 cannot be reproduced by single-density spectro-photometric models, even under\r\nextreme assumptions on the ionisation parameter and electron density. Multi-zone photoionisation modelling\r\nperformed with the HOMERUN code demonstrates that star formation must be occurring in a strongly stratified\r\nISM, where both low-/intermediate-density gas and high-density regions (log(ne/cm−3\r\n) ≳ 4) coexist. The\r\nGHZ2 emission landscape is consistent with either a composite star-formation plus AGN scenario, or with\r\nstar formation occurring in a combination of radiation- and matter-bounded regions. Purely radiation-bounded\r\nstellar models fail to reproduce the observed He II emission, making an additional hard ionising component\r\nunavoidable."}],"file":[{"date_updated":"2026-06-02T06:38:59Z","file_name":"2026_OpenJourAstrophysics_Castellano.pdf","access_level":"open_access","file_id":"21935","checksum":"ec33ca56b8836c61cb01e26893d43cbf","success":1,"creator":"dernst","content_type":"application/pdf","date_created":"2026-06-02T06:38:59Z","file_size":4855934,"relation":"main_file"}],"DOAJ_listed":"1","intvolume":"         9","OA_type":"diamond","doi":"10.33232/001c.160281","file_date_updated":"2026-06-02T06:38:59Z","status":"public","type":"journal_article","tmp":{"short":"CC BY (4.0)","image":"/images/cc_by.png","name":"Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)","legal_code_url":"https://creativecommons.org/licenses/by/4.0/legalcode"},"author":[{"last_name":"Castellano","first_name":"M.","full_name":"Castellano, M."},{"last_name":"Napolitano","first_name":"L.","full_name":"Napolitano, L."},{"full_name":"Moreschini, B.","first_name":"B.","last_name":"Moreschini"},{"full_name":"Calabrò, A.","last_name":"Calabrò","first_name":"A."},{"full_name":"Christensen, L.","last_name":"Christensen","first_name":"L."},{"full_name":"Llerena, M.","first_name":"M.","last_name":"Llerena"},{"first_name":"T. J.L.C.","last_name":"Bakx","full_name":"Bakx, T. J.L.C."},{"first_name":"F.","last_name":"Belfiore","full_name":"Belfiore, F."},{"full_name":"Bevacqua, D.","first_name":"D.","last_name":"Bevacqua"},{"first_name":"M.","last_name":"Dickinson","full_name":"Dickinson, M."},{"full_name":"Fontana, A.","last_name":"Fontana","first_name":"A."},{"last_name":"Gandolfi","first_name":"G.","full_name":"Gandolfi, G."},{"first_name":"T.","last_name":"Gasparetto","full_name":"Gasparetto, T."},{"full_name":"Marconi, A.","first_name":"A.","last_name":"Marconi"},{"first_name":"Sara","id":"edaf889c-c7cd-11ef-ab1b-bb28c431bd29","last_name":"Mascia","full_name":"Mascia, Sara"},{"full_name":"Merlin, E.","first_name":"E.","last_name":"Merlin"},{"full_name":"Morishita, T.","last_name":"Morishita","first_name":"T."},{"last_name":"Nanayakkara","first_name":"T.","full_name":"Nanayakkara, T."},{"full_name":"Paris, D.","last_name":"Paris","first_name":"D."},{"full_name":"Pentericci, L.","first_name":"L.","last_name":"Pentericci"},{"first_name":"B.","last_name":"Pérez-Díaz","full_name":"Pérez-Díaz, B."},{"first_name":"G.","last_name":"Roberts-Borsani","full_name":"Roberts-Borsani, G."},{"first_name":"S.","last_name":"Rojas-Ruiz","full_name":"Rojas-Ruiz, S."},{"first_name":"P.","last_name":"Santini","full_name":"Santini, P."},{"first_name":"T.","last_name":"Treu","full_name":"Treu, T."},{"first_name":"E.","last_name":"Vanzella","full_name":"Vanzella, E."},{"last_name":"Vulcani","first_name":"B.","full_name":"Vulcani, B."},{"full_name":"Wang, X.","last_name":"Wang","first_name":"X."},{"last_name":"Yoon","first_name":"I.","full_name":"Yoon, I."},{"first_name":"J.","last_name":"Zavala","full_name":"Zavala, J."}],"ddc":["520"],"acknowledgement":"We thank the referee for the constructive comments that\r\nhelped us improve the manuscript. We thank S. Finkelstein,\r\nY. Harikane, C. Mason, and D. Stark for the useful comments.\r\nWe thank Tony Roman (Program Coordinator) and Glenn\r\nWahlgren (NIRSpec reviewer) for the assistance in the\r\npreparation of GO-3073 observations. This work is based\r\non observations made with the NASA/ESA/CSA James\r\nWebb Space Telescope (JWST). The JWST data presented in this article were obtained from the Mikulski Archive for\r\nSpace Telescopes (MAST) at the Space Telescope Science\r\nInstitute. The specific observations analysed are associated with program JWST-GO-3073 and can be accessed\r\nvia https://doi.org/10.17909/4r6b-bx96 (first pointing) and\r\nhttps://doi:10.17909/zq4g-r525 (second pointing). We\r\nacknowledge financial support from NASA through grant\r\nJWST-ERS-1324 and JWST-GO-3073. Support was also\r\nprovided by the PRIN 2022 MUR project 2022CB3PJ3 –\r\nFirst Light And Galaxy aSsembly (FLAGS) funded by the\r\nEuropean Union – Next Generation EU, by INAF GO Grant\r\n2024 ”Revealing the nature of bright galaxies at cosmic\r\ndawn with deep JWST spectroscopy”, by INAF Mini-grant\r\n2022 “Reionization and Fundamental Cosmology with\r\nHigh-Redshift Galaxies”, and by INAF Large Grant 2022\r\n“Extragalactic Surveys with JWST”. L.N. acknowledges\r\nsupport from grant “Progetti per Avvio alla Ricerca - Tipo\r\n1, Unveiling Cosmic Dawn: Galaxy Evolution with CAPERS” (AR1241906F947685). EV acknowledges financial\r\nsupport through grants INAF GO Grant 2024 “Mapping Star\r\nCluster Feedback in a Galaxy 450 Myr after the Big Bang”\r\nand by the European Union – NextGenerationEU within\r\nPRIN 2022 project n.20229YBSAN - Globular clusters\r\nin cosmological simulations and lensed fields: from their\r\nbirth to the present epoch. AM acknowledges support\r\nfrom project PRIN-MUR project “PROMETEUS” financed\r\nby the European Union - Next Generation EU, Mission 4\r\nComponent 1 CUP B53D2300475000. AM acknowledges\r\nsupport from Ricerca Fondamentale INAF under Mini Grant\r\n2023 ”Quantitative Spectroscopy of Ionized Nebulae and\r\nGalaxies (QSING)” and under Data Analysis Grant 2024\r\n“Accurate measurements of metallicity in galaxies with a new\r\napproach to photoionization modelling”.","date_created":"2026-05-31T22:02:14Z","month":"04","date_published":"2026-04-09T00:00:00Z","publication_status":"published","article_type":"original","user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","department":[{"_id":"JoMa"}],"article_processing_charge":"No","citation":{"chicago":"Castellano, M., L. Napolitano, B. Moreschini, A. Calabrò, L. Christensen, M. Llerena, T. J.L.C. Bakx, et al. “Investigating Ionising Sources and the Complex Interstellar Medium of GHZ2 at Z=12.3.” <i>The Open Journal of Astrophysics</i>. Maynooth Academic Publishing, 2026. <a href=\"https://doi.org/10.33232/001c.160281\">https://doi.org/10.33232/001c.160281</a>.","ama":"Castellano M, Napolitano L, Moreschini B, et al. Investigating ionising sources and the complex interstellar medium of GHZ2 at z=12.3. <i>The Open Journal of Astrophysics</i>. 2026;9. doi:<a href=\"https://doi.org/10.33232/001c.160281\">10.33232/001c.160281</a>","mla":"Castellano, M., et al. “Investigating Ionising Sources and the Complex Interstellar Medium of GHZ2 at Z=12.3.” <i>The Open Journal of Astrophysics</i>, vol. 9, Maynooth Academic Publishing, 2026, doi:<a href=\"https://doi.org/10.33232/001c.160281\">10.33232/001c.160281</a>.","apa":"Castellano, M., Napolitano, L., Moreschini, B., Calabrò, A., Christensen, L., Llerena, M., … Zavala, J. (2026). Investigating ionising sources and the complex interstellar medium of GHZ2 at z=12.3. <i>The Open Journal of Astrophysics</i>. Maynooth Academic Publishing. <a href=\"https://doi.org/10.33232/001c.160281\">https://doi.org/10.33232/001c.160281</a>","ista":"Castellano M, Napolitano L, Moreschini B, Calabrò A, Christensen L, Llerena M, Bakx TJLC, Belfiore F, Bevacqua D, Dickinson M, Fontana A, Gandolfi G, Gasparetto T, Marconi A, Mascia S, Merlin E, Morishita T, Nanayakkara T, Paris D, Pentericci L, Pérez-Díaz B, Roberts-Borsani G, Rojas-Ruiz S, Santini P, Treu T, Vanzella E, Vulcani B, Wang X, Yoon I, Zavala J. 2026. Investigating ionising sources and the complex interstellar medium of GHZ2 at z=12.3. The Open Journal of Astrophysics. 9.","short":"M. Castellano, L. Napolitano, B. Moreschini, A. Calabrò, L. Christensen, M. Llerena, T.J.L.C. Bakx, F. Belfiore, D. Bevacqua, M. Dickinson, A. Fontana, G. Gandolfi, T. Gasparetto, A. Marconi, S. Mascia, E. Merlin, T. Morishita, T. Nanayakkara, D. Paris, L. Pentericci, B. Pérez-Díaz, G. Roberts-Borsani, S. Rojas-Ruiz, P. Santini, T. Treu, E. Vanzella, B. Vulcani, X. Wang, I. Yoon, J. Zavala, The Open Journal of Astrophysics 9 (2026).","ieee":"M. Castellano <i>et al.</i>, “Investigating ionising sources and the complex interstellar medium of GHZ2 at z=12.3,” <i>The Open Journal of Astrophysics</i>, vol. 9. Maynooth Academic Publishing, 2026."},"volume":9,"arxiv":1,"OA_place":"publisher","has_accepted_license":"1","oa":1,"scopus_import":"1","publisher":"Maynooth Academic Publishing","PlanS_conform":"1","fulldoi":"https://doi.org/10.33232/001c.160281","_id":"21934","publication_identifier":{"eissn":["2565-6120"]},"publication":"The Open Journal of Astrophysics"},{"quality_controlled":"1","external_id":{"arxiv":["2505.09542"]},"year":"2026","intvolume":"       705","abstract":[{"lang":"eng","text":"The abundant population of little red dots (LRDs), compact objects with red UV to optical colors and broad Balmer lines at high redshift, is revealing new insights into the properties of early active galactic nuclei (AGN). Perhaps the most surprising features of this population are the presence of Balmer absorption and ubiquitous strong Balmer breaks. Recent models link these features to an active supermassive black hole (SMBH) cocooned in very dense gas (NH ∼ 1024 cm−2). We present a stringent test of such models using VLT/MUSE observations of A2744-45924, the most luminous LRD known to date (LHα ≈ 1044 erg s−1), located behind the Abell-2744 lensing cluster at z = 4.464 (μ = 1.8). We detect a moderately extended Lyα nebula (h ≈ 5.7 pkpc), spatially offset from the point-like Hα seen by JWST by ≈1.6 pkpc. The Lyα emission is narrow (FWHM = 270 ± 15 km s−1), and faint (Lyα = 0.07Hα) compared to Lyα nebulae typically observed around quasars of similar luminosity. We detect compact N IV]λ1486 emission, spatially aligned with Hα, and a spatial shift in the far-UV continuum matching the Lyα offset. We discuss that Hα and Lyα have distinct physical origins: Hα originates from the AGN, while Lyα is powered by star formation. In the environment of A2744-45924, we identified four extended Lyα halos (Δz < 0.02, Δr < 100 pkpc). Their Lyα luminosities match the expectations based on Hα emission, and show no evidence for radiation from A2744-45924 affecting its surroundings. The lack of strong, compact, and broad Lyα and the absence of a luminous extended halo, suggest that the UV AGN light is obscured by dense gas cloaking the SMBH with a covering factor close to unity."}],"article_number":"A147","file":[{"file_id":"21224","success":1,"content_type":"application/pdf","creator":"dernst","checksum":"3782e03bc0843438aae8487f6af779c5","date_created":"2026-02-16T07:35:03Z","file_name":"2026_AstronomyAstrophysics_Torralba.pdf","date_updated":"2026-02-16T07:35:03Z","access_level":"open_access","relation":"main_file","file_size":2259914}],"day":"14","title":"A weak Ly α halo for an extremely bright little red dot. Indications of enshrouded supermassive black hole growth","date_updated":"2026-07-08T06:38:23Z","oa_version":"Published Version","language":[{"iso":"eng"}],"type":"journal_article","OA_type":"diamond","file_date_updated":"2026-02-16T07:35:03Z","status":"public","doi":"10.1051/0004-6361/202555596","date_created":"2026-01-25T23:01:41Z","acknowledgement":"We thank the anonymous referee for constructive and useful comments. We thank Sebastiano Cantalupo for comments on the draft. Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere under ESO programme 114.27M6.001. Funded by the European Union (ERC, AGENTS, 101076224). Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or the European Research Council. Neither the European Union nor the granting authority can be held responsible for them. We acknowledge funding from JWST program GO-3516. This work is based in part on observations made with the NASA/ESA/CSA James Webb Space Telescope. The data were obtained from the Mikulski Archive for Space Telescopes at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-03127 for JWST. These observations are associated with program #3516. MG thanks the Max Planck Society for support through the MPRG. FDE acknowledges support by the Science and Technology Facilities Council (STFC), by the ERC through Advanced Grant 695671 “QUENCH”, and by the UKRI Frontier Research grant RISEandFALL. TU acknowledges funding from the ERC-AdG grant SPECMAP-CGM, GA 101020943. GK acknowledges support from the MERAC foundation.","author":[{"full_name":"Torralba Torregrosa, Alberto","first_name":"Alberto","id":"018f0249-0e87-11f0-b167-cbce08fbd541","last_name":"Torralba Torregrosa","orcid":"0000-0001-5586-6950"},{"last_name":"Matthee","orcid":"0000-0003-2871-127X","first_name":"Jorryt J","id":"7439a258-f3c0-11ec-9501-9df22fe06720","full_name":"Matthee, Jorryt J"},{"first_name":"Gabriele","last_name":"Pezzulli","full_name":"Pezzulli, Gabriele"},{"full_name":"Urrutia, Tanya","first_name":"Tanya","last_name":"Urrutia"},{"full_name":"Gronke, Max","first_name":"Max","last_name":"Gronke"},{"first_name":"Sara","id":"edaf889c-c7cd-11ef-ab1b-bb28c431bd29","last_name":"Mascia","full_name":"Mascia, Sara"},{"last_name":"D’Eugenio","first_name":"Francesco","full_name":"D’Eugenio, Francesco"},{"last_name":"Di Cesare","first_name":"Claudia","id":"2d002343-372f-11ef-98ec-a164d20427cb","full_name":"Di Cesare, Claudia"},{"last_name":"Eilers","first_name":"Anna Christina","full_name":"Eilers, Anna Christina"},{"full_name":"Greene, Jenny E.","first_name":"Jenny E.","last_name":"Greene"},{"first_name":"Edoardo","id":"4053390a-6b68-11ef-9828-a3b8adef8d0a","last_name":"Iani","orcid":"0000-0001-8386-3546","full_name":"Iani, Edoardo"},{"first_name":"Yuzo","last_name":"Ishikawa","full_name":"Ishikawa, Yuzo"},{"full_name":"Mackenzie, Ruari","last_name":"Mackenzie","first_name":"Ruari"},{"last_name":"Naidu","first_name":"Rohan P.","full_name":"Naidu, Rohan P."},{"full_name":"Navarrete, Benjamín","id":"aa14a535-50c9-11ef-b52e-e0c373d10148","first_name":"Benjamín","last_name":"Navarrete"},{"full_name":"Kotiwale, Gauri","first_name":"Gauri","id":"1438afc8-1ff6-11ee-9fa6-cd4a75d66875","last_name":"Kotiwale"}],"ddc":["520"],"corr_author":"1","tmp":{"short":"CC BY (4.0)","image":"/images/cc_by.png","name":"Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)","legal_code_url":"https://creativecommons.org/licenses/by/4.0/legalcode"},"user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","article_type":"original","date_published":"2026-01-14T00:00:00Z","publication_status":"published","month":"01","volume":705,"citation":{"ista":"Torralba Torregrosa A, Matthee JJ, Pezzulli G, Urrutia T, Gronke M, Mascia S, D’Eugenio F, Di Cesare C, Eilers AC, Greene JE, Iani E, Ishikawa Y, Mackenzie R, Naidu RP, Navarrete B, Kotiwale G. 2026. A weak Ly α halo for an extremely bright little red dot. Indications of enshrouded supermassive black hole growth. Astronomy &#38; Astrophysics. 705, A147.","apa":"Torralba Torregrosa, A., Matthee, J. J., Pezzulli, G., Urrutia, T., Gronke, M., Mascia, S., … Kotiwale, G. (2026). A weak Ly α halo for an extremely bright little red dot. Indications of enshrouded supermassive black hole growth. <i>Astronomy &#38; Astrophysics</i>. EDP Sciences. <a href=\"https://doi.org/10.1051/0004-6361/202555596\">https://doi.org/10.1051/0004-6361/202555596</a>","mla":"Torralba Torregrosa, Alberto, et al. “A Weak Ly α Halo for an Extremely Bright Little Red Dot. Indications of Enshrouded Supermassive Black Hole Growth.” <i>Astronomy &#38; Astrophysics</i>, vol. 705, A147, EDP Sciences, 2026, doi:<a href=\"https://doi.org/10.1051/0004-6361/202555596\">10.1051/0004-6361/202555596</a>.","short":"A. Torralba Torregrosa, J.J. Matthee, G. Pezzulli, T. Urrutia, M. Gronke, S. Mascia, F. D’Eugenio, C. Di Cesare, A.C. Eilers, J.E. Greene, E. Iani, Y. Ishikawa, R. Mackenzie, R.P. Naidu, B. Navarrete, G. Kotiwale, Astronomy &#38; Astrophysics 705 (2026).","ieee":"A. Torralba Torregrosa <i>et al.</i>, “A weak Ly α halo for an extremely bright little red dot. Indications of enshrouded supermassive black hole growth,” <i>Astronomy &#38; Astrophysics</i>, vol. 705. EDP Sciences, 2026.","chicago":"Torralba Torregrosa, Alberto, Jorryt J Matthee, Gabriele Pezzulli, Tanya Urrutia, Max Gronke, Sara Mascia, Francesco D’Eugenio, et al. “A Weak Ly α Halo for an Extremely Bright Little Red Dot. Indications of Enshrouded Supermassive Black Hole Growth.” <i>Astronomy &#38; Astrophysics</i>. EDP Sciences, 2026. <a href=\"https://doi.org/10.1051/0004-6361/202555596\">https://doi.org/10.1051/0004-6361/202555596</a>.","ama":"Torralba Torregrosa A, Matthee JJ, Pezzulli G, et al. A weak Ly α halo for an extremely bright little red dot. Indications of enshrouded supermassive black hole growth. <i>Astronomy &#38; Astrophysics</i>. 2026;705. doi:<a href=\"https://doi.org/10.1051/0004-6361/202555596\">10.1051/0004-6361/202555596</a>"},"article_processing_charge":"No","department":[{"_id":"JoMa"},{"_id":"GradSch"}],"das_tickbox":"1","oa":1,"has_accepted_license":"1","project":[{"_id":"bd9b2118-d553-11ed-ba76-db24564edfea","grant_number":"101076224","name":"Young galaxies as tracers and agents of cosmic reionization"}],"OA_place":"publisher","arxiv":1,"publication":"Astronomy & Astrophysics","_id":"21045","publication_identifier":{"issn":["0004-6361"],"eissn":["1432-0746"]},"fulldoi":"https://doi.org/10.1051/0004-6361/202555596","publisher":"EDP Sciences","PlanS_conform":"1","scopus_import":"1"},{"corr_author":"1","tmp":{"short":"CC BY (4.0)","image":"/images/cc_by.png","name":"Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)","legal_code_url":"https://creativecommons.org/licenses/by/4.0/legalcode"},"author":[{"orcid":"0000-0001-5586-6950","last_name":"Torralba Torregrosa","first_name":"Alberto","id":"018f0249-0e87-11f0-b167-cbce08fbd541","full_name":"Torralba Torregrosa, Alberto"},{"id":"7439a258-f3c0-11ec-9501-9df22fe06720","first_name":"Jorryt J","last_name":"Matthee","orcid":"0000-0003-2871-127X","full_name":"Matthee, Jorryt J"},{"first_name":"Andrea","last_name":"Weibel","full_name":"Weibel, Andrea"},{"last_name":"Naidu","first_name":"Rohan P.","full_name":"Naidu, Rohan P."},{"full_name":"Ma, Yilun","last_name":"Ma","first_name":"Yilun"},{"full_name":"Cloonan, Aidan P.","first_name":"Aidan P.","last_name":"Cloonan"},{"id":"502cfd30-32c1-11ee-a9a4-d8dad5c6739e","first_name":"Aayush A","last_name":"Desai","full_name":"Desai, Aayush A"},{"full_name":"De Graaff, Anna","last_name":"De Graaff","first_name":"Anna"},{"last_name":"Greene","first_name":"Jenny E.","full_name":"Greene, Jenny E."},{"last_name":"Jespersen","first_name":"Christian Kragh","full_name":"Jespersen, Christian Kragh"},{"first_name":"Ivan","id":"9a9394cb-3200-11ee-973b-f5ba2a8b16e4","orcid":"0000-0001-5346-6048","last_name":"Kramarenko","full_name":"Kramarenko, Ivan"},{"id":"edaf889c-c7cd-11ef-ab1b-bb28c431bd29","first_name":"Sara","last_name":"Mascia","full_name":"Mascia, Sara"},{"first_name":"Pascal A.","last_name":"Oesch","full_name":"Oesch, Pascal A."},{"full_name":"Sun, Wendy Q.","last_name":"Sun","first_name":"Wendy Q."},{"last_name":"Williams","first_name":"Christina C.","full_name":"Williams, Christina C."}],"ddc":["520"],"issue":"2","acknowledgement":"IOP Science home\r\nThe Astrophysical Journal Letters\r\nThe American Astronomical Society, find out more.\r\n\r\nThe following article isOpen access\r\nA Black Hole Star at Cosmic Noon: Extreme Balmer Break, Photospheric Continuum, and Broad Absorption by Thick Winds in a Little Red Dot at z = 1.7\r\nAlberto Torralba, Jorryt Matthee, Andrea Weibel, Rohan P. Naidu, Yilun Ma, Aidan P. Cloonan, Aayush Desai, Anna de Graaff, Jenny E. Greene, Christian Kragh JespersenShow full author list\r\n\r\nPublished 2026 June 30 • © 2026. The Author(s). Published by the American Astronomical Society.\r\nThe Astrophysical Journal Letters, Volume 1005, Number 2\r\nCitation Alberto Torralba et al 2026 ApJL 1005 L37\r\nDOI 10.3847/2041-8213/ae7bfd\r\n\r\nPDFOpens in a new tab.ePub\r\nAuthors\r\nFigures\r\nTables\r\nReferences\r\nArticle data\r\nPDFOpens in a new tab.ePub\r\nArticle metrics\r\n122 Total downloads\r\n\r\nShare this article\r\nArticle information\r\nAbstract\r\nRecent studies at high redshift have revealed an enigmatic class of little red dots (LRDs) with extreme Balmer breaks, stronger than in any stellar atmosphere. However, it is unclear whether such objects exist at lower redshift, especially given the low number of LRDs reported at z ≲ 2. Here, we report the discovery of PAN-BH*-1, an LRD with an extreme Balmer break at z = 1.73, identified from JWST/NIRCam pure-parallel imaging taken by the PANORAMIC survey, and confirmed by deep VLT/X-Shooter spectroscopy. The rest-optical to near-infrared spectral energy distribution of PAN-BH*-1 is consistent with a photospheric continuum with effective temperature Teff ≈ 4800 K. The broad Hα emission line shows remarkably deep absorption, stronger than previously measured in any LRD. The absorption trough spans from −520 to +267 km s−1 with respect to the systemic redshift. The presence of blue- and red-shifted absorption suggests complex dynamics of the obscuring gas along the line of sight. We speculate that the absorption trough can be produced by a thick wind launched from a thick, rotating photospheric disk, the latter being the source of the red optical continuum. While the source is unresolved in the rest-optical JWST data (reff < 47 pc), the rest-near-UV Hubble Space Telescope imaging shows an extended morphology with \r\n kpc, which we interpret as a host galaxy with a stellar mass of ∼108 M⊙, in line with the narrow Hα emission. The discovery of this object at cosmic noon highlights the feasibility of systematic searches for extreme LRDs with wide-area facilities such as Euclid and Roman.\r\n\r\nExport citation and abstract\r\nBibTeXRIS\r\n\r\nPrevious article in issue\r\nNext article in issue\r\n\r\nOriginal content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.\r\n\r\n1. Introduction\r\nThe unprecedented sensitivity of JWST has enabled the discovery of a new, abundant population of objects at redshifts z ≈ 3–9 nicknamed the “little red dots” (LRDs). These are characterized by their compact rest-frame optical morphology, broad emission lines, and a characteristic rest-UV to optical “V-shape” in their spectral energy distributions (SED; e.g., D. D. Kocevski et al. 2023; V. Kokorev et al. 2024; J. Matthee et al. 2024; I. Labbe et al. 2025).\r\n\r\nThe nature of LRDs is highly debated (see K. Inayoshi & L. C. Ho 2025, for a recent overview) as the LRDs show systematic differences with respect to other types of active galactic nuclei (AGN), such as faintness in X-rays (e.g., T. T. Ananna et al. 2024; M. Yue et al. 2024), mid-to-far-infrared dust emission (e.g., G. C. K. Leung et al. 2025; C. C. Williams et al. 2024; I. Delvecchio et al. 2025; D. J. Setton et al. 2025; M. Xiao et al. 2025), and radio (e.g., G. Mazzolari et al. 2026; M. A. Latif et al. 2025; K. Perger et al. 2025, see A. J. Gloudemans et al. 2025).\r\n\r\nA recurring spectral feature of LRDs is the presence of a strong Balmer break (e.g., D. J. Setton et al. 2025; B. Wang et al. 2024; R. E. Hviding et al. 2025; W. Q. Sun et al. 2026), in some cases stronger than any star or stellar population can produce. The two most prominent examples known to date are The Cliff at z ≈ 3.5 (A. de Graaff et al. 2025a) and MoM-BH* at z ≈ 7.8 (R. P. Naidu et al. 2025). The joint appearance of strong Balmer lines as well as strong Balmer breaks has been modeled as being due to absorption by a dense, neutral gas with a high column density in the line of sight to a highly ionizing source (K. Inayoshi & R. Maiolino 2025; X. Ji et al. 2025; A. Sneppen et al. 2026; A. Torralba et al. 2026). These observations have sparked the development of new theoretical models, ranging from a spherical envelope analogous to stellar atmospheres (e.g., M. C. Begelman & J. Dexter 2026; D. Kido et al. 2025; H. Liu et al. 2025; D. Nandal & A. Loeb 2026) or a thick accretion disk (e.g., H. Liu et al. 2025, 2026; K. Inayoshi et al. 2025; Y.-X. Chen et al. 2026).\r\n\r\nBesides their spectral features, the evolution of the LRD number densities is also in stark contrast to other types of AGNs (e.g., K. Inayoshi 2025). At 4 ≲ z ≲ 7, LRDs represent a few percent of the galaxy population (e.g., D. D. Kocevski et al. 2023, 2025; J. E. Greene et al. 2024; V. Kokorev et al. 2024; X. Lin et al. 2024; R. Maiolino et al. 2024; J. Matthee et al. 2024), with number densities of ≳10−5 Mpc−3. The number density does not appear to drop quickly beyond z > 5 (e.g., J. Zhang et al. 2026), with various LRDs having been confirmed at z  >  8 (V. Kokorev et al. 2023; A. J. Taylor et al. 2025; R. Tripodi et al. 2025), well beyond the quasar redshift record (F. Wang et al. 2021). Photometric LRD candidates exist beyond z  >  10 (T. S. Tanaka et al. 2025). In turn, the number density of LRDs seems to decline steeply at z  <  4 (e.g., Y. Ma et al. 2026), with estimates of a number density of ∼10−6 cMpc−3 at z ∼ 2 and even ∼10−10 cMpc−3 at z ≈ 0.3 (X. Lin et al. 2026). While it is challenging to ensure a uniform selection function across such a large redshift baseline and dedicated spectroscopic follow-up of such lower redshift candidates has only just started, it is challenging to attribute five orders of magnitude to such effects.\r\n\r\nMotivated by the discovery of rare objects with extreme Balmer breaks at z  >  3 and the very small number of known LRDs at lower redshift, we performed a dedicated search for extreme Balmer break objects using a template-match approach on a large compilation of JWST NIRCam data over ≈0.3 deg2 and z ≈ 1.5–7.0. This survey is presented in A. Weibel et al. (2026a). As part of an ongoing ground-based spectroscopic campaign of LRD candidates at z ∼ 2 (Y. Ma et al. 2026), we followed up the most luminous candidate with a photometric redshift of z ≈ 2 with the X-Shooter spectrograph on the Very Large Telescope (VLT). In this Letter, we present the discovery and spectroscopic confirmation of PAN-BH*-1, a luminous LRD at z = 1.73 with an extreme Balmer break comparable to the strongest observed in any LRD (and, in general, any astrophysical source). The low redshift of this source enables high-resolution spectroscopy from ground-based observatories that is otherwise impossible to obtain at high redshift.\r\n\r\nThroughout this Letter, we use a ΛCDM cosmology with Ωm = 0.31, ΩΛ = 0.69, and h = 0.677 as described by Planck Collaboration et al. (2020). All the magnitudes are given in the AB system (J. B. Oke & J. E. Gunn 1983).\r\n\r\n2. Observations\r\n2.1. Photometry and Source Selection\r\nWe identified PAN-BH*-1 (ID: PAN-1115, RA, DEC: 40.015835, −1.659363 J2000) as part of a systematic search across ≈0.3 deg2 of JWST NIRCam legacy imaging comprising at least six filters of coverage (A. Weibel et al. 2026b). Notably, this dataset includes the Cycle 1 pure parallel survey PANORAMIC (PID: 2514, PIs: Williams & Oesch; C. C. Williams et al. 2025) that contributes 28 of the 35 independent lines of sight, thereby enabling the discovery of rare objects such as PAN-BH*-1 across diverse large-scale structure environments. Specifically, this source was identified in the footprint j024000m0142 of the PANORAMIC DR1,15 which is adjacent to the A370 field (G. O. Abell et al. 1989), where archival images by the Hubble Space Telescope (HST) are available from the BUFFALO survey (C. L. Steinhardt et al. 2020). The HST/ACS images were processed with grizli and also released as part of the PANORAMIC dataset.\r\n\r\nPAN-BH*-1 is in the outskirts of the A370 lensing cluster, but the magnification is only μ ≈ 1.05 according to the models from A. Niemiec et al. (2023). Throughout the rest of the paper, we report the uncorrected flux measurements, since the effect of magnification (∼5%) is negligible given the uncertainties in the observations and the lensing model.\r\n\r\nThe search strategy and full photometric selection are described in a companion paper (A. Weibel et al. 2026a). Briefly, that work presents a new selection of LRDs as a combination of a “black hole star” template (BH*; R. P. Naidu et al. 2025) embedded in a host galaxy, instead of the typically used “V-shaped” selections (e.g., D. D. Kocevski et al. 2025; V. Kokorev et al. 2024). The host galaxies are modeled using eazy’s blue_sfhz templates. The BH*s are modeled using a novel template set comprising empirical luminosity-based stacks constructed in W. Q. Sun et al. (2026), the cloudy template from R. P. Naidu et al. (2025), and by using spectra of prominent LRDs spanning the observed effective temperature range (I. Labbe et al. 2024; A. de Graaff et al. 2025a; B. Wang et al. 2026).\r\n\r\nPAN-BH*-1 stood out as one of the few sources where the BH* template effectively dominated all the light over the full wavelength range covered by NIRCam (hence the name). The redshift of PAN-BH*-1 was estimated to be zphot = 1.85. Follow-up VLT/X-Shooter spectroscopy confirmed the redshift as zspec = 1.731 (see Section 3.2).\r\n\r\nPAN-BH*-1 is also covered by archival data from the VLT with the HAWK-I camera in the Ks band (G. B. Brammer et al. 2016) and in data from the Spitzer Space Telescope in IRAC bands 1 and 3 (3.6 and 5.7 μm), and MIPS 24 μm (P. Capak 2019). PAN-BH*-1 is detected in the Ks band and in the two IRAC filters. Performing Spitzer photometry of this source is challenging due to the large point spread function (PSF) and a neighboring source, especially in the MIPS band. However, the NIRCam photometry of the neighboring source suggests it has a limited contribution to the IRAC fluxes. The details of the photometry extraction are described in Appendix A, and the measured magnitudes in Table 2.\r\n\r\n2.2. VLT/X-Shooter Spectroscopy\r\nPAN-BH*-1 was observed for 5.8 ks with the X-Shooter spectrograph (J. Vernet et al. 2011) on the VLT as a bright backup target for program 116.294D (PI: Matthee) in visitor mode on 2025 December 17. The main aim of this program was to confirm candidate LRDs at cosmic noon (Y. Ma et al. 2026). These observations confirmed the redshift through the detection of Hα at z = 1.731. A DDT program (ID 116.2AQ0; PI: Matthee) obtained additional follow-up data of PAN-BH*-1 in service mode for 26.2 ks during 2026 January 10–26, yielding a total exposure time of 8.9 hr. X-Shooter observes with three arms simultaneously, UVB, VIS, and near-infrared (NIR), covering rest-frame wavelengths of ≈0.14–0.9 μm, albeit hampered by skyline emission and telluric absorption, primarily in the rest-frame optical.\r\n\r\nThe observing conditions were clear, with a seeing ranging from 05 to 07 (median 06). The service mode observations were primarily conducted during dark nights, with some gray (FLI = 0.03–0.6, median 0.1), and a typical airmass of 1.35. We used UVB, VIS, and NIR slits with widths 10, 09, and 09, yielding a nominal resolution of R = 5400, 8900, and 5600, respectively (FWHM ∼53 km s−1 for NIR). The target acquisition was done using blind offsets from a reference star, due to the target being too faint for direct acquisition. We used a standard nodding on the slit pattern, with 4″ nod throws in an ABBA pattern, and 1″ jitters in the NIR arm to improve the sky subtraction. In each observing block of ≈1 hr, the exposure times were 700, 655, and (2×)365 s for the three arms at each nod position.\r\n\r\nThe reduction of the X-Shooter data uses a combination of EsoRex libraries16 and Python code based on the reduction pipeline employed in J. Matthee et al. (2021). Each observing block was reduced separately. We used standard stars taken during the observing night for a first-pass flux calibration. Telluric corrections were applied using the molecfit tool (A. Smette et al. 2015) implemented in the X-Shooter EsoRex pipeline. Telluric stars were observed during the visitor nights, but they were not always observed during the service mode observations in January. For those observations, we took the telluric star that was observed at the closest observing date. Based on the variation in telluric absorption among the reference stars taken during this period, we estimate the variation in the transmission and propagate the uncertainty in the telluric correction. For each observing block, we then extracted an optimally extracted 1D spectrum using the spatial profile of the Hα line, thus accounting for seeing variations and (more importantly) minor errors in the accuracy of the slit pointing. Before median combining these spectra, we normalize them by the median Hα flux of all observations to account for variations in slit losses and flux calibrations.\r\n\r\nBesides Hα (integrated S/N = 75) and Hβ (integrated S/N = 6; Section 3.2), we also detect continuum emission in the best regions in the H and K bands at 1.6 μm and 2.1 μm, respectively, with a low signal-to-noise ratio (S/N) of ∼1 per resolution element. Unfortunately, the [O iii] λλ4960, 5008 doublet is undetectable because the observed wavelengths are impacted by very strong telluric absorption. No other lines or continuum are detected in the X-Shooter spectrum.\r\n\r\n3. Properties of PAN-BH*-1\r\n3.1. Spectral Shape: A Photospheric Continuum with Strong Hα Emission\r\nThe photometric SED of PAN-BH*-1 has remarkable similarities with The Cliff (Figure 1): luminous in the rest optical, with a sudden drop toward the rest-UV around the Balmer limit, and very weak near-to-mid infrared continuum emission. With a rough extrapolation of the two HST photometric points using a power-law fit (fλ ∝ λβ), we obtain a UV slope of β = −0.1 ± 1.2, and MUV = −16.7 ± 0.7. For the rest-frame optical to NIR data, we fit a Planck blackbody law to the JWST data points, after subtracting the measured Hα flux (see Section 3.2) from the F200W photometry. The rest-optical and NIR photometry of PAN-BH*-1 is remarkably well described by a single temperature blackbody with T = 4204 K (with a best-fit ). We measure the strength of the Balmer break from the fν ratio F115W/F814W = 7 ± 1, in line with the Balmer break strengths of The Cliff (; A. de Graaff et al. 2025a)17 and MoM-BH* (7.8 ± 1.8; R. P. Naidu et al. 2025), measured from JWST/NIRSpec PRISM spectra as fν,4000–4100/fν,3620−3720. In Figure 2, we compare the Balmer break strength with the spectroscopic sample of A. de Graaff et al. (2025b), showing that out of 134 sources, only two have breaks significantly above 5. This suggests that PAN-BH*-1 has among the most extreme Balmer breaks known, although we caution that our value is derived from wide-band photometry with pivot wavelengths corresponding to 4212 and 3042 Å, respectively, rather than from spectroscopy.\r\n\r\nZoom InZoom OutReset image size\r\nFigure 1. SED of PAN-BH*-1 Top: cutouts from all the HST and JWST images in which PAN-BH*-1 is covered. It shows a remarkably compact morphology in all the wavelengths, resolved only in the HST F606W and F814W bands (Section 3.3). Bottom: photometry from JWST/NIRCam (blue squares), HST/ACS (purple pentagons), and Spitzer/IRAC+MIPS (red hexagons, and red triangle for the 5σ upper limit). The empty square is the F200W flux after subtracting the Hα flux measured from X-Shooter spectroscopy. We show the spectrum of The Cliff for comparison (gray line), shifted to z = 1.73 and normalized to the F150W flux of PAN-BH*-1. We also show the best-fitting blackbody spectrum (blue dashed line) and the best model from the synthetic LRD atmosphere models from H. Liu et al. (2026), shifted to z = 1.73 (green line), undersampled by a factor of 500 for clarity.\r\n\r\nDownload figure:\r\n\r\nStandard imageHigh-resolution image\r\nZoom InZoom OutReset image size\r\nFigure 2. Spectroscopic sample of LRDs by redshift and Balmer break strength. We plot the redshift and Balmer break strength of PAN-BH*-1, and the JWST sample from A. de Graaff et al. (2025b) (purple diamonds), and three local LRDs in X. Lin et al. (2026), for comparison. We also highlight three sources with a particularly strong Balmer break: The Cliff (A. de Graaff et al. 2025a), MoM-BH* (R. P. Naidu et al. 2025), and CAPERS-LRDz9 (A. J. Taylor et al. 2025). The Balmer break strength of the JWST spectroscopic sample is computed as fν,4000–4100/fν,3620–3720, whereas the value for PAN-BH*-1 is directly obtained from the F115W/F814W photometry.\r\n\r\nDownload figure:\r\n\r\nStandard imageHigh-resolution image\r\n3.2. Hα and Hβ Emission Lines\r\nThe Hα profile appears as a complex combination of a broad line with strong absorption close to the systemic redshift. We fit the Hα emission line with a similar model as the one used in A. Torralba et al. (2026) and J. Matthee et al. (2026). The Hα model consists of two Gaussian emission components (with narrow and intermediate line widths), and a broad symmetric exponential convolved with the intermediate profile and parameterized as in F. D’Eugenio et al. (2025a). The absorption is implemented as an opacity law defined as e−τ(λ), where τ(λ) also follows a single Gaussian velocity distribution (F. D’Eugenio et al. 2025a, 2025b; A. Torralba et al. 2026). For simplicity, we assume a covering factor of Cf = 1 for the absorbing gas. In previous works, the width of the narrow component is tied to that of [O iii], assuming both components come from the same region, often interpreted as the interstellar medium (ISM) of the host galaxy. In this case, we have no information about [O iii] due to this doublet falling in a wavelength range heavily affected by strong telluric absorption. We fit the Hα line after masking relevant skylines and strong telluric absorption bands. The fitted Hα parameters are listed in Table 1 and the best-fit model is shown in Figure 3. The absorption feature is notably strong, with an equivalent width of EWabs = −148 ± 12 Å with respect to the fitted continuum and 12.2 ± 0.2 Å if including the broad emission component. The absorption corresponds to a Balmer optical depth at the line center of , reaching roughly the continuum level. The FWHM of the single Gaussian fitted to the absorber is 283  ±  8 km s−1, and is offset from the systemic redshift by −94 ± 4 km s−1. We note that this parameterization is somewhat arbitrary, and we discuss in detail the absorber properties in Section 4.\r\n\r\nZoom InZoom OutReset image size\r\nFigure 3. Hα spectrum, and the best fit to our fiducial model. We show the X-Shooter R ∼ 5600 spectrum of the Hα line of PAN-BH*-1, along with the best-fit to the model described in Section 3.2; total model (red solid line) and individual components (discontinuous color lines). The red wing of the line is severely affected by telluric absorption, thus the large uncertainties.\r\n\r\nDownload figure:\r\n\r\nStandard imageHigh-resolution image\r\nTable 1. Properties of PAN-BH*-1\r\n\r\nParameter\tValue\tUnit\r\nWidth (FWHM; Hα)\r\nExponential\t1257 ± 27\tkm s−1\r\nIntermediate\t687 ± 43\tkm s−1\r\nNarrow\t184 ± 12\tkm s−1\r\nAbsorption\t283 ± 8\tkm s−1\r\nFlux (Hα)\r\nExponential\t643 ± 7\t10−18 erg s−1 cm−2\r\nIntermediate\t19 ± 5\t10−18 erg s−1 cm−2\r\nNarrow\t38 ± 3\t10−18 erg s−1 cm−2\r\nTotal\t522 ± 7\t10−18 erg s−1 cm−2\r\nGeneral properties\r\n(LHα/erg s−1)\t43.046 ± 0.006\t⋯\r\nEW0(Hα)\t520 ± 20\tÅ\r\nSFR(Hα, narrow)a\t2.1 ± 0.2\tM⊙ yr−1\r\nSFR(Hα, narrow)b\t3.3 ± 0.3\tM⊙ yr−1\r\nreff,UV (F606W+F814W)\t\tkpc\r\nreff,opt (F200W)\t<0.047\tkpc\r\nHα/Hβ (total)\t>9.4\t⋯\r\nHα/Hβ (narrow)\t5 ± 1\t⋯\r\nNotes. aCalibration from I. G. Kramarenko et al. (2026). bCalibration from R. C. Kennicutt & N. J. Evans (2012). SFR values calculated assuming no dust attenuation.\r\n\r\nDownload table as: \r\nASCIITypeset image\r\n\r\nThe Hβ line is marginally detected. After undersampling the spectrum by a factor 5, a hint of a weak narrow component can be identified (Figure 4), along with a tentative absorption at the same mean velocity as in Hα. We fit the best Hα model to the Hβ spectrum, only rescaling it by a multiplicative factor, and adding a flat continuum component. By doing this, we find an Hβ flux of (47 ± 8) × 10−18 erg s−1 cm−2 (S/N ≈ 6). Conservatively, we obtain a Balmer decrement of Hα/Hβ > 9.4 (at a 3σ confidence level), in line with the high decrements found for the LRD population (e.g., G. P. Nikopoulos et al. 2026; A. de Graaff et al. 2025b; J. Matthee et al. 2026). In Figure 5, we show the Hβ spectrum compared to the rescaled Hα model. By matching the best-fit Hα profile with the data at the expected observed wavelength for Hβ (±5000 km s−1), we obtain a better agreement (, BIC = 1537) than fitting a flat continuum only (, BIC = 1658) with ΔBIC = 121 ≫ 10, strongly favoring a detection of a broad Hβ emission line, and securing the spectroscopic redshift. Similarly, we fit a narrow Gaussian to Hβ with the same width and velocity as the Hα best-fit model, assuming a completely saturated absorption. We obtain a Balmer decrement for the narrow component of Hα/Hβ = 5 ± 1, which would imply a dust extinction of using a J. A. Cardelli et al. (1989) attenuation law, under the assumption of case B recombination. However, due to the low S/N of Hβ this result is only tentative, and compatible with a standard Case B value within ∼2σ.\r\n\r\nZoom InZoom OutReset image size\r\nFigure 4. X-Shooter spectrum of Hα and Hβ of PAN-BH*-1 (blue). We compare to the spectrum of The Cliff (gray; data from JWST DDT #9433), normalized in each panel to the flux of PAN-BH*-1 in the range v ∈ (−3000, −2000) km s−1. Due to the low S/N, the Hβ spectrum of PAN-BH*-1 is rebinned to a coarser grid by a factor 5, after masking the most relevant skylines.\r\n\r\nDownload figure:\r\n\r\nStandard imageHigh-resolution image\r\nZoom InZoom OutReset image size\r\nFigure 5. Hβ spectrum. The spectrum is rebinned by a factor of 10 with inverse variance flux weighting for visual clarity, due to the low S/N. We compare to the best-fit Hα model, scaled by a factor of 0.112. In the bottom panel, we show the χ residuals between the spectrum and the rescaled Hα model in black, and for only the continuum in pink (ΔBIC = 121 strongly favoring the presence of a broad Hβ line).\r\n\r\nDownload figure:\r\n\r\nStandard imageHigh-resolution image\r\n3.3. Spatial Morphology\r\nIn order to assess whether PAN-BH*-1 is spatially resolved, we use the Bayesian profile fitting software pysersic (I. Pasha & T. B. Miller 2023)18 to fit a single Sérsic profile to the JWST and HST imaging data of PAN-BH*-1. For JWST/NIRCam, we choose F200W as the filter with the highest S/N in the short wavelength channel, benefiting from a high spatial resolution and probing rest-frame optical wavelengths. To model its PSF, we use version 2.2.0 of the stpsf software (formerly webbpsf, M. D. Perrin et al. 2014). For the two HST bands F606W and F814W, we instead construct empirical PSFs from public imaging data in the GOODS-S field following A. Weibel et al. (2024). In all three bands, we sample the posterior with the No U-turn sampler in two chains with 1000 warm-up and 2000 sampling steps each. We find that PAN-BH*-1 is unresolved with NIRCam in F200W where the effective radius converges toward the edge of the prior at 0.25 pixels. Using the 95th percentile of the posterior chains as an upper limit on the effective radius, we find a rest-optical size of reff < 47 pc.\r\n\r\nPAN-BH*-1 appears to be resolved in the HST images corresponding to rest-frame pivot 0.2 and 0.3 μm, respectively. Due to the low signal-to-noise of the F606W and F814W photometry, we fit both bands simultaneously fixing all the morphological parameters in both images. We measure physical effective radii of  kpc (see Appendix B). The modest stretching by the foreground A370 lensing cluster could imply a correction of ∼10% to the measured radius (A. Niemiec et al. 2023), which we disregard given the uncertainties. These measured sizes are consistent with the typical sizes for galaxies with a stellar mass ≲ 109 M⊙ at z = 1.75 (A. van der Wel et al. 2014). These findings are consistent with the scenario of a compact LRD “engine” dominating the rest-optical light embedded in a host galaxy, whose contribution becomes significant blueward of the Balmer break (see A. P. Cloonan et al. 2026, for a relevant discussion).\r\n\r\n4. Absorber Kinematics\r\nAs described in Section 3.2, the velocity distribution of the absorber is empirically modeled with a Gaussian, which we find has a central velocity of −94 ± 4 km s−1 relative to the redshift of the narrow emission component (adopted as systemic). The absorption trough extends from negative to positive velocities with respect to the redshift of the narrow component, but also with respect to the center of the symmetric exponential wings. However, there are several degeneracies between the shape of the absorber and other components of the emission line, such as the narrow central emission (see Section 3.2). Furthermore, direct interpretation of the absorber center velocity shift is challenging in an optically thick gas with presumably complex dynamics, and it does not necessarily trace bulk motion. A more robust, physically motivated pair of quantities is the minimum and maximum absorber velocities. We define them as the values where the transmission of the Balmer absorber increases to 99%,  km s−1 and  km s−1. These values trace the largest velocities in the line of sight of gas with significant Balmer absorption. The absorbing trough extends over 787 ± 17 km s−1 under this definition. The values of and are relatively agnostic to the choice of the shape of the absorber, since they are determined by the wavelength where the line profile deviates from a broad, symmetric exponential profile. In Figure 6, we illustrate three proposed configurations of the velocity distribution of the absorbing gas that could explain the shape of the observed Balmer absorption, and we discuss these scenarios below.\r\n\r\nZoom InZoom OutReset image size\r\nFigure 6. Geometric configurations for the absorber. We illustrate three scenarios that could give rise to the observed Balmer absorption in PAN-BH*-1. In scenario (a), the obscuring agent is a thick screen of gas with a certain bulk velocity, and turbulent motions produce the broadening of the absorption trough. In (b), there are two (or more) absorbers with opposite velocities in the line of sight. These first two scenarios are dynamically unstable; therefore, variability is expected in the absorption. Lastly, in (c), we observed an extended source through a disk wind with a rotational component (vϕ) in addition to the poloidal (nonazimuthal) velocity (vp). In the last scenario, the redshifted absorption is produced by streamlines that oppose the observer when projected along the line of sight, despite the fact that the gas is outflowing from the central source.\r\n\r\nDownload figure:\r\n\r\nStandard imageHigh-resolution image\r\n4.1. Unstable Gas Flows?\r\nThe fact that there is significant absorption at both negative and positive velocities with respect to the systemic redshift cannot be simply explained by an axisymmetric outflowing or inflowing wind. In the case of observing a compact object through a spherically symmetric, nonturbulent bulk flow, a classical P Cygni profile is expected, with a purely blueshifted absorption (or redshifted if the wind is infalling). The fact that we also see redshifted absorption rules out this simple scenario. In principle, turbulent motions could also produce broadening of the absorbing medium (scenario a in Figure 6). However, the required turbulent velocity dispersion σturb ≈ 120 km s−1 (from the Gaussian fit in Section 3.2) is comparable to the mean velocity of the absorption trough, meaning that turbulence dominates the gas flow. In such a case, strong variability of the absorption profile would be expected, given the typical dynamical crossing times (see Sect. 4.1 in F. D’Eugenio et al. 2025b). For example, for a radius of 1016 cm (e.g., A. Torralba et al. 2026) and a mass of 106 M⊙, the dynamical freefall time is  yr. Moreover, the turbulent velocity would be highly supersonic, and the dissipation timescale would be comparable to the dynamical time (e.g., M.-M. Mac Low 1999). Alternatively, in the context of a strong Balmer absorber at z ∼ 7, F. D’Eugenio et al. (2026) recently discussed a “breathing mode” scenario with cyclic inflows and outflows along the same line of sight, with the gas being in different phases at different depths (scenario b in Figure 6; see also K. Park et al. 2017). In this case, the same arguments regarding the stability of the absorber would apply, and absorber variability is expected on observed timescales of ∼5 yr (for a source at z = 1.7), which is testable with future observations.\r\n\r\n4.2. The Case for the Disk Wind Hypothesis\r\nAn alternative, dynamically stable scenario is a disk wind configuration (scenario c in Figure 6). Here, the wind would be launched from a thick disk near the central engine, which we speculate could be the source of the optical continuum emission (e.g., H. Liu et al. 2025, 2026; L. Zwick et al. 2025; Y.-X. Chen et al. 2026). A rotating disk would imprint to the wind an azimuthal velocity component (vϕ). Observations at specific lines of sight, particularly for high inclination angles (close to edge-on) where the rotational component dominates the poloidal velocity, can give rise to both blueshifted and redshifted absorption features (D. Proga et al. 2000; P. B. Hall et al. 2002, 2013; D. Proga & T. R. Kallman 2004; M. Giustini & D. Proga 2012). Most observed LRDs have blueshifted P Cygni–like absorbers (J. Matthee et al. 2026), which can be naively interpreted as a uniformly expanding shell. The low incidence of redshifted Balmer absorbers in LRD spectra (e.g., I. Labbe et al. 2024; A. de Graaff et al. 2025a; F. D’Eugenio et al. 2025b, 2026; Y. Ma et al. 2026) can therefore be explained by the requirement of high inclination angles to observe such features (see also A. Sneppen et al. 2026). Such a picture is broadly in line with disk wind models for AGN with broad absorption lines (e.g., P. B. Hall et al. 2002; H. Zhou et al. 2019) and around stars with circumstellar disks (e.g., J. Erkal et al. 2022), such as accreting T Tauri stars (S. Edwards et al. 2006) or cataclysmic variables (D. Proga 2003).\r\n\r\n4.3. Implications of Rotating Winds for the Emission Lines of LRDs\r\nThe disk wind hypothesis would imply that a photosphere in the shape of a rotating disk is the source of the optical continuum emission, and drives winds that can explain the observed absorption trough. Emission lines originating in a thin rotating disk would have a double-peaked profile in the idealized case (for most inclination angles), but this is not necessarily true if the disk is not sufficiently thin (e.g., N. Murray & J. Chiang 1997), for instance, in the case of a puffed-up disk associated with super-Eddington accretion (e.g., H. Liu et al. 2026). In addition, most line emission would not be produced directly at the base of the disk, but slightly outside (e.g., via collisional cooling or residual recombination; A. Torralba et al. 2026), where the rotational velocity is lower, and the dynamics are complex (e.g., G. A. Shields 1977).\r\n\r\nThe Balmer lines of most LRDs are dominated by broad, symmetric exponential components that are associated with broadening by electron scattering (e.g., V. Rusakov et al. 2026; J. Matthee et al. 2026). For PAN-BH*-1, the Hα line profile of PAN-BH*-1 is compatible with a broad exponential profile emerging through a dense wind where the absorption trough is produced. In dense gas with a large column density of neutral hydrogen, and optically thick to Balmer transitions (NHI,2s ≳ 1014 cm−2), resonant scattering effects become important. Crucially, resonant scattering impacts Hα and Hβ differently (e.g., S.-J. Chang et al. 2026), hence the 3D radiative transfer and photon redistribution of both lines may produce different profiles (see, e.g., Figure 2 in D. Proga 2003). Therefore, the empirical fitting and interpretation of the absorption profiles becomes nontrivial. Dedicated radiative transfer modeling is necessary to study such effects, and they can be tested in other emission lines with high optical depth, such as He i λ10830 Å, or resonant lines like C iv λ1550.\r\n\r\n5. Implications for the Galaxy and Black Hole Masses\r\n5.1. Properties of the Host Galaxy\r\nAssuming that the narrow component of Hα corresponds to ISM emission in the host galaxy, we compute the associated star formation rate using the local calibration from R. C. Kennicutt & N. J. Evans (2012) and assuming no dust attenuation. We obtain SFR(Hα) = 3.3 ± 0.3 M⊙ yr−1. A somewhat lower value of SFR(Hα) = 2.1 ± 0.2 M⊙ yr−1 is obtained using the high-redshift (z ≳ 4) calibrations in I. G. Kramarenko et al. (2026), which might be more appropriate for a young dwarf galaxy with a bursty star formation history. The star formation rates are low, but in line with a main-sequence galaxy with (extrapolating the relation from J. S. Speagle et al. 2014). Assuming zero dust attenuation, the UV absolute magnitude (MUV = −16.7 ± 0.7; Section 3.1) would imply SFR(UV) = 0.18 ± 0.12 M⊙ yr−1 (R. C. Kennicutt & N. J. Evans 2012). The discrepancy between the UV and Hα inferred star formation rate suggests there is some amount of dust attenuation in the host galaxy.\r\n\r\nWe derive a dynamical mass from the width of the narrow component Hα line and the estimated UV size as , adopting the empirical virial correction K(n)K(q) from A. van der Wel et al. (2022), where K(n) and K(q) are functions of the best-fit ellipticity and Sérsic index (see Appendix B). Adopting a Mdyn/M* factor of 40 as found by A. de Graaff et al. (2024) for dwarf galaxies at high redshift, we infer a stellar mass of . However, the Mdyn/M* is very uncertain in this regime, and the uncertainty can span over 1 dex (A. Saldana-Lopez et al. 2025). We advise caution in interpreting this result, as there are large uncertainties in the measurements of the narrow Hα component, the HST morphology, and the empirical relations used.\r\n\r\nAs discussed in Section 4, the absorption profile is compatible with broadening by a rotating disk wind, and numerical modeling of such configurations often predicts a narrow component arising from increased transmission due to purely kinematic effects in the wind geometry (D. Proga et al. 2000; D. Proga 2003; D. Proga & T. R. Kallman 2004). This would be an alternative explanation for at least part of the narrow component flux. On the other hand, most LRDs present narrow [O iii] emission that is often associated with the host galaxy. Indeed, the ionized gas producing [O iii] emission should have associated emission in the Hα and higher-order Balmer lines. However, constraining this component largely depends on the assumptions on dust attenuation or ISM conditions, and requires very high S/N and resolution data. Deep, space-based follow-up observations of PAN-BH*-1 would be very constraining for the wind kinematics (e.g., by the joint analysis of Hβ) and to assess whether a narrow component comes from a host galaxy (e.g., by comparing to a narrow Hβ component or [O iii] λλ4960, 5008).\r\n\r\n5.2. Black Hole Mass From Photosphere Models\r\nThe general physical setup of LRDs is an open debate, and their masses are a major unknown. Due to the multiple differences with respect to the classical AGN population, the validity of standard virial calibrations has been questioned (e.g., V. Rusakov et al. 2026; J. E. Greene et al. 2026; A. Sneppen et al. 2026; A. Torralba et al. 2026, although see, e.g., M. Brazzini et al. 2025, 2026; J. Scholtz et al. 2026 for an alternative interpretation).\r\n\r\nOne can obtain a mass estimate assuming a system in radiative equilibrium with Lbol/LEdd = 1 (e.g., H. Umeda et al. 2026); this yields a total mass of ≈106 M⊙, using the bolometric luminosity from integrating the best-fit blackbody in Section 3.1. Recently, H. Liu et al. (2026) developed a synthetic spectral library of LRD atmosphere models. In these models, the density of the photosphere is regulated by the net surface gravity of an optically thick atmosphere, enabling constraints on the mass of the system. We fit the JWST photometry of PAN-BH*-1 using the models from H. Liu et al. (2026), assuming a negligible contribution from a host galaxy to the optical continuum. The best-fit model has effective temperature Teff = 4800 K, surface gravity , and metallicity (; see Figure 1). The best-fit implies a total mass of the system (BH plus gas) of (Equation (6) in H. Liu et al. 2026, assuming hydrostatic equilibrium). For the second and third best fits, we obtain and −2, respectively (, respectively; with the same metallicity and effective temperature), which would imply lower limits to the system mass between and 4. The bolometric luminosity of PAN-BH*-1 (from the integral of the best-fit green curve in Figure 1) implies an Eddington luminosity ratio of L/LEdd ≲ 13, assuming the best-fit mass from the H. Liu et al. (2026) models. The elevated Eddington ratio is in line with the hypothesis of a radiation-driven wind discussed in Section 4, and allows for somewhat larger system masses. The low masses obtained with this model, combined with the stellar mass inferred from dynamical arguments for the host galaxy (Section 3.3) set lower limits to the BH-to-stellar mass ratio of MBH/M* ≳ 10−4–10−2, which are compatible with the relations observed in the Local Universe, within the large uncertainties (A. E. Reines & M. Volonteri 2015).\r\n\r\n6. Conclusions\r\nIn this Letter, we presented the discovery and spectroscopic confirmation of PAN-BH*-1, an LRD with an extreme Balmer break at z = 1.731. The strength of the Balmer break (F115W/F814W = 7 ± 1) is comparable to the most extreme LRDs known, The Cliff (A. de Graaff et al. 2025a) and MoM-BH* (R. P. Naidu et al. 2025). We summarize the observations and our main conclusions as follows.\r\n\r\n\r\n1.  \r\nWe obtained deep VLT/X-Shooter spectroscopy of PAN-BH*-1. The Hα emission line is luminous and broad (LHα = 1043 erg s−1), and has an unusually strong absorption. Hβ is detected with an S/N ≈ 6, and we conservatively estimate a lower limit for the Balmer decrement of Hα/Hβ > 9.4 (at a 3σ confidence level), in line with other LRDs in the literature (e.g., A. de Graaff et al. 2025b; G. P. Nikopoulos et al. 2026).\r\n2.  \r\nThe absorption trough spans from −520 to 267 km s−1 (at a transmission level of 99%). We interpret the presence of blue- and redshifted absorption as produced by a disk wind, analogous to those analyzed in the context of broad absorption line quasars or accreting stars. This hypothesis would imply that the source of the optical continuum is likely a thick photospheric disk.\r\n3.  \r\nWe detect a narrow Hα component (FWHM = 184 ± 12 km s−1), which we interpret as probing a host galaxy with M* ≈ 108 M⊙ and SFR = 2–3 M⊙. This interpretation is in line with the extended rest-NUV morphology measured in the HST bands (\r\n kpc).\r\n4.  \r\nBy fitting the synthetic atmosphere models of H. Liu et al. (2026), we estimate a system mass (BH+envelope) of 104–106 M⊙. The inferred masses, together with the stellar mass inferred from morphology and narrow emission line dynamics, imply BH-to-stellar mass ratios of 10−2–10−4, close to the extrapolated trend in the local Universe (A. E. Reines & M. Volonteri 2015).\r\n5.  \r\nThe confirmation of this source at cosmic noon (magnitude of ≈22 in the K band, Hα flux ≈5 × 10−16 erg s−1 cm−2) proves the feasibility of detecting extreme LRDs at such epochs with wide-area spectroscopic surveys like Euclid or the forthcoming Nancy Grace Roman Space Telescope.\r\n\r\nAcknowledgments\r\nA.T. thanks Debasish Dutta and Tamara Bogdanović for useful conversations about stellar and AGN winds.\r\n\r\nWe thank the scientific referee for the useful and constructive feedback, which helped improve the quality of this paper.\r\n\r\nJ.M. and A.T. acknowledge funding by the European Union (ERC, AGENTS, 101076224). The work of CCW is supported by NOIRLab, which is managed by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with the National Science Foundation. A.P.C. warmly acknowledges the support of the National Science Foundation through the NSF Graduate Research Fellowship Program. A.d.G. acknowledges support from a Clay Fellowship awarded by the Smithsonian Astrophysical Observatory.\r\n\r\nBased on observations made with ESO Telescopes at the Paranal Observatory under program IDs 116.294D and 116.2AQ0.\r\n\r\nThis work is based in part on observations made with the NASA/ESA/CSA James Webb Space Telescope. The data were obtained from the Mikulski Archive for Space Telescopes at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-03127 for JWST. These observations are associated with programs #2514 and #9433. C.C.W. gratefully acknowledges support for program JWST-GO-2514 provided by NASA through a grant from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-03127. The authors acknowledge the team led by co-PIs R. Maiolino and F. D’Eugenio for developing their observing program with a zero-exclusive-access period.\r\n\r\nThis research is based on observations made with the NASA/ESA Hubble Space Telescope obtained from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5–26555. These observations are associated with program #15117.\r\n\r\nThe JWST and HST data presented in this article were obtained from the Mikulski Archive for Space Telescopes (MAST) at the Space Telescope Science Institute. The specific observations analyzed can be accessed via doi:10.17909/ydwx-st06.\r\n\r\nThis work is based in part on observations made with the Spitzer Space Telescope, which was operated by the Jet Propulsion Laboratory, California Institute of Technology under a contract with NASA. The Spitzer data used in this work can be found in doi:10.26131/IRSA3.\r\n\r\nThis work was supported by the International Space Science Institute (ISSI) in Bern, through ISSI International Team project #25-659 “Little Red Dots, Big Open Questions.”\r\n\r\nJWST cartoon in Figure 6, credit: NASA.\r\n\r\nFacilities: VLT:Kueyen - Very Large Telescope (Kueyen) (X-Shooter), VLT:Yepun (HAWK-I), JWST - James Webb Space Telescope (NIRCam, NIRspec), HST - Hubble Space Telescope satellite (ACS), Spitzer - Spitzer Space Telescope satellite (IRAC, MIPS) - .\r\n\r\nSoftware: astropy (Astropy Collaboration et al. 2013, 2018; Astropy Collaboration et al. 2022), NumPy (C. R. Harris et al. 2020), SciPy (P. Virtanen et al. 2020), pysersic (I. Pasha & T. B. Miller 2023), stpsf (M. D. Perrin et al. 2014), lmfit (M. Newville et al. 2014), EsoRex (ESO CPL Development Team 2015), Claude (used for Python coding; https://claude.ai/), SEP (K. Barbary 2016).","date_created":"2026-07-12T22:02:17Z","dataavailabilitystatement":"Based on observations made with ESO Telescopes at the Paranal Observatory under program IDs 116.294D and 116.2AQ0.\r\n\r\nThis work is based in part on observations made with the NASA/ESA/CSA James Webb Space Telescope. The data were obtained from the Mikulski Archive for Space Telescopes at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-03127 for JWST. These observations are associated with programs #2514 and #9433. C.C.W. gratefully acknowledges support for program JWST-GO-2514 provided by NASA through a grant from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-03127. The authors acknowledge the team led by co-PIs R. Maiolino and F. D’Eugenio for developing their observing program with a zero-exclusive-access period.\r\n\r\nThis research is based on observations made with the NASA/ESA Hubble Space Telescope obtained from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5–26555. These observations are associated with program #15117.\r\n\r\nThe JWST and HST data presented in this article were obtained from the Mikulski Archive for Space Telescopes (MAST) at the Space Telescope Science Institute. The specific observations analyzed can be accessed via doi:10.17909/ydwx-st06.\r\n\r\nThis work is based in part on observations made with the Spitzer Space Telescope, which was operated by the Jet Propulsion Laboratory, California Institute of Technology under a contract with NASA. The Spitzer data used in this work can be found in doi:10.26131/IRSA3.\r\n\r\nThis work was supported by the International Space Science Institute (ISSI) in Bern, through ISSI International Team project #25-659 “Little Red Dots, Big Open Questions.”\r\n\r\nJWST cartoon in Figure 6, credit: NASA.\r\n\r\nFacilities: VLT:Kueyen - Very Large Telescope (Kueyen) (X-Shooter), VLT:Yepun (HAWK-I), JWST - James Webb Space Telescope (NIRCam, NIRspec), HST - Hubble Space Telescope satellite (ACS), Spitzer - Spitzer Space Telescope satellite (IRAC, MIPS) - .\r\n\r\nSoftware: astropy (Astropy Collaboration et al. 2013, 2018; Astropy Collaboration et al. 2022), NumPy (C. R. Harris et al. 2020), SciPy (P. Virtanen et al. 2020), pysersic (I. Pasha & T. B. Miller 2023), stpsf (M. D. Perrin et al. 2014), lmfit (M. Newville et al. 2014), EsoRex (ESO CPL Development Team 2015), Claude (used for Python coding; https://claude.ai/), SEP (K. Barbary 2016).","OA_type":"gold","status":"public","file_date_updated":"2026-07-13T07:46:22Z","doi":"10.3847/2041-8213/ae7bfd","type":"journal_article","researchdata_availability":"yes","language":[{"iso":"eng"}],"oa_version":"Published Version","day":"10","title":"A black hole star at cosmic noon: Extreme Balmer break, photospheric continuum, and broad absorption by thick winds in a Little Red Dot at z = 1.7","date_updated":"2026-07-13T08:08:41Z","article_number":"L37","abstract":[{"lang":"eng","text":"Recent studies at high redshift have revealed an enigmatic class of little red dots (LRDs) with extreme Balmer breaks, stronger than in any stellar atmosphere. However, it is unclear whether such objects exist at lower redshift, especially given the low number of LRDs reported at z ≲ 2. Here, we report the discovery of PAN-BH*-1, an LRD with an extreme Balmer break at z = 1.73, identified from JWST/NIRCam pure-parallel imaging taken by the PANORAMIC survey, and confirmed by deep VLT/X-Shooter spectroscopy. The rest-optical to near-infrared spectral energy distribution of PAN-BH*-1 is consistent with a photospheric continuum with effective temperature Teff ≈ 4800 K. The broad Hα emission line shows remarkably deep absorption, stronger than previously measured in any LRD. The absorption trough spans from −520 to +267 km s−1 with respect to the systemic redshift. The presence of blue- and red-shifted absorption suggests complex dynamics of the obscuring gas along the line of sight. We speculate that the absorption trough can be produced by a thick wind launched from a thick, rotating photospheric disk, the latter being the source of the red optical continuum. While the source is unresolved in the rest-optical JWST data (reff < 47 pc), the rest-near-UV Hubble Space Telescope imaging shows an extended morphology with (formular displayed) kpc, which we interpret as a host galaxy with a stellar mass of ∼10^8 M⊙, in line with the narrow Hα emission. The discovery of this object at cosmic noon highlights the feasibility of systematic searches for extreme LRDs with wide-area facilities such as Euclid and Roman."}],"DOAJ_listed":"1","file":[{"date_created":"2026-07-13T07:46:22Z","file_id":"22274","checksum":"7600db260d799ddea45cf3bd01effe41","success":1,"creator":"dernst","content_type":"application/pdf","date_updated":"2026-07-13T07:46:22Z","file_name":"2026_AstrophysicalJourLetters_Torralba.pdf","access_level":"open_access","relation":"main_file","file_size":5419071}],"intvolume":"      1005","year":"2026","external_id":{"arxiv":["2603.28335"]},"quality_controlled":"1","supplementarymaterial":"yes","scopus_import":"1","publisher":"IOP Publishing","fulldoi":"https://doi.org/10.3847/2041-8213/ae7bfd","publication_identifier":{"issn":["2041-8205"],"eissn":["2041-8213"]},"_id":"22263","publication":"The Astrophysical Journal Letters","OA_place":"publisher","arxiv":1,"project":[{"_id":"bd9b2118-d553-11ed-ba76-db24564edfea","grant_number":"101076224","name":"Young galaxies as tracers and agents of cosmic reionization"}],"has_accepted_license":"1","oa":1,"department":[{"_id":"JoMa"},{"_id":"IlCa"},{"_id":"GradSch"}],"article_processing_charge":"Yes","das_tickbox":"1","citation":{"short":"A. Torralba Torregrosa, J.J. Matthee, A. Weibel, R.P. Naidu, Y. Ma, A.P. Cloonan, A.A. Desai, A. De Graaff, J.E. Greene, C.K. Jespersen, I. Kramarenko, S. Mascia, P.A. Oesch, W.Q. Sun, C.C. Williams, The Astrophysical Journal Letters 1005 (2026).","mla":"Torralba Torregrosa, Alberto, et al. “A Black Hole Star at Cosmic Noon: Extreme Balmer Break, Photospheric Continuum, and Broad Absorption by Thick Winds in a Little Red Dot at z = 1.7.” <i>The Astrophysical Journal Letters</i>, vol. 1005, no. 2, L37, IOP Publishing, 2026, doi:<a href=\"https://doi.org/10.3847/2041-8213/ae7bfd\">10.3847/2041-8213/ae7bfd</a>.","apa":"Torralba Torregrosa, A., Matthee, J. J., Weibel, A., Naidu, R. P., Ma, Y., Cloonan, A. P., … Williams, C. C. (2026). A black hole star at cosmic noon: Extreme Balmer break, photospheric continuum, and broad absorption by thick winds in a Little Red Dot at z = 1.7. <i>The Astrophysical Journal Letters</i>. IOP Publishing. <a href=\"https://doi.org/10.3847/2041-8213/ae7bfd\">https://doi.org/10.3847/2041-8213/ae7bfd</a>","ista":"Torralba Torregrosa A, Matthee JJ, Weibel A, Naidu RP, Ma Y, Cloonan AP, Desai AA, De Graaff A, Greene JE, Jespersen CK, Kramarenko I, Mascia S, Oesch PA, Sun WQ, Williams CC. 2026. A black hole star at cosmic noon: Extreme Balmer break, photospheric continuum, and broad absorption by thick winds in a Little Red Dot at z = 1.7. The Astrophysical Journal Letters. 1005(2), L37.","ieee":"A. Torralba Torregrosa <i>et al.</i>, “A black hole star at cosmic noon: Extreme Balmer break, photospheric continuum, and broad absorption by thick winds in a Little Red Dot at z = 1.7,” <i>The Astrophysical Journal Letters</i>, vol. 1005, no. 2. IOP Publishing, 2026.","ama":"Torralba Torregrosa A, Matthee JJ, Weibel A, et al. A black hole star at cosmic noon: Extreme Balmer break, photospheric continuum, and broad absorption by thick winds in a Little Red Dot at z = 1.7. <i>The Astrophysical Journal Letters</i>. 2026;1005(2). doi:<a href=\"https://doi.org/10.3847/2041-8213/ae7bfd\">10.3847/2041-8213/ae7bfd</a>","chicago":"Torralba Torregrosa, Alberto, Jorryt J Matthee, Andrea Weibel, Rohan P. Naidu, Yilun Ma, Aidan P. Cloonan, Aayush A Desai, et al. “A Black Hole Star at Cosmic Noon: Extreme Balmer Break, Photospheric Continuum, and Broad Absorption by Thick Winds in a Little Red Dot at z = 1.7.” <i>The Astrophysical Journal Letters</i>. IOP Publishing, 2026. <a href=\"https://doi.org/10.3847/2041-8213/ae7bfd\">https://doi.org/10.3847/2041-8213/ae7bfd</a>."},"volume":1005,"month":"07","publication_status":"published","date_published":"2026-07-10T00:00:00Z","article_type":"original","user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87"},{"quality_controlled":"1","external_id":{"arxiv":["2601.06968"]},"year":"2026","intvolume":"       708","DOAJ_listed":"1","file":[{"relation":"main_file","file_size":591297,"creator":"dernst","content_type":"application/pdf","checksum":"94cc1327f363d69995984b06e18e2645","success":1,"file_id":"22890","date_created":"2026-09-09T12:55:37Z","access_level":"open_access","file_name":"2026_AstronomyAstrophysics_Schaerer.pdf","date_updated":"2026-09-09T12:55:37Z"}],"abstract":[{"text":"Using deep, medium-resolution, JWST rest-optical spectra of a sample of typical star-forming galaxies (Lyman-break galaxies and Lyman-α emitters) from the LyC22 survey at z ∼ 3, we determined the nebular abundances of N, O, and Ne relative to H for a subsample of 25 objects with a direct method based on auroral [O III] λ4363 line detections. Our measurements increased the number of accurate N/O determinations at z ∼ 2 − 4 using a homogeneous approach. We found a mean value of log(N/O) = −+0.25−0.21 over a metallicity range of 12 + log(O/H) = 7.56 to 8.44. The observed N/O ratio and scatter are indistinguishable from that observed in low-z galaxies and H II regions over the same metallicity range, thus showing no redshift evolution of N/O for typical galaxies over a significant fraction of cosmic time. We also show that typical z ∼ 3 galaxies have a similar offset in the BPT diagram to galaxies from the low-z Lyman Continuum Survey (LzLCS) when compared to the average of SDSS galaxies, and we demonstrate that this offset is not due to enhanced nitrogen abundances. Our results establish a basis for future studies of the evolution of N and O at higher redshifts.","lang":"eng"}],"article_number":"A242","date_updated":"2026-09-09T12:59:51Z","title":"Nitrogen abundances in star-forming galaxies 2.2 Gyr after the Big Bang are not elevated","day":"01","language":[{"iso":"eng"}],"oa_version":"Published Version","researchdata_availability":"yes","type":"journal_article","status":"public","file_date_updated":"2026-09-09T12:55:37Z","doi":"10.1051/0004-6361/202556832","OA_type":"diamond","date_created":"2026-09-06T22:01:57Z","dataavailabilitystatement":"The data used are publicly available at the Mikulski Archive for Space Telescope (MAST),\r\nand can be accessed at https://dx.doi.org/10.17909/x6d5-vd44.","acknowledgement":"Y.I., N.G., R.M.-C., and D.S. acknowledge support from\r\nproject No. 224866 carried out in the framework of the Joint Call “UkrainianSwiss Joint Research Projects: Call for Proposals 2023”. This work is based in\r\npart on observations made with the NASA/ESA/CSA James Webb Space Telescope. The data were obtained from the Mikulski Archive for Space Telescopes\r\nat the Space Telescope Science Institute, which is operated by the Association\r\nof Universities for Research in Astronomy, Inc., under NASA contract NAS 5-\r\n03127 for JWST. These observations are associated with program # 1869. Support for program # 1869 was provided by NASA through a grant from the Space\r\nTelescope Science Institute, which is operated by the Association of Universities\r\nfor Research in Astronomy, Inc., under NASA contract NAS 5-03127","ddc":["520"],"author":[{"first_name":"D.","last_name":"Schaerer","full_name":"Schaerer, D."},{"full_name":"Izotov, Y. I.","last_name":"Izotov","first_name":"Y. I."},{"full_name":"Marques-Chaves, R.","first_name":"R.","last_name":"Marques-Chaves"},{"first_name":"C. C.","last_name":"Steidel","full_name":"Steidel, C. C."},{"last_name":"Reddy","first_name":"N.","full_name":"Reddy, N."},{"first_name":"A. E.","last_name":"Shapley","full_name":"Shapley, A. E."},{"last_name":"Mascia","id":"edaf889c-c7cd-11ef-ab1b-bb28c431bd29","first_name":"Sara","full_name":"Mascia, Sara"},{"full_name":"Chisholm, J.","last_name":"Chisholm","first_name":"J."},{"full_name":"Flury, S. R.","first_name":"S. R.","last_name":"Flury"},{"last_name":"Guseva","first_name":"N.","full_name":"Guseva, N."},{"full_name":"Heckman, T.","first_name":"T.","last_name":"Heckman"},{"full_name":"Henry, A.","last_name":"Henry","first_name":"A."},{"last_name":"Inoue","first_name":"A. K.","full_name":"Inoue, A. K."},{"first_name":"I.","last_name":"Jung","full_name":"Jung, I."},{"full_name":"Kusakabe, H.","first_name":"H.","last_name":"Kusakabe"},{"full_name":"Mawatari, K.","first_name":"K.","last_name":"Mawatari"},{"full_name":"Oesch, P.","last_name":"Oesch","first_name":"P."},{"full_name":"Östlin, G.","last_name":"Östlin","first_name":"G."},{"full_name":"Pentericci, L.","last_name":"Pentericci","first_name":"L."},{"first_name":"N.","last_name":"Roy","full_name":"Roy, N."},{"full_name":"Saldana-Lopez, A.","first_name":"A.","last_name":"Saldana-Lopez"},{"last_name":"Sato","first_name":"R.","full_name":"Sato, R."},{"full_name":"Vanzella, E.","last_name":"Vanzella","first_name":"E."},{"full_name":"Verhamme, A.","last_name":"Verhamme","first_name":"A."},{"first_name":"B.","last_name":"Wang","full_name":"Wang, B."}],"tmp":{"short":"CC BY (4.0)","image":"/images/cc_by.png","name":"Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)","legal_code_url":"https://creativecommons.org/licenses/by/4.0/legalcode"},"user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","article_type":"original","date_published":"2026-04-01T00:00:00Z","publication_status":"published","month":"04","volume":708,"citation":{"apa":"Schaerer, D., Izotov, Y. I., Marques-Chaves, R., Steidel, C. C., Reddy, N., Shapley, A. E., … Wang, B. (2026). Nitrogen abundances in star-forming galaxies 2.2 Gyr after the Big Bang are not elevated. <i>Astronomy &#38; Astrophysics</i>. EDP Sciences. <a href=\"https://doi.org/10.1051/0004-6361/202556832\">https://doi.org/10.1051/0004-6361/202556832</a>","ista":"Schaerer D, Izotov YI, Marques-Chaves R, Steidel CC, Reddy N, Shapley AE, Mascia S, Chisholm J, Flury SR, Guseva N, Heckman T, Henry A, Inoue AK, Jung I, Kusakabe H, Mawatari K, Oesch P, Östlin G, Pentericci L, Roy N, Saldana-Lopez A, Sato R, Vanzella E, Verhamme A, Wang B. 2026. Nitrogen abundances in star-forming galaxies 2.2 Gyr after the Big Bang are not elevated. Astronomy &#38; Astrophysics. 708, A242.","mla":"Schaerer, D., et al. “Nitrogen Abundances in Star-Forming Galaxies 2.2 Gyr after the Big Bang Are Not Elevated.” <i>Astronomy &#38; Astrophysics</i>, vol. 708, A242, EDP Sciences, 2026, doi:<a href=\"https://doi.org/10.1051/0004-6361/202556832\">10.1051/0004-6361/202556832</a>.","short":"D. Schaerer, Y.I. Izotov, R. Marques-Chaves, C.C. Steidel, N. Reddy, A.E. Shapley, S. Mascia, J. Chisholm, S.R. Flury, N. Guseva, T. Heckman, A. Henry, A.K. Inoue, I. Jung, H. Kusakabe, K. Mawatari, P. Oesch, G. Östlin, L. Pentericci, N. Roy, A. Saldana-Lopez, R. Sato, E. Vanzella, A. Verhamme, B. Wang, Astronomy &#38; Astrophysics 708 (2026).","ieee":"D. Schaerer <i>et al.</i>, “Nitrogen abundances in star-forming galaxies 2.2 Gyr after the Big Bang are not elevated,” <i>Astronomy &#38; Astrophysics</i>, vol. 708. EDP Sciences, 2026.","ama":"Schaerer D, Izotov YI, Marques-Chaves R, et al. Nitrogen abundances in star-forming galaxies 2.2 Gyr after the Big Bang are not elevated. <i>Astronomy &#38; Astrophysics</i>. 2026;708. doi:<a href=\"https://doi.org/10.1051/0004-6361/202556832\">10.1051/0004-6361/202556832</a>","chicago":"Schaerer, D., Y. I. Izotov, R. Marques-Chaves, C. C. Steidel, N. Reddy, A. E. Shapley, Sara Mascia, et al. “Nitrogen Abundances in Star-Forming Galaxies 2.2 Gyr after the Big Bang Are Not Elevated.” <i>Astronomy &#38; Astrophysics</i>. EDP Sciences, 2026. <a href=\"https://doi.org/10.1051/0004-6361/202556832\">https://doi.org/10.1051/0004-6361/202556832</a>."},"das_tickbox":"1","department":[{"_id":"JoMa"}],"article_processing_charge":"No","oa":1,"has_accepted_license":"1","OA_place":"publisher","arxiv":1,"publication":"Astronomy & Astrophysics","_id":"22817","publication_identifier":{"eissn":["1432-0746"],"issn":["0004-6361"]},"fulldoi":"https://doi.org/10.1051/0004-6361/202556832","supplementarymaterial":"no","PlanS_conform":"1","publisher":"EDP Sciences","scopus_import":"1"},{"article_type":"original","user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","month":"12","publication_status":"published","date_published":"2025-12-01T00:00:00Z","citation":{"ama":"Liu Y, Mascia S, Pentericci L, et al. A Lyman continuum analysis of ∼100 galaxies at z spec∼ 3 in the Abell 2744 cluster field. <i>Astronomy &#38; Astrophysics</i>. 2025;704. doi:<a href=\"https://doi.org/10.1051/0004-6361/202556410\">10.1051/0004-6361/202556410</a>","chicago":"Liu, Y., Sara Mascia, L. Pentericci, P. Watson, A. Alavi, P. Bergamini, M. Bradač, et al. “A Lyman Continuum Analysis of ∼100 Galaxies at z Spec∼ 3 in the Abell 2744 Cluster Field.” <i>Astronomy &#38; Astrophysics</i>. EDP Sciences, 2025. <a href=\"https://doi.org/10.1051/0004-6361/202556410\">https://doi.org/10.1051/0004-6361/202556410</a>.","apa":"Liu, Y., Mascia, S., Pentericci, L., Watson, P., Alavi, A., Bergamini, P., … Wang, X. (2025). A Lyman continuum analysis of ∼100 galaxies at z spec∼ 3 in the Abell 2744 cluster field. <i>Astronomy &#38; Astrophysics</i>. EDP Sciences. <a href=\"https://doi.org/10.1051/0004-6361/202556410\">https://doi.org/10.1051/0004-6361/202556410</a>","ista":"Liu Y, Mascia S, Pentericci L, Watson P, Alavi A, Bergamini P, Bradač M, Calabrò A, Glazebrook K, Henry A, Llerena M, Merlin E, Metha B, Nanayakkara T, Napolitano L, Roy N, Siana B, Vanzella E, Vulcani B, Wang X. 2025. A Lyman continuum analysis of ∼100 galaxies at z spec∼ 3 in the Abell 2744 cluster field. Astronomy &#38; Astrophysics. 704, A328.","mla":"Liu, Y., et al. “A Lyman Continuum Analysis of ∼100 Galaxies at z Spec∼ 3 in the Abell 2744 Cluster Field.” <i>Astronomy &#38; Astrophysics</i>, vol. 704, A328, EDP Sciences, 2025, doi:<a href=\"https://doi.org/10.1051/0004-6361/202556410\">10.1051/0004-6361/202556410</a>.","short":"Y. Liu, S. Mascia, L. Pentericci, P. Watson, A. Alavi, P. Bergamini, M. Bradač, A. Calabrò, K. Glazebrook, A. Henry, M. Llerena, E. Merlin, B. Metha, T. Nanayakkara, L. Napolitano, N. Roy, B. Siana, E. Vanzella, B. Vulcani, X. Wang, Astronomy &#38; Astrophysics 704 (2025).","ieee":"Y. Liu <i>et al.</i>, “A Lyman continuum analysis of ∼100 galaxies at z spec∼ 3 in the Abell 2744 cluster field,” <i>Astronomy &#38; Astrophysics</i>, vol. 704. EDP Sciences, 2025."},"volume":704,"department":[{"_id":"JoMa"}],"article_processing_charge":"No","has_accepted_license":"1","oa":1,"OA_place":"publisher","arxiv":1,"publication_identifier":{"issn":["0004-6361"],"eissn":["1432-0746"]},"_id":"20932","publication":"Astronomy & Astrophysics","scopus_import":"1","publisher":"EDP Sciences","PlanS_conform":"1","fulldoi":"https://doi.org/10.1051/0004-6361/202556410","quality_controlled":"1","year":"2025","external_id":{"arxiv":["2507.11045"]},"abstract":[{"text":"Identifying Lyman continuum (LyC) leakers at intermediate redshifts is crucial for understanding the properties of cosmic reionizers because the opacity of the intergalactic medium (IGM) prevents the direct detection of LyC emission from sources during the Epoch of Reionization (EoR). In this study, we confirm two new LyC candidate leakers at z ∼ 3 in the Abell 2744 cluster field, with absolute escape fractions (fesc) of 0.83−0.80+0.15 and 0.74−0.70+0.23, respectively. The LyC emission was detected using HST/WFC3/F275W and F336W imaging. These two candidate leakers appear to be faint (MUV = −17.61 ± 0.06 and −18.22 ± 0.10), exhibit blue UV continuum slopes (β = −2.43 ± 0.05 and −1.92 ± 0.09), have low masses (M★ ∼ 107.51 ± 0.03 and 107.17 ± 0.15 M⊙) and Lyα equivalent widths of 90 ± 3 Å and 28 ± 12 Å, respectively. These two LyC candidate leakers were detected in a catalog of 91 spectroscopically confirmed sources using public spectra from the JWST and/or MUSE. We also analyzed properties that were proposed as indirect indicators of LyC emission, such as Lyα, the O32 ratio, and M★. We created a galaxy subsample that was selected according to these properties, stacked the LyC observations of this subsample, and assessed the limits of the escape fractions in the stacks. We aim to enhance our understanding of LyC escape mechanisms and improve our predictions of the LyC fesc during the EoR by analyzing the individual candidates and the stacks in the context of the currently limited sample of known LyC leakers at z ∼ 3.","lang":"eng"}],"article_number":"A328","file":[{"access_level":"open_access","file_name":"2025_AstronomyAstrophysics_Liu.pdf","date_updated":"2026-01-05T09:26:17Z","date_created":"2026-01-05T09:26:17Z","success":1,"content_type":"application/pdf","creator":"dernst","checksum":"3e6061f3c4bfb521b3333ea4913c241a","file_id":"20938","file_size":4642530,"relation":"main_file"}],"DOAJ_listed":"1","intvolume":"       704","language":[{"iso":"eng"}],"oa_version":"Published Version","day":"01","date_updated":"2026-02-16T12:14:52Z","title":"A Lyman continuum analysis of ∼100 galaxies at z spec∼ 3 in the Abell 2744 cluster field","OA_type":"diamond","doi":"10.1051/0004-6361/202556410","file_date_updated":"2026-01-05T09:26:17Z","status":"public","type":"journal_article","acknowledgement":"We acknowledge support from the National Science Foundation of China – 12225301, INAF Large grant “Spectroscopic survey with JWST” jand from PRIN 2022 MUR project 2022CB3PJ3 – First Light And Galaxy aSsembly (FLAGS) funded by the European Union – Next Generation EU, and Postgraduate Scholarship Program under the grant of China Scholarship Council. P.W. and B.V. acknowledge support from the INAF Mini Grant ‘1.05.24.07.01 RSN1: Spatially Resolved Near-IR Emission of Intermediate-Redshift Jellyfish Galaxies’ (PI Watson). We acknowledge A. Acebron, C. Grillo, and P. Rosati for their fundamental contribution to the strong lensing analysis and results. We also extend our gratitude to the JWST and HST teams for their efforts in designing, building, and operating these transformative missions.","date_created":"2026-01-04T23:01:35Z","tmp":{"short":"CC BY (4.0)","image":"/images/cc_by.png","name":"Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)","legal_code_url":"https://creativecommons.org/licenses/by/4.0/legalcode"},"author":[{"first_name":"Y.","last_name":"Liu","full_name":"Liu, Y."},{"last_name":"Mascia","first_name":"Sara","id":"edaf889c-c7cd-11ef-ab1b-bb28c431bd29","full_name":"Mascia, Sara"},{"last_name":"Pentericci","first_name":"L.","full_name":"Pentericci, L."},{"first_name":"P.","last_name":"Watson","full_name":"Watson, P."},{"full_name":"Alavi, A.","first_name":"A.","last_name":"Alavi"},{"full_name":"Bergamini, P.","first_name":"P.","last_name":"Bergamini"},{"last_name":"Bradač","first_name":"M.","full_name":"Bradač, M."},{"last_name":"Calabrò","first_name":"A.","full_name":"Calabrò, A."},{"last_name":"Glazebrook","first_name":"K.","full_name":"Glazebrook, K."},{"full_name":"Henry, A.","first_name":"A.","last_name":"Henry"},{"last_name":"Llerena","first_name":"M.","full_name":"Llerena, M."},{"first_name":"E.","last_name":"Merlin","full_name":"Merlin, E."},{"full_name":"Metha, B.","last_name":"Metha","first_name":"B."},{"full_name":"Nanayakkara, T.","last_name":"Nanayakkara","first_name":"T."},{"full_name":"Napolitano, L.","first_name":"L.","last_name":"Napolitano"},{"full_name":"Roy, N.","last_name":"Roy","first_name":"N."},{"first_name":"B.","last_name":"Siana","full_name":"Siana, B."},{"last_name":"Vanzella","first_name":"E.","full_name":"Vanzella, E."},{"full_name":"Vulcani, B.","last_name":"Vulcani","first_name":"B."},{"first_name":"X.","last_name":"Wang","full_name":"Wang, X."}],"ddc":["520"]},{"acknowledgement":"This work is based on observations made with the NASA/ESA/CSA James Webb Space Telescope. The data were obtained from the Mikulski Archive for Space Telescopes at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-03127 for JWST. These observations are associated with programs GTO 1243, ERS 1345, DDT 2750, and GTO 1180, 1181, 3215, 1210, 1286. Funded by the European Union (ERC, AGENTS, 101076224). Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or the European Research Council. Neither the European Union nor the granting authority can be held responsible for them. We acknowledge support from the INAF Large Grant 2022 “Extragalactic Surveys with JWST” (PI Pentericci). We acknowledge support from INAF Mini-grant “Reionization and Fundamental Cosmology with High-Redshift Galaxies” and from PRIN 2022 MUR project 2022CB3PJ3 - First Light And Galaxy aSsembly (FLAGS) funded by the European Union – Next Generation EU. RA acknowledges support of Grant PID2023-147386NB-I00 funded by MICIU/AEI/10.13039/501100011033 and by ERDF/EU, and the Severo Ochoa grant CEX2021-001131-S funded by MCIN/AEI/10.13039/50110001103. The project that gave rise to these results received the support of a fellowship from the “la Caixa” Foundation (ID 100010434). The fellowship code is LCF/BQ/PR24/12050015. LC acknowledges support from grants PID2022-139567NB-I00 and PIB2021-127718NB-I00 funded by the Spanish Ministry of Science and Innovation/State Agency of Research MCIN/AEI/10.13039/501100011033 and by “ERDF A way of making Europe”.","date_created":"2026-01-28T15:24:24Z","tmp":{"short":"CC BY (4.0)","image":"/images/cc_by.png","name":"Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)","legal_code_url":"https://creativecommons.org/licenses/by/4.0/legalcode"},"corr_author":"1","ddc":["520"],"author":[{"full_name":"Mascia, Sara","first_name":"Sara","id":"edaf889c-c7cd-11ef-ab1b-bb28c431bd29","last_name":"Mascia"},{"first_name":"L.","last_name":"Pentericci","full_name":"Pentericci, L."},{"first_name":"M.","last_name":"Llerena","full_name":"Llerena, M."},{"full_name":"Calabrò, A.","last_name":"Calabrò","first_name":"A."},{"id":"7439a258-f3c0-11ec-9501-9df22fe06720","first_name":"Jorryt J","last_name":"Matthee","orcid":"0000-0003-2871-127X","full_name":"Matthee, Jorryt J"},{"last_name":"Flury","first_name":"S.","full_name":"Flury, S."},{"first_name":"F.","last_name":"Pacucci","full_name":"Pacucci, F."},{"full_name":"Jaskot, A.","first_name":"A.","last_name":"Jaskot"},{"full_name":"Amorín, R. O.","first_name":"R. O.","last_name":"Amorín"},{"full_name":"Bhatawdekar, R.","first_name":"R.","last_name":"Bhatawdekar"},{"full_name":"Castellano, M.","last_name":"Castellano","first_name":"M."},{"full_name":"Cleri, N.","last_name":"Cleri","first_name":"N."},{"full_name":"Costantin, L.","last_name":"Costantin","first_name":"L."},{"full_name":"Davis, K.","last_name":"Davis","first_name":"K."},{"first_name":"Claudia","id":"2d002343-372f-11ef-98ec-a164d20427cb","last_name":"Di Cesare","full_name":"Di Cesare, Claudia"},{"last_name":"Dickinson","first_name":"M.","full_name":"Dickinson, M."},{"full_name":"Fontana, A.","last_name":"Fontana","first_name":"A."},{"full_name":"Guo, Y.","last_name":"Guo","first_name":"Y."},{"last_name":"Giavalisco","first_name":"M.","full_name":"Giavalisco, M."},{"full_name":"Holwerda, B. W.","last_name":"Holwerda","first_name":"B. W."},{"full_name":"Hu, W.","last_name":"Hu","first_name":"W."},{"full_name":"Huertas-Company, M.","last_name":"Huertas-Company","first_name":"M."},{"full_name":"Jung, Intae","last_name":"Jung","first_name":"Intae"},{"first_name":"J.","last_name":"Kartaltepe","full_name":"Kartaltepe, J."},{"last_name":"Kashino","first_name":"D.","full_name":"Kashino, D."},{"full_name":"Koekemoer, A. M.","last_name":"Koekemoer","first_name":"A. M."},{"last_name":"Lucas","first_name":"R. A.","full_name":"Lucas, R. A."},{"first_name":"J.","last_name":"Lotz","full_name":"Lotz, J."},{"full_name":"Napolitano, L.","last_name":"Napolitano","first_name":"L."},{"last_name":"Jogee","first_name":"S.","full_name":"Jogee, S."},{"full_name":"Wilkins, S.","first_name":"S.","last_name":"Wilkins"}],"status":"public","doi":"10.1051/0004-6361/202553760","file_date_updated":"2026-02-09T07:28:08Z","OA_type":"diamond","type":"journal_article","file":[{"relation":"main_file","file_size":9994234,"date_created":"2026-02-09T07:28:08Z","checksum":"990e384ca19e14b35296712d3b9e2919","success":1,"content_type":"application/pdf","creator":"dernst","file_id":"21166","access_level":"open_access","date_updated":"2026-02-09T07:28:08Z","file_name":"2025_AstronomyAstrophysics_Mascia.pdf"}],"DOAJ_listed":"1","abstract":[{"lang":"eng","text":"Compact, star-forming galaxies with high star formation rate surface densities (ΣSFR) are often efficient Lyman continuum (LyC) emitters at z ≤ 4.5, likely because intense stellar feedback creates low-density channels that allow photons to escape. Irregular or disturbed morphologies, such as those resulting from mergers, can also facilitate LyC escape by creating anisotropic gas distributions. We investigated the influence of galaxy morphology on LyC production and escape at redshifts 5 ≤ z ≤ 7 using observations from various James Webb Space Telescope (JWST) surveys. Our sample consists of 436 sources, which are predominantly low-mass (∼10^8.15 M\f), star-forming galaxies with ionizing photon efficiency (ξion) values consistent with canonical expectations. Since direct measurements of fesc are not possible during the Epoch of  Reionization (EoR), we predicted fesc for high-redshift galaxies by applying survival analysis to a subsample of LyC emitters from the Low-Redshift Lyman Continuum Survey (LzLCS), selected to be direct analogs of reionization-era galaxies. We find that these galaxies exhibit, on average, modest predicted escape fractions (∼0.04). In addition, we evaluated the correlation between morphological features and LyC emission. Our findings indicate that neither ξion nor the predicted fesc values show a significant correlation with the presence of merger signatures. This suggests that in low-mass galaxies at z ≥ 5, strong morphological disturbances are not the primary mechanism driving LyC emission and leakage. Instead, compactness and star formation activity likely play a more pivotal role in regulating LyC escape. "}],"article_number":"A122","intvolume":"       701","oa_version":"Published Version","language":[{"iso":"eng"}],"date_updated":"2026-02-09T07:33:46Z","title":"Little impact of mergers and galaxy morphology on the production and escape of ionizing photons in the early Universe","day":"01","quality_controlled":"1","year":"2025","external_id":{"arxiv":["2501.08268"]},"_id":"21060","publication_identifier":{"issn":["0004-6361"],"eissn":["1432-0746"]},"publication":"Astronomy & Astrophysics","publisher":"EDP Sciences","scopus_import":"1","PlanS_conform":"1","fulldoi":"https://doi.org/10.1051/0004-6361/202553760","has_accepted_license":"1","oa":1,"arxiv":1,"OA_place":"publisher","project":[{"name":"Young galaxies as tracers and agents of cosmic reionization","grant_number":"101076224","_id":"bd9b2118-d553-11ed-ba76-db24564edfea"}],"citation":{"mla":"Mascia, Sara, et al. “Little Impact of Mergers and Galaxy Morphology on the Production and Escape of Ionizing Photons in the Early Universe.” <i>Astronomy &#38; Astrophysics</i>, vol. 701, A122, EDP Sciences, 2025, doi:<a href=\"https://doi.org/10.1051/0004-6361/202553760\">10.1051/0004-6361/202553760</a>.","ista":"Mascia S, Pentericci L, Llerena M, Calabrò A, Matthee JJ, Flury S, Pacucci F, Jaskot A, Amorín RO, Bhatawdekar R, Castellano M, Cleri N, Costantin L, Davis K, Di Cesare C, Dickinson M, Fontana A, Guo Y, Giavalisco M, Holwerda BW, Hu W, Huertas-Company M, Jung I, Kartaltepe J, Kashino D, Koekemoer AM, Lucas RA, Lotz J, Napolitano L, Jogee S, Wilkins S. 2025. Little impact of mergers and galaxy morphology on the production and escape of ionizing photons in the early Universe. Astronomy &#38; Astrophysics. 701, A122.","apa":"Mascia, S., Pentericci, L., Llerena, M., Calabrò, A., Matthee, J. J., Flury, S., … Wilkins, S. (2025). Little impact of mergers and galaxy morphology on the production and escape of ionizing photons in the early Universe. <i>Astronomy &#38; Astrophysics</i>. EDP Sciences. <a href=\"https://doi.org/10.1051/0004-6361/202553760\">https://doi.org/10.1051/0004-6361/202553760</a>","short":"S. Mascia, L. Pentericci, M. Llerena, A. Calabrò, J.J. Matthee, S. Flury, F. Pacucci, A. Jaskot, R.O. Amorín, R. Bhatawdekar, M. Castellano, N. Cleri, L. Costantin, K. Davis, C. Di Cesare, M. Dickinson, A. Fontana, Y. Guo, M. Giavalisco, B.W. Holwerda, W. Hu, M. Huertas-Company, I. Jung, J. Kartaltepe, D. Kashino, A.M. Koekemoer, R.A. Lucas, J. Lotz, L. Napolitano, S. Jogee, S. Wilkins, Astronomy &#38; Astrophysics 701 (2025).","ieee":"S. Mascia <i>et al.</i>, “Little impact of mergers and galaxy morphology on the production and escape of ionizing photons in the early Universe,” <i>Astronomy &#38; Astrophysics</i>, vol. 701. EDP Sciences, 2025.","ama":"Mascia S, Pentericci L, Llerena M, et al. Little impact of mergers and galaxy morphology on the production and escape of ionizing photons in the early Universe. <i>Astronomy &#38; Astrophysics</i>. 2025;701. doi:<a href=\"https://doi.org/10.1051/0004-6361/202553760\">10.1051/0004-6361/202553760</a>","chicago":"Mascia, Sara, L. Pentericci, M. Llerena, A. Calabrò, Jorryt J Matthee, S. Flury, F. Pacucci, et al. “Little Impact of Mergers and Galaxy Morphology on the Production and Escape of Ionizing Photons in the Early Universe.” <i>Astronomy &#38; Astrophysics</i>. EDP Sciences, 2025. <a href=\"https://doi.org/10.1051/0004-6361/202553760\">https://doi.org/10.1051/0004-6361/202553760</a>."},"volume":701,"article_processing_charge":"No","department":[{"_id":"JoMa"}],"article_type":"original","user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","month":"09","publication_status":"published","date_published":"2025-09-01T00:00:00Z"},{"language":[{"iso":"eng"}],"oa_version":"Published Version","day":"01","date_updated":"2026-02-16T12:11:39Z","title":"Evolution of the UV slope of galaxies at cosmic morning (z > 4): The properties of extremely blue galaxies","article_number":"A234","abstract":[{"lang":"eng","text":"We present an analysis of the UV continuum slope, β, using a sample of 726 galaxies with z > 4, selected from a mixture of JWST ERS, GTO, and GO observational programs. We considered only spectroscopic data obtained with the low-resolution (R ∼ 30 − 300) PRISM/CLEAR NIRSpec configuration. Studying the correlation between β and MUV, we find an overall decreasing trend, described by β = ( − 0.055 ± 0.017)MUV + ( − 2.98 ± 0.34). This is consistent with previous studies, where brighter galaxies show redder β values. However, when analyzing the trend in separate redshift bins, we find that at high redshift the relation becomes much flatter and is consistent with a flat slope within 1σ. Furthermore, we find that β tends to decrease with redshift, following β = ( − 0.075 ± 0.010)z + ( − 1.496 ± 0.056). This is consistent with most recent results showing a steepening of the spectra at higher z. We selected a sample of galaxies with extremely blue slopes (i.e., β < −2.6). Such slopes are steeper than predicted by stellar evolution models – even for dust-free, young, metal-poor populations – when the contribution of nebular emission is included. We selected 44 extremely blue galaxies (XBGs) and investigated the possible physical origin of their steep slopes by comparing them to a subsample of redder galaxies (matched in Δz = ±0.5 and ΔMUV = ±0.2). We find that XBGs have younger stellar populations, stronger ionization fields, lower dust attenuation, and lower but not pristine metallicity (∼10% Z⊙) compared to red galaxies. However, these properties alone cannot explain the extreme β values. Using indirect inference of Lyman continuum escape with the most recent models, we estimated the escape fraction fesc > 10% in at least 25% of the XBGs, whereas all the red sources exhibit much lower fesc values. A reduced nebular continuum contribution – resulting from either a high escape fraction or a bursty star formation history – is likely the origin of the extremely blue slopes."}],"file":[{"file_size":2442076,"relation":"main_file","access_level":"open_access","file_name":"2025_AstronomyAstrophysics_Dottorini.pdf","date_updated":"2025-06-30T08:22:08Z","checksum":"100f897d468de9d0113277c870035b62","success":1,"creator":"dernst","content_type":"application/pdf","file_id":"19932","date_created":"2025-06-30T08:22:08Z"}],"intvolume":"       698","year":"2025","external_id":{"arxiv":["2412.01623"],"isi":["001510826300019"]},"quality_controlled":"1","isi":1,"tmp":{"short":"CC BY (4.0)","image":"/images/cc_by.png","name":"Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)","legal_code_url":"https://creativecommons.org/licenses/by/4.0/legalcode"},"author":[{"full_name":"Dottorini, D.","last_name":"Dottorini","first_name":"D."},{"last_name":"Calabrò","first_name":"A.","full_name":"Calabrò, A."},{"first_name":"L.","last_name":"Pentericci","full_name":"Pentericci, L."},{"first_name":"Sara","id":"edaf889c-c7cd-11ef-ab1b-bb28c431bd29","last_name":"Mascia","full_name":"Mascia, Sara"},{"last_name":"Llerena","first_name":"M.","full_name":"Llerena, M."},{"full_name":"Napolitano, L.","first_name":"L.","last_name":"Napolitano"},{"full_name":"Santini, P.","first_name":"P.","last_name":"Santini"},{"last_name":"Roberts-Borsani","first_name":"G.","full_name":"Roberts-Borsani, G."},{"last_name":"Castellano","first_name":"M.","full_name":"Castellano, M."},{"first_name":"R.","last_name":"Amorin","full_name":"Amorin, R."},{"first_name":"M.","last_name":"Dickinson","full_name":"Dickinson, M."},{"full_name":"Fontana, A.","last_name":"Fontana","first_name":"A."},{"first_name":"N.","last_name":"Hathi","full_name":"Hathi, N."},{"full_name":"Hirschmann, M.","last_name":"Hirschmann","first_name":"M."},{"last_name":"Koekemoer","first_name":"A. M.","full_name":"Koekemoer, A. M."},{"last_name":"Lucas","first_name":"R. A.","full_name":"Lucas, R. A."},{"full_name":"Merlin, E.","last_name":"Merlin","first_name":"E."},{"full_name":"Morales, A.","last_name":"Morales","first_name":"A."},{"full_name":"Pacucci, F.","last_name":"Pacucci","first_name":"F."},{"full_name":"Wilkins, S.","first_name":"S.","last_name":"Wilkins"},{"last_name":"Arrabal Haro","first_name":"P.","full_name":"Arrabal Haro, P."},{"full_name":"Bagley, M.","last_name":"Bagley","first_name":"M."},{"full_name":"Finkelstein, S. L.","last_name":"Finkelstein","first_name":"S. L."},{"first_name":"J.","last_name":"Kartaltepe","full_name":"Kartaltepe, J."},{"full_name":"Papovich, C.","first_name":"C.","last_name":"Papovich"},{"last_name":"Pirzkal","first_name":"N.","full_name":"Pirzkal, N."}],"ddc":["520"],"acknowledgement":"We acknowledges support from the INAF Large Grant for Extragalactic Surveys with JWST and from the PRIN 2022 MUR project 2022CB3PJ3 – First Light And Galaxy aSsembly (FLAGS) funded by the European Union – Next Generation EU. PS acknowledges INAF Mini Grant 2022 “The evolution of passive galaxies through cosmic time”. Part of the research activities described in this paper were carried out with the contribution of the Next Generation EU funds within the National Recovery and Resilience Plan (PNRR), Mission 4 – Education and Research, Component 2 – From Research to Business (M4C2), Investment Line 3.1 – Strengthening and creation of Research Infrastructures, Project IR0000034 – “STILES – Strengthening the Italian Leadership in ELT and SKA”. RA acknowledges support of Grant project PID2023-147386NB-I00 funded by MICIU/AEI/10.13039/501100011033 and by ERDF/EU, and the Severo Ochoa grant CEX2021-001131-S funded by MCIN/AEI/10.13039/50110001103.","date_created":"2025-06-29T22:01:15Z","OA_type":"diamond","status":"public","file_date_updated":"2025-06-30T08:22:08Z","doi":"10.1051/0004-6361/202453267","type":"journal_article","article_processing_charge":"No","department":[{"_id":"JoMa"}],"citation":{"short":"D. Dottorini, A. Calabrò, L. Pentericci, S. Mascia, M. Llerena, L. Napolitano, P. Santini, G. Roberts-Borsani, M. Castellano, R. Amorin, M. Dickinson, A. Fontana, N. Hathi, M. Hirschmann, A.M. Koekemoer, R.A. Lucas, E. Merlin, A. Morales, F. Pacucci, S. Wilkins, P. Arrabal Haro, M. Bagley, S.L. Finkelstein, J. Kartaltepe, C. Papovich, N. Pirzkal, Astronomy &#38; Astrophysics 698 (2025).","mla":"Dottorini, D., et al. “Evolution of the UV Slope of Galaxies at Cosmic Morning (z &#62; 4): The Properties of Extremely Blue Galaxies.” <i>Astronomy &#38; Astrophysics</i>, vol. 698, A234, EDP Sciences, 2025, doi:<a href=\"https://doi.org/10.1051/0004-6361/202453267\">10.1051/0004-6361/202453267</a>.","ista":"Dottorini D, Calabrò A, Pentericci L, Mascia S, Llerena M, Napolitano L, Santini P, Roberts-Borsani G, Castellano M, Amorin R, Dickinson M, Fontana A, Hathi N, Hirschmann M, Koekemoer AM, Lucas RA, Merlin E, Morales A, Pacucci F, Wilkins S, Arrabal Haro P, Bagley M, Finkelstein SL, Kartaltepe J, Papovich C, Pirzkal N. 2025. Evolution of the UV slope of galaxies at cosmic morning (z &#62; 4): The properties of extremely blue galaxies. Astronomy &#38; Astrophysics. 698, A234.","apa":"Dottorini, D., Calabrò, A., Pentericci, L., Mascia, S., Llerena, M., Napolitano, L., … Pirzkal, N. (2025). Evolution of the UV slope of galaxies at cosmic morning (z &#62; 4): The properties of extremely blue galaxies. <i>Astronomy &#38; Astrophysics</i>. EDP Sciences. <a href=\"https://doi.org/10.1051/0004-6361/202453267\">https://doi.org/10.1051/0004-6361/202453267</a>","ieee":"D. Dottorini <i>et al.</i>, “Evolution of the UV slope of galaxies at cosmic morning (z &#62; 4): The properties of extremely blue galaxies,” <i>Astronomy &#38; Astrophysics</i>, vol. 698. EDP Sciences, 2025.","chicago":"Dottorini, D., A. Calabrò, L. Pentericci, Sara Mascia, M. Llerena, L. Napolitano, P. Santini, et al. “Evolution of the UV Slope of Galaxies at Cosmic Morning (z &#62; 4): The Properties of Extremely Blue Galaxies.” <i>Astronomy &#38; Astrophysics</i>. EDP Sciences, 2025. <a href=\"https://doi.org/10.1051/0004-6361/202453267\">https://doi.org/10.1051/0004-6361/202453267</a>.","ama":"Dottorini D, Calabrò A, Pentericci L, et al. Evolution of the UV slope of galaxies at cosmic morning (z &#62; 4): The properties of extremely blue galaxies. <i>Astronomy &#38; Astrophysics</i>. 2025;698. doi:<a href=\"https://doi.org/10.1051/0004-6361/202453267\">10.1051/0004-6361/202453267</a>"},"volume":698,"month":"06","publication_status":"published","date_published":"2025-06-01T00:00:00Z","article_type":"original","user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","publisher":"EDP Sciences","scopus_import":"1","fulldoi":"https://doi.org/10.1051/0004-6361/202453267","publication_identifier":{"issn":["0004-6361"],"eissn":["1432-0746"]},"_id":"19930","publication":"Astronomy & Astrophysics","OA_place":"publisher","arxiv":1,"has_accepted_license":"1","oa":1},{"OA_type":"diamond","status":"public","doi":"10.1051/0004-6361/202453251","file_date_updated":"2025-07-08T06:17:02Z","type":"journal_article","tmp":{"short":"CC BY (4.0)","image":"/images/cc_by.png","name":"Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)","legal_code_url":"https://creativecommons.org/licenses/by/4.0/legalcode"},"author":[{"full_name":"Llerena, M.","last_name":"Llerena","first_name":"M."},{"full_name":"Pentericci, L.","first_name":"L.","last_name":"Pentericci"},{"first_name":"L.","last_name":"Napolitano","full_name":"Napolitano, L."},{"full_name":"Mascia, Sara","last_name":"Mascia","first_name":"Sara","id":"edaf889c-c7cd-11ef-ab1b-bb28c431bd29"},{"last_name":"Amorín","first_name":"R.","full_name":"Amorín, R."},{"full_name":"Calabrò, A.","first_name":"A.","last_name":"Calabrò"},{"last_name":"Castellano","first_name":"M.","full_name":"Castellano, M."},{"last_name":"Cleri","first_name":"N. J.","full_name":"Cleri, N. J."},{"first_name":"M.","last_name":"Giavalisco","full_name":"Giavalisco, M."},{"first_name":"N. A.","last_name":"Grogin","full_name":"Grogin, N. A."},{"last_name":"Hathi","first_name":"N. P.","full_name":"Hathi, N. P."},{"last_name":"Hirschmann","first_name":"M.","full_name":"Hirschmann, M."},{"last_name":"Koekemoer","first_name":"A. M.","full_name":"Koekemoer, A. M."},{"full_name":"Nanayakkara, T.","last_name":"Nanayakkara","first_name":"T."},{"last_name":"Pacucci","first_name":"F.","full_name":"Pacucci, F."},{"full_name":"Shen, L.","last_name":"Shen","first_name":"L."},{"full_name":"Wilkins, S. M.","first_name":"S. M.","last_name":"Wilkins"},{"first_name":"I.","last_name":"Yoon","full_name":"Yoon, I."},{"last_name":"Yung","first_name":"L. Y.A.","full_name":"Yung, L. Y.A."},{"first_name":"R.","last_name":"Bhatawdekar","full_name":"Bhatawdekar, R."},{"full_name":"Lucas, R. A.","last_name":"Lucas","first_name":"R. A."},{"last_name":"Wang","first_name":"X.","full_name":"Wang, X."},{"first_name":"P.","last_name":"Arrabal Haro","full_name":"Arrabal Haro, P."},{"last_name":"Bagley","first_name":"M. B.","full_name":"Bagley, M. B."},{"full_name":"Finkelstein, S. L.","first_name":"S. L.","last_name":"Finkelstein"},{"last_name":"Kartaltepe","first_name":"J. S.","full_name":"Kartaltepe, J. S."},{"first_name":"E.","last_name":"Merlin","full_name":"Merlin, E."},{"last_name":"Papovich","first_name":"C.","full_name":"Papovich, C."},{"last_name":"Pirzkal","first_name":"N.","full_name":"Pirzkal, N."},{"first_name":"P.","last_name":"Santini","full_name":"Santini, P."}],"ddc":["520"],"acknowledgement":"We thank the anonymous referee for the detailed review and useful suggestions that helped to improve this paper. We wish to thank all our colleagues in the CEERS collaboration for their hard work and valuable contributions to this project. We thank Pietro Bergamini for providing us with the magnification factors for the lensed sources. MLl acknowledges support from the INAF Large Grant 2022 “Extragalactic Surveys with JWST” (PI L. Pentericci), the PRIN 2022 MUR project 2022CB3PJ3 – First Light And Galaxy aSsembly (FLAGS) funded by the European Union – Next Generation EU, and INAF Mini-grant “Galaxies in the epoch of Reionization and their analogs at lower redshift” (PI M. Llerena). RA acknowledges support of grant PID2023-147386NB-I00 funded by MICIU/AEI/10.13039/501100011033 and by ERDF/EU, and the Severo Ochoa grant CEX2021-001131-S This work is based on observations made with the NASA/ESA/CSA James Webb Space Telescope (JWST). The JWST data presented in this article were obtained from the Mikulski Archive for Space Telescopes (MAST) at the Space Telescope Science Institute. The specific observations analyzed are associated with program JWST-GO-3073 and can be accessed via DOI. We acknowledge support from INAF Mini-grant “Reionization and Fundamental Cosmology with High-Redshift Galaxies”. This work has made extensive use of Python packages astropy (Astropy Collaboration 2018), numpy (Harris et al. 2020), Matplotlib (Hunter 2007) and LiMe (Fernández et al. 2024).","date_created":"2025-07-06T22:01:23Z","year":"2025","external_id":{"arxiv":["2412.01358"],"isi":["001512479700026"]},"quality_controlled":"1","isi":1,"language":[{"iso":"eng"}],"oa_version":"Published Version","day":"20","date_updated":"2026-02-16T12:12:15Z","title":"The ionizing photon production efficiency of star-forming galaxies at z ∼ 4–10","article_number":"A302","abstract":[{"text":"Context. Investigating the ionizing emission of star-forming galaxies and the escape fraction of ionizing photons is critical to understanding their contribution to reionization and their impact on the surrounding environment. The number of ionizing photons available to reionize the intergalactic medium (IGM) depends on not only the abundance of galaxies but also their efficiency in producing ionizing photons (ξion). This quantity is thus fundamental to quantify the role of faint versus bright sources in driving this process, as we must assess their relative contribution to the total ionizing emissivity.\r\n\r\nAims. Our goal is to estimate the ξion using Balmer lines (Hα or Hβ) in a sample of 761 galaxies at 4 ≤ z ≤ 10 selected from different JWST spectroscopic surveys. We aim to determine the redshift evolution of ξion and the relation of ξion with the physical properties of the galaxies.\r\n\r\nMethods. We used the available HST and JWST photometry to perform a spectral energy distribution (SED) fitting in the sample to determine their physical properties and relate them with ξion. We used the BAGPIPES code for the SED fitting and assumed a delayed exponential model for the star formation history. We used the NIRSpec spectra from prism or grating configurations to estimate Balmer luminosities, and then constrained ξion values after dust correction.\r\n\r\nResults. We find a mean value of 1025.22 Hz erg−1 for ξion in the sample with an observed scatter of 0.42 dex. We find an increase in the median values of ξion with redshift from 1025.09 Hz erg−1 at z ∼ 4.18 to 1025.28 Hz erg−1 at z ∼ 7.14, confirming the redshift evolution of ξion found in other studies. Regarding the relation between ξion and physical properties, we find a decrease in ξion with increasing stellar mass, indicating that low-mass galaxies are efficient producers of ionizing photons. We also find an increase in ξion with increasing specific star formation rate (sSFR) and increasing UV absolute magnitude. This indicates that faint galaxies and galaxies with high sSFR are also efficient producers. We also investigated the relation of ξion with the rest-frame equivalent width (EW) of [OIII]λ5007 and find that galaxies with the higher EW([OIII]λ5007) are more efficient producers of ionizing photons, with the best fit leading to the relation log(ξion)  =  0.43 × log(EW[OIII])+23.99. Similarly, we find that galaxies with higher O32 = [OIII]λ5007/[OII]λλ3727,3729 and lower gas-phase metallicities (based on the R23 = ([OIII]λλ4959,5007+[OII]λλ3727,3729)/Hβ calibration) show higher ξion values.","lang":"eng"}],"file":[{"relation":"main_file","file_size":7557993,"checksum":"92745034d9448d38b6b0394407ae39a0","success":1,"creator":"dernst","content_type":"application/pdf","file_id":"19974","date_created":"2025-07-08T06:17:02Z","access_level":"open_access","file_name":"2025_AstronomyAstrophysics_Llerena.pdf","date_updated":"2025-07-08T06:17:02Z"}],"intvolume":"       698","arxiv":1,"OA_place":"publisher","has_accepted_license":"1","oa":1,"publisher":"EDP Sciences","scopus_import":"1","fulldoi":"https://doi.org/10.1051/0004-6361/202453251","_id":"19967","publication_identifier":{"eissn":["1432-0746"],"issn":["0004-6361"]},"publication":"Astronomy & Astrophysics","month":"06","publication_status":"published","date_published":"2025-06-20T00:00:00Z","article_type":"original","user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","article_processing_charge":"No","department":[{"_id":"JoMa"}],"citation":{"short":"M. Llerena, L. Pentericci, L. Napolitano, S. Mascia, R. Amorín, A. Calabrò, M. Castellano, N.J. Cleri, M. Giavalisco, N.A. Grogin, N.P. Hathi, M. Hirschmann, A.M. Koekemoer, T. Nanayakkara, F. Pacucci, L. Shen, S.M. Wilkins, I. Yoon, L.Y.A. Yung, R. Bhatawdekar, R.A. Lucas, X. Wang, P. Arrabal Haro, M.B. Bagley, S.L. Finkelstein, J.S. Kartaltepe, E. Merlin, C. Papovich, N. Pirzkal, P. Santini, Astronomy &#38; Astrophysics 698 (2025).","apa":"Llerena, M., Pentericci, L., Napolitano, L., Mascia, S., Amorín, R., Calabrò, A., … Santini, P. (2025). The ionizing photon production efficiency of star-forming galaxies at z ∼ 4–10. <i>Astronomy &#38; Astrophysics</i>. EDP Sciences. <a href=\"https://doi.org/10.1051/0004-6361/202453251\">https://doi.org/10.1051/0004-6361/202453251</a>","mla":"Llerena, M., et al. “The Ionizing Photon Production Efficiency of Star-Forming Galaxies at z ∼ 4–10.” <i>Astronomy &#38; Astrophysics</i>, vol. 698, A302, EDP Sciences, 2025, doi:<a href=\"https://doi.org/10.1051/0004-6361/202453251\">10.1051/0004-6361/202453251</a>.","ista":"Llerena M, Pentericci L, Napolitano L, Mascia S, Amorín R, Calabrò A, Castellano M, Cleri NJ, Giavalisco M, Grogin NA, Hathi NP, Hirschmann M, Koekemoer AM, Nanayakkara T, Pacucci F, Shen L, Wilkins SM, Yoon I, Yung LYA, Bhatawdekar R, Lucas RA, Wang X, Arrabal Haro P, Bagley MB, Finkelstein SL, Kartaltepe JS, Merlin E, Papovich C, Pirzkal N, Santini P. 2025. The ionizing photon production efficiency of star-forming galaxies at z ∼ 4–10. Astronomy &#38; Astrophysics. 698, A302.","ieee":"M. Llerena <i>et al.</i>, “The ionizing photon production efficiency of star-forming galaxies at z ∼ 4–10,” <i>Astronomy &#38; Astrophysics</i>, vol. 698. EDP Sciences, 2025.","chicago":"Llerena, M., L. Pentericci, L. Napolitano, Sara Mascia, R. Amorín, A. Calabrò, M. Castellano, et al. “The Ionizing Photon Production Efficiency of Star-Forming Galaxies at z ∼ 4–10.” <i>Astronomy &#38; Astrophysics</i>. EDP Sciences, 2025. <a href=\"https://doi.org/10.1051/0004-6361/202453251\">https://doi.org/10.1051/0004-6361/202453251</a>.","ama":"Llerena M, Pentericci L, Napolitano L, et al. The ionizing photon production efficiency of star-forming galaxies at z ∼ 4–10. <i>Astronomy &#38; Astrophysics</i>. 2025;698. doi:<a href=\"https://doi.org/10.1051/0004-6361/202453251\">10.1051/0004-6361/202453251</a>"},"volume":698},{"oa":1,"has_accepted_license":"1","arxiv":1,"OA_place":"publisher","publication":"Monthly Notices of the Royal Astronomical Society","_id":"20661","publication_identifier":{"eissn":["1365-2966"],"issn":["0035-8711"]},"fulldoi":"https://doi.org/10.1093/mnras/staf1837","scopus_import":"1","publisher":"Oxford University Press","PlanS_conform":"1","user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","article_type":"original","publication_status":"published","date_published":"2025-12-01T00:00:00Z","month":"12","volume":544,"citation":{"ieee":"N. Dalmasso <i>et al.</i>, “Quantifying spectroscopic flux variations between JWST NIRISS and NIRSpec: Slit losses in emission line measurements of z ∼ 1-3 galaxies,” <i>Monthly Notices of the Royal Astronomical Society</i>, vol. 544, no. 2. Oxford University Press, pp. 1915–1925, 2025.","short":"N. Dalmasso, P.J. Watson, T. Treu, M. Trenti, B. Vulcani, T. Nanayakkara, M. Bradač, T. Jones, K. Boyett, X. Wang, S. Mascia, L. Pentericci, Monthly Notices of the Royal Astronomical Society 544 (2025) 1915–1925.","apa":"Dalmasso, N., Watson, P. J., Treu, T., Trenti, M., Vulcani, B., Nanayakkara, T., … Pentericci, L. (2025). Quantifying spectroscopic flux variations between JWST NIRISS and NIRSpec: Slit losses in emission line measurements of z ∼ 1-3 galaxies. <i>Monthly Notices of the Royal Astronomical Society</i>. Oxford University Press. <a href=\"https://doi.org/10.1093/mnras/staf1837\">https://doi.org/10.1093/mnras/staf1837</a>","ista":"Dalmasso N, Watson PJ, Treu T, Trenti M, Vulcani B, Nanayakkara T, Bradač M, Jones T, Boyett K, Wang X, Mascia S, Pentericci L. 2025. Quantifying spectroscopic flux variations between JWST NIRISS and NIRSpec: Slit losses in emission line measurements of z ∼ 1-3 galaxies. Monthly Notices of the Royal Astronomical Society. 544(2), 1915–1925.","mla":"Dalmasso, Nicolò, et al. “Quantifying Spectroscopic Flux Variations between JWST NIRISS and NIRSpec: Slit Losses in Emission Line Measurements of z ∼ 1-3 Galaxies.” <i>Monthly Notices of the Royal Astronomical Society</i>, vol. 544, no. 2, Oxford University Press, 2025, pp. 1915–25, doi:<a href=\"https://doi.org/10.1093/mnras/staf1837\">10.1093/mnras/staf1837</a>.","ama":"Dalmasso N, Watson PJ, Treu T, et al. Quantifying spectroscopic flux variations between JWST NIRISS and NIRSpec: Slit losses in emission line measurements of z ∼ 1-3 galaxies. <i>Monthly Notices of the Royal Astronomical Society</i>. 2025;544(2):1915-1925. doi:<a href=\"https://doi.org/10.1093/mnras/staf1837\">10.1093/mnras/staf1837</a>","chicago":"Dalmasso, Nicolò, Peter J. Watson, Tommaso Treu, Michele Trenti, Benedetta Vulcani, Themiya Nanayakkara, Maruša Bradač, et al. “Quantifying Spectroscopic Flux Variations between JWST NIRISS and NIRSpec: Slit Losses in Emission Line Measurements of z ∼ 1-3 Galaxies.” <i>Monthly Notices of the Royal Astronomical Society</i>. Oxford University Press, 2025. <a href=\"https://doi.org/10.1093/mnras/staf1837\">https://doi.org/10.1093/mnras/staf1837</a>."},"department":[{"_id":"JoMa"}],"article_processing_charge":"Yes","type":"journal_article","OA_type":"gold","file_date_updated":"2025-11-24T09:02:04Z","status":"public","doi":"10.1093/mnras/staf1837","date_created":"2025-11-23T23:01:38Z","issue":"2","acknowledgement":"This research was supported in part by the Australian Research Council Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D), through project number CE170100013. This research was supported in part by The Dr Albert Shimmins Fund through the Albert Shimmins Postgraduate Writing Up Award (University of Melbourne). This work is based on observations made with the NASA/ESA/CSA James Webb Space Telescope. The data were obtained from the Mikulski Archive for Space Telescopes at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5–03127 for JWST. These observations are associated with programmes JWST-ERS-1324, JWST-GO-2561, and JWST-DDT-2756. BV and PW acknowledge support from the INAF Large Grant 2022 ‘Extragalactic Surveys with JWST’ (PI Pentericci), the INAF Mini\r\nGrant ‘1.05.24.07.01 RSN1: Spatially-Resolved Near-IR Emission of Intermediate-Redshift Jellyfish Galaxies’ (PI Watson), and are supported by the European Union – NextGenerationEU RFF M4C2 1.1 PRIN 2022 project 2022ZSL4BL INSIGHT. MB acknowledges support from the ERC Advanced Grant FIRSTLIGHT and Slovenian national research agency ARIS through grants N1-0238 and P1-0188. ","author":[{"full_name":"Dalmasso, Nicolò","last_name":"Dalmasso","first_name":"Nicolò"},{"last_name":"Watson","first_name":"Peter J.","full_name":"Watson, Peter J."},{"full_name":"Treu, Tommaso","first_name":"Tommaso","last_name":"Treu"},{"first_name":"Michele","last_name":"Trenti","full_name":"Trenti, Michele"},{"full_name":"Vulcani, Benedetta","first_name":"Benedetta","last_name":"Vulcani"},{"first_name":"Themiya","last_name":"Nanayakkara","full_name":"Nanayakkara, Themiya"},{"full_name":"Bradač, Maruša","last_name":"Bradač","first_name":"Maruša"},{"last_name":"Jones","first_name":"Tucker","full_name":"Jones, Tucker"},{"full_name":"Boyett, Kristan","last_name":"Boyett","first_name":"Kristan"},{"first_name":"Xin","last_name":"Wang","full_name":"Wang, Xin"},{"full_name":"Mascia, Sara","last_name":"Mascia","first_name":"Sara","id":"edaf889c-c7cd-11ef-ab1b-bb28c431bd29"},{"full_name":"Pentericci, Laura","first_name":"Laura","last_name":"Pentericci"}],"ddc":["520"],"tmp":{"short":"CC BY (4.0)","image":"/images/cc_by.png","name":"Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)","legal_code_url":"https://creativecommons.org/licenses/by/4.0/legalcode"},"isi":1,"page":"1915-1925","quality_controlled":"1","external_id":{"isi":["001615620500001"],"arxiv":["2510.27036"]},"year":"2025","intvolume":"       544","abstract":[{"lang":"eng","text":"We analyse James Webb Space Telescope (JWST) Near Infrared Imager and Slitless Spectrograph (NIRISS) and Near Infrared Spectrograph (NIRSpec) spectroscopic observations in the Abell 2744 galaxy cluster field. From approximately 120 candidates, we identify 12 objects with at least two prominent emission lines among [O II] λ3727, H β λ4861, [O III] λ4959, [O III] λ5007, and H α λ6563 that are spectroscopically confirmed by both instruments. Our key findings reveal systematic differences between the two spectrographs based on source morphology and shutter aperture placement. Compact objects show comparable or higher\r\nintegrated flux in NIRSpec relative to NIRISS (within 1σ uncertainties), while extended sources consistently display higher flux in NIRISS measurements. This pattern reflects NIRSpec’s optimal coverage for compact objects while potentially undersampling extended sources. Quantitative analysis demonstrates that NIRSpec recovers at least 63 per cent of NIRISS-measured flux when the slit covers >15 per cent of the source or when Re < 1 kpc. For lower coverage or larger effective radii, the recovered flux varies from 24 per cent to 63 per cent. When studying the H α λ6563/[O III] λ5007 emission line ratio, we observe that\r\nmeasurements from these different spectrographs can vary by up to ∼0.3 dex, with significant implications for metallicity and star formation rate characterizations for individual galaxies. These results highlight the importance of considering instrumental effects when combining multi-instrument spectroscopic data and demonstrate that source morphology critically influences flux\r\nrecovery between slit-based and slitless spectroscopic modes in JWST observations."}],"file":[{"relation":"main_file","file_size":1952887,"file_id":"20674","content_type":"application/pdf","creator":"dernst","success":1,"checksum":"2caff0a3b81fed114408377323298b43","date_created":"2025-11-24T09:02:04Z","file_name":"2025_MonthlyNoticesRAS_Dalmasso.pdf","date_updated":"2025-11-24T09:02:04Z","access_level":"open_access"}],"DOAJ_listed":"1","day":"01","date_updated":"2025-12-01T15:23:21Z","title":"Quantifying spectroscopic flux variations between JWST NIRISS and NIRSpec: Slit losses in emission line measurements of z ∼ 1-3 galaxies","oa_version":"Published Version","language":[{"iso":"eng"}]}]