{"publication":"Astronomy and Astrophysics","date_created":"2026-01-25T23:01:41Z","OA_type":"diamond","day":"14","ddc":["520"],"volume":705,"oa_version":"Published Version","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."}],"OA_place":"publisher","tmp":{"short":"CC BY (4.0)","legal_code_url":"https://creativecommons.org/licenses/by/4.0/legalcode","image":"/images/cc_by.png","name":"Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)"},"article_type":"original","intvolume":"       705","file":[{"relation":"main_file","file_id":"21224","success":1,"date_created":"2026-02-16T07:35:03Z","checksum":"3782e03bc0843438aae8487f6af779c5","file_size":2259914,"content_type":"application/pdf","file_name":"2026_AstronomyAstrophysics_Torralba.pdf","creator":"dernst","date_updated":"2026-02-16T07:35:03Z","access_level":"open_access"}],"month":"01","file_date_updated":"2026-02-16T07:35:03Z","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.","language":[{"iso":"eng"}],"type":"journal_article","publication_status":"published","article_number":"A147","status":"public","quality_controlled":"1","publication_identifier":{"issn":["0004-6361"],"eissn":["1432-0746"]},"oa":1,"PlanS_conform":"1","citation":{"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 and 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>.","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 and 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 and 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 and Astrophysics</i>. 2026;705. doi:<a href=\"https://doi.org/10.1051/0004-6361/202555596\">10.1051/0004-6361/202555596</a>","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 and 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 and Astrophysics</i>. EDP Sciences. <a href=\"https://doi.org/10.1051/0004-6361/202555596\">https://doi.org/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 and Astrophysics 705 (2026)."},"scopus_import":"1","title":"A weak Ly α halo for an extremely bright little red dot. Indications of enshrouded supermassive black hole growth","arxiv":1,"article_processing_charge":"No","author":[{"id":"018f0249-0e87-11f0-b167-cbce08fbd541","last_name":"Torralba Torregrosa","first_name":"Alberto","orcid":"0000-0001-5586-6950","full_name":"Torralba Torregrosa, Alberto"},{"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":"Gabriele","last_name":"Pezzulli","full_name":"Pezzulli, Gabriele"},{"last_name":"Urrutia","first_name":"Tanya","full_name":"Urrutia, Tanya"},{"last_name":"Gronke","first_name":"Max","full_name":"Gronke, Max"},{"full_name":"Mascia, Sara","first_name":"Sara","last_name":"Mascia","id":"edaf889c-c7cd-11ef-ab1b-bb28c431bd29"},{"full_name":"D’Eugenio, Francesco","first_name":"Francesco","last_name":"D’Eugenio"},{"id":"2d002343-372f-11ef-98ec-a164d20427cb","first_name":"Claudia","last_name":"Di Cesare","full_name":"Di Cesare, Claudia"},{"full_name":"Eilers, Anna Christina","last_name":"Eilers","first_name":"Anna Christina"},{"last_name":"Greene","first_name":"Jenny E.","full_name":"Greene, Jenny E."},{"orcid":"0000-0001-8386-3546","full_name":"Iani, Edoardo","id":"4053390a-6b68-11ef-9828-a3b8adef8d0a","first_name":"Edoardo","last_name":"Iani"},{"first_name":"Yuzo","last_name":"Ishikawa","full_name":"Ishikawa, Yuzo"},{"first_name":"Ruari","last_name":"Mackenzie","full_name":"Mackenzie, Ruari"},{"first_name":"Rohan P.","last_name":"Naidu","full_name":"Naidu, Rohan P."},{"id":"aa14a535-50c9-11ef-b52e-e0c373d10148","first_name":"Benjamín","last_name":"Navarrete","full_name":"Navarrete, Benjamín"},{"full_name":"Kotiwale, Gauri","id":"1438afc8-1ff6-11ee-9fa6-cd4a75d66875","last_name":"Kotiwale","first_name":"Gauri"}],"doi":"10.1051/0004-6361/202555596","user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","date_published":"2026-01-14T00:00:00Z","external_id":{"arxiv":["2505.09542"]},"department":[{"_id":"JoMa"},{"_id":"GradSch"}],"project":[{"name":"Young galaxies as tracers and agents of cosmic reionization","_id":"bd9b2118-d553-11ed-ba76-db24564edfea","grant_number":"101076224"}],"year":"2026","has_accepted_license":"1","license":"https://creativecommons.org/licenses/by/4.0/","_id":"21045","date_updated":"2026-02-16T07:46:53Z","corr_author":"1","publisher":"EDP Sciences"}