[{"tmp":{"image":"/images/cc_by.png","name":"Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)","short":"CC BY (4.0)","legal_code_url":"https://creativecommons.org/licenses/by/4.0/legalcode"},"acknowledgement":"We thank the two anonymous referees for their insightful comments that have strengthened this work. “Mirage or Miracle” is but the latest link in a long chain of surveys that have built COSMOS into a premier extragalactic legacy field. We are thankful to all the teams who have contributed to this legacy, particularly those mentioned in §3 for leading recent JWST programs whose imaging\r\nwe have incorporated in our analysis. We are grateful to Vasily Belokurov for help in compiling the Milky Way reference sample featured in Fig 8. We thank Danielle Berg for sharing a highly complete, highly decimalized NUV vacuum line list. We are grateful to our program’s NIRSpec reviewer, Dan Coe, and program coordinator, Allison Vick, for valuable input on our MSA design. We acknowledge illuminating conversations with Risa Wechsler and Chao-Lin Kuo about early reionization. RPN thanks Neil Pappalardo and Jane Pappalardo for their generous support of the MIT Pappalardo Fellowships in Physics, and for their enthusiasm and encouragement for seeking galaxies at the highest redshifts. RPN acknowledges funding from JWST program GO5224. Support for this work was provided by NASA through the NASA Hubble Fellowship grant HST-HF2-51515.001-A awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Incorporated, under NASA contract NAS5-26555. 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. Funded by the European Union (ERC, AGENTS, 101076224 and HEAVYMETAL, 101071865). Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of\r\nthe European Union or the European Research Council. Neither the European Union nor the granting authority can be held responsible for them. The Cosmic Dawn Center (DAWN) is funded by the Danish National Research Foundation under grant DNRF140. This work has also been supported by JSPS KAKENHI Grant Number 23H00131. HA acknowledges support from CNES, focused on the JWST mission, and the Programme National Cosmology and Galaxies (PNCG)\r\nof CNRS/INSU with INP and IN2P3, co-funded by CEA and CNES. HA is supported by the French National Research Agency (ANR) under the project FIRSTGAL, grant number ANR-24-CE31-0838. SB is supported by the UK Research and Innovation (UKRI) Future Leaders Fellowship [grant number MR/V023381/1]. R.D. acknowledges support from the INAF GO 2022\r\ngrant “The birth of the giants: JWST sheds light on the build-up of quasars at cosmic dawn” and by the PRIN MUR “2022935STW”, RFF M4.C2.1.1, CUP J53D23001570006 and C53D23000950006. Computations supporting this paper were run on MIT’s Engaging cluster. This publication made use of the NASA Astrophysical Data System for bibliographic information. Some of the data products presented herein were retrieved from the Dawn JWST Archive (DJA). DJA is an initiative of the Cosmic Dawn Center (DAWN), which is funded by the Danish National Research Foundation under grant DNRF140. Software used in developing this work includes: matplotlib (Hunter 2007), jupyter (Kluyver et al. 2016), IPython (P´erez & Granger 2007), numpy (Oliphant 2015), scipy (Virtanen et al. 2020), TOPCAT (Taylor 2005), and Astropy (Astropy Collaboration et al. 2013).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\r\nTelescopes 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 # 5224.","doi":"10.33232/001c.156033","main_file_link":[{"url":"https:/​/​doi.org/​10.33232/​001c.156033","open_access":"1"}],"citation":{"apa":"Naidu, R. P., Oesch, P. A., Brammer, G., Weibel, A., Li, Y., Matthee, J. J., … Whitaker, K. E. (2026). A cosmic miracle: A remarkably luminous galaxy at zspec = 14.44 confirmed with JWST. <i>The Open Journal of Astrophysics</i>. Maynooth Academic Publishing. <a href=\"https://doi.org/10.33232/001c.156033\">https://doi.org/10.33232/001c.156033</a>","ama":"Naidu RP, Oesch PA, Brammer G, et al. A cosmic miracle: A remarkably luminous galaxy at zspec = 14.44 confirmed with JWST. <i>The Open Journal of Astrophysics</i>. 2026;9. doi:<a href=\"https://doi.org/10.33232/001c.156033\">10.33232/001c.156033</a>","chicago":"Naidu, Rohan P., Pascal A. Oesch, Gabriel Brammer, Andrea Weibel, Yijia Li, Jorryt J Matthee, John Chisholm, et al. “A Cosmic Miracle: A Remarkably Luminous Galaxy at Zspec = 14.44 Confirmed with JWST.” <i>The Open Journal of Astrophysics</i>. Maynooth Academic Publishing, 2026. <a href=\"https://doi.org/10.33232/001c.156033\">https://doi.org/10.33232/001c.156033</a>.","ista":"Naidu RP, Oesch PA, Brammer G, Weibel A, Li Y, Matthee JJ, Chisholm J, Pollock CL, Heintz KE, Johnson BD, Shen X, Hviding RE, Leja J, Tacchella S, Ganguly A, Witten C, Atek H, Belli S, Bose S, Bouwens R, Dayal P, Decarli R, De Graaff A, Fudamoto Y, Giovinazzo E, Greene JE, Illingworth G, Inoue AK, Kane SG, Labbe I, Leonova E, Marques-Chaves R, Meyer RA, Nelson EJ, Roberts-Borsani G, Schaerer D, Simcoe RA, Stefanon M, Sugahara Y, Toft S, Van Der Wel A, Van Dokkum P, Walter F, Watson D, Weaver JR, Whitaker KE. 2026. A cosmic miracle: A remarkably luminous galaxy at zspec = 14.44 confirmed with JWST. The Open Journal of Astrophysics. 9.","mla":"Naidu, Rohan P., et al. “A Cosmic Miracle: A Remarkably Luminous Galaxy at Zspec = 14.44 Confirmed with JWST.” <i>The Open Journal of Astrophysics</i>, vol. 9, Maynooth Academic Publishing, 2026, doi:<a href=\"https://doi.org/10.33232/001c.156033\">10.33232/001c.156033</a>.","ieee":"R. P. Naidu <i>et al.</i>, “A cosmic miracle: A remarkably luminous galaxy at zspec = 14.44 confirmed with JWST,” <i>The Open Journal of Astrophysics</i>, vol. 9. Maynooth Academic Publishing, 2026.","short":"R.P. Naidu, P.A. Oesch, G. Brammer, A. Weibel, Y. Li, J.J. Matthee, J. Chisholm, C.L. Pollock, K.E. Heintz, B.D. Johnson, X. Shen, R.E. Hviding, J. Leja, S. Tacchella, A. Ganguly, C. Witten, H. Atek, S. Belli, S. Bose, R. Bouwens, P. Dayal, R. Decarli, A. De Graaff, Y. Fudamoto, E. Giovinazzo, J.E. Greene, G. Illingworth, A.K. Inoue, S.G. Kane, I. Labbe, E. Leonova, R. Marques-Chaves, R.A. Meyer, E.J. Nelson, G. Roberts-Borsani, D. Schaerer, R.A. Simcoe, M. Stefanon, Y. Sugahara, S. Toft, A. Van Der Wel, P. Van Dokkum, F. Walter, D. Watson, J.R. Weaver, K.E. Whitaker, The Open Journal of Astrophysics 9 (2026)."},"day":"30","ddc":["520"],"publication":"The Open Journal of Astrophysics","publisher":"Maynooth Academic Publishing","has_accepted_license":"1","OA_place":"publisher","department":[{"_id":"JoMa"}],"type":"journal_article","publication_status":"published","quality_controlled":"1","date_published":"2026-01-30T00:00:00Z","title":"A cosmic miracle: A remarkably luminous galaxy at zspec = 14.44 confirmed with JWST","month":"01","scopus_import":"1","intvolume":"         9","_id":"21342","year":"2026","language":[{"iso":"eng"}],"article_type":"original","article_processing_charge":"No","PlanS_conform":"1","status":"public","abstract":[{"lang":"eng","text":"JWST has revealed a stunning population of bright galaxies at surprisingly early epochs, z > 10,\r\nwhere few such sources were expected. Here we present the most distant example of this class yet – MoM-z14, a luminous (MUV = −20.2) source in the COSMOS legacy field at zspec = 14.44+0.02−0.02 that expands the observational frontier to a mere 280 million years after the Big Bang. The redshift is confirmed with NIRSpec/prism spectroscopy through a sharp Lyman-α break and ≈ 3σ detections of five rest-UV emission lines. The number density of bright zspec ≈ 14 − 15 sources implied by our “Mirage or Miracle” survey spanning ≈ 350 arcmin2 is > 100× larger (182+329 −105×) than pre-JWST consensus models. The high EWs of UV lines (≈15−35˚A) signal a rising star-formation history, with a ≈10× increase in the last 5 Myr (SFR5Myr/SFR50Myr = 9.9 +3.0 −5.8). The source is extremely compact (circularized re = 74+15\r\n−12 pc), and yet elongated (b/a = 0.25+0.11−0.06), suggesting an AGN is not the dominant source of UV light. The steep UV slope (β = −2.5 +0.2 −0.2) implies negligible dust attenuation\r\nand a young stellar population. The absence of a strong damping wing provides tentative evidence that the immediate surroundings of MoM-z14 may be partially ionized at a redshift where virtually every reionization model predicts a ≈ 100% neutral fraction. The nitrogen emission and highly supersolar [N/C]> 1 hint at an abundance pattern similar to local globular clusters that may have once hosted luminous supermassive stars. Since this abundance pattern is also common among the most ancient stars born in the Milky Way, we may be directly witnessing the formation of such stars in dense clusters, connecting galaxy evolution across the entire sweep of cosmic time. "}],"arxiv":1,"oa_version":"Published Version","user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","external_id":{"arxiv":["2505.11263"]},"volume":9,"OA_type":"diamond","oa":1,"publication_identifier":{"eissn":["2565-6120"]},"date_updated":"2026-02-24T07:37:17Z","project":[{"grant_number":"101076224","name":"Young galaxies as tracers and agents of cosmic reionization","_id":"bd9b2118-d553-11ed-ba76-db24564edfea"}],"author":[{"full_name":"Naidu, Rohan P.","last_name":"Naidu","first_name":"Rohan P."},{"first_name":"Pascal A.","last_name":"Oesch","full_name":"Oesch, Pascal A."},{"full_name":"Brammer, Gabriel","first_name":"Gabriel","last_name":"Brammer"},{"last_name":"Weibel","first_name":"Andrea","full_name":"Weibel, Andrea"},{"full_name":"Li, Yijia","last_name":"Li","first_name":"Yijia"},{"first_name":"Jorryt J","last_name":"Matthee","id":"7439a258-f3c0-11ec-9501-9df22fe06720","orcid":"0000-0003-2871-127X","full_name":"Matthee, Jorryt J"},{"full_name":"Chisholm, John","first_name":"John","last_name":"Chisholm"},{"last_name":"Pollock","first_name":"Clara L.","full_name":"Pollock, Clara L."},{"full_name":"Heintz, Kasper E.","first_name":"Kasper E.","last_name":"Heintz"},{"last_name":"Johnson","first_name":"Benjamin D.","full_name":"Johnson, Benjamin D."},{"full_name":"Shen, Xuejian","first_name":"Xuejian","last_name":"Shen"},{"full_name":"Hviding, Raphael E.","last_name":"Hviding","first_name":"Raphael E."},{"full_name":"Leja, Joel","first_name":"Joel","last_name":"Leja"},{"last_name":"Tacchella","first_name":"Sandro","full_name":"Tacchella, Sandro"},{"full_name":"Ganguly, Arpita","last_name":"Ganguly","first_name":"Arpita"},{"first_name":"Callum","last_name":"Witten","full_name":"Witten, Callum"},{"first_name":"Hakim","last_name":"Atek","full_name":"Atek, Hakim"},{"full_name":"Belli, Sirio","last_name":"Belli","first_name":"Sirio"},{"full_name":"Bose, Sownak","first_name":"Sownak","last_name":"Bose"},{"first_name":"Rychard","last_name":"Bouwens","full_name":"Bouwens, Rychard"},{"full_name":"Dayal, Pratika","first_name":"Pratika","last_name":"Dayal"},{"full_name":"Decarli, Roberto","first_name":"Roberto","last_name":"Decarli"},{"last_name":"De Graaff","first_name":"Anna","full_name":"De Graaff, Anna"},{"full_name":"Fudamoto, Yoshinobu","first_name":"Yoshinobu","last_name":"Fudamoto"},{"full_name":"Giovinazzo, Emma","last_name":"Giovinazzo","first_name":"Emma"},{"full_name":"Greene, Jenny E.","last_name":"Greene","first_name":"Jenny E."},{"last_name":"Illingworth","first_name":"Garth","full_name":"Illingworth, Garth"},{"last_name":"Inoue","first_name":"Akio K.","full_name":"Inoue, Akio K."},{"first_name":"Sarah G.","last_name":"Kane","full_name":"Kane, Sarah G."},{"first_name":"Ivo","last_name":"Labbe","full_name":"Labbe, Ivo"},{"full_name":"Leonova, Ecaterina","first_name":"Ecaterina","last_name":"Leonova"},{"first_name":"Rui","last_name":"Marques-Chaves","full_name":"Marques-Chaves, Rui"},{"full_name":"Meyer, Romain A.","first_name":"Romain A.","last_name":"Meyer"},{"full_name":"Nelson, Erica J.","first_name":"Erica J.","last_name":"Nelson"},{"first_name":"Guido","last_name":"Roberts-Borsani","full_name":"Roberts-Borsani, Guido"},{"last_name":"Schaerer","first_name":"Daniel","full_name":"Schaerer, Daniel"},{"full_name":"Simcoe, Robert A.","last_name":"Simcoe","first_name":"Robert A."},{"full_name":"Stefanon, Mauro","first_name":"Mauro","last_name":"Stefanon"},{"full_name":"Sugahara, Yuma","last_name":"Sugahara","first_name":"Yuma"},{"full_name":"Toft, Sune","first_name":"Sune","last_name":"Toft"},{"full_name":"Van Der Wel, Arjen","last_name":"Van Der Wel","first_name":"Arjen"},{"full_name":"Van Dokkum, Pieter","first_name":"Pieter","last_name":"Van Dokkum"},{"full_name":"Walter, Fabian","first_name":"Fabian","last_name":"Walter"},{"first_name":"Darach","last_name":"Watson","full_name":"Watson, Darach"},{"first_name":"John R.","last_name":"Weaver","full_name":"Weaver, John R."},{"full_name":"Whitaker, Katherine E.","last_name":"Whitaker","first_name":"Katherine E."}],"date_created":"2026-02-22T23:01:35Z"},{"title":"21 Balmer Jump Street: The nebular continuum at high redshift and implications for the bright galaxy problem, UV continuum slopes, and early stellar populations","scopus_import":"1","month":"07","date_published":"2025-07-25T00:00:00Z","_id":"20192","year":"2025","intvolume":"         8","article_type":"original","article_processing_charge":"No","language":[{"iso":"eng"}],"PlanS_conform":"1","status":"public","oa_version":"Published Version","arxiv":1,"abstract":[{"lang":"eng","text":"We study the physical origin and spectroscopic impact of extreme nebular emission in high-redshift galaxies. The nebular continuum, which can appear during an extreme starburst, is of particular importance as it tends to redden UV slopes and has a significant contribution to the UV luminosities of galaxies. Furthermore, its shape can be used to infer the gas density and temperature of the interstellar medium. First, we provide a theoretical background, showing how different stellar populations (SPS models, initial mass functions (IMFs), and stellar temperatures) and nebular conditions impact observed galaxy spectra. We demonstrate that, for systems with strong nebular continuum emission, 1) UV fluxes can increase by up to 0.7~mag (or more in the case of hot/massive stars) above the stellar continuum, which may help reconcile the surprising abundance of bright high-redshift galaxies and the elevated UV luminosity density at z>10, 2) at high gas densities, UV slopes can redden from \\beta<-2.5 to \\beta\\sim-1, 3) observational measurements of \\xi_{\\rm ion} are gross underestimates, and 4) UV downturns from two-photon emission can masquerade as damped Ly\\alpha systems. Second, we present a dataset of 58 galaxies observed with NIRSpec on JWST at 2.5<z<9.0 that are selected to have strong nebular continuum emission via the detection of the Balmer jump. Five of the 58 spectra are consistent with being dominated by nebular emission, exhibiting both a Balmer jump and a UV downturn consistent with two-photon emission. For some galaxies, this may imply the presence of hot massive stars and a top-heavy IMF. We conclude by exploring the properties of spectroscopically confirmed z>10 galaxies, finding that UV slopes and UV downturns are in some cases redder or steeper than expected from SPS models, which may hint at more exotic (e.g. hotter/more massive stars or AGN) ionizing sources."}],"OA_type":"diamond","oa":1,"volume":8,"user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","external_id":{"arxiv":["2408.03189"]},"date_updated":"2025-09-30T14:29:33Z","publication_identifier":{"eissn":["2565-6120"]},"author":[{"full_name":"Katz, Harley","first_name":"Harley","last_name":"Katz"},{"first_name":"Alex J.","last_name":"Cameron","full_name":"Cameron, Alex J."},{"full_name":"Saxena, Aayush","first_name":"Aayush","last_name":"Saxena"},{"first_name":"Laia","last_name":"Barrufet","full_name":"Barrufet, Laia"},{"full_name":"Choustikov, Nicholas","first_name":"Nicholas","last_name":"Choustikov"},{"full_name":"Cleri, Nikko J.","first_name":"Nikko J.","last_name":"Cleri"},{"first_name":"Anna","last_name":"De Graaff","full_name":"De Graaff, Anna"},{"first_name":"Richard S.","last_name":"Ellis","full_name":"Ellis, Richard S."},{"first_name":"Robert A.E.","last_name":"Fosbury","full_name":"Fosbury, Robert A.E."},{"full_name":"Heintz, Kasper E.","first_name":"Kasper E.","last_name":"Heintz"},{"full_name":"Maseda, Michael","first_name":"Michael","last_name":"Maseda"},{"full_name":"Matthee, Jorryt J","orcid":"0000-0003-2871-127X","id":"7439a258-f3c0-11ec-9501-9df22fe06720","last_name":"Matthee","first_name":"Jorryt J"},{"full_name":"Mcconachie, Ian","first_name":"Ian","last_name":"Mcconachie"},{"full_name":"Oesch, Pascal A.","last_name":"Oesch","first_name":"Pascal A."}],"date_created":"2025-08-17T22:01:37Z","acknowledgement":"HK thanks Andrey Kravtsov for insightful comments and thoughtful discussions. We sincerely thank the PIs and Co-Is of the JWST programs where spectral data was made publicly available on the DJA. We refer interested readers to the following papers for survey descriptions regarding the spectral data: Bunker et al. (2023a); D’Eugenio et al. (2024); Bezanson et al. (2022); Barrufet et al. (2024); de Graaff et al. (2024); Finkelstein et al. (2024); Glazebrook et al. (2024); Pierel et al. (2024); Siebert et al. (2024); Maseda et al. (2024). 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 programs listed in Table 1. AJC and AS acknowledge funding from the “FirstGalaxies” Advanced Grant from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (Grant agreement No. 789056). ","tmp":{"image":"/images/cc_by.png","name":"Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)","short":"CC BY (4.0)","legal_code_url":"https://creativecommons.org/licenses/by/4.0/legalcode"},"doi":"10.33232/001c.142570","citation":{"ista":"Katz H, Cameron AJ, Saxena A, Barrufet L, Choustikov N, Cleri NJ, De Graaff A, Ellis RS, Fosbury RAE, Heintz KE, Maseda M, Matthee JJ, Mcconachie I, Oesch PA. 2025. 21 Balmer Jump Street: The nebular continuum at high redshift and implications for the bright galaxy problem, UV continuum slopes, and early stellar populations. The Open Journal of Astrophysics. 8.","chicago":"Katz, Harley, Alex J. Cameron, Aayush Saxena, Laia Barrufet, Nicholas Choustikov, Nikko J. Cleri, Anna De Graaff, et al. “21 Balmer Jump Street: The Nebular Continuum at High Redshift and Implications for the Bright Galaxy Problem, UV Continuum Slopes, and Early Stellar Populations.” <i>The Open Journal of Astrophysics</i>. Maynooth Academic Publishing, 2025. <a href=\"https://doi.org/10.33232/001c.142570\">https://doi.org/10.33232/001c.142570</a>.","apa":"Katz, H., Cameron, A. J., Saxena, A., Barrufet, L., Choustikov, N., Cleri, N. J., … Oesch, P. A. (2025). 21 Balmer Jump Street: The nebular continuum at high redshift and implications for the bright galaxy problem, UV continuum slopes, and early stellar populations. <i>The Open Journal of Astrophysics</i>. Maynooth Academic Publishing. <a href=\"https://doi.org/10.33232/001c.142570\">https://doi.org/10.33232/001c.142570</a>","ama":"Katz H, Cameron AJ, Saxena A, et al. 21 Balmer Jump Street: The nebular continuum at high redshift and implications for the bright galaxy problem, UV continuum slopes, and early stellar populations. <i>The Open Journal of Astrophysics</i>. 2025;8. doi:<a href=\"https://doi.org/10.33232/001c.142570\">10.33232/001c.142570</a>","mla":"Katz, Harley, et al. “21 Balmer Jump Street: The Nebular Continuum at High Redshift and Implications for the Bright Galaxy Problem, UV Continuum Slopes, and Early Stellar Populations.” <i>The Open Journal of Astrophysics</i>, vol. 8, Maynooth Academic Publishing, 2025, doi:<a href=\"https://doi.org/10.33232/001c.142570\">10.33232/001c.142570</a>.","short":"H. Katz, A.J. Cameron, A. Saxena, L. Barrufet, N. Choustikov, N.J. Cleri, A. De Graaff, R.S. Ellis, R.A.E. Fosbury, K.E. Heintz, M. Maseda, J.J. Matthee, I. Mcconachie, P.A. Oesch, The Open Journal of Astrophysics 8 (2025).","ieee":"H. Katz <i>et al.</i>, “21 Balmer Jump Street: The nebular continuum at high redshift and implications for the bright galaxy problem, UV continuum slopes, and early stellar populations,” <i>The Open Journal of Astrophysics</i>, vol. 8. Maynooth Academic Publishing, 2025."},"day":"25","file_date_updated":"2025-09-30T14:28:25Z","ddc":["520"],"publication":"The Open Journal of Astrophysics","has_accepted_license":"1","OA_place":"publisher","publisher":"Maynooth Academic Publishing","file":[{"file_id":"20412","success":1,"content_type":"application/pdf","file_size":1836432,"relation":"main_file","date_created":"2025-09-30T14:28:25Z","date_updated":"2025-09-30T14:28:25Z","file_name":"2025_OpenJourAstrophysics_Katz.pdf","creator":"dernst","checksum":"ba469d132907147f9e86d87f9124dd14","access_level":"open_access"}],"department":[{"_id":"JoMa"}],"quality_controlled":"1","type":"journal_article","publication_status":"published"}]