[{"department":[{"_id":"JoMa"}],"date_created":"2026-04-12T22:01:49Z","citation":{"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>","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.","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>","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).","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.","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>."},"publisher":"IOP Publishing","status":"public","month":"03","tmp":{"name":"Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)","legal_code_url":"https://creativecommons.org/licenses/by/4.0/legalcode","image":"/images/cc_by.png","short":"CC BY (4.0)"},"quality_controlled":"1","date_published":"2026-03-20T00:00:00Z","issue":"1","publication_identifier":{"issn":["0004-637X"],"eissn":["1538-4357"]},"intvolume":"      1000","_id":"21710","OA_place":"publisher","author":[{"full_name":"Papovich, Casey","last_name":"Papovich","first_name":"Casey"},{"full_name":"Cole, Justin W.","last_name":"Cole","first_name":"Justin W."},{"last_name":"Hu","first_name":"Weida","full_name":"Hu, Weida"},{"first_name":"Steven L.","last_name":"Finkelstein","full_name":"Finkelstein, Steven L."},{"full_name":"Shen, Lu","first_name":"Lu","last_name":"Shen"},{"full_name":"Arrabal Haro, Pablo","last_name":"Arrabal Haro","first_name":"Pablo"},{"full_name":"Amorín, Ricardo O.","last_name":"Amorín","first_name":"Ricardo O."},{"last_name":"Backhaus","first_name":"Bren E.","full_name":"Backhaus, Bren E."},{"full_name":"Bagley, Micaela B.","last_name":"Bagley","first_name":"Micaela B."},{"first_name":"Rachana","last_name":"Bhatawdekar","full_name":"Bhatawdekar, Rachana"},{"full_name":"Calabrò, Antonello","first_name":"Antonello","last_name":"Calabrò"},{"first_name":"Adam C.","last_name":"Carnall","full_name":"Carnall, Adam C."},{"full_name":"Cleri, Nikko J.","first_name":"Nikko J.","last_name":"Cleri"},{"full_name":"Daddi, Emanuele","first_name":"Emanuele","last_name":"Daddi"},{"full_name":"Dickinson, Mark","last_name":"Dickinson","first_name":"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."},{"full_name":"Jaskot, Anne E.","first_name":"Anne E.","last_name":"Jaskot"},{"full_name":"Koekemoer, Anton M.","last_name":"Koekemoer","first_name":"Anton M."},{"full_name":"Llerena, Mario","last_name":"Llerena","first_name":"Mario"},{"first_name":"Ray A.","last_name":"Lucas","full_name":"Lucas, Ray A."},{"full_name":"Mascia, Sara","id":"edaf889c-c7cd-11ef-ab1b-bb28c431bd29","last_name":"Mascia","first_name":"Sara"},{"first_name":"Fabio","last_name":"Pacucci","full_name":"Pacucci, Fabio"},{"full_name":"Pentericci, Laura","last_name":"Pentericci","first_name":"Laura"},{"full_name":"Pérez-González, Pablo G.","last_name":"Pérez-González","first_name":"Pablo G."},{"last_name":"Pirzkal","first_name":"Nor","full_name":"Pirzkal, Nor"},{"full_name":"Raghunathan, Srinivasan","first_name":"Srinivasan","last_name":"Raghunathan"},{"full_name":"Seillé, Lise Marie","last_name":"Seillé","first_name":"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"}],"external_id":{"arxiv":["2505.08870"]},"arxiv":1,"oa_version":"Published Version","user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","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).","has_accepted_license":"1","file":[{"file_id":"21791","date_updated":"2026-05-04T10:40:07Z","creator":"dernst","content_type":"application/pdf","date_created":"2026-05-04T10:40:07Z","relation":"main_file","access_level":"open_access","checksum":"0031a6f197a3fa8c2845de10b6bdc696","success":1,"file_size":6670398,"file_name":"2026_AstrophysicalJour_Papovich.pdf"}],"article_processing_charge":"Yes","article_type":"original","date_updated":"2026-05-04T10:44:57Z","publication":"The Astrophysical Journal","type":"journal_article","license":"https://creativecommons.org/licenses/by/4.0/","ddc":["520"],"scopus_import":"1","file_date_updated":"2026-05-04T10:40:07Z","doi":"10.3847/1538-4357/ae3b25","publication_status":"published","day":"20","OA_type":"gold","oa":1,"volume":1000,"title":"Galaxies in the epoch of reionization are all bark and no bite-plenty of ionizing photons, low escape fractions","year":"2026","article_number":"111","language":[{"iso":"eng"}],"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."}]}]