Most of the photons that reionized the Universe came from dwarf galaxies

• 成果类型: Article
• 署名作者: Atek, Hakim; Labbe, Ivo; Furtak, Lukas J.; Chemerynska, Iryna; Fujimoto, Seiji; Setton, David J.; Miller, Tim B.; Oesch, Pascal; Bezanson, Rachel; Price, Sedona H.; Dayal, Pratika; Zitrin, Adi; Kokorev, Vasily; Weaver, John R.; Brammer, Gabriel; van Dokkum, Pieter; Williams, Christina C.; Cutler, Sam E.; Feldmann, Robert; Fudamoto, Yoshinobu; Greene, Jenny E.; Leja, Joel; Maseda, Michael, V; Muzzin, Adam; Pan, Richard; Papovich, Casey; Nelson, Erica J.; Nanayakkara, Themiya; Stark, Daniel P.; Stefanon, Mauro; Suess, Katherine A.; Wang, Bingjie; Whitaker, Katherine E.
• 署名单位: Centre National de la Recherche Scientifique (CNRS); Sorbonne Universite; Swinburne University of Technology; Ben-Gurion University of the Negev; University of Texas System; University of Texas Austin; Pennsylvania Commonwealth System of Higher Education (PCSHE); University of Pittsburgh; Pennsylvania Commonwealth System of Higher Education (PCSHE); University of Pittsburgh; Northwestern University; Northwestern University; University of Geneva; University of Copenhagen; Niels Bohr Institute; University of Groningen; Kapteyn Astronomical Institute; University of Massachusetts System; University of Massachusetts Amherst; Yale University; University of Arizona; University of Zurich; Waseda University; National Institutes of Natural Sciences (NINS) - Japan; National Astronomical Observatory of Japan (NAOJ); Princeton University; Pennsylvania Commonwealth System of Higher Education (PCSHE); Pennsylvania State University; Pennsylvania State University - University Park; Pennsylvania Commonwealth System of Higher Education (PCSHE); Pennsylvania State University; Pennsylvania State University - University Park; Pennsylvania Commonwealth System of Higher Education (PCSHE); Pennsylvania State University; Pennsylvania State University - University Park; University of Wisconsin System; University of Wisconsin Madison; York University - Canada; Tufts University; Texas A&M University System; Texas A&M University College Station; Texas A&M University System; Texas A&M University College Station; University of Colorado System; University of Colorado Boulder; University of Valencia; University of California System; University of California Santa Cruz; Stanford University; Stanford University
• 刊物名称: Nature
• ISSN/ISSBN: 0028-5180
• DOI: 10.1038/s41586-024-07043-6
• 发表日期: 2024-02-29
• 关键词: similar-to 6; lyman-continuum; luminosity function; escape fractions; stellar; MODEL; EFFICIENCY; RESOLUTION; release; dust

摘要

The identification of sources driving cosmic reionization, a major phase transition from neutral hydrogen to ionized plasma around 600-800 Myr after the Big Bang(1-3), has been a matter of debate(4). Some models suggest that high ionizing emissivity and escape fractions (f(esc)) from quasars support their role in driving cosmic reionization(5,6). Others propose that the high f(esc) values from bright galaxies generate sufficient ionizing radiation to drive this process(7). Finally, a few studies suggest that the number density of faint galaxies, when combined with a stellar-mass-dependent model of ionizing efficiency and f(esc), can effectively dominate cosmic reionization(8,9). However, so far, comprehensive spectroscopic studies of low-mass galaxies have not been done because of their extreme faintness. Here we report an analysis of eight ultra-faint galaxies (in a very small field) during the epoch of reionization with absolute magnitudes between M-UV approximate to -17 mag and -15 mag (down to 0.005L* (refs. 10,11)). We find that faint galaxies during the first thousand million years of the Universe produce ionizing photons with log[xi(ion) (Hz erg(-1))] = 25.80 +/- 0.14, a factor of 4 higher than commonly assumed values(12). If this field is representative of the large-scale distribution of faint galaxies, the rate of ionizing photons exceeds that needed for reionization, even for escape fractions of the order of 5%.