_version_ 1866917968133226496
author Witstok, Joris
Jakobsen, Peter
Maiolino, Roberto
Helton, Jakob M.
Johnson, Benjamin D.
Robertson, Brant E.
Tacchella, Sandro
Cameron, Alex J.
Smit, Renske
Bunker, Andrew J.
Saxena, Aayush
Sun, Fengwu
Alberts, Stacey
Arribas, Santiago
Baker, William M.
Bhatawdekar, Rachana
Boyett, Kristan
Cargile, Phillip A.
Carniani, Stefano
Charlot, Stéphane
Chevallard, Jacopo
Curti, Mirko
Curtis-Lake, Emma
D'Eugenio, Francesco
Eisenstein, Daniel J.
Hainline, Kevin N.
Jones, Gareth C.
Kumari, Nimisha
Maseda, Michael V.
Pérez-González, Pablo G.
Rinaldi, Pierluigi
Scholtz, Jan
Übler, Hannah
Williams, Christina C.
Willmer, Christopher N. A.
Willott, Chris
Zhu, Yongda
author_facet Witstok, Joris
Jakobsen, Peter
Maiolino, Roberto
Helton, Jakob M.
Johnson, Benjamin D.
Robertson, Brant E.
Tacchella, Sandro
Cameron, Alex J.
Smit, Renske
Bunker, Andrew J.
Saxena, Aayush
Sun, Fengwu
Alberts, Stacey
Arribas, Santiago
Baker, William M.
Bhatawdekar, Rachana
Boyett, Kristan
Cargile, Phillip A.
Carniani, Stefano
Charlot, Stéphane
Chevallard, Jacopo
Curti, Mirko
Curtis-Lake, Emma
D'Eugenio, Francesco
Eisenstein, Daniel J.
Hainline, Kevin N.
Jones, Gareth C.
Kumari, Nimisha
Maseda, Michael V.
Pérez-González, Pablo G.
Rinaldi, Pierluigi
Scholtz, Jan
Übler, Hannah
Williams, Christina C.
Willmer, Christopher N. A.
Willott, Chris
Zhu, Yongda
contents $\require{mediawiki-texvc}$Cosmic Reionisation commenced when ultraviolet (UV) radiation produced in the first galaxies began illuminating the cold, neutral gas that filled the primordial Universe. Recent James Webb Space Telescope (JWST) observations have shown that surprisingly UV-bright galaxies were in place beyond redshift $z = 14$, when the Universe was less than $300 \, \mathrm{Myr}$ old. Smooth turnovers of their UV continua have been interpreted as damping-wing absorption of Lyman-$α$ (Ly$α$), the principal hydrogen transition. However, spectral signatures encoding crucial properties of these sources, such as their emergent radiation field, largely remain elusive. Here we report spectroscopy from the JWST Advanced Deep Extragalactic Survey (JADES) of a galaxy at redshift $z = 13.0$ that reveal a singular, bright emission line unambiguously identified as Ly$α$, in addition to a smooth turnover. We observe an equivalent width of $\text{EW}_\mathrm{Lyα} > 40 \, Å$ (rest frame), previously only seen at $z < 9$ where the intervening intergalactic medium (IGM) becomes increasingly ionised. Together with an extremely blue UV continuum, the unexpected Ly$α$ emission indicates the galaxy is a prolific producer and leaker of ionising photons. This suggests massive, hot stars or an active galactic nucleus (AGN) have created an early reionised region to prevent complete extinction of Ly$α$, thus shedding new light on the nature of the earliest galaxies and the onset of Reionisation only $330 \, \mathrm{Myr}$ after the Big Bang.
format Preprint
id arxiv_https___arxiv_org_abs_2408_16608
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Witnessing the onset of reionisation via Lyman-$α$ emission at redshift 13
Witstok, Joris
Jakobsen, Peter
Maiolino, Roberto
Helton, Jakob M.
Johnson, Benjamin D.
Robertson, Brant E.
Tacchella, Sandro
Cameron, Alex J.
Smit, Renske
Bunker, Andrew J.
Saxena, Aayush
Sun, Fengwu
Alberts, Stacey
Arribas, Santiago
Baker, William M.
Bhatawdekar, Rachana
Boyett, Kristan
Cargile, Phillip A.
Carniani, Stefano
Charlot, Stéphane
Chevallard, Jacopo
Curti, Mirko
Curtis-Lake, Emma
D'Eugenio, Francesco
Eisenstein, Daniel J.
Hainline, Kevin N.
Jones, Gareth C.
Kumari, Nimisha
Maseda, Michael V.
Pérez-González, Pablo G.
Rinaldi, Pierluigi
Scholtz, Jan
Übler, Hannah
Williams, Christina C.
Willmer, Christopher N. A.
Willott, Chris
Zhu, Yongda
Astrophysics of Galaxies
$\require{mediawiki-texvc}$Cosmic Reionisation commenced when ultraviolet (UV) radiation produced in the first galaxies began illuminating the cold, neutral gas that filled the primordial Universe. Recent James Webb Space Telescope (JWST) observations have shown that surprisingly UV-bright galaxies were in place beyond redshift $z = 14$, when the Universe was less than $300 \, \mathrm{Myr}$ old. Smooth turnovers of their UV continua have been interpreted as damping-wing absorption of Lyman-$α$ (Ly$α$), the principal hydrogen transition. However, spectral signatures encoding crucial properties of these sources, such as their emergent radiation field, largely remain elusive. Here we report spectroscopy from the JWST Advanced Deep Extragalactic Survey (JADES) of a galaxy at redshift $z = 13.0$ that reveal a singular, bright emission line unambiguously identified as Ly$α$, in addition to a smooth turnover. We observe an equivalent width of $\text{EW}_\mathrm{Lyα} > 40 \, Å$ (rest frame), previously only seen at $z < 9$ where the intervening intergalactic medium (IGM) becomes increasingly ionised. Together with an extremely blue UV continuum, the unexpected Ly$α$ emission indicates the galaxy is a prolific producer and leaker of ionising photons. This suggests massive, hot stars or an active galactic nucleus (AGN) have created an early reionised region to prevent complete extinction of Ly$α$, thus shedding new light on the nature of the earliest galaxies and the onset of Reionisation only $330 \, \mathrm{Myr}$ after the Big Bang.
title Witnessing the onset of reionisation via Lyman-$α$ emission at redshift 13
topic Astrophysics of Galaxies
url https://arxiv.org/abs/2408.16608