Rights statement: This is a pre-copy-editing, author-produced PDF of an article accepted for publication in Monthly Notices of the Royal Astronomical Society following peer review. The definitive publisher-authenticated version Jorryt Matthee, Rohan P Naidu, Gabriele Pezzulli, Max Gronke, David Sobral, Pascal A Oesch, Matthew Hayes, Dawn Erb, Daniel Schaerer, Ricardo Amorín, Sandro Tacchella, Ana Paulino-Afonso, Mario Llerena, João Calhau, Huub Röttgering, (Re)Solving reionization with Lyα: how bright Lyα Emitters account for the z ≈ 2–8 cosmic ionizing background, Monthly Notices of the Royal Astronomical Society, Volume 512, Issue 4, June 2022, Pages 5960–5977 is available online at: https://academic.oup.com/mnras/article/512/4/5960/6553844
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Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
}
TY - JOUR
T1 - (Re)Solving Reionization with Lyα
T2 - How Bright Lyα Emitters account for the $z\approx2-8$ Cosmic Ionizing Background
AU - Matthee, Jorryt
AU - Naidu, Rohan P.
AU - Pezzulli, Gabriele
AU - Gronke, Max
AU - Sobral, David
AU - Oesch, Pascal A.
AU - Hayes, Matthew
AU - Erb, Dawn
AU - Schaerer, Daniel
AU - Amorín, Ricardo
AU - Tacchella, Sandro
AU - Paulino-Afonso, Ana
AU - Llerena, Mario
AU - Calhau, João
AU - Röttgering, Huub
N1 - This is a pre-copy-editing, author-produced PDF of an article accepted for publication in Monthly Notices of the Royal Astronomical Society following peer review. The definitive publisher-authenticated version Jorryt Matthee, Rohan P Naidu, Gabriele Pezzulli, Max Gronke, David Sobral, Pascal A Oesch, Matthew Hayes, Dawn Erb, Daniel Schaerer, Ricardo Amorín, Sandro Tacchella, Ana Paulino-Afonso, Mario Llerena, João Calhau, Huub Röttgering, (Re)Solving reionization with Lyα: how bright Lyα Emitters account for the z ≈ 2–8 cosmic ionizing background, Monthly Notices of the Royal Astronomical Society, Volume 512, Issue 4, June 2022, Pages 5960–5977 is available online at: https://academic.oup.com/mnras/article/512/4/5960/6553844
PY - 2022/6/30
Y1 - 2022/6/30
N2 - The cosmic ionizing emissivity from star-forming galaxies has long been anchored to UV luminosity functions. Here we introduce an emissivity framework based on Ly$\alpha$ emitters (LAEs), which naturally hones in on the subset of galaxies responsible for the ionizing background due to the intimate connection between the production and escape of Ly$\alpha$ and LyC photons. Using constraints on the escape fractions of bright LAEs ($L_{\rm{Ly\alpha}}>0.2 L^{*}$) at $z\approx2$ obtained from resolved Ly$\alpha$ profiles, and arguing for their redshift-invariance, we show that: (i) quasars and LAEs together reproduce the relatively flat emissivity at $z\approx2-6$, which is non-trivial given the strong evolution in both the star-formation density and quasar number density at these epochs and (ii) LAEs produce late and rapid reionization between $z\approx6-9$ under plausible assumptions. Within this framework, the $>10\times$ rise in the UV population-averaged $f_{\rm{esc}}$ between $z\approx3-7$ naturally arises due to the same phenomena that drive the growing Ly$\alpha$ emitter fraction with redshift. Generally, a LAE dominated emissivity yields a peak in the distribution of the ionizing budget with UV luminosity as reported in latest simulations. Using our adopted parameters ($f_{\rm{esc}}=50\%$, $\xi_{\rm{ion}}=10^{25.9}$ Hz erg$^{-1}$ for half the bright LAEs), we find that a highly ionizing minority of galaxies with $M_{\rm UV}5$. We conclude with proposed observational tests to further develop our suggested Ly$\alpha$-anchored formalism.
AB - The cosmic ionizing emissivity from star-forming galaxies has long been anchored to UV luminosity functions. Here we introduce an emissivity framework based on Ly$\alpha$ emitters (LAEs), which naturally hones in on the subset of galaxies responsible for the ionizing background due to the intimate connection between the production and escape of Ly$\alpha$ and LyC photons. Using constraints on the escape fractions of bright LAEs ($L_{\rm{Ly\alpha}}>0.2 L^{*}$) at $z\approx2$ obtained from resolved Ly$\alpha$ profiles, and arguing for their redshift-invariance, we show that: (i) quasars and LAEs together reproduce the relatively flat emissivity at $z\approx2-6$, which is non-trivial given the strong evolution in both the star-formation density and quasar number density at these epochs and (ii) LAEs produce late and rapid reionization between $z\approx6-9$ under plausible assumptions. Within this framework, the $>10\times$ rise in the UV population-averaged $f_{\rm{esc}}$ between $z\approx3-7$ naturally arises due to the same phenomena that drive the growing Ly$\alpha$ emitter fraction with redshift. Generally, a LAE dominated emissivity yields a peak in the distribution of the ionizing budget with UV luminosity as reported in latest simulations. Using our adopted parameters ($f_{\rm{esc}}=50\%$, $\xi_{\rm{ion}}=10^{25.9}$ Hz erg$^{-1}$ for half the bright LAEs), we find that a highly ionizing minority of galaxies with $M_{\rm UV}5$. We conclude with proposed observational tests to further develop our suggested Ly$\alpha$-anchored formalism.
KW - galaxies: high-redshift
KW - intergalactic medium
KW - cosmology: observations
KW - dark ages
KW - reionization
KW - first stars
KW - ultraviolet: galaxies
U2 - 10.1093/mnras/stac801
DO - 10.1093/mnras/stac801
M3 - Journal article
VL - 512
SP - 5960
EP - 5977
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
SN - 0035-8711
IS - 4
ER -