TY - JOUR
T1 - An empirical reionization history model inferred from the low-redshift Lyman continuum survey and the star-forming galaxies at z > 8
AU - Lin, Yu Heng
AU - Scarlata, Claudia
AU - Williams, Hayley
AU - Chen, Wenlei
AU - Kelly, Patrick
AU - Langeroodi, Danial
AU - Hjorth, Jens
AU - Chisholm, John
AU - Koekemoer, Anton M.
AU - Zitrin, Adi
AU - Diego, Jose M.
N1 - Publisher Copyright:
© 2023 The Author(s). Published by Oxford University Press on behalf of Royal Astronomical Society.
PY - 2024/1/1
Y1 - 2024/1/1
N2 - We present a new analysis of the rest-frame ultraviolet (UV) and optical spectra of a sample of three z > 8 galaxies discovered behind the gravitational lensing cluster RX J2129.4+0009. We combine these observations with z > 7.5 galaxies from the literature, for which similar measurements are available. As already pointed out in other studies, the high [O iii]λ5007/[O ii]λ3727 ratios (O32) and steep UV continuum slopes (β) are consistent with the values observed for low-redshift Lyman continuum emitters, suggesting that such galaxies contribute to the ionizing budget of the intergalactic medium. We construct a logistic regression model to estimate the probability of a galaxy being a Lyman continuum emitter based on the measured MUV, β, and O32. Using this probability and the UV luminosity function, we construct an empirical model that estimates the contribution of high-redshift galaxies to reionization. The preferred scenario in our analysis shows that at z ∼8, the average escape fraction of the galaxy population [i.e. including both LyC emitters (LCEs) and non-emitters] varies with MUV, with intermediate UV luminosity (-19 < MUV < -16) galaxies having larger escape fraction. Galaxies with faint UV luminosity (-16 < MUV < -13.5) contribute most of the ionizing photons. The relative contribution of faint versus bright galaxies depends on redshift, with the intermediate UV galaxies becoming more important over time. UV bright galaxies, although more likely to be LCEs at a given log(O32) and β, contribute the least of the total ionizing photon budget.
AB - We present a new analysis of the rest-frame ultraviolet (UV) and optical spectra of a sample of three z > 8 galaxies discovered behind the gravitational lensing cluster RX J2129.4+0009. We combine these observations with z > 7.5 galaxies from the literature, for which similar measurements are available. As already pointed out in other studies, the high [O iii]λ5007/[O ii]λ3727 ratios (O32) and steep UV continuum slopes (β) are consistent with the values observed for low-redshift Lyman continuum emitters, suggesting that such galaxies contribute to the ionizing budget of the intergalactic medium. We construct a logistic regression model to estimate the probability of a galaxy being a Lyman continuum emitter based on the measured MUV, β, and O32. Using this probability and the UV luminosity function, we construct an empirical model that estimates the contribution of high-redshift galaxies to reionization. The preferred scenario in our analysis shows that at z ∼8, the average escape fraction of the galaxy population [i.e. including both LyC emitters (LCEs) and non-emitters] varies with MUV, with intermediate UV luminosity (-19 < MUV < -16) galaxies having larger escape fraction. Galaxies with faint UV luminosity (-16 < MUV < -13.5) contribute most of the ionizing photons. The relative contribution of faint versus bright galaxies depends on redshift, with the intermediate UV galaxies becoming more important over time. UV bright galaxies, although more likely to be LCEs at a given log(O32) and β, contribute the least of the total ionizing photon budget.
KW - dark ages, reionization, first stars
KW - galaxies: clusters: general
KW - galaxies: high-redshift
KW - gravitational lensing: strong
UR - http://www.scopus.com/inward/record.url?scp=85179013858&partnerID=8YFLogxK
U2 - 10.1093/mnras/stad3483
DO - 10.1093/mnras/stad3483
M3 - Article
AN - SCOPUS:85179013858
SN - 0035-8711
VL - 527
SP - 4173
EP - 4182
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
IS - 2
ER -