TY - JOUR
T1 - Semi-analytic forecasts for JWST - III. Intrinsic production efficiency of Lyman-continuum radiation
AU - Aaron Yung, L. Y.
AU - Somerville, Rachel S.
AU - Popping, Gergö
AU - Finkelstein, Steven L.
N1 - Funding Information:
The authors of this paper would like to thank Adriano Fontana et al. for organizing the ‘The Growth of Galaxies in the Early Universe – V’ conference in Sesto, Italy, which fostered significant discussions that inspired the creation of this work. We also thank Selma de Mink and Stephen Wilkins for useful comments and discussions. We also thank the anonymous referee for the constructive comments that improved this work. AY and RSS thank the Downsbrough family for their generous support, and gratefully acknowledge funding from the Simons Foundation.
Publisher Copyright:
© 2020 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society
PY - 2020/5/1
Y1 - 2020/5/1
N2 - The James Webb Space Telescope is expected to enable transformational progress in studying galaxy populations in the very early Universe, during the epoch of reionization. A critical parameter for understanding the sources that reionized the Universe is the Lyman-continuum production efficiency, ξion, defined as the rate of production of ionizing photons divided by the intrinsic UV luminosity. In this work, we combine self-consistent star formation and chemical enrichment histories predicted by semi-analytic models of galaxy formation with stellar population synthesis (SPS) models to predict the expected dependence of ξion on galaxy properties and cosmic epoch from z = 4-10. We then explore the sensitivity of the production rate of ionizing photons, N ion, to the choice of SPS model and the treatment of stellar feedback in our galaxy formation model. We compare our results to those of other simulations, constraints from empirical models, and observations. We find that adopting SPS models that include binary stars predict about a factor of 2 more ionizing radiation than models that only assume single stellar populations. We find that UV-faint, low-mass galaxies have values of ξion about 0.25 dex higher than those of more massive galaxies, but find weak evolution with cosmic time, about 0.2 dex from z ∼ 12-4 at fixed rest-UV luminosity. We provide predictions of N ion as a function of Mh and a number of other galaxy properties. All results presented in this work are available at https://www.simonsfoundation.org/semi-analytic-forecasts-for-jwst/.
AB - The James Webb Space Telescope is expected to enable transformational progress in studying galaxy populations in the very early Universe, during the epoch of reionization. A critical parameter for understanding the sources that reionized the Universe is the Lyman-continuum production efficiency, ξion, defined as the rate of production of ionizing photons divided by the intrinsic UV luminosity. In this work, we combine self-consistent star formation and chemical enrichment histories predicted by semi-analytic models of galaxy formation with stellar population synthesis (SPS) models to predict the expected dependence of ξion on galaxy properties and cosmic epoch from z = 4-10. We then explore the sensitivity of the production rate of ionizing photons, N ion, to the choice of SPS model and the treatment of stellar feedback in our galaxy formation model. We compare our results to those of other simulations, constraints from empirical models, and observations. We find that adopting SPS models that include binary stars predict about a factor of 2 more ionizing radiation than models that only assume single stellar populations. We find that UV-faint, low-mass galaxies have values of ξion about 0.25 dex higher than those of more massive galaxies, but find weak evolution with cosmic time, about 0.2 dex from z ∼ 12-4 at fixed rest-UV luminosity. We provide predictions of N ion as a function of Mh and a number of other galaxy properties. All results presented in this work are available at https://www.simonsfoundation.org/semi-analytic-forecasts-for-jwst/.
KW - Cosmology: theory
KW - Dark ages
KW - First stars
KW - Galaxies: evolution
KW - Galaxies: formation
KW - Galaxies: high-redshift
KW - Galaxies: star formation
KW - Reionization
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U2 - 10.1093/mnras/staa714
DO - 10.1093/mnras/staa714
M3 - Article
AN - SCOPUS:85085370159
SN - 0035-8711
VL - 494
SP - 1002
EP - 1017
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
IS - 1
ER -