SILVERRUSH. VI. A simulation of Lyα emitters in the reionization epoch and a comparison with Subaru Hyper SuprimeCam survey early data
Abstract
The survey of Lyman α emitters (LAEs) with the Subaru Hyper SuprimeCam, called SILVERRUSH (Ouchi et al. 2018, PASJ, 70, S13), is producing massive data of LAEs at z ≳ 6. Here we present LAE simulations to compare the SILVERRUSH data. In 162^{3} comoving Mpc^{3} boxes, where numerical radiative transfer calculations of reionization were performed, LAEs have been modeled with physically motivated analytic recipes as a function of halo mass. We have examined 2^{3} models depending on the presence or absence of dispersion of halo Lyα emissivity, dispersion of the halo Lyα optical depth, τ_{α}, and halo mass dependence of τ_{α}. The unique free parameter in our model, a pivot value of τ_{α}, is calibrated so as to reproduce the z = 5.7 Lyα luminosity function (LF) of SILVERRUSH. We compare our model predictions with Lyα LFs at z = 6.6 and 7.3, LAE angular autocorrelation functions (ACFs) at z = 5.7 and 6.6, and LAE fractions in Lyman break galaxies at 5 < z < 7. The Lyα LFs and ACFs are reproduced by multiple models, but the LAE fraction turns out to be the most critical test. The dispersion of τ_{α} and the halo mass dependence of τ_{α} are essential to explain all observations reasonably. Therefore, a simple model of onetoone correspondence between halo mass and Lyα luminosity with a constant Lyα escape fraction has been ruled out. Based on our best model, we present a formula to estimate the intergalactic neutral hydrogen fraction, x_{H I}, from the observed Lyα luminosity density at z ≳ 6. We finally obtain x_{H I}=0.5_{0.3}^{+0.1} as a volumeaverage at z = 7.3.
 Publication:

Publications of the Astronomical Society of Japan
 Pub Date:
 June 2018
 DOI:
 10.1093/pasj/psy048
 arXiv:
 arXiv:1801.00067
 Bibcode:
 2018PASJ...70...55I
 Keywords:

 dark ages;
 reionization;
 first stars;
 galaxies: evolution;
 galaxies: formation;
 galaxies: highredshift;
 intergalactic medium;
 Astrophysics  Astrophysics of Galaxies
 EPrint:
 PASJ in press, 30 pages, 20 figures