SCORCH I: The Galaxy-Halo Connection in the First Billion Years
Abstract
SCORCH (Simulations and Constructions of the Reionization of Cosmic Hydrogen) is a new project to study the Epoch of Reionization (EoR). In this first paper, we probe the connection between observed high-redshift galaxies and simulated dark matter halos to better understand the primary source of ionizing radiation. High-resolution N-body simulations are run to quantify the abundance of dark matter halos as a function of mass M, accretion rate \dot{M}, and redshift z. A new fit for the halo mass function dn/dM is ≈20% more accurate at the high-mass end. A novel approach is used to fit the halo accretion rate function {dn}/d\dot{M} in terms of the halo mass function. Abundance matching against the observed galaxy luminosity function is used to estimate the luminosity-mass relation and the luminosity-accretion-rate relation. The inferred star formation efficiency is not monotonic with M nor \dot{M}, but reaches a maximum value at a characteristic mass ∼ 2× {10}11 {M}⊙ and a characteristic accretion rate ∼ 6× {10}2 {M}⊙ {{{yr}}}-1 at z ≈ 6. We find a universal EoR luminosity-accretion-rate relation and construct a fiducial model for the galaxy luminosity function. The Schechter parameters evolve such that {φ }\star decreases, {M}\star is fainter, and α is steeper at higher redshifts. We forecast for the upcoming James Webb Space Telescope and show that with apparent magnitude limit {m}{{AB}}≈ 31 (32), it can observe ≳ 11 (24) unlensed galaxies per square degree per unit redshift at least down to {M}\star at z ≲ 13 (14).
- Publication:
-
The Astrophysical Journal
- Pub Date:
- November 2015
- DOI:
- 10.1088/0004-637X/813/1/54
- arXiv:
- arXiv:1507.02685
- Bibcode:
- 2015ApJ...813...54T
- Keywords:
-
- cosmology: theory;
- dark ages;
- reionization;
- first stars;
- galaxies: high-redshift;
- large-scale structure of universe;
- methods: numerical;
- Astrophysics - Cosmology and Nongalactic Astrophysics
- E-Print:
- Published in ApJ, 16 pages, 12 figures, 3 tables