Abstract
We present the results of cosmological hydrodynamic simulations with
zoom-in initial conditions, and investigate the formation of the first
galaxies and their evolution towards observable galaxies at $z \sim 6$.
We focus on three different galaxies which end up in halos with masses
$M_{h} = 2.4 \times10^{10}~h^{-1}\; M_{\odot}$ (Halo-10), $1.6
\times10^{11}~h^{-1}\; M_{\odot}$ (Halo-11) and $0.7
\times10^{12}~h^{-1} M_{\odot}$ (Halo-12) at z=6. Our simulations also
probe impacts of different sub-grid assumptions, i.e., SF efficiency and
cosmic reionization, on SF histories in the first galaxies. We find that
star formation occurs intermittently due to supernova (SN) feedback at z
> 10, and then it proceeds more smoothly as the halo mass grows at
lower redshifts. Galactic disks are destroyed due to SN feedback, while
galaxies in simulations with no-feedback or lower SF efficiency models
can sustain galactic disk for long periods > 10 Myr. The expulsion of
gas at the galactic center also affects the inner dark matter density
profile. However, SN feedback does not seem to keep the shallow profile
of dark matter for a long period. Our simulated galaxies in Halo-11 and
Halo-12 reproduce the star formation rates (SFR) and stellar masses of
observed Lyman-$\alpha$ emitters (LAEs) at z = 7-8 fairly well given
observational uncertainties. In addition, we investigate the effect of
UV background radiation on star formation as an external feedback
source, and find that earlier reionization extends the quenching time of
star formation due to photo-ionization heating, but does not affect the
stellar mass at z=6.
| Original language | English |
|---|---|
| Journal | Astrophysical Journal |
| Volume | 846 |
| Issue number | 1 |
| DOIs | |
| Publication status | Published - 23 Apr 2017 |
Keywords / Materials (for Non-textual outputs)
- Astrophysics - Astrophysics of Galaxies