Dark-ages Reionization and Galaxy Formation Simulation - XV. Stellar
  evolution and feedback in dwarf galaxies at high redshift
  We directly compare predictions of dwarf galaxy properties in a semi-analytic
model (SAM) with those extracted from a high-resolution hydrodynamic
simulation. We focus on galaxies with halo masses of 1e9<Mvir/Msol<1e11 at high
redshift ($z\ge5$). We find that, with the modifications previously proposed in
Qin et al. (2018), including to suppress the halo mass and baryon fraction, as
well as to modulate gas cooling and star formation efficiencies, the SAM can
reproduce the cosmic evolution of galaxy properties predicted by the
hydrodynamic simulation. These include the galaxy stellar mass function, total
baryonic mass, star-forming gas mass and star formation rate at $z\sim5-11$.
However, this agreement is only possible by reducing the star formation
threshold relative to that suggested by local observations. Otherwise, too much
star-forming gas is trapped in quenched dwarf galaxies. We further find that
dwarf galaxies rapidly build up their star-forming reservoirs in the early
universe ($z>10$), with the relevant time-scale becoming significantly longer
towards lower redshifts. This indicates efficient accretion in cold mode in
these low-mass objects at high redshift. Note that the improved SAM, which has
been calibrated against hydrodynamic simulations, can provide more accurate
predictions of high-redshift dwarf galaxy properties that are essential for
reionization study.
