The first galaxies: simulating their feedback-regulated assembly
  We investigate the formation of a galaxy reaching a virial mass of $~ 10^8$
solar mass at $z=10$ by carrying out a zoomed radiation-hydrodynamical
cosmological simulation. This simulation traces Population~III (Pop~III) star
formation, characterized by a modestly top-heavy initial mass function (IMF),
and considers stellar feedback such as photoionization heating from Pop III and
Population~II (Pop~II) stars, mechanical and chemical feedback from supernovae
(SNe), and X-ray feedback from accreting black holes (BHs) and high-mass X-ray
binaries (HMXBs). We self-consistently impose a transition in star formation
mode from top-heavy Pop III to low-mass Pop~II, and find that the star
formation rate in the computational box is dominated by Pop~III until $z=13$,
and by Pop~II thereafter. The simulated galaxy experiences bursty star
formation, with a substantially reduced gas content due to photoionization
heating from Pop~III and Pop~II stars, together with SN feedback. All the gas
within the simulated galaxy is metal-enriched above $10^{-5}$ solar, such that
there are no remaining pockets of primordial gas. The simulated galaxy has an
estimated observed flux of $~10^{-3} nJy$, which is too low to be detected by
the James Webb Space Telescope (JWST) without strong lensing amplification. We
also show that our simulated galaxy is similar in terms of stellar mass to
Segue 2, the least luminous dwarf known in the Local Group.
