The Aurora radiation-hydrodynamical simulations of reionization:
  calibration and first results
  We introduce a new suite of radiation-hydrodynamical simulations of galaxy
formation and reionization called Aurora. The Aurora simulations make use of a
spatially adaptive radiative transfer technique that lets us accurately capture
the small-scale structure in the gas at the resolution of the hydrodynamics, in
cosmological volumes. In addition to ionizing radiation, Aurora includes
galactic winds driven by star formation and the enrichment of the universe with
metals synthesized in the stars. Our reference simulation uses 2x512^3 dark
matter and gas particles in a box of size 25 comoving Mpc/h with a force
softening scale of at most 0.28 kpc/h. It is accompanied by simulations in
larger and smaller boxes and at higher and lower resolution, employing up to
2x1024^3 particles, to investigate numerical convergence. All simulations are
calibrated to yield simulated star formation rate (SFR) functions in close
agreement with observational constraints at redshift z = 7 and to achieve
reionization at z = 8.3, which is consistent with the observed optical depth to
reionization. We focus on the design and calibration of the simulations and
present some first results. The median stellar metallicities of low-mass
galaxies at z = 6 are consistent with the metallicities of dwarf galaxies in
the Local Group, which are believed to have formed most of their stars at high
redshifts. After reionization, the mean photoionization rate decreases
systematically with increasing resolution. This coincides with a systematic
increase in the abundance of neutral hydrogen absorbers in the IGM.
