NUMERICAL GALAXY CATALOG. I. A SEMIANALYTIC MODEL OF GALAXY FORMATION WITH TV-BODY SIMULATIONS

摘要

We construct the Numerical Galaxy Catalog (νGC), based on a semianalytic model of galaxy formation combined with high-resolution N-body simulations in a Λ-dominated flat cold dark matter (ΛCDM) cosmological model. The model includes several essential ingredients for galaxy formation, such as merging histories of dark halos taken directly from N-body simulations, radiative gas cooling, star formation, heating by supernova explosions (supernova feedback), mergers of galaxies, population synthesis, and extinction by internal dust and intervening H I clouds. As the first paper in a series using this model, we focus on basic photometric, structural, and kinematical properties of galaxies at present and at high redshift. Two sets of model parameters are examined, strong and weak supernova feedback models, which are in good agreement with observational luminosity functions of local galaxies within observational uncertainties. Both models agree well with many observations of, e.g., cold gas mass-to-stellar luminosity ratios of spiral galaxies, H I mass functions, galaxy sizes, faint galaxy number counts and photometric redshift distributions in optical passbands, isophotal angular sizes, and cosmic star formation rates. In particular, the strong supernova feedback model is in much better agreement with near-infrared (K'-band) faint galaxy number counts and redshift distribution than the weak-feedback model and our previous semianalytic models based on the extended Press-Schechter formalism. Observed Tully-Fisher relations for bright galaxies and color-magnitude relations for dwarf elliptical galaxies in clusters of galaxies are broadly reproduced, but no agreement with observations is obtained over whole ranges. Nevertheless, they show improvements over results produced by other semianalytic models. A direction to be pursued in overcoming the remaining problems is also discussed. We find that the resolution of N-body simulations, which is down to 3 x 10~9 solar mass, for the minimum mass of dark halos consisting of 10 dark matter particles in our model, plays a significant role in galaxy formation, and that merging histories of dark halos directly taken from N-body simulations produce results different from models based on the extended Press-Schechter model even if the mass function of dark halos at present is set to be the same as that obtained by the same N-body simulations used here.