COSMOLOGICAL SIMULATIONS OF GALAXY FORMATION II: MATCHING THE OBSERVATIONAL PROPERTIES OF DISK GALAXIES

We have used fully cosmological, high resolution N-body + SPH simulations to follow the formation of disk galaxies with a rotational velocity between 140 and 280 km/s in a ΛCDM universe. The simulations include gas cooling, star formation (SF), the effects of a uniform UV background and a physically motivated description of feedback from supernovae (SN). The host dark matter (DM) halos have a spin and last major merger redshift typical of galaxy sized halos as measured in recent large scale N–Body simulations. Galaxies formed rotationally supported disks with realistic exponential scale lengths and fall on the I-band and baryonic Tully-Fisher relations. The combination of UV background and SN feedback drastically reduced the number of visible satellites orbiting inside a Milky Way sized halo, bringing it fair agreement with observations. Feedback delays SF in small galaxies and more massive ones contain older stellar populations. The current star formation rates as a function of galaxy stellar mass are in good agreement with those measured by the SDSS.