Galaxy formation with local photoionization feedback – I. Methods

Photoionization Eeects during Galaxy Formation

Photoionization, Numerical Resolution, and Galaxy Formation

Using cosmological simulations that incorporate gas dynamics and gravitational forces, we investigate the influence of photoionization by an ultraviolet radiation background on the formation of galaxies. In our highest resolution simulations, we find that photoionization has essentially no effect on the baryonic mass function of galaxies at z = 2, down to our resolution limit of ∼ 5× 10M⊙. We d...

Effects of Photoionization on Galaxy Formation

We investigate the e ects of the observed UV background radiation on galaxy formation. Photoionization by UV radiation decreases the cooling rate of the gas in halos, so that objects with only large density contrasts can self-shield against the background radiation, thereby allowing the shielded neutral cores to cool and form stars. In the context of the CDM model, we use the criterion that sel...

Tracing Galaxy Formation with Stellar Halos I: Methods

If the favored hierarchical cosmological model is correct, then the Milky Way system should have accreted ∼ 100− 200 luminous satellite galaxies in the past ∼ 12 Gyr. We model this process using a hybrid semi-analytic plus N-body approach which distinguishes explicitly between the evolution of light and dark matter in accreted satellites. This distinction is essential to our ability to produce ...

The Effects of Photoionization on Galaxy Formation — II: Satellite Galaxies in the Local Group

We use a self-consistent model of galaxy formation and the evolution of the intergalactic medium to study the effects of the reionization of the universe at high redshift on the properties of satellite galaxies like those seen around the Milky Way. Photoionization suppresses the formation of small galaxies, so that surviving satellites are preferentially those that formed before the universe re...