Date:
Tue, 22/09/200913:00-14:00
Location:
Kaplun Bldg, seminar room, 2nd floor
Cold and hot modes of accretion onto galaxies
As gas is accreted into galactic halos its gravitational energy is converted into thermal energy. This process usually involves strong shocks ("virial shocks"). I will discuss the stability of virial shocks in the presence of significant cooling, and show that when halos are smaller than ~10^12 solar masses the halo gas cannot be in hydrostatic equilibrium around galaxies. Rather, accreted gas will free-fall until it hits the galaxies. In some conditions, cold filaments will survive within a hot, diffuse halo. This scenario has implications on galaxy attributes, and in particular the color-magnitude bi-modality of galactic population observed in SDSS. I will then relate that phenomena to high-z star forming galaxies, and discuss interactions of these cold streams with the galaxy.
As gas is accreted into galactic halos its gravitational energy is converted into thermal energy. This process usually involves strong shocks ("virial shocks"). I will discuss the stability of virial shocks in the presence of significant cooling, and show that when halos are smaller than ~10^12 solar masses the halo gas cannot be in hydrostatic equilibrium around galaxies. Rather, accreted gas will free-fall until it hits the galaxies. In some conditions, cold filaments will survive within a hot, diffuse halo. This scenario has implications on galaxy attributes, and in particular the color-magnitude bi-modality of galactic population observed in SDSS. I will then relate that phenomena to high-z star forming galaxies, and discuss interactions of these cold streams with the galaxy.