Galaxies 09: Assembly, Gas Content and Star Formation History of Galaxies

Alyson Brooks
Caltech

The Role of Cold Flows in the Early Growth of Galaxies

Using high resolution cosmological hydrodynamical simulations and comparisons to semi-analytic models, I will demonstrate that cold gas accretion, particularly along filaments, modifies the standard picture of shocked gas accretion and cooling onto galaxy disks. Even when a hot halo is able to develop in more massive galaxies, there exist dense filaments that penetrate inside of the virial radius and deliver cold gas to the central galaxy, leading to star formation at higher redshifts than predicted by the standard model. For galaxies up to $\sim$L$^*$, cold accretion gas is responsible for the star formation in the disk at all times to the present. In concert with supernovae feedback, star formation in the disk is regulated, leading to the development of a cold gas reservoir that helps to quickly reform disks despite disruption in major mergers.

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