March 11, Tuesday
Speaker: Andrey Kravtsov, Chicago
Location: UCB, Hearst Field Annex B-1 – 1:10 pm
Title: “Order out of chaos: stellar masses and sizes of galaxies and their host dark matter halos”
Abstract: Galaxy formation is a complex, hierarchical, highly non-linear process, which involves gravitational collapse of dark matter and baryons, supersonic, highly compressible and turbulent flows of gas, cooling and heating of gas, star formation, and stellar feedback. Nevertheless, despite the apparent complexity of these processes, galaxies exhibit a number of striking regularities, such as tight correlations between galaxy sizes and stellar masses and the mass and extent of their parent halos dominated by dark matter. I will discuss our current understanding of halo structure and physical motivation for the definition of halo radius and mass. I will also summarize the relations between stellar mass and halo mass and galaxy sizes and halo virial radius. I will show that the latter relation is close to linear, which indicates that sizes of galaxies of all types are set by specific angular momentum induced by gravitational torques during galaxy formation. In addition, I will show that stellar surface density profiles of galaxies of different morphological types at radii beyond half-mass radius have similar shape. The stellar mass-halo mass relation is tight, but its shape is complex and is determined by the complicated physics of star formation and feedback. I will show that the current generation of galaxy formation simulations is capable of reproducing the shape of this relation with reasonable set of assumptions about feedback physics.
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