The Zen of Galaxies

Mon, October 05, 2015

Over the past decade a quiet revolution has taken place in our picture of galaxy evolution. Rather than evolving through violent mergers, galaxies live quiet lives on narrow scaling relations. This is explained elegantly by the so-called "equilibrium model" of galaxy formation. I will present a simple extension to this model that can explain the finite scatter observed in galaxy scaling relations as the consequence of variability in cosmological accretion. I will also show how the same variability that gives rise to scatter in these relations, when coupled with the physics of gas transport within disks, can explain the structure of gas disks in local and high redshift galaxies. Finally I will present the results of detailed simulations of isolated dwarf galaxies. With these simulations I will show how ordinary photoelectric heating can explain the long depletion times observed in dwarfs, and I will argue that the equilibrium model can still be applied to these galaxies despite their long depletion times.