Neal Dalal, CITA

"The handwaver's guide to dark matter halos"

Dark matter halos play an important role in many areas of astrophysics and cosmology,
and the properties of halos influence a wide variety of observables. Our understanding
of halos is based almost entirely on N-body simulations, with relatively poor theoretical
understanding of what determines halo properties. In my talk, I will try to give a simple
way to understand many properties of halos, including their density profiles, their
abundance, and their clustering. Using an extremely simple model, it is possible to match
the results of N-body simulations across a wide range of cosmologies, even better than
commonly used empirical fitting formulae. Using this approach, we can also predict how
halos and their resident galaxies behave in cosmologies that depart from the standard LCDM
model, which I will illustrate with some examples.