My research is primarily focused on the emergence of structure in the universe.  I use a combination of cosmological hydrodynamic simulations and good old fashioned analytic theory to figure out how the tiny fluctuations in density that were present when the universe was only 300 thousand years old, become the galaxies and black holes that we see after 14 billion years of cosmic evolution.  I consider myself an observationally-oriented theorist, in that I make predictions that can be explicitly compared to current and future observations.
I have been waging a  three-pronged campaign against the mysteries of the universe.  
On the largest scales, I study the Intergalactic Medium.  This is where most of the baryons in the universe live and it’s the reservoir of material out of which galaxies form.  It is both the source of star formation and the sink of the biproducts of star formation.    Because it is mostly Hydrogen, it’s also the part of cosmological simulations that we understand the best.  This make the IGM a very powerful tool to study galaxy growth and evolution.
On the smallest scales, I study supermassive black holes.  These beasts lie at the heart of all galaxies where they can wreak havoc on their galactic hosts.   How do they grow, what is their distribution of fundamental properties, and how do they interact with their environs?
On intermediate scales, I study our very own Milky Way Galaxy.   The Milky Way provides a laboratory for precision understanding of the phenomena we can see in the distant universe.