Research
To the left is a simulation depicting a model for the Milky Way's stellar halo from Bullock & Johnston 2005. The favored cosmological model predicts that the Milky Way should have accreted many small galaxies in the past, and that the signature of these events can be seen by looking for clumps in in the stellar distribution far from our galaxy. See work on this topic by UCI graduate student Chris Purcell.
Galaxy Stellar Halos
Dark Matter and Dwarf Galaxies
Dwarf satellite companions of the Milky Way and Andromeda include the least luminous, most metal poor, and most dark matter dominated galaxies in the known Universe. Their properties constrain the nature of dark matter and very threshold of galaxy formation. Manoj Kaplinghat, Louie Strigari, and I are working with a large group at Irvine to understand these extreme systems. UCI graduate students Greg Martinez, Miguel Rocha, Kyle Stewart, Erik Tollerud, and Joe Wolf are working on related topics.
Among the biggest questions in galaxy formation is why galaxies have so little normal matter compared to dark matter. Most researchers believe that these ‘missing baryons’ are in low-density hot gas (or plasma) between galaxies and in galaxy halos.
T. Kaufmann, A. Maller, T. Fang and I are simulating gas cooling and galaxy formation to understand these issues. One of our simulations from Kaufmann et al. 2009 is shown on the left. The work may help understand the origin of the mysterious High Velocity Clouds that orbit around the Milky Way Galaxy.
Gas cooling and the formation of galaxies
Galaxy mergers play vital roles in building and destroying galaxies. The top figure to the left shows a merger tree derived from a large cosmological N-body simulation by UCI graduate student Kyle Stewart .
The lower figure is taken from a simulation by UCI graduate student Chris Purcell. Along with S. Kazanzitis, we are investigates the impact of galaxy mergers on galaxy disks.
Galaxy mergers and interactions
Link to my publications in chronological order
