Some Research Interests:

MW satellites
Dark Matter and the Smallest Galaxies

Louis Strigari, Manoj Kaplinghat and I are studying the dwarf galaxies of the Local Group in order to understand structure formation on the smallest scales.  Click here for a link to our relevant papers.

We recently discoverd that all of these galaxies share a common mass scale.  A press release on this result may be found here.  Click here for another nice image.

See work on this topic by UCI graduate students Greg Martinez, Erik Tollerud, and Joe Wolf.

stellar halo

Galaxy Stellar Halos


To the left is a simulation snapshot depicting a model for the Milky Way's stellar halo.  Kathryn Johnston and I  working on models of stellar halo formation based on the expected accretion histories of Milky-Way size dark matter halos. 

See work on this topic by UCI graduate student Chris Purcell.

Click here for a movie.  This page has information and images.

Gas Halo
Gas Cooling and Galaxy Formation


Tobias Kaufmann, Ari Maller, Taotao Fang and I are studying gas cooling and galaxy formation.  A preliminary description of our work may be found here.

The work may help understand the origin of the mysterious High Velocity Clouds that orbit around the Milky Way Galaxy.

See Maller & Bullock 2004 for a related discussion of these issues.

merger tree
Galaxy Merger Histories

Bestsy Barton and I along with several graduate students and McCue Fellow Jeff Cooke have a large research program to undertsand how mergers shape the formation of galaxies in the universe.   See, for example, work by UCI PhD Joel Berrier on this topic.

The figure to the left shows a merger tree derived from a large cosmological N-body simulation by graduate student Kyle Stewart .


See this simulation movie by graduate student Chris Purcell which investigates the impact of galaxy mergers on the morphology disks.
minor merger