PI: Andrew Wetzel

Andrew Wetzel

I am an assistant professor in the department of physics at the University of California, Davis.  I earned my Ph.D. in astrophysics at the University of California, Berkeley and pursued postdoctoral research at Yale UniversityCaltech, and Carnegie Observatories. Read more about my background.

I am fortunate to pursue research with the fantastic group below.


Sarah Loebman

Sarah Loebman is a NASA Hubble Fellow. Sarah is a stellar dynamicist at heart who works on all aspects of the Milky Way, from the formation and evolution of stars and star clusters in its disk, including their dynamics and elemental abundances, to its diffuse stellar halo, including how to measure the mass and shape of the Milky Way’s dark-matter halo. Sarah lives at the intersection of theory/simulation and observations, and she also is a leader in Big Data techniques.

Samantha Benincasa

Samantha Benincasa is a postdoctoral research scholar. She works on simulations of galaxy formation to understand the inter-stellar medium (ISM) gas in the Milky Way and nearby galaxies. She is particularly interested in giant molecular clouds (GMCs): their lifetimes, dynamics in the disk how they give rise to star formation, and how they are affected by stellar feedback.

Ph.D. Students

Jenna Samuel

Jenna Samuel works on low-mass ‘dwarf’ galaxies, in particular, the satellites of the Milky Way and Andromeda (M31). Jenna’s current research focuses on the origin of their spatial and velocity distributions, including the meaning and origin of observed planes of satellites. She also is interested in understanding (and disentangling) the roles of (internal) stellar feedback and (external) host halo environment on the evolution of dwarf galaxies.

Isaiah Santistevan

Isaiah Santistevan works on the ‘near-far connection’:  understanding the role of nearby dwarf galaxies during the epoch of reionization, including how we can infer the contribution of low-mass galaxies to the UV luminosity function across cosmic time. Isaiah also is interested in developing new models, using our cosmological simulations, to infer the full orbital histories of all of the dwarf galaxies in the Local Group.

Matt Bellardini

Matt Bellardini works on the formation of the disk of the Milky Way, including stellar and gas dynamics, thin+thick disk formation, and how to use stellar ages and abundances to reconstruct the formation history of the Milky Way via ‘galactic archaeology’.

Undergraduate Students

Sierra Chapman

Sierra Chapman is an undergraduate student majoring in physics. Her research focuses on predictions for the population of dark-matter subhalos in the halo of the Milky Way, including encounter rates of subhalos with the Milky Way’s disk and stellar streams.






Preet Patel

Preet Patel is an undergraduate student at the University of Michigan, but he has joined us in research for two summers, including via a Blue Waters Student Internship in 2018. His research focuses on predictions for elemental abundance patterns in the stars of low-mass (dwarf) galaxies and how we can use them to understand these galaxies’ formation histories.


Theodore, Ph.D.

Theodore is our group’s Chief Morale Officer. He joined our group after a short stay at LA county’s Baldwin Park Animal Care Center. Deciding that astrophysics might be more interesting than squirrel chasing, he earned his Pretty hairy Dog (Ph.D.) degree at Caltech (advised by JoAnn Boyd). He then pursued a postdog fellowship at Carnegie Observatories. As you can see, he effectively runs our group.