I primarily explore how the Local Group, together with numerical simulations, can inform galaxy formation theory. Most recently, I have begun working with the FIRE (Feedback in Realistic Environments) collaboration to include hydrodyanmics, star formation, and stellar/supernova feedback in cosmological simulations of the Local Group.

A large set of movies illustrating the evolution of Milky Way-mass galaxies in the FIRE simulations are available here.

A similar set of movies for the recently completed ELVIS on FIRE suite is in progress.


The ELVIS on FIRE suite of simulations apply the FIRE models for star formation, feedback, and other baryonic physics to environments that are designed to mimic the real Local Group by containing two Milky Way-size galaxies with similar relative kinematics to the Milky Way and Andromeda themselves. The suite, which is still in progress, reproduces both the number and internal structure of dwarf galaxies around the Milky Way. The image above cycles between the 3D dark matter, stellar, and gas density throughout the simulated volume, demonstrating that the wealth of structure in the former is not always reproduced by the (observable) baryons.


The publicly available Exploring the Local Volume in Simulations (ELVIS) suite, consisting of 12 Local Group-like halo pairs and 24 mass-matched isolated halos, allows for a statistical understanding of the LG and its history, and provides the basis for predictions regarding future observations. ELVIS has enabled over thirty publications since its inception, and continues to provide an ideal laboratory for exploring LCDM predictions for structure in the Local Group.

Dwarf Galaxies

Predicted to be the most dark matter dominated objects in the Universe, dwarfs may be crucial for understanding, e.g., the particle nature of dark matter, the earliest epochs of galaxy formation, and the aftermath of reionization. Their abundances, internal profiles (i.e., cuspy vs cored), total masses, star formation histories, metallicities, and phase-space distributions around the Milky Way and Andromeda galaxies all provide tests of the standard paradigm and galaxy formation physics.

Image credit: ESO DSS-2


First Author Publications

Nth Author Publications


  • University of California, Irvine Irvine, CA USA

    Ph.D., Physics & Astronomy, awarded June 2015

    Advisor: James S. Bullock

    Dissertation: "Galaxy Formation in the Local Group"

  • University of California, Irvine Irvine, CA USA

    M.S., Physics & Astronomy, awarded December 2010

  • Haverford College, Haverford, PA USA

    B.S., Astronomy and Physics, awarded May 2009

Professional Appointments

  • Einstein Fellow

    California Institute of Technology

    August 2015 - present

Fellowships and Awards

  • Einstein Postdoctoral Fellowship,


    Awarded July 2015

  • Chancellor's Club Dissertation Fellowship

    University of California, Irvine

    Awarded December 2015

  • Price Prize

    Ohio State University

    Awarded July 2014

  • Chancellor's Fellowship

    University of California, Irvine

    Awarded February 2009

  • Summer Research Fellowship

    University of California, Irvine

    Awarded February 2009

Research Interests

Dwarf galaxy formation and theoretical cosmology, e.g.:

The effects of the Milky Way's proximity to Andromeda

The impact of environment on dwarf galaxy evolution

Simulations of structure formation on all scales

The evolution of the smallest galaxies in the Universe

Hydrodynamical simulations of the Local Group

Teaching Experience

  • Graduate Teaching Assistant

    University of California, Irvine

    September 2009 - June 2010 and March 2014 - June 2014

  • Teaching Assistant

    California State Summer School for Mathematics and Science

    Astronomy Cluster

    July 2010, 2011, and 2012

  • Physics Clinic Tutor

    Haverford College

    February 2007 - May 2009

Mentoring Experience

  • Mentored Jaspreet Lally, at the time an undergraduate at University of California, Irvine, on how to run and analyze simulations of dwarf galaxies in isolation with a time varying potential to search for core formation, resulting in an authorship on Garrison-Kimmel et al., 2013.
  • Mentored Kyle Lee, currently an undergraduate at Chapman University, on how to set up, simulate, and analyze cosmological simulations, including selecting isolated Milky Way hosts for zoom-in simulations, resulting in an authorship on Garrison-Kimmel et al., 2014.
  • Mentored Emma Bardwell, an undergraduate at Case Western University, on a project exploring the relationship between halo mass and galaxy stellar mass, and the impact of scatter in that relation, resulting in an authorship on Garrison-Kimmel et al., 2016.
  • Mentored Kris Burke, an undergraduate at University of California, Irvine, on simulating the cosmological evolution of galaxies with a central potential to explore the impact of the Milky Way disk on the substructure population with minimal CPU cost.