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.

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