Both the milky way (MW) and its massive neighbor, M31, host systems of satellite dwarf galaxies that are relics of their assembly history. NASA observatories, such as HST, wfirst, and jwst, and survey…

The National Aeronautics and Space Administration (NASA) awarded a $356,444.54 grant to the University of Arizona (doing business as the Arizona Board of Regents) to conduct research on modeling the impact of massive satellite galaxies, such as the Large Magellanic Cloud and Messier 33, on the dark matter distribution and halo potentials of the Milky Way and Andromeda galaxies. This research aims to develop a more accurate theoretical framework for understanding the assembly history and structure of the local group of galaxies. The grant does not have a set-aside designation and was awarded on September 1, 2018 with a completion date of December 21, 2022. The University of Arizona, a U.S. state government entity, 1862 land grant college, Hispanic Serving Institution, and state-controlled institution of higher education, will perform the work under this NASA Astrophysics Theory Program (ATP) grant at its facilities in Tucson, Arizona.

Both the milky way (MW) and its massive neighbor, M31, host systems of satellite dwarf galaxies that are relics of their assembly history. NASA observatories, such as HST, wfirst, and jwst, and survey missions, such as gaia and lsst, have/will be used to identify new substructure about the MW and M31 and measure the kinematics of local group members with unprecedented accuracy. The ultimate goal for these data is to learn about the assembly and structure of the dark matter halos of the MW and M31. To this end, this substructure (e.g., satellite galaxies) is typically considered as isolated, point mass-tracers of their host potentials. This assumption, however, breaks down if the total mass of the satellite is a significant fraction of the host mass, which is the case for the LMC and M33. Such massive satellites will modify and contribute to the dark matter distribution of the host, changing the shape of the halo potential in a non-symmetrical, time-evolving manner. As such, the LMC and M33 have the potential to perturb the kinematics of all tracers of the halo potential of both M31 and the MW, such as globular clusters, halo STARS, stellar streams, and smaller satellites orbiting in the halo. To date, this effect has not been accounted for in models of the local group. The goal of this NASA ATP program is to use high-resolution, n-body simulations to build time-evolving models of the dark matter distribution about the MW and M31, owing to the evolution of their massive satellites. Analytic realizations of the resulting potentials will be released to the community. In addition, this program will place these new models of the local group and the evolution of massive satellites in a cosmological context. Astrophysicists do not currently have an appropriate theoretical framework to study the assembly history of our local group. The proposed detailed theoretical study of how massive dwarfs influence the dark matter halo of their hosts is thus both timely and critical to all efforts to understand the structure and evolution of the dark matter distribution of the MW, M31 and analogous systems.