Particle and Astroparticle Physics Seminar

Dark matter annihilation vs. astrophysics: the gamma-ray signal from the dwarf galaxy Reticulum II

Alex Geringer-Sameth

Carnegie Mellon University

I will present results from a search for gamma-ray emission in many recently discovered Milky Way satellites. The Reticulum II dwarf, one of our nearest neighbors, shows evidence for a signal in Fermi data. The detected emission is consistent with annihilating dark matter with a particle mass less than a few hundred GeV. Different ways of treating the background yield different significances and I will discuss the caveats involved. Dynamical modeling, based on spectroscopic observations of member stars, is used to infer the dark matter density profile of Reticulum II, and shows that its annihilation signal should be among the largest of the known dwarfs. I will discuss current progress on determining whether gamma-ray signals in dwarf galaxies can be explained by conventional astrophysical processes.