Fermi Gamma-ray Space Telescope

A Search for Dark Matter Annihilation in Newly Discovered Dwarf Galaxies

A. Geringer-Sameth

Abstract:

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 -- ranging from 2.3 sigma to greater than 3.7 sigma (after trials) -- and I will discuss the caveats involved. Spectroscopic observations of member stars are used to infer the density profile of Reticulum II, showing that its annihilation signal should be among the largest of the known dwarfs. I will discuss several tests that a dark matter interpretation must pass.