Dark matter annihilation factors in the Milky Way's dwarf spheroidal galaxies

Abstract

The Milky Way’s dwarf spheroidal (dSph) galaxies are among the best targets for the indirect detection of dark matter (DM) with γ-rays. The expected gamma-ray flux depends on the so-called ‘J-factor’, the integral of the squared DM density along the line-of-sight. Using a large number of simulated dSphs, we have defined an optimized Jeans analysis setup for the reconstruction of the DM density with stellar-kinematic data. Employing this setup, we provide here estimates of astrophysical J-factors for twenty-two Galactic dSphs, including the newly discovered Reticulum II. We finally identify several criteria that may indicate a contamination of a kinematic dataset by interlopers, leading to unreliable J-factors. We find that the kinematic sample of Segue I, one of the closest dSph, might be affected by this issue.