Speaker
Description
Dwarf spheroidal galaxies (dSphs) are considered promising targets for indirect Dark Matter (DM) identification. The (mostly frequentist) analyses of gamma-ray photons originating from dSphs have allowed to set stringent limits on the DM self-annihilation cross-section. Conventional search strategies rely on quantifying the abundance of DM, by calculating the so-called J-factor. This quantity can be estimated from the kinematic properties of the stellar population of dSphs by means of Bayesian methods, which introduce significant systematic uncertainties due to the inevitable influence of priors. Here we describe a fully frequentist method for deriving J-factors and their uncertainties, which improves upon previous studies by making the statistical treatment of J more consistent with most gamma-ray analyses. Validation is performed using the simulation suite released by Gaia Challenge, showing that the method possesses good statistical properties. We apply the technique on a kinematic sample from 20 dSphs. We also implement our likelihoods of J to derive new upper limits on the DM annihilation cross-section. The new limits and the implications of these findings for DM searches are discussed.
