A generic method to constrain the dark matter model parameters from Fermi observations of dwarf spheroids

Abstract

Observation of γ-rays from dwarf galaxies is an effective wayto search for particle dark matter. Using 4-year data of Fermi-LATobservations on a series of Milky Way satellites, we develop ageneral way to search for the signals from dark matter annihilationin such objects. Instead of giving prior information about the energy spectrum of dark matter annihilation, we bin the Fermi-LAT data intoseveral energy bins and build a likelihood map in the ``energy bin- flux'' plane. The final likelihood of any spectrum can be easily derived through combining the likelihood of all the energy bins.It gives consistent result with that directly calculated usingthe Fermi Scientific Tool. This method is very efficient for the study of any specific dark matter models with γ-rays.We use the new likelihood map with Fermi-LAT 4 year data to fitthe parameter space in three representative dark matter models: i) toy dark matter model, ii) effective dark matter operators, and iii) supersymmetric neutralino dark matter.