W-WIMP Annihilation as a Source of the Fermi Bubbles

Abstract

The Fermi Gamma-ray Space Telescope discovered two \gamma-ray emitting bubble-shaped structures that extend nearly symmetrically on either side of our Galaxy and appear morphologically connected to the Galactic center. The origin of the emission is still not entirely clear. It was recently shown that the spectral shape of the emission from the Fermi bubbles is well described by an approximately 50 GeV dark matter particle annihilating to b \bar b, with a normalization corresponding to a velocity average annihilation cross section of < \sigma_b v > ~ 8 \times 10^{-27} cm^3/s. We study the minimal hidden sector recently introduced by Weinberg and examine to what extent its weakly-interacting massive particles (W-WIMPs) are capable of accommodating both the desired effective annihilation rate into quarks and the observed relic density.