The Fermi Haze from Dark Matter Annihilations and Anisotropic Diffusion

Recently we identified a large extended diffuse gamma-ray structure

towards the Galactic center in full sky gamma-ray maps produced by the

Fermi Gamma-Ray Space Telescope. This feature was dubbed the Fermi

"haze" (Dobler et al. 2010) and more recently the Fermi "bubbles" (Su

et al 2010). The Fermi haze is hard spectrum inverse Compton

radiation from a population of energetic electrons that are too hard

to be produced by typical astrophysical mechanisms, such as supernova

shocks. While more exotic astrophysical scenarios may be plausible,

here we explore the possibility that the hard spectrum electrons are

due to dark matter annihlations in the Galactic halo and are

propagated to the required volume by anisotropic diffusion effects.

We develop a self-consistent anisotropic diffusion model and show that

both the morphology and spectrum are well fit by the model. In

addition, this model (which utilizes an XDM model for the dark matter

particle with a self-annihilation cross section Sommerfeld enhancement

of 100) also produces the microwave synchrotron haze and locally

observed cosmic-ray excesses by Fermi and PAMELA.