THE<i>FERMI</i>HAZE: A GAMMA-RAY COUNTERPART TO THE MICROWAVE HAZE

Abstract

The Fermi Gamma-Ray Space Telescope reveals a diffuse inverse Compton signal\nin the inner Galaxy with a similar spatial morphology to the microwave haze\nobserved by WMAP, supporting the synchrotron interpretation of the microwave\nsignal. Using spatial templates, we regress out pi0 gammas, as well as IC and\nbremsstrahlung components associated with known soft-synchrotron counterparts.\nWe find a significant gamma-ray excess towards the Galactic center with a\nspectrum that is significantly harder than other sky components and is most\nconsistent with IC from a hard population of electrons. The morphology and\nspectrum are consistent with it being the IC counterpart to the electrons which\ngenerate the microwave haze seen at WMAP frequencies. In addition, the implied\nelectron spectrum is hard; electrons accelerated in supernova shocks in the\ndisk which then diffuse a few kpc to the haze region would have a softer\nspectrum. We describe the full sky Fermi maps used in this analysis and make\nthem available for download.\n