http://arxiv.org/abs/1608.04351
The extragalactic $\gamma$-ray background, and its spatial anisotropy, could potentially contain a signature of dark matter annihilation or particle decay. Astrophysical foregrounds, such as blazars and star-forming galaxies, however, dominate the $\gamma$-ray background, precluding an easy detection of the signal associated with the dark matter annihilation or decay in the background intensity spectrum. The dark matter imprint on the $\gamma$-ray background is expected to be correlated with large-scale structure tracers. In some cases such a cross-correlation is even expected to have a higher signal-to-noise ratio than the auto-correlation. A reliable tracer of the dark matter distribution in the large-scale structure is lensing of the cosmic microwave background (CMB) and the cosmic infrared background (CIB) is a reliable tracer of star-forming galaxies. We analyze Fermi-LAT data taken over 92 months and study the cross-correlation with Planck CMB lensing, Planck CIB, and Fermi-$\gamma$ maps. We put upper limits on the dark matter annihilation cross section from the cross-power spectra with the $\gamma$-ray background anisotropies. The unbiased power spectrum estimation is validated with simulations that include cross-correlated signals. We also provide a set of systematic tests and show no significant contaminations are found for the measurements presented here. Using $\gamma$-ray background map from 92-month data, we find the best constraint on the dark matter annihilation with a $1\sigma$ confidence level upper limit of $10^{-24}$ cm$^{3}$ s$^{-1}$, when the mass of dark matter particles is between 20 and 100 GeV.
C. Feng, A. Cooray and B. Keating
Tue, 16 Aug 16
13/57
Comments: 13 pages, 16 figures
You must be logged in to post a comment.