Fermi Gamma-ray Space Telescope

Cross Correlation of Extragalactic Gamma-ray Background and Luminous Red Galaxies

S. Horiuchi
M. Shirasaki, N. Yoshida

Abstract:

Recent measurements of the angular cross correlation between the extragalactic gamma-ray background (EGB) and probes of large scale structure open the possibility of testing dark matter on extragalactic scales. Here, we focus on Luminous Red Galaxies (LRGs) as a potential target to search for dark matter annihilation. We report results of the cross correlation of the EGB measured by Fermi-LAT and LRGs taken from SDSS. The expected gamma-ray contribution from astrophysical origins is estimated from the LRG properties and gamma-ray scaling relations, and found to be negligible. We implement careful treatment of uncertainties with realistic mock LRG catalogs and multiple Galactic gamma-ray foreground models. We find our result is consistent with a null signal, and set new limits on the dark matter cross section. We discuss how LRGs would be ideal targets for probing dark matter annihilation in future surveys.