Fermi LAT Search for Photon Lines from 30 to 200 GeV and Dark Matter Implications

Abstract

Dark matter (DM) particle annihilation or decay can produce monochromatic ${\hat{I}}^3$-rays readily distinguishable from astrophysical sources. ${\hat{I}}^3$-ray line limits from 30 GeV to 200 GeV obtained from 11 months of Fermi Large Area Space Telescope data from 20-300 GeV are presented using a selection based on requirements for a ${\hat{I}}^3$-ray line analysis, and integrated over most of the sky. We obtain ${\hat{I}}^3$-ray line flux upper limits in the range $0.6-4.5\times 10^{-9}{\mathrm{cm}}^{-2}{\mathrm{s}}^{-1}$, and give corresponding DM annihilation cross-section and decay lifetime limits. Theoretical implications are briefly discussed.

6 pages, 1 figure. Accepted for publication by The Physical Review Letters