A Robust Approach to Constraining Dark Matter from Gamma-Ray Data

TL;DR

This paper introduces a novel gamma-ray data analysis technique to constrain dark matter properties with minimal assumptions, applying it to Fermi telescope data to set limits on dark matter mass and annihilation cross section.

Contribution

The authors develop a background-agnostic method leveraging symmetry and pixel independence to constrain dark matter, accounting for halo profile uncertainties.

Findings

Set upper limits on gamma-ray flux near the Galactic Center.

Derived constraints on dark matter annihilation cross section around 10^-25 cm^3 s^-1.

Applied method to Fermi data to produce new dark matter parameter bounds.

Abstract

Photons produced in the annihilations of dark matter particles can be detected by gamma-ray telescopes; this technique of indirect detection serves as a cornerstone of the upcoming assault on the dark matter paradigm. The main obstacle to the extraction of information about dark matter from the annihilation photons is the presence of large and uncertain gamma-ray backgrounds. We present a new technique for using gamma-ray data to constrain the properties of dark matter that makes minimal assumptions about the dark matter and the backgrounds. The technique relies on two properties of the expected signal from annihilations of the smooth dark matter component in our galaxy: 1) it is approximately rotationally symmetric around the axis connecting us to the Galactic Center, and 2) variations from the mean signal are uncorrelated from one pixel to the next. We apply this technique to recent data from the Fermi telescope to generate constraints on the dark matter mass and cross section for a variety of annihilation channels. We quantify the uncertainty introduced into our constraints by uncertainties in the halo profile and by the possibility that the halo is triaxial. The resultant constraint, the flux F \leq 4.5\times10^-6 cm^-2 s^-1 sr^-1 for energies between 1 and 100 GeV at an angle 15 degrees away from the Galactic Center, translates into an upper limit on the velocity weighted annihilation cross section of order 10^-25 cm^3 s^-1 depending on the annihilation mode.