A Search for Dark Matter in the Galactic Halo with HAWC

TL;DR

This paper reports on HAWC gamma-ray observatory observations of the Galactic halo, setting strong limits on dark matter annihilation and decay at TeV to PeV energies, impacting models explaining IceCube neutrinos.

Contribution

First to use HAWC data to place robust limits on TeV-PeV dark matter annihilation and decay in the Galactic halo.

Findings

Established new limits on dark matter annihilation cross-section.

Constrained dark matter decay lifetime models.

Impacted theories linking PeV neutrinos to dark matter decay.

Abstract

The High Altitude Water Cherenkov (HAWC) gamma-ray observatory is a wide field-of-view observatory sensitive to 500 GeV - 100 TeV gamma rays and cosmic rays. With its observations over 2/3 of the sky every day, the HAWC observatory is sensitive to a wide variety of astrophysical sources, including possible gamma rays from dark matter. Dark matter annihilation and decay in the Milky Way Galaxy should produce gamma-ray signals across many degrees on the sky. The HAWC instantaneous field-of-view of 2 sr enables observations of extended regions on the sky, such as those from dark matter in the Galactic halo. Here we show limits on the dark matter annihilation cross-section and decay lifetime from HAWC observations of the Galactic halo with 15 months of data. These are some of the most robust limits on TeV and PeV dark matter, largely insensitive to the dark matter morphology. These limits begin to constrain models in which PeV IceCube neutrinos are explained by dark matter which primarily decays into hadrons.