Search for Dark Matter Gamma-ray Emission from the Andromeda Galaxy with the High-Altitude Water Cherenkov Observatory

TL;DR

This study used 1017 days of HAWC Observatory data to search for gamma-ray signals from dark matter in the Andromeda Galaxy, setting new constraints on dark matter properties in the TeV range.

Contribution

First comprehensive gamma-ray search for dark matter in M31 using HAWC data, providing the most stringent decay limits for certain mass ranges and channels.

Findings

No dark matter signal detected in M31.

Set new limits on dark matter decay and annihilation for masses 1-100 TeV.

Provided gamma-ray flux limits across 5 energy bins from 1 to 100 TeV.

Abstract

The Andromeda Galaxy (M31) is a nearby ($\sim$780 kpc) galaxy similar to our own Milky Way. Observational evidence suggests that it resides in a large halo of dark matter (DM), making it a good target for DM searches. We present a search for gamma rays from M31 using 1017 days of data from the High Altitude Water Cherenkov (HAWC) Observatory. With its wide field of view and constant monitoring, HAWC is well-suited to search for DM in extended targets like M31. No DM annihilation or decay signal was detected for DM masses from 1 to 100 TeV in the $b\bar{b}$, $t\bar{t}$, $\tau^{+}\tau^{-}$, $\mu^{+}\mu^{-}$, and $W^{+}W^{-}$ channels. Therefore we present limits on those processes. Our limits nicely complement the existing body of DM limits from other targets and instruments. Specifically the DM decay limits from our benchmark model are the most constraining for DM masses from 25 TeV to 100 TeV in the $b\bar{b}, t\bar{t}$ and $\mu^{+}\mu{-}$ channels. In addition to DM-specific limits, we also calculate general gamma-ray flux limits for M31 in 5 energy bins from 1 TeV to 100 TeV.