Search for Gamma-ray Spectral Lines from Dark Matter Annihilation in Dwarf Galaxies with the High-Altitude Water Cherenkov Observatory

TL;DR

This paper reports a search for gamma-ray spectral lines from dark matter annihilation in dwarf galaxies using 1038 days of HAWC data, setting the most stringent limits between 20 and 100 TeV.

Contribution

First search for gamma-ray spectral lines from dark matter in dwarf galaxies using HAWC with event-by-event energy reconstruction.

Findings

Most constraining spectral line limits from 20 to 100 TeV.

Updated limits on continuum channels.

No detection of spectral lines.

Abstract

Local dwarf spheroidal galaxies (dSphs) are nearby dark-matter dominated systems, making them excellent targets for searching for gamma rays from particle dark matter interactions. If dark matter annihilates or decays directly into two gamma rays (or a gamma ray and a neutral particle), a monochromatic spectral line is created. At TeV energies, no other processes are expected to produce spectral lines, making this a very clean indirect dark matter search channel. With the development of event-by-event energy reconstruction, we can now search for spectral lines with the High Altitude Water Cherenkov (HAWC) Observatory. HAWC is a wide field of view survey instrument located in central Mexico that observes gamma rays from <1 TeV to >100 TeV. In this work we present results from a recent search for spectral lines from local, dark matter dominated dwarf galaxies using 1038 days of HAWC data. We also present updated limits on several continuum channels that were reported in a previous publication. Our gamma-ray spectral line limits are the most constraining obtained so far from 20 TeV to 100 TeV.