Constraints on the Diffuse Gamma-Ray Background with HAWC

TL;DR

This paper uses the HAWC observatory to set new limits on the diffuse gamma-ray background above 1 TeV, which has implications for understanding astrophysical sources and dark matter.

Contribution

It introduces improved analysis techniques for HAWC data to better isolate gamma-ray signals and provides the first constraints on the DGB at TeV energies.

Findings

Set new upper limits on the DGB above 1 TeV

Enhanced background rejection methods for HAWC data

Implications for dark matter and multimessenger astrophysics

Abstract

The Diffuse Gamma-Ray Background (DGB) above 100 GeV at high-latitudes is expected to be produced by unresolved extragalactic objects such as active galactic nuclei, isotropic Galactic gamma-rays, and possible emission from dark matter annihilations or decays in the Galactic dark matter halo. The DGB has been observed up to nearly 1 TeV, but has yet to be detected at higher energies. Detections or stringent limits on the DGB above this energy would have strong multimessenger consequences, such as constraining the origin of astrophysical neutrinos observed in IceCube. The High Altitude Water Cherenkov (HAWC) observatory has its highest sensitivity to gamma rays above 1 TeV and observes over 2/3 of the sky each day. With its high energy reach and large areal coverage, HAWC can significantly improve searches of the DGB at TeV energies. We will investigate parameter cuts to the HAWC dataset to better isolate gamma-ray air showers from background hadronic showers. This, combined with new background estimation techniques will improve the HAWC sensitivity to the DGB. We will present a limit on the DGB with HAWC as well as its implications for multimessenger and dark matter studies.