Limits on the Diffuse Gamma-Ray Background above 10 TeV with HAWC

The high-energy Diffuse Gamma-Ray Background (DGRB) is expected to be produced by unresolved isotropically distributed astrophysical objects, potentially including dark matter annihilation or decay emissions in galactic or extragalactic structures. The DGRB has only been observed below 1 TeV; above this energy, upper limits have been reported. Observations or stringent limits on the DGRB above this energy could have significant multi-messenger implications, such as constraining the origin of TeV-PeV astrophysical neutrinos detected by IceCube. The High Altitude Water Cherenkov (HAWC) Observatory, located in central Mexico at 4100 m above sea level, is sensitive to gamma rays from a few hundred GeV to several hundred TeV and continuously observes a wide field-of-view (2 sr). With its high-energy reach and large area coverage, HAWC is well-suited to notably improve searches for the DGRB at TeV energies. In this work, strict cuts have been applied to the HAWC dataset to better isolate gamma-ray air showers from background hadronic showers. The sensitivity to the DGRB was then verified using 535 days of Crab data and Monte Carlo simulations, leading to new limits above 10 TeV on the DGRB as well as prospective implications for multi-messenger studies.
Comment: 8 pages, 3 figures