Abstract
The discovery of diffuse sub-PeV gamma-rays by the Tibet AS$_\gamma$ Collaboration promises to revolutionize our understanding of the high-energy astrophysical universe. It has been shown that these data broadly agree with prior theoretical expectations. We study the impact of this discovery on a well-motivated new physics scenario: PeV-scale decaying dark matter (DM). Considering a wide range of final states in DM decay, a number of DM density profiles, and numerous astrophysical background models, we find that these data provide the most stringent limit on DM lifetime for various Standard Model final states. In particular, we find that the strongest constraints are derived for DM masses in between a few PeV to a few tens of PeV. Near-future data of these high-energy gamma-rays can be used to discover PeV-scale decaying DM.
Highlights
What is the best way to search for dark matter (DM) in a particular mass range? Given the large number of astrophysical evidences of DM and a much larger list of wellmotivated DM candidates, it is important to answer the question by considering various techniques and observables [1–6]
It has been anticipated for decades that high-energy cosmic-ray interaction with interstellar gas will produce high-energy gamma-rays and this will give us a unique insight into the high-energy astrophysics of the MW
Considering various SM final states and astrophysical production models of sub-PeV gamma-rays, we find that these data reveal the strongest constraint on decaying PeV-scale DM for most of the two-body final states
Summary
What is the best way to search for dark matter (DM) in a particular mass range? Given the large number of astrophysical evidences of DM and a much larger list of wellmotivated DM candidates, it is important to answer the question by considering various techniques and observables [1–6]. After the publication of this discovery, a number of works revisited the high-energy diffuse gamma-ray production in the MW due to hadronic and leptonic processes [22–26] These works confirmed that the Tibet ASγ data can be reproduced using viable astrophysical parameters. Considering a wide variety of astrophysical backgrounds and various two-body SM final states, we find that our constraints are better than various previous constraints for most of the channels This is a very promising result; it demonstrates that near-future data on sub-PeV gamma-rays from regions of the Galaxy which contain a higher DM density have the potential to discover DM. Our results imply that a better understanding of the production mechanism, energy spectrum, and angular spectrum of these photons, along with a near-future larger dataset of sub-PeV gamma-rays will allow one to show that this is the most superior technique of searching PeV-scale decaying DM
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