Constraining Gravitational Dark Matter with LHAASO and Fermi-LAT

TL;DR

This paper uses gamma-ray data from LHAASO and Fermi-LAT to set new constraints on gravitationally produced decaying dark matter candidates, significantly narrowing the allowed parameter space for several models.

Contribution

It provides the first comprehensive bounds on multiple dark matter candidates using diffuse gamma-ray observations, especially constraining gravitational production mechanisms.

Findings

Dark photon, RHN, and pNGB interaction strengths constrained to ~10^{-30} for TeV-scale DM.

Non-minimally coupled scalar constrained to ~10^{-10}.

Photon-dark photon oscillations exclude new parameter space for dark photons above 10 GeV.

Abstract

We use diffuse Galactic high energy gamma ray data from LHAASO and Fermi-LAT to constrain gravitationally produced decaying dark matter (DM). Focusing on four benchmark candidates: a dark photon, a heavy right-handed neutrino (RHN), a pseudo-Nambu-Goldstone boson (pNGB), and a non-minimally coupled scalar we derive bounds on the DM mass and its couplings to the visible sector. For dark photons, RHNs, and pNGBs, the combined data constrain the relevant interaction strength to $\lesssim\mathcal{O}(10^{-30})$ for DM masses $\gtrsim\mathcal{O}$(TeV), while the non-minimally coupled scalar is limited to $\lesssim\mathcal{O}(10^{-10})$. Moreover, photon-dark photon oscillations yield strong constraints for massive dark photon beyond 10 GeV, closing a region of parameter space previously left unconstrained.