Constraining Gravitational Dark Matter with LHAASO and Fermi-LAT
Basabendu Barman, Arindam Das, Prantik Sarmah, Rakesh Kumar SivaKumar
TL;DR
This work constrains gravitationally produced decaying DM by comparing the predicted diffuse Galactic gamma-ray flux from DM decays to LHAASO and Fermi-LAT observations. It analyzes four benchmark DM candidates—dark photon, heavy right-handed neutrino (RHN), a massive pseudo-Nambu–Goldstone boson (pNGB), and a non-minimally coupled scalar—yielding bounds on their masses and visible-sector couplings. For dark photon, RHN, and pNGB, the combined data require the relevant couplings to be smaller than about $\mathcal{O}(10^{-30})$ for $m_{DM} \gtrsim \text{TeV}$, while the non-minimally coupled scalar is constrained at $\lesssim\mathcal{O}(10^{-10})$, with photon–dark photon oscillations giving $\varepsilon \lesssim 10^{-3}$ for $m_X \gtrsim 10$ GeV. These results connect gravitational production in the early Universe to high-energy gamma-ray observations, illustrating how gravity portals can be probed by diffuse Galactic $\gamma$-rays and informing early-Universe cosmology and reheating constraints.
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.