Dark Matter Gamma-ray searches in Galaxy Clusters: Status and prospects

Center for Astrophysics and Cosmology, University of Nova Gorica, Vipavska 11c, 5270 Ajdovščina, Slovenia

^* e-mail: judit.perez@ung.si

Published online: 6 March 2025

Abstract

Galaxy clusters are the largest structures in the Universe, being dark matter (DM) dominated objects. For DM decay, they yield the highest expected fluxes with respect to other prime targets. ForDMannihilation, clusters can provide fluxes comparable to dwarf spheroidal galaxies, as long as the contribution from substructures is taken into account. We present the analysis of 12 years of Fermi-LAT data in the direction of 49 clusters. We modelled the expected substructure population in these objects, providing benchmark models to quantify the uncertainty on their contribution to the annihilation flux. From the combined search, we found a signal of 2.5-3.0σ significance, potentially associated with DM or hadronic induced emission from the intracluster region by cosmic rays. Looking into the future, we discuss the prospects of the Cherenkov Telescope Array Observatory (CTAO), to detect diffuse γ-ray emission from the Perseus galaxy cluster. With its improvement in sensitivy of more than one order of magnitude with respect to current IACTs, we derive the tightest constraints for DM decay scenarios in the TeV range, reaching values of τ_DM ∼ 10²⁷s.