Bounds on WIMP dark matter from galaxy clusters at low redshift

In this work, we study the cross-correlation between Fermi-LAT diffuse γ-ray maps and galaxy cluster catalogues in order to search for a diffuse dark matter (DM) signal. We employ an accurate estimation of the error covariance matrix and we select four galaxy cluster catalogues at low-redshift 0 < z < 0.2 with large halo mass M 500 > 10 ¹³ M ⊙ including infrared, optical, and X-ray wavebands. We consider weakly interacting massive particle (WIMP) DM with 100 per cent branching ratios into τ ⁺ τ ⁻ , $b\bar{b}$ , W ⁺ W ⁻ , and μ ⁺ μ ⁻ . No evidence for a WIMP DM signal is identified, and we derive competitive bounds. The WIMP thermally averaged cross-section is excluded at 95 per cent C.L. for DM masses below 20 GeV and annihilation in the τ ⁺ τ ⁻ channel.