Constraints on the dark matter-baryon interaction cross section from galaxy cluster thermodynamics

Dark matter (DM) models with a non-zero DM-baryon interaction cross section imply energy transfer between DM and baryons. We present a new method of constraining the DM-baryon interaction cross section and DM particle mass for velocity-independent interactions using the virialization and thermal equilibrium of galaxy clusters. If DM cools baryons, this cooling rate is limited by the net heating rate of other mechanisms in the cluster. We use the REFLEX clusters from the MCXC cluster catalog with mass estimates from the Atacama Cosmology Telescope (ACT) catalog of Sunyaev-Zel'dovich (SZ) selected galaxy clusters. This yields 95% upper bounds on the DM-proton interaction cross section for velocity-independent interactions of σ₀<9.3×10^-28 cm² for DM masses, m_χ = 10^-4 - 10^-1 GeV. These constraints are within an order of magnitude of the best constraints derived in this mass range, and serve as a complementary, independent constraint. Introducing more complexity into the thermodynamic equilibrium conditions, and considering new data from upcoming surveys, could further improve constraints.