ChandraObservations of the Lensing Cluster EMSS 1358+6245: Implications for Self‐interacting Dark Matter

We present Chandra observations of EMSS 1358+6245, a relaxed cooling flowcluster of galaxies at z = 0.328. We employ a new deprojection technique toconstruct temperature, gas, and dark matter profiles. We confirm the presenceof cool gas in the cluster core, and our deprojected temperature profile forthe hot component is isothermal over 30 kpc < r < 0.8 Mpc. Fitting the massprofile to an NFW model yields r_s = 153 [+161,-83] kpc and c = 8.4[+3.4,-2.3]. We find good agreement between our dark matter profile and weakgravitational lensing measurements. We place an upper limit of 42 kpc (90%confidence limit) on the size of any constant density core. We compare thisresult to recent simulations and place a conservative upper limit on the darkmatter particle scattering cross section of 0.1 cm^2/g. This limit implies thatthe cross-section must be velocity dependent if the relatively shallow coremass profiles of dwarf galaxies are a direct result of dark matterself-interaction.