1812.06981
Observable tests of self-interacting dark matter in galaxy clusters: BCG wobbles in a constant density core
Harvey, et al
Models of CDM always predict a cusp, centrally concentrated distribution of DM in galaxy clusters. Constant density cores would be strong evidence for beyond-CDM physics, such as self-interacting dark matter (SIDM). An observable consequence would be oscillations of the BCG in otherwise relaxed galaxy clusters. Offset BCGs have indeed been observed -- but only interpreted via a simplified, analytic model of oscillations. Compare these observations to the BAHAMAS-SIDM suite of cosmo sims, which include SIDM and a full hydrodynamical treatment of SF and feedback. Predict that the median offset of BCGs increases with the SIDM cross-section and cluster mass, while CDM exhibits no trend in mass. Interpolating between the simulated cross-sections, find that the observations (of 10 clusters) have a 38% probability of being consistent with CDM, and prefer cross-section sigma/m<0.22 cm^2/g at 95 % CL. This is on the verge of discriminating between DM models that would explain discrepancies in the behavior of dwarf galaxies, and will be improved by larger surveys by Euclid or SuperBIT.
Observable tests of self-interacting dark matter in galaxy clusters: BCG wobbles in a constant density core
Harvey, et al
Models of CDM always predict a cusp, centrally concentrated distribution of DM in galaxy clusters. Constant density cores would be strong evidence for beyond-CDM physics, such as self-interacting dark matter (SIDM). An observable consequence would be oscillations of the BCG in otherwise relaxed galaxy clusters. Offset BCGs have indeed been observed -- but only interpreted via a simplified, analytic model of oscillations. Compare these observations to the BAHAMAS-SIDM suite of cosmo sims, which include SIDM and a full hydrodynamical treatment of SF and feedback. Predict that the median offset of BCGs increases with the SIDM cross-section and cluster mass, while CDM exhibits no trend in mass. Interpolating between the simulated cross-sections, find that the observations (of 10 clusters) have a 38% probability of being consistent with CDM, and prefer cross-section sigma/m<0.22 cm^2/g at 95 % CL. This is on the verge of discriminating between DM models that would explain discrepancies in the behavior of dwarf galaxies, and will be improved by larger surveys by Euclid or SuperBIT.
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