The effects of self-interacting dark matter on the stripping of galaxies that fall into clusters

We use the Cluster-EAGLE (C-EAGLE) hydrodynamical simulations to investigate the effects of self-interacting dark matter (SIDM) on galaxies as they fall into clusters. We find that SIDM galaxies follow similar orbits to their cold dark matter (CDM) counterparts, but end up with similar to 25 per cent less mass by the present day. One in three SIDM galaxies is entirely disrupted, compared to one in five CDM galaxies. However, the excess stripping will be harder to observe than suggested by previous DM-only simulations because the most stripped galaxies form cores and also lose stars: The most discriminating objects become unobservable. The best test will be to measure the stellar-to-halo mass relation (SHMR) for galaxies with stellar mass 10(10)-10(11) M-circle dot. This is 8 times higher in a cluster than in the field for a CDM universe, but 13 times higher for an SIDM universe. Given intrinsic scatter in the SHMR, these models could be distinguished with noise-free galaxy-galaxy strong lensing of similar to 32 cluster galaxies.

Automated summary

In this study, the Cluster-EAGLE (C-EAGLE) hydrodynamical simulations were used to investigate the effects of self-interacting dark matter (SIDM) on galaxies as they fall into clusters. The results showed that SIDM galaxies follow similar orbits to their cold dark matter (CDM) counterparts but end up with about 25% less mass by the present day. Additionally, one in three SIDM galaxies were entirely disrupted compared to one in five CDM galaxies. However, the excess stripping of SIDM galaxies would be harder to observe due to the formation of cores and the loss of stars.