DARKSKIES: A suite of super-sampled zoom-in simulations of galaxy clusters with self-interacting dark matter

Abstract

We present the "DARKSKIES" suite of one hundred, zoom-in hydrodynamic simulations of massive ($M_{200}>5\times10^{14}{\rm M}_\odot)$ galaxy clusters with self-interacting dark matter (SIDM). We super-sample the simulations such that $m_{\rm DM}/m_{\rm gas}\sim0.1$, enabling us to simulate a dark matter particle mass of $m=0.68\times10^{8}M_\odot$ an order of magnitude faster, whilst exploring SIDM in the core of clusters at extremely high resolution. We calibrate the baryonic feedback to produce observationally consistent and realistic galaxy clusters across all simulations and simulate five models of velocity-independent SIDM targeting the expected sensitivity of future telescopes - $\sigma_{\rm DM}/m=0.,0.01,0.05,0.1,0.2$ cm$^2$/g. We find the density profiles exhibit the characteristic core even in the smallest of cross-sections, with cores developing only at late times ($z<0.5$). We investigate the dynamics of the brightest cluster galaxy inside the dark matter halo and find in SIDM cosmologies there exists a so-called wobbling not observed in collisionless dark matter. We find this wobble is driven by accreting mass on to a cored density profile with the signal peaking at $z=0.25$ and dropping thereafter. This finding is further supported by the existence of an anti-correlation between the offset between the BCG and the dark matter halo and its relative velocity in SIDM only, a hallmark of harmonic oscillation.