Simulating the dust content of galaxies and their surrounding gas is challenging due to the wide range of physical processes affecting the dust evolution. Here we present cosmological hydrodynamical simulations of a cluster of galaxies, M 200,crit = 6 × 10 14 M , including a novel dust model for the moving mesh code AREPO. This model includes dust production, growth, supernova-shock-driven destruction, ion-collision-driven thermal sputtering, and high temperature dust cooling through far infrared re-radiation of collisionally deposited electron energies. Adopting a rather low thermal sputtering rate, we find, consistent with observations, a present-day overall dust-to-gas ratio of ∼ 2 × 10 −5 , a total dust mass of ∼ 2 × 10 9 M , and a dust mass fraction of ∼ 3 × 10 −6 . The typical thermal sputtering timescales within ∼ 100 kpc are around ∼ 10 Myr, and increase towards the outer parts of the cluster to ∼ 10 3 Myr at a cluster-centric distance of 1 Mpc. The condensation of gas phase metals into dust grains reduces high temperature metal-line cooling, but also leads to additional dust infrared cooling. The additional infrared cooling changes the overall cooling rate in the outer parts of the cluster, beyond ∼ 1 Mpc, by factors of a few. This results in noticeable changes of the entropy, temperature, and density profiles of cluster gas once dust formation is included. The emitted dust infrared emission due to dust cooling is consistent with observational constraints.

The splashback radius, Rsp, is a physically motivated halo boundary that separates infalling and collapsed matter of haloes. We study Rsp in the hydrodynamic and dark matter only IllustrisTNG simulations. The most commonly adopted signature of Rsp is the radius at which the radial density profiles are steepest. Therefore, we explicitly optimise our density profile fit to the profile slope and find that this leads to a $\sim 5\%$ larger radius compared to other optimisations. We calculate Rsp for haloes with masses between 1013 − 15M⊙ as a function of halo mass, accretion rate and redshift. Rsp decreases with mass and with redshift for haloes of similar M200m in agreement with previous work. We also find that Rsp/R200m decreases with halo accretion rate. We apply our analysis to dark matter, gas and satellite galaxies associated with haloes to investigate the observational potential of Rsp. The radius of steepest slope in gas profiles is consistently smaller than the value calculated from dark matter profiles. The steepest slope in galaxy profiles, which are often used in observations, tends to agree with dark matter profiles but is lower for less massive haloes. We compare Rsp in hydrodynamic and N-body dark matter only simulations and do not find a significant difference caused by the addition of baryonic physics. Thus, results from dark matter only simulations should be applicable to realistic haloes.

We present a new set of cosmological zoom-in simulations of a MW-like galaxy which for the first time include elastic velocity-dependent self interacting dark matter (SIDM) and IllustrisTNG physics. With these simulations we investigate the interaction between SIDM and baryons and its effects on the galaxy evolution process. We also introduce a novel set of modified DMO simulations which can reasonably replicate the effects of fully realized hydrodynamics on the DM halo while simplifying the analysis and lowering the computational cost. We find that baryons change the thermal structure of the central region of the halo to a greater extent than the SIDM scatterings for MW-like galaxies. Additionally, we find that the new thermal structure of the MW-like halo causes SIDM to create cuspier central densities rather than cores because the SIDM scatterings remove the thermal support by transferring heat away from the center of the galaxy. We find that this effect, caused by baryon contraction, begins to affect galaxies with a stellar mass of 108 M⊙ and increases in strength to the MW-mass scale.

No abstract