The splashback boundary of haloes in hydrodynamic simulations

The splashback radius, $R_{\rm sp}$, is a physically motivated halo boundary that separates infalling and collapsed matter of haloes. We study sp}$ in the hydrodynamic dark only IllustrisTNG simulations. most commonly adopted signature radius at which radial density profiles are steepest. Therefore, we explicitly optimise our profile fit to slope find this leads $\sim5\%$ larger compared other optimisations. calculate for haloes with masses between $10^{13-15}{\rm M}_{\odot}$ as function mass, accretion rate redshift. decreases mass redshift similar $M_{\rm200m}$ agreement previous work. also sp}/R_{\rm200m}$ rate. apply analysis matter, gas satellite galaxies associated investigate observational potential sp}$. steepest consistently smaller than value calculated from profiles. galaxy profiles, often used observations, tends agree but lower less massive compare N-body simulations do not significant difference caused by addition baryonic physics. Thus, results should be applicable realistic