Cool Core Clusters from Cosmological Simulations

RASIA, ELENA; BORGANI, STEFANO; MURANTE, GIUSEPPE; PLANELLES, SUSANA; BECK, ALEXANDER; BIFFI, VERONICA; RAGONE FIGUEROA, CINTHIA; GRANATO, GIAN LUIGI; STEINBORN, LISA ; DOLAG, KLAUS

ASTROPHYSICAL JOURNAL

IOP PUBLISHING LTD

Año: 2015 vol. 813

0004-637X

We present results obtained from a set of cosmological hydrodynamic simulations of galaxy clusters,aimed at comparing predictions with observational data on the diversity between cool-core (CC) and non-cool-core (NCC) clusters. Our simulations include the effects of stellar and AGN feedback and are basedon an improved version of the smoothed particle hydrodynamics code GADGET-3, which ameliorates gasmixing and better captures gas-dynamical instabilities by including a suitable artificial thermal diffusion.In this Letter, we focus our analysis on the entropy profiles, the primary diagnostic we used to classify thedegree of cool-coreness of clusters, and on the iron profiles. In keeping with observations, our simulatedclusters display a variety of behaviors in entropy profiles: they range from steadily decreasing profilesat small radii, characteristic of cool-core systems, to nearly flat core isentropic profiles, characteristic ofnon-cool-core systems. Using observational criteria to distinguish between the two classes of objects, wefind that they occur in similar proportions in both simulations and in observations. Furthermore, wealso find that simulated cool-core clusters have profiles of iron abundance that are steeper than thoseof NCC clusters, which is also in agreement with observational results. We show that the capabilityof our simulations to generate a realistic cool-core structure in the cluster population is due to AGNfeedback and artificial thermal diffusion: their combined action allows us to naturally distribute theenergy extracted from super-massive black holes and to compensate for the radiative losses of low-entropygas with short cooling time residing in the cluster core.