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Title: COOL CORE CLUSTERS FROM COSMOLOGICAL SIMULATIONS

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 active galactic nucleus (AGN) feedback and are based on an improved version of the smoothed particle hydrodynamics code GADGET-3, which ameliorates gas mixing 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 the degree of cool-coreness of clusters, and the iron profiles. In keeping with observations, our simulated clusters display a variety of behaviors in entropy profiles: they range from steadily decreasing profiles at small radii, characteristic of CC systems, to nearly flat core isentropic profiles, characteristic of NCC systems. Using observational criteria to distinguish between the two classes of objects, we find that they occur in similar proportions in both simulations and observations. Furthermore, we also find that simulated CC clusters have profiles of iron abundance that are steeper than those of NCC clusters, which is also in agreement with observational results. We show that the capability of ourmore » simulations to generate a realistic CC structure in the cluster population is due to AGN feedback and artificial thermal diffusion: their combined action allows us to naturally distribute the energy extracted from super-massive black holes and to compensate for the radiative losses of low-entropy gas with short cooling time residing in the cluster core.« less
Authors:
; ; ; ; ;  [1] ; ; ;  [2] ;  [3]
  1. INAF, Osservatorio Astronomico di Trieste, via Tiepolo 11, I-34131, Trieste (Italy)
  2. Universitäts-Sternwarte München, Scheinerstr.1, D-81679 München (Germany)
  3. Instituto de Astronomá Teórica y Experimental (IATE), Consejo Nacional de Investigaciones Cientiíficas y Técnicas de la República Argentina (CONICET), Observatorio Astronómico, Universidad Nacional de Córdoba, Laprida 854, X5000BGR, Córdoba (Argentina)
Publication Date:
OSTI Identifier:
22518730
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 813; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; BLACK HOLES; COMPARATIVE EVALUATIONS; COMPUTERIZED SIMULATION; COSMOLOGY; ENTROPY; G CODES; GALAXY CLUSTERS; GALAXY NUCLEI; HYDRODYNAMICS; IRON; ISENTROPIC PROCESSES; THERMAL DIFFUSION; X-RAY GALAXIES