Metal distribution in the intracluster medium: a comprehensive numerical study of twelve galaxy clusters^⋆

¹ Institute of Astro- and Particle Physics, University of Innsbruck, Austria
e-mail harald.hoeller@uibk.ac.at
² Observatories of the Carnegie Institution for Science, Pasadena, CA, USA
³ Argelander-Institut für Astronomie, Bonn, Germany

Received: 31 December 2013
Accepted: 1 July 2014

Abstract

We present a simulation setup for studying the dynamical and chemical evolution of the intracluster medium (ICM) and analyze a sample of 12 galaxy clusters that are diverse both kinetically (pre-merger, merging, virialized) and in total mass (M_vir = 1.17 × 10¹⁴ − 1.06 × 10¹⁵ M_⊙). We analyzed the metal mass fraction in the ICM as a function of redshift and discuss radial trends as well as projected 2D metallicity maps. The setup combines high mass resolution N-body simulations with the semi-analytical galaxy formation model Galacticus for consistent treatment of the subgrid physics (such as galactic winds and ram-pressure stripping) in the cosmological hydrodynamical simulations. The interface between Galacticus and the hydro simulation of the ICM with FLASH is discussed with respect to observations of star formation rate histories, radial star formation trends in galaxy clusters, and the metallicity at different redshifts. As a test for the robustness of the wind model, we compare three prescriptions from different approaches. For the wind model directly taken from Galacticus, we find mean ICM metallicities between 0.2−0.8 Z_⊙ within the inner 1 Mpc at z = 0. The main contribution to the metal mass fraction comes from galactic winds. The outflows are efficiently mixed in the ICM, leading to a steady homogenization of metallicities until ram-pressure stripping becomes effective at low redshifts. We find a very peculiar and yet common drop in metal mass fractions within the inner ~200 kpc of the cool cores, which is due to a combination of wind suppression by outer pressure within our model and a lack of mixing after the formation of these dense regions.