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Impact of stochastic gas motions on galaxy cluster abundance profiles
Authors:P Rebusco  E Churazov  H Böhringer  W Forman
Institution:Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Strasse 1, 85741 Garching, Germany;Space Research Institute (IKI), Profsoyuznaya 84/32, Moscow 117810, Russia;MPI für Extraterrestrische Physik, PO Box 1603, 85740 Garching, Germany;Harvard–Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138, USA
Abstract:The impact of stochastic gas motions on the metal distribution in cluster cores is evaluated. Peaked abundance profiles are a characteristic feature of clusters with cool cores, and abundance peaks are probably associated with the brightest cluster galaxies (BCGs), which dwell in cluster cores. However, the width of the abundance peaks is significantly broader than the BCG light distribution, suggesting that some gas motions are transporting metals originating from within the BCG. Assuming that this process can be treated as diffusive, and using the brightest X-ray cluster A426 (Perseus) as an example, we estimate that a diffusion coefficient of the order of  2 × 1029 cm2 s−1  is needed to explain the width of the observed abundance profiles. Much lower (higher) diffusion coefficients would result in too peaked (too shallow) profiles. Such diffusion could be produced by stochastic gas motions, and our analysis provides constraints on the product of their characteristic velocity and their spatial coherence scale. We speculate that the activity of the supermassive black hole of the BCG is driving the stochastic gas motions in cluster cores. When combined with the assumption that the dissipation of the same motions is a key gas heating mechanism, one can estimate both the velocity and the spatial scale of such diffusive processes.
Keywords:cooling flows  galaxies: clusters: general  galaxies: clusters: individual: Perseus
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