Effervescent heating: constraints from nearby cooling flow clusters observed with XMM-Newton

¹ Institut für Astrophysik, Leopold-Franzens Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria e-mail: Rocco.Piffaretti@uibk.ac.at
² SRON National Institute for Space Research, Sorbonnelaan 2, 3584 CA Utrecht, The Netherlands

Received: 17 October 2005
Accepted: 31 January 2006

Abstract

Aims.We have used deprojected radial density and temperature profiles of a sample of 16 nearby CF clusters observed with XMM-Newton to test whether the effervescent heating model can satisfactorily explain the dynamics of CF clusters.

Methods.For each cluster we derived the required extra heating as a function of cluster-centric distance for various values of the unknown parameters  (mass deposition rate) and f_c (conduction efficiency). We fitted the extra heating curve using the AGN effervescent heating function and derived the AGN parameters L (the time-averaged luminosity) and r₀ (the scale radius where the bubbles start rising in the ICM).

Results.While we do not find any solution with the effervescent heating model for only one object, we do show that AGN and conduction heating are not cooperating effectively for half of the objects in our sample. For most of the clusters we find that, when a comparison is possible, the derived AGN scale radius r₀ and the observed AGN jet extension have the same order of magnitude. The AGN luminosities required to balance radiative losses are substantially lowered if the fact that the AGN deposits energy within a finite volume is taken into account. For the Virgo cluster, we find that the AGN power derived from the effervescent heating model is in good agreement with the observed jet power.