Institute of Astronomy

Non-gravitational entropy and energy `profiles' in clusters - Implications for AGN feedback and Pre-heating

SpeakerTalk DateTalk Series
Subhabrata Majumdar (Tata Institute)28 July 2017Institute of Astronomy Galaxies Discussion Group

Abstract

Non-gravitational feedback affects the nature of the intracluster medium (ICM). X-ray cooling of the ICM and in situ energy feedback from active galactic nuclei (AGNs) and supernovae, as well as pre-heating of the gas at epochs preceding the formation of clusters, are proposed mechanisms for such feedback. I will present the non-gravitational entropy injection profiles and resulting non-gravitational energy feedback profiles, of the intra-cluster medium for a large
sample of clusters using data SZ (Planck) and X-Ray(ROSAT) observations, from deep inside cluster cores up to r200. This is the first estimate of 'feedback profiles' (and not only the mean feedback energy per particle) from observations. Estimate of the non-gravitational energy in the cluster cores and their correlation with radio observations (NRAO/VLA) strongly point at AGN (in situ) feedback. Moreover,
we show that for the sample as a whole and throughout the entire radial range, the non-gravitational entropy/energy profiles conclusively rule all ICM pre-heating scenarios. We demonstrate the robustness of our results w.r.t sample selection, X-Ray analysis procedures, non-radiative entropy modelling. Time permitting, I will also demonstrate a new scheme for identifying cool vs non-cool core clusters.

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