Excess entropy and energy feedback from within cluster cores up to r200

Abstract

We estimate the ‘non-gravitational’ entropy-injection profiles, ΔK, and the resultant energy feedback profiles, ΔE, of the intracluster medium for 17 clusters using their Planck Sunyaev–Zel'dovich and ROSAT X-ray observations, spanning a large radial range from 0.2r500 up to r200. The feedback profiles are estimated by comparing the observed entropy, at fixed gas mass shells, with theoretical entropy profiles predicted from non-radiative hydrodynamic simulations. We include non-thermal pressure and gas clumping in our analysis. The inclusion of non-thermal pressure and clumping results in changing the estimates for r500 and r200 by 10–20 per cent. When clumpiness is not considered it leads to an underestimation of ΔK ≈ 300 keV cm2 at r500 and ΔK ≈ 1100 keV cm2 at r200. On the other hand, neglecting non-thermal pressure results in an overestimation of ΔK ≈ 100 keV cm2 at r500 and underestimation of ΔK ≈ 450 keV cm2 at r200. For the estimated feedback energy, we find that ignoring clumping leads to an underestimation of energy per particle ΔE ≈ 1 keV at r500 and ΔE ≈ 1.5 keV at r200. Similarly, neglect of the non-thermal pressure results in an overestimation of ΔE ≈ 0.5 keV at r500 and underestimation of ΔE ≈ 0.25 keV at r200. We find entropy floor of ΔK ≈ 300 keV cm2 is ruled out at ≈3σ throughout the entire radial range and ΔE ≈ 1 keV at more than 3σ beyond r500, strongly constraining intracluster medium pre-heating scenarios. We also demonstrate robustness of results w.r.t. sample selection, X-ray analysis procedures, entropy modelling, etc.