Title:	Little evidence for entropy and energy excess beyond r500 - an end to ICM pre-heating?
Authors:	Iqbal, Asif Majumdar, Subhabrata Nath, Biman B. Ettori, Stefano Eckert, Dominique Malik, Manzoor A
Keywords:	Galaxies: clusters Intracluster medium Cosmological parameters
Issue Date:	Feb-2017
Publisher:	Oxford University Press for the Royal Astronomical Society
Citation:	Monthly Notices of the Royal Astronomical Society Letters , 2017, Vol. 465, L99-L103
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. While cooling and AGN feedbacks are dominant in cluster cores, the signatures of a pre-heated ICM are expected to be present even at large radii. To estimate the degree of pre-heating, with minimum confusion from AGN feedback/cooling, we study the excess entropy and non-gravitational energy profiles up to r200 for a sample of 17 galaxy clusters using joint data sets of Planck Sunyaev–Zel'dovich pressure and ROSAT/Position Sensitive Proportional Counter gas density profiles. The canonical value of pre-heating entropy floor of ≳300 keV cm2, needed in order to match cluster scalings, is ruled out at ≈3σ. We also show that the feedback energy of 1 keV particle−1 is ruled out at 5.2σ beyond r500. Our analysis takes both non-thermal pressure and clumping into account which can be important in outer regions. Our results based on the direct probe of the ICM in the outermost regions do not support any significant pre-heating.
Description:	Open Access
URI:	http://hdl.handle.net/2289/6654
ISSN:	0035-8711 1365-2966 - (online)
Alternative Location:	http://adsabs.harvard.edu/abs/2017MNRAS.465L..99I http://arxiv.org/abs/1606.00014 http://dx.doi.org/10.1093/mnrasl/slw220
Copyright:	2016 The authors & the Royal Astronomical Society
Appears in Collections:	Research Papers (A&A)

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