Little evidence for entropy and energy excess beyond $r_{500}$ - An end
  to ICM preheating?
  Non-gravitational feedback affects the nature of the intra-cluster medium
(ICM). X-ray cooling of the ICM and in situ energy feedback from AGN's and SNe
as well as {\it preheating} 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 preheated ICM are
expected to be present even at large radii. To estimate the degree of
preheating, with minimum confusion from AGN feedback/cooling, we study the
excess entropy and non-gravitational energy profiles upto $r_{200}$ for a
sample of 17 galaxy clusters using joint data sets of {\it Planck} SZ pressure
and {\it ROSAT/PSPC} gas density profiles. The canonical value of preheating
entropy floor of $\gtrsim 300$ keV cm$^2$, needed in order to match cluster
scalings, is ruled out at $\approx 3\sigma$. We also show that the feedback
energy of 1 keV/particle is ruled out at 5.2$\sigma$ beyond $r_{500}$. 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 preheating.
