We study the effect of entropy injection in the intracluster medium (ICM) in
light of the recent observationally determined universal pressure profile of
the ICM. Beginning with a power-law entropy profile that is expected in the
absence of any feedback, we show that a simple universal prescription of
entropy injection results in the final, observed universal pressure profile.
This simple prescription has two components, one associated with an overall
increase in entropy and another associated with injection in the central parts
of the cluster. Importantly, both the components of entropy injection are
needed to produce the final universal pressure profile. This is indicative of a
need of both preheating the ICM as well {\it in situ} AGN/SNe heating. We
demonstrate the usefulness of the method by extending the calculations to
clusters at high redshift, and predict redshift evolution of cluster scaling
relations that can be tested against data. We show that the self-similar
evolution of the universal pressure profile is equivalent to a negative
evolution of entropy injection with redshift, with a scaling Sinj∝(1+z)−0.8Sinj(z=0). We also show the current observational data are
indicative of the entropy injection decreasing with redshift.Comment: 9 pages, 8 figures, accepted for publication in MNRAS, Comments
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