Journal Article

Intracluster gas pressure, entropy injection and redshift evolution

Biman B. Nath and Subhabrata Majumdar

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 416, issue 1, pages 279-287
Published in print September 2011 | ISSN: 0035-8711
Published online August 2011 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2011.19033.x
Intracluster gas pressure, entropy injection and redshift evolution

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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 pre-heating the ICM as well in situ active galactic nuclei/supernovae 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.

Keywords: galaxies: clusters: general; intergalactic medium; cosmology: miscellaneous; X-rays: galaxies: clusters

Journal Article.  6815 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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