Heating and Cooling of the Intracluster Medium

          @misc{ scivideos_PIRSA:09040034,
            doi = {10.48660/09040034},
            url = {https://pirsa.org/09040034},
            author = {Babul, Arif},
            keywords = {Cosmology},
            language = {en},
            title = {Heating and Cooling of the Intracluster Medium},
            publisher = {Perimeter Institute for Theoretical Physics},
            year = {2009},
            month = {apr},
            note = {PIRSA:09040034 see, \url{https://scivideos.org/pirsa/09040034}}
          }
          

Abstract

The observed thermal properties of the ICM shows much greater dispersion than expected if the gas was subject only to shock-heating by mergers and during infall. This diversity can be best understood as a byproduct of AGN feedback occurring in galaxies destined to become cluster members, both before and after cluster formation. Theoretical considerations suggest that the level of preheating ought to vary from one proto-cluster region to another. The entropy profiles of roughly 50% of the clusters with long central cooling times require that the gas be "preheated" to high entropy. Gas density profiles in such systems form hot central cores. Clusters with gas that isn't preheated to sufficiently high values forms peaked density profiles. I will show how variable preheating explain the various observed X-ray/X-ray correlations and discuss some of its implications for SZ studies. I will also present optical results that shed new light on the fate of the cold gas in cooling-unstable clusters, and propose observations tests of the "AGN preheating" aspect of the picture.