The Regulation of Cooling and Star Formation in Luminous Galaxies by Active Galactic Nucleus Feedback and the Cooling-Time/Entropy Threshold for the Onset of Star Formation

Using broadband optical imaging and Chandra X-ray data for a sample of 46 cluster central dominant galaxies (CDGs), we investigate the connection between star formation, the intracluster medium (ICM), and the central active galactic nucleus (AGN). We report the discovery of a remarkably sharp thresh...

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Published inThe Astrophysical journal Vol. 687; no. 2; pp. 899 - 918
Main Authors Rafferty, D. A, McNamara, B. R, Nulsen, P. E. J
Format Journal Article
LanguageEnglish
Published Chicago, IL IOP Publishing 10.11.2008
University of Chicago Press
Subjects
Astronomy
Earth, ocean, space
Exact sciences and technology
X ray cluster of galaxies
galaxies: clusters: general
Elliptical galaxies
Cosmic x-ray sources
Cooling flow
cooling flows
Entropy
Galaxy clusters
Active galaxies
galaxies: elliptical and lenticular, cD
Star formation
Feedback
Active galaxy nuclei
Galaxy nuclei
X-rays: galaxies: clusters
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Summary:Using broadband optical imaging and Chandra X-ray data for a sample of 46 cluster central dominant galaxies (CDGs), we investigate the connection between star formation, the intracluster medium (ICM), and the central active galactic nucleus (AGN). We report the discovery of a remarkably sharp threshold for the onset of star formation that occurs when the central cooling time of the hot atmosphere falls below [image] yr, or equivalently when the central entropy falls below [image]30 keV cm super(2). In addition to this criterion, star formation in cooling flows also appears to require that the X-ray and galaxy centroids lie within [image]20 kpc of each other and that the jet (cavity) power is smaller than the X-ray cooling luminosity. These three criteria, together with the high ratio of cooling time to AGN outburst (cavity) age across our sample, directly link the presence of star formation and AGN activity in CDGs to cooling instabilities in the intracluster plasma. Our results provide compelling evidence that AGN feedback into the hot ICM is largely responsible for regulating cooling and star formation in the cores of clusters, leading to the significant growth of supermassive black holes in CDGs at late times.
Bibliography:ObjectType-Article-2
SourceType-Scholarly Journals-1
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content type line 23
ISSN:0004-637X
1538-4357
DOI:10.1086/591240