The Regulation of Cooling and Star Formation in Luminous Galaxies by AGN Feedback
Abstract
We use broadband optical imaging and Chandra X-ray data for a sample of 47 cluster central dominant galaxies (CDGs) to investigate the connection between star formation, the intracluster medium (ICM), and the central active galactic nucleus (AGN). By comparing the near-UV color gradients to the X-ray-derived properties on similar spatial scales, we find that a CDG is likely to experience significant star formation when: 1) the X-ray and galaxy centroids are within ~ 20 kpc of each other, 2) the central cooling time of the hot atmosphere is much less than ~ 8x10^8 yr (or has an entropy of less than ~ 30 keV cm^2), and 3) the ratio of jet (cavity) power to X-ray cooling luminosity is approximately less than unity. These conditions, in addition to the high ratio of cooling time to AGN outburst (cavity) age across our sample, are consistent with the idea that cooling and star formation at the centers of cooling flows are regulated by AGN feedback. Our results provide compelling evidence for a cycle of cooling, star formation, and energetic feedback that may be regulating the growth of bulges and their supermassive black holes at late times.Keywords
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