The Growth of Black Holes and Bulges at the Cores of Cooling Flows

The intracluster medium (ICM) at the center of a majority of galaxy clusters has a cooling time less than 10 yr [1]. In the absence of a source of heat, this gas should cool, resulting in a slow inward flow of material know as a “cooling flow”. However, recent high-resolution X-ray spectra from XMMNewton do not show the features expected if large amounts of gas are cooling below kT ∼ 2 keV [2]. The emerging picture of cooling flows is one in which most of the cooling is roughly balanced by heating from the active galactic nucleus (AGN) due to accretion onto the central supermassive black hole (BH). In this regulated-cooling scenario, net cooling from the ICM would lead to condensation of gas onto the central galaxy, driving the star formation observed in many systems (e.g., [3]). We test this scenario using star formation rates (SFRs), ICM cooling rates, and AGN heating and BH growth rates for a sample of cooling flows with AGN-created X-ray cavities.