Publication Details

This article was originally published as: McNamara, BR, Rafferty, DA, Birzan, L, et al, The Starburst in the Abell 1835 Cluster Central Galaxy: A Case Study of Galaxy Formation Regulated by an Outburst from a Supermassive Black Hole, The Astrophysical Journal, 2006, 648(1), 164-175. Copyright 2006 University of Chicago Press. The journal can be found here.


We present an analysis of the starburst in the Abell 1835 cluster's cD galaxy. The dense gas surrounding the galaxy is radiating X-rays at a rate of ∼1045 ergs s-1, which is consistent with a cooling rate of ∼1000–2000 M⊙ yr-1. However, Chandra and XMM-Newton observations found less than 200 M⊙ yr-1 of cooling below ∼2 keV, a level that is consistent with the cD's current star formation rate of 100–180 M⊙ yr-1. One or more heating agents (feedback) must then be replenishing the remaining radiative losses. Supernova explosions and thermal conduction are unable to do so. However, the active galactic nucleus (AGN) is pumping ∼e;1.4 × 1045 ergs s-1into the hot gas, which is enough power to offset most of the radiative cooling losses. The AGN jet power exceeds the radio synchrotron power by ∼4000 times, making this one of the most radiatively inefficient radio sources known. The jet power implies that the supermassive black hole has accreted at a mean rate of ∼0.3 M⊙ yr-1 over the last 40 Myr or so, which is a small fraction of the Eddington accretion rate for a ∼109 M⊙ black hole. The ratio of black hole growth rate by accretion to bulge growth by star formation is consistent with the slope of the (Magorrian) relationship between bulge and central black hole mass in nearby quiescent galaxies. The starburst follows the Schmidt-Kennicutt parameterizations, indicating that the local environment is not substantially altering the IMF and other conditions leading to the onset of star formation. The consistency between net cooling, heating (feedback), and the cooling sink (star formation) in this system resolves the primary objection to traditional cooling flow models.

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