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[2.14] Constraining accretion models for nearby supermassive black holes

T. Di Matteo (Harvard), R.M. Johnstone, S.W. Allen, A.C. Fabian, K Iwasawa (IoA, Cambridge, UK)

We examine the implications of the detection of a nuclear X-ray source in the cD galaxy NGC 6166 at the center of the cooling flow cluster Abell 2199. The galaxy has previously-reported evidence for a supermassive black hole in its nucleus with M_BH ~10⁹ M_\odot. The new constraints are obtained from Chandra observations. The remarkably low luminosity of the source, (L_{x,2-10 keV} ~10⁴¹ erg s^-1), despite its location in an extremely gas-rich enviroment, suggests that the accretion process around the central black hole has to occur at extremely low radiative efficiency. The Chandra observations, for the first time, allow us to constrain unequivocally advection-dominated accretion and jet models. Important implications for other similar 'dead-qso' sources are discussed.

TDM is supported by a NASA - Chandra Postdoctoral Fellowship.