EDP Sciences
Free access
Volume 414, Number 3, February II 2004
Page(s) 895 - 903
Section Extragalactic astronomy
DOI http://dx.doi.org/10.1051/0004-6361:20031683

A&A 414, 895-903 (2004)
DOI: 10.1051/0004-6361:20031683

A scheme to unify low-power accreting black holes

Jet-dominated accretion flows and the radio/X-ray correlation
H. Falcke1, 2, 3, E. Körding3 and S. Markoff4

1  ASTRON, PO Box 2, 7990 AA Dwingeloo, The Netherlands
2  Adjunct Professor, Astronomy Department, University of Nijmegen, Postbus 9010, 6500 GL Nijmegen, The Netherlands
3  Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
4  Massachusetts Institute of Technology, Center for Space Research, 77 Massachusetts Ave., Rm. NE80-6035, Cambridge, MA 02139, USA

(Received 20 May 2003 / Accepted 30 October 2003)

We explore the evolution in power of black holes of all masses, and their associated jets, within the scheme of an accretion rate-dependent state transition. Below a critical value of the accretion rate all systems are assumed to undergo a transition to a state where the dominant accretion mode is optically thin and radiatively inefficient. In these significantly sub-Eddington systems, the spectral energy distribution is predicted to be dominated by non-thermal emission from a relativistic jet whereas near-Eddington black holes will be dominated instead by emission from the accretion disk. Reasonable candidates for such a sub-Eddington state include X-ray binaries in the hard and quiescent states, the Galactic Center (Sgr A*), LINERs, FR I radio galaxies, and a large fraction of BL Lac objects. Standard jet physics predicts non-linear scaling between the optically thick (radio) and optically thin (optical or X-ray) emission of these systems, which has been confirmed recently in X-ray binaries. We show that this scaling relation is also a function of black hole mass and only slightly of the relativistic Doppler factor. Taking the scaling into account we show that indeed hard and quiescent state X-ray binaries, LINERs, FR I radio galaxies, and BL Lacs can be unified and fall on a common radio/X-ray correlation. This suggests that jet domination is an important stage in the luminosity evolution of accreting black hole systems.

Key words: X-rays: binaries -- radiation mechanisms: non-thermal -- stars: winds, outflows -- black hole physics -- accretion, accretion disks

Offprint request: H. Falcke, falcke@astron.nl

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