Issue |
A&A
Volume 447, Number 3, March I 2006
|
|
---|---|---|
Page(s) | 813 - 825 | |
Section | Astrophysical processes | |
DOI | https://doi.org/10.1051/0004-6361:20052689 | |
Published online | 10 February 2006 |
A unified accretion-ejection paradigm for black hole X-ray binaries
I. The dynamical constituents
1
Laboratoire d'Astrophysique, Observatoire de Grenoble, BP 53, 38041 Grenoble Cedex 9, France e-mail: Jonathan.Ferreira@obs.ujf-grenoble.fr
2
Institut de Physique Nucléaire de Lyon, 43 Bd 11 novembre 1918, 69622 Villeurbanne Cedex, France
Received:
12
January
2005
Accepted:
19
October
2005
We present a new picture for the central regions
of Black Hole X-ray Binaries. In our view, these central regions have a
multi-flow configuration which consists in (1) an outer standard
accretion disc down to a transition radius rJ; (2) an inner magnetized
accretion disc below rJ driving (3) a non relativistic self-collimated
electron-proton jet surrounding, when adequate conditions for pair
creation are met; (4) a ultra relativistic electron-positron beam.
This accretion-ejection paradigm provides a simple explanation to the
canonical spectral states, from radio to X/γ-rays, by varying the
transition radius rJ and disc accretion rate
independently. Large values of rJ correspond to the
Quiescent state for low
and the Hard state for larger
. These states are characterized by the presence of a steady electron-proton MHD jet emitted by the disc below rJ. The
hard X-ray component is expected to form at the jet basis. When rI
becomes smaller than the marginally stable orbit ri, the whole disc
resembles a standard accretion disc with no jet, characteristic of the
Soft state. Intermediate states correspond to situations where
. At large
, an unsteady pair cascade process is triggered
within the jet axis, giving birth to flares and ejection of relativistic
pair blobs. This would correspond to the luminous intermediate state,
sometimes referred to as the Very High state, with its associated
superluminal motions.
The variation of rJ independently of
is a necessary ingredient in this picture. It arises from the presence of a large scale vertical magnetic field threading the disc. Features such as possible hysteresis and the presence of quasi-periodic oscillations would naturally fit within this new framework.
Key words: black hole physics / accretion, accretion disks / magnetohydrodynamics (MHD) / ISM: jets and outflows / X-rays: binaries
© ESO, 2006
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