Accretion and ejection in black-hole X-ray transients

Abstract

Aims: We summarize the current observational picture of the outbursts of black-hole X-ray transients (BHTs), based on the evolution traced in a hardness-luminosity diagram (HLD), and we offer a physical interpretation. Methods: The basic ingredient in our interpretation is the Poynting-Robertson Cosmic Battery (PRCB, Contopoulos & Kazanas 1998), which provides locally the poloidal magnetic field needed for the ejection of the jet. In addition, we make two assumptions, easily justifiable. The first is that the mass-accretion rate to the black hole in a BHT outburst has a generic bell-shaped form. This is guaranteed by the observational fact that all BHTs start their outburst and end it at the quiescent state. The second assumption is that at low accretion rates the accretion flow is geometrically thick, ADAF-like, while at high accretion rates it is geometrically thin. Results: Both, at the beginning and the end of an outburst, the PRCB establishes a strong poloidal magnetic field in the ADAF-like part of the accretion flow, and this explains naturally why a jet is always present in the right part of the HLD. In the left part of the HLD, the accretion flow is in the form of a thin disk, and such a disk cannot sustain a strong poloidal magnetic filed. Thus, no jet is expected in this part of the HLD. The counterclockwise traversal of the HLD is explained as follows: the poloidal magnetic field in the ADAF forces the flow to remain ADAF and the source to move upwards in the HLD rather than to turn left. Thus, the history of the system determines the counterclockwise traversal of the HLD. As a result, no BHT is expected to ever traverse the entire HLD curve in the clockwise direction. Conclusions: We offer a physical interpretation of accretion and ejection in BHTs with only one parameter, the mass transfer rate.

Accepted for publication in A&A

References in corpus (15)

• X-ray Properties of Black-Hole Binaries
• Modelling the behaviour of accretion flows in X-ray binaries
• A Long, Hard Look at the Low-Hard State in Accreting Black Holes
• A radio-emitting outflow in the quiescent state of A0620-00: implications for modelling low-luminosity black hole binaries
• Testing Accretion Disk Theory in Black Hole X-ray Binaries
• Magnetically Arrested Disks and Origin of Poynting Jets: Numerical Study
• The 2003 Outburst of the X-ray Transient H 1743-322: Comparisons with the Black Hole Microquasar XTE J1550-564
• A Prominent Accretion Disk in the Low-Hard State of the Black Hole Candidate SWIFT J1753.5-0127
• Advection/Diffusion of Large-Scale B-Field in Accretion Disks
• Revealing accretion onto black holes: X-ray reflection throughout three outbursts of GX 339-4
• A jet model for Galactic black-hole X-ray sources: Some constraining correlations
• The Cosmic Battery Revisited
• Fast variability as a probe of the smallest regions around accreting black holes
• Disk-Evaporation Fed Corona: Structure and Evaporation Feature with Magnetic Field
• Simulations of the Poynting--Robertson Cosmic Battery in Resistive Accretion Disks

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• Inclination effects on the X-ray emission of Galactic black-hole binaries
• Truncated accretion discs in black hole X-ray binaries: dynamics and variability signatures
• The X-ray view of black-hole candidate Swift J1842.5-1124 during its 2008 outburst
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