Magneto centrifugal winds from accretion discs around black hole binaries

Abstract

We want to test if self-similar magneto-hydrodynamic (MHD) accretion-ejection models can explain the observational results for accretion disk winds in BHBs. In our models, the density at the base of the outflow, from the accretion disk, is not a free parameter, but is determined by solving the full set of dynamical MHD equations without neglecting any physical term. Different MHD solutions were generated for different values of (a) the disk aspect ratio ($\epsilon$) and (b) the ejection efficiency ($p$). We generated two kinds of MHD solutions depending on the absence (cold solution) or presence (warm solution) of heating at the disk surface. The cold MHD solutions are found to be inadequate to account for winds due to their low ejection efficiency. The warm solutions can have sufficiently high values of $p(\gtrsim 0.1)$ which is required to explain the observed physical quantities in the wind. The heating (required at the disk surface for the warm solutions) could be due to the illumination which would be more efficient in the Soft state. We found that in the Hard state a range of ionisation parameter is thermodynamically unstable, which makes it impossible to have any wind at all, in the Hard state. Our results would suggest that a thermo-magnetic process is required to explain winds in BHBs.

Draft contains 6 pages and 6 figures. Accepted for publication in Astronomical Notes (AN) as Conference Proceedings of XMM-Newton 2015 Science Workshop - The Extremes of Black Hole Accretion

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• X-ray Properties of Black-Hole Binaries
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• Spectrum Synthesis Modeling of the X-ray Spectrum of GRO J1655-40 Taken During the 2005 Outburst
• Magnetically-Driven Accretion-Disk Winds and Ultra-Fast Outflows in PG1211+143
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Cited by in corpus (5)

• A unified accretion-ejection paradigm for black hole X-ray binaries. II. Observational signatures of jet-emitting disks
• The current state of disk wind observations in BHLMXBs through X-ray absorption lines in the iron band
• Winds and Disk Turbulence Exert Equal Torques on Thick Magnetically Arrested Disks
• A variable magnetic disc wind in the black hole X-ray binary GRS 1915+105?
• Influence of the turbulent magnetic pressure on isothermal jet emitting disks