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HYDROMAGNETICS OF ADVECTIVE ACCRETION FLOWS AROUND BLACK HOLES: REMOVAL OF ANGULAR MOMENTUM BY LARGE-SCALE MAGNETIC STRESSES

Mukhopadhyay, Banibrata and Chatterjee, Koushik (2015) HYDROMAGNETICS OF ADVECTIVE ACCRETION FLOWS AROUND BLACK HOLES: REMOVAL OF ANGULAR MOMENTUM BY LARGE-SCALE MAGNETIC STRESSES. In: ASTROPHYSICAL JOURNAL, 807 (1).

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Official URL: http://dx.doi.org/10.1088/0004-637X/807/1/43

Abstract

We show that the removal of angular momentum is possible in the presence of large-scale magnetic stresses in geometrically thick, advective, sub-Keplerian accretion flows around black holes in steady state, in the complete absence of alpha-viscosity. The efficiency of such an angular momentum transfer could be equivalent to that of alpha-viscosity with alpha = 0.01-0.08. Nevertheless, the required field is well below its equipartition value, leading to a magnetically stable disk flow. This is essentially important in order to describe the hard spectral state of the sources when the flow is non/sub-Keplerian. We show in our simpler 1.5 dimensional, vertically averaged disk model that the larger the vertical-gradient of the azimuthal component of the magnetic field is, the stronger the rate of angular momentum transfer becomes, which in turn may lead to a faster rate of outflowing matter. Finding efficient angular momentum transfer in black hole disks via magnetic stresses alone, is very interesting when the generic origin of alpha-viscosity is still being explored.

Item Type: Journal Article
Publication: ASTROPHYSICAL JOURNAL
Publisher: IOP PUBLISHING LTD
Additional Information: Copy right for this article belongs to the IOP PUBLISHING LTD, TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND
Keywords: accretion, accretion disks; galaxies: active; ISM: jets and outflows; magnetohydrodynamics (MHD); X-rays: binaries
Department/Centre: Division of Physical & Mathematical Sciences > Physics
Date Deposited: 26 Aug 2015 06:31
Last Modified: 26 Aug 2015 06:31
URI: http://eprints.iisc.ac.in/id/eprint/52248

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