Vol 17, No 10 (2017) / Ghosh

A 2.5-dimensional viscous, resistive, advective magnetized accretion-outflow coupling in black hole systems: a higher order polynomial approximation

Shubhrangshu Ghosh


The correlated and coupled dynamics of accretion and outflow around black holes (BHs) are essentially governed by the fundamental laws of conservation as outflow extracts matter, momentum and energy from the accretion region. Here we analyze a robust form of 2.5-dimensional viscous, resistive, advective magnetized accretion-outflow coupling in BH systems. We solve the complete set of coupled MHD conservation equations self-consistently, through invoking a generalized polynomial expansion in two dimensions. We perform a critical analysis of the accretion-outflow region and provide a complete quasi-analytical family of solutions for advective flows. We obtain the physically plausible outflow solutions at high turbulent viscosity parameter α( ≳ 0.3), and at a reduced scale-height, as magnetic stresses compress or squeeze the flow region. We found that the value of the large-scale poloidal magnetic field \(\bar{B}_{\rm P}\) is enhanced with the increase of the geometrical thickness of the accretion flow. On the other hand, differential magnetic torque (\(−r^2 \bar{B}_φ \bar{B}_z\)) increases with the increase in \(\dot{M}\). \(\bar{B}_{\rm P} , −r^2 \bar{B}φ \bar{B}z\) as well as the plasma beta βP get strongly augmented with the increase in the value of α, enhancing the transport of vertical flux outwards. Our solutions indicate that magnetocentrifugal acceleration plausibly plays a dominant role in effusing out plasma from the radial accretion flow in a moderately advective paradigm which is more centrifugally dominated. However in a strongly advective paradigm it is likely that the thermal pressure gradient would play a more contributory role in the vertical transport of plasma.


accretion, accretion disks — black hole physics — magnetohydrodynamics — galaxies: active — galaxies: jets — X-rays: binaries

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DOI: https://doi.org/10.1088/1674–4527/17/10/104


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