Stationary Axisymmetric Configuration of the Resistive Thick Accretion Tori around a Schwarzschild Black Hole

TL;DR

This paper extends the Newtonian model of resistive thick accretion tori around Schwarzschild black holes to a fully general relativistic framework, analyzing how magnetic fields and conductivity influence disc structure and dynamics.

Contribution

It provides the first general relativistic solutions for resistive accretion tori with magnetic fields, including effects of finite conductivity on disc properties.

Findings

Magnetic field structure is significantly altered by electrical conductivity.

Radial inflow, pressure, and density are strongly affected by conductivity.

Azimuthal velocity remains sub-Keplerian regardless of conductivity.

Abstract

We examine a thick accretion disc in the presence of external gravity and intrinsic dipolar magnetic field due to a non-rotating central object. In this paper, we generalize the Newtonian theory of stationary axisymmetric resistive tori of Tripathy, Prasanna $\&$ Das (1990) by including the fully general relativistic features. If we are to obtain the steady state configuration, we have to take into account the finite resistivity for the magnetofluid in order to avoid the piling up of the field lines anywhere in the accretion discs. The efficient value of conductivity must be much smaller than the classical conductivity to be astrophysically interesting. The accreting plasma in the presence of an external dipole magnetic field gives rise to a current in the azimuthal direction. The azimuthal current produced due to the motion of the magnetofluid modifies the magnetic field structure inside the disc and generates a poloidal magnetic field for the disc. The solutions we have found show that the radial inflow, pressure and density distributions are strongly modified by the electrical conductivity both in relativistic and Newtonian regimes. However, the range of conductivity coefficient is different for both regimes, as well as that of the angular momentum parameter and the radius of the innermost stable circular orbit. Furthermore, it is shown that the azimuthal velocity of the disc which is not dependent on conductivity is sub-Keplerian in all radial distances for both regimes. Owing to the presence of pressure gradient and magnetic forces. This work may also be important for the general relativistic computational magnetohydrodynamics that suffers from the lack of exact analytic solutions that are needed to test computer codes.