Effects of magnetic field on the radiation pressure-dominated discs around neutron stars

Abstract

We supplement the analytic solution obtained by [O. M. Matthews et al., Mon. Not. R. Astron. Soc. 356, 66 (2005)] to investigate the steady-state structure of radiation pressure-dominated disc under the influence of a stellar magnetic field which deploys a torque. The solutions converge to the non-magnetic [N. I. Shakura and R. A. Sunyaev, Astron. Astrophys. 24, 337 (1973)] form when magnetic field of the star tends to zero and also at large radii. Effects of varying the mass accretion rates and the spin period of a typical neutron star on the disc parameters are presented. We further report that the presence of a magnetic correction term k reduces the radial extent upto which radiation pressure and electron scattering continue to be the major source of pressure and opacity, respectively. We also report that magnetic effects amplify the viscous timescale several times in the inner disc.