Model for an optically thick torus in local thermodynamic equilibrium around a black hole

Università di TrentoLaboratorio di Matematica Applicata, via Messiano 77, 38123 Trento, Italy
e-mail: olindo.zanotti@unitn.it

Received: 24 December 2013
Accepted: 23 January 2014

Abstract

We propose a simple model for an optically thick radiative torus in local thermodynamic equilibrium around a Kerr black hole. The hydrodynamics structure, which is not affected by the radiation field, is the same as for the so-called polish doughnuts. Under the assumption of isentropic fluid and polytropic equation of state, a simple stationary and axisymmetric solution to the relativistic radiation hydrodynamics equations is possible, for which the temperature of the torus scales like the specific enthalpy. The astrophysical relevance of the model is briefly discussed.