2008MNRAS.383.1397L

A spinar is a collapsing object with quasi-equilibrium. Its equilibrium is maintained by the balance of centrifugal and gravitational forces and its evolution is determined by its magnetic field. A model of spinar quasi-equilibrium has recently been discussed in the context of an extralong X-ray plateau in a gamma-ray burst.

In this paper, we propose a simple non-stationary three-parameter collapse model with the determining role of rotation and magnetic field. The input parameters of the theory are the mass, angular momentum and magnetic field of the collapsar. The model includes an approximate description of the following effects: the centrifugal force, the relativistic effects of the Kerr metrics, the pressure of nuclear matter, the dissipation of angular momentum as a result of the magnetic field, the decrease of the dipole magnetic moment as a result of compression and general-relativity effects (the black hole has no hair), neutrino cooling, time dilatation and gravitational redshift.

The model describes the temporal behaviour of the central engine and demonstrates the qualitative variety of the types of such behaviour in nature.

We apply our approach to an explanation of the observed features of all types of gamma-ray bursts. In particular, the model allows the unification of the phenomena of precursors, X-ray and optical flares, and the appearance of a plateau on the time-scale of several thousand seconds.