Spinar Paradigm and Gamma Ray Bursts Central Engine

Abstract

A spinar is a quasi-equilibrium collapsing object whose equilibrium is maintained by the balance of centrifugal and gravitational forces and whose evolution is determined by its magnetic field. The spinar quasi equilibrium model recently discussed as the course for extralong X-ray plateu in GRB (Lipunov & Gorbovskoy, 2007). We propose a simple non stationary three-parameter collapse model with the determining role of rotation and magnetic field in this paper. The input parameters of the theory are the mass, angular momentum, and magnetic field of the collapsar. The model includes approximate description of the following effects: centrifugal force, relativistic effects of the Kerr metrics, pressure of nuclear matter, dissipation of angular momentum due to magnetic field, decrease of the dipole magnetic moment due to compression and general-relativity effects (the black hole has no hare), neutrino cooling, time dilatation, and gravitational redshift. The model describes the temporal behavior of the central engine and demonstrates the qualitative variety of the types of such behavior in nature. We apply our approach to explain the observed features of gamma-ray bursts of all types. In particular, the model allows the phenomena of precursors, x-ray and optical bursts, and the appearance of a plateau on time scales of several thousand seconds to be unified.