Energy Source Of Gamma-ray Bursts Research Articles

Quark deconfinement in neutron stars and gamma-ray bursts

We discuss a model for the energy source of gamma-ray burst which is based on the "delayed conversion" of a metastable pure hadronic compact star ("neutron star") to a quark star (hybrid star or strange star).

Non-stationary hyperaccretion of stellar-mass black holes in three dimensions: torus evolution and neutrino emission

We present three-dimensional hydrodynamic simulations of the evolution of self-gravitating, thick accretion discs around hyperaccreting stellar-mass black holes. The black hole-torus systems are considered to be remnants of compact object mergers, in which case the disc is not fed by an external mass reservoir and the accretion is non-stationary. Our models take into account viscous dissipation, described by an α-law, a detailed equation of state for the disc gas, and an approximate treatment of general relativistic effects on the disc structure by using a pseudo-Newtonian potential for the black hole including its possible rotation and spin-up during accretion. Magnetic fields are ignored. The neutrino emission of the hot disc is treated by a neutrino-trapping scheme, and the vv-annihilation near the disc is evaluated in a post-processing step. Our simulations show that the neutrino emission and energy deposition by vv-annihilation increase sensitively with the disc mass, with the black hole spin in case of a disc in corotation, and in particular with the α-viscosity. We find that for sufficiently large α-viscosity, vv-annihilation can be a viable energy source for gamma-ray bursts.

Gravitational collapse of a Hagedorn fluid in Vaidya geometry

The gravitational collapse of a high-density null charged matter fluid, satisfying the Hagedorn equation of state, is considered in the framework of the Vaidya geometry. The general solution of the gravitational field equations can be obtained in an exact parametric form. The conditions for the formation of a naked singularity, as a result of the collapse of the compact object, are also investigated. For an appropriate choice of the arbitrary integration functions the null radial outgoing geodesic, originating from the shell focussing central singularity, admits one or more positive roots. Hence a collapsing Hagedorn fluid could end either as a black hole, or as a naked singularity. A possible astrophysical application of the model, to describe the energy source of gamma-ray bursts, is also considered.

Conversion of Neutron Stars to Strange Stars as the Central Engine of Gamma-Ray Bursts

We study the conversion of a neutron star to a strange star as a possible energy source for gamma-ray bursts. We use different recent models for the equation of state of neutron star matter and strange quark matter. We show that the total amount of energy liberated in the conversion is in the range of &parl0;1-4&parr0;x1053 ergs (1 order of magnitude larger than previous estimates) and is in agreement with the energy required to power gamma-ray burst sources at cosmological distances.

CELESTIAL GAMMA RAY BURSTS DETECTOR DEVELOPMENT AND MODEL SIMULATIONS

CELESTIAL GAMMA RAY BURSTS DETECTOR DEVELOPMENT AND MODEL SIMULATIONS