Population synthesis of gamma-ray bursts with precursor activity and the spinar paradigm

We study statistical properties of long gamma-ray bursts (GRBs) produced by the collapsing cores of WR stars in binary systems. Fast rotation of the cores enables a two-stage collapse scenario, implying the formation of a spinar-like object. A burst produced by such a collapse consists of two pulses, whose energy budget is enough to explain observed GRBs. We calculate models of spinar evolution using results from a population synthesis of binary systems (done by the `Scenario Machine') as initial parameters for the rotating massive cores. Among the resulting bursts, events with the weaker first peak, namely, precursor, are identified, and the precursor-to-main-pulse time separations fully agree with the range of the observed values. The calculated fraction of long GRBs with precursor (about 10 per cent of the total number of long GRBs) and the durations of the main pulses are also consistent with observations. Precursors with lead times greater by up to one order of magnitude than those observed so far are expected to be about twice less numerous. Independently of a GRB model assumed, we predict the existence of precursors that arrive up to >~ 10^3 s in advance of the main events of GRBs.Comment: 11 pages, 9 figures; published versio

Cosmological Models of Gamma-Ray Bursts

We review models of cosmological gamma-ray bursts (GRBs). The statistical and $\gamma$-ray transparency issues are summarized. Neutron-star and black-hole merger scenarios are described and estimates of merger rates are summarized. We review the simple fireball models for GRBs and the recent work on non-simple fireballs. Alternative cosmological models, including models where GRBs are analogs of active galactic nuclei and where they are produced by high-field, short period pulsars, are also mentioned. The value of neutrino astronomy to solve the GRB puzzle is briefly reviewed.Comment: 12 pages, no figures, uuencoded compressed postscript file. Invited review to appear in the proceedings of the 29th ESLAB Symposium "Towards the Source of Gamma-Ray Bursts," Noordwijk, Netherlands, 25-27 April, 199

METHOD FOR THE BEST SOLUTIONS SEARCH IN MULTIOBJECTIVE DECISION PROBLEMS

This paper describes a method for con structing a decision rule providing the isolation of the most preferable soluti ons in multiobjective decision problems. The method is based on the iterative procedure for constructing decision rules. Criteria of meaning-fulness and consistency of received information are formulated. The results are given of applying the method to solution of the most preferable alternatives searc