V.M.Lipunov , K.A.Postnov ,
I.E.Panchenko , and H.E. Jorgensen
Faculty of Physics, Moscow University, 117234 Moscow, Russia
Sternberg Astronomical Institute, Moscow University, 119899 Moscow, Russia
Astronomical Observatory, Ostervoldgade 3, DK-1350 Copenhagen, Denmark
Evolution of the coalescence rate of double neutron stars (NS) and neutron star - black hole (BH) binaries are computed for model galaxies with different star formation rates. Assuming gamma-ray bursts (GRB) to originate from NS+NS or NS+BH merging in distant galaxies, theoretical - distributions for gamma-ray bursts (GRB) are calculated for the first time taking the computed merging rates into account. We use a flat cosmological model ( ) with different values of the cosmological constant and under various assumptions about the star formation history in galaxies. The calculated source evolution predicts a 5-10 times increase of the source statistics at count rates 3-10 times lower than the exising BATSE sensitivity limit. The most important parameter in fitting the 2nd BATSE catalogue is the initial redshift of star formation, which is found to be depending on a poorly determined average spectral index of GRB.