MERGING OF BINARY WHITE-DWARFS, NEUTRON-STARS AND BLACK-HOLES UNDER THE INFLUENCE OF GRAVITATIONAL-WAVE RADIATION

By means of a numerical scenario code, we derive the rates of mergers of components of binary white dwarfs, neutron stars and black holes as functions of the ages of the progenitor populations. The rate of merg ers of binary CO (or ONe) dwarfs with total mass of components greater than or similar to M(Ch) is consistent with the 'observed' rate of oc currence of Type Ia supernovae (SNeIa) in the Galaxy. We show that, fo r galaxies with continuing intense star formation, the history of star formation is not significant for the present rate of SNeIa, because a bout 60 per cent of SNeIa descend from populations younger than approx imately 10(9) yr. Assuming that Type Bi and Type II supernovae (SNeIb and SNeII) descend, respectively, from compact helium remnants of init ially massive (M greater than or similar to 10 M .) components of clos e binaries and from massive stars that managed to retain their extende d hydrogen envelopes, we estimate their rates and derive linear relati ons between the rates of occurrence of SNeIa, SNeIb and SNeII that hav e the same trend along the portion of the Hubble sequence for non-elli ptical galaxies as indicated by observations. We compute the average d istances that merging pairs with neutron star and/or black hole compon ents can travel prior to mergers, and find that the overwhelming major ity of merger events have to occur within the volume of the parental g alaxies.