However, the coalescence time of the NS+NS and NS+BH binaries can be very long, and some of the mergers should take place in rather old stellar population, even in elliptical galaxies where there should be no noticeable star formation. This property can help to distingwish the binary merger GRB from the GRB from massive star collapses.
|Figure 1: Coalescence time distributions for different kick velocities normalized for a sample galaxy with instantaneous star formation of .Left: NS+NS. Right: NS+BH|
|Figure 2: The ratio of the coalescence rates in spiral and elliptical galaxies at different redshift for different kick velocities. a) Left panel: NS+NS. b) Right panel: NS+BH|
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