The energy source has remained to be the great mystery in understanding of the gamma-ray bursts ( GRBs ) if the events are placed at cosmological distances as indicated by a number of recent observations .
The currently popular models include ( 1 ) the merger of two neutron stars or a neutron star and a black hole binary and ( 2 ) the hypernova scenario of the collapse of a massive member in a close binary .
Since a neutron star will inevitably collapse into a black hole if its mass exceeds the limit M _ { max } \approx 3 M _ { \odot } , releasing a total binding gravitational energy of \sim 10 ^ { 54 } erg , we explore semi-empirically the possibility of attributing the energy source of GRB to the accretion-induced collapse of a neutron star ( AICNS ) in a massive X-ray binary system consisting of a neutron star and a type O/B companion .
This happens because a significant mass flow of \sim 10 ^ { -3 } – 10 ^ { -4 } M _ { \odot } yr ^ { -1 } may be transferred onto the neutron star through the Roche-lobe overflow and primarily during the spiral-in phase when it plunges into the envelope of the companion , which may eventually lead to the AICNS before the neutron star merges with the core of the companion .
In this scenario , a “ dirty ” fireball with a moderate amount of beaming is naturally expected because of the nonuniformity of the stellar matter surrounding the explosion inside the companion , and a small fraction ( \sim 0.1 \% ) of the energy is sufficient to create the observed GRBs .
In addition , the bulk of the ejecting matter of the companion star with a relatively slow expansion rate may act as the afterglow .
Assuming a non-evolutionary model for galaxies , we estimate that the birthrate of the AICNS events is about 2 per day within a volume to redshift z = 1 for an \Omega _ { 0 } = 1 universe , consistent with the reported GRB rate .
It appears that the AICNS scenario , as a result of stellar evolution , may provide a natural explanation for the origin of GRBs and therefore deserves to be further investigated in the theoretical study of GRBs .