Speaker
Description
I will present smoothed-particle hydrodynamics (SPH) simulations of the binary-driven hypernova (BdHN) scenario for long gamma-ray bursts (GRBs), focusing on the stability of the binary system during the supernova (SN) explosion. The progenitor of a BdHN consists of a carbon–oxygen (CO) star and a neutron-star (NS) companion. The core collapse of the CO star triggers an SN explosion and forms a newborn NS ($\nu$NS) at its center. Part of the SN ejecta is subsequently accreted by both the NS companion and the $\nu$NS.
BdHNe are classified into three subclasses according to the binary orbital period and the resulting accretion process. In BdHN I systems, characterized by compact orbits with periods of a few minutes, the NS companion reaches its critical mass and collapses into a black hole (BH), releasing about 1e52 erg. BdHN II systems have longer orbital periods, from tens of minutes to a few hours; the NS companion gains mass but remains stable, with an energy release of 1e50 - 1e52 erg. In BdHN III systems, with orbital periods of days, accretion is negligible and the released energy is of order 1e50 erg.
I will investigate whether the binary remains gravitationally bound after the SN explosion, leading to NS–BH systems in BdHN I and NS–NS systems in BdHN II and III, or whether the explosion disrupts the binary. The existence of bound remnants would support an evolutionary connection between the long- and short-GRB populations.