Hypercritical Accretion, Induced Gravitational Collapse, and Binary-Driven Hypernovae

TL;DR

This paper presents the first full numerical simulations of the induced gravitational collapse (IGC) process in binary systems, explaining the connection between certain supernovae and gamma-ray bursts through detailed hydrodynamic modeling.

Contribution

It provides comprehensive numerical simulations of the IGC phenomenon, advancing beyond simplified models to explain the binary evolution leading to GRBs and SNe Ic association.

Findings

IGC occurs in short timescales (100-1000s) due to photon trapping and neutrino cooling.

Simulations show the accretion process leads to black hole formation when the neutron star reaches critical mass.

The scenario explains why GRBs are associated only with SN Ic with little or no helium.

Abstract

The induced gravitational collapse (IGC) paradigm has been successfully applied to the explanation of the concomitance of gamma-ray bursts (GRBs) with supernovae (SNe) Ic. The progenitor is a tight binary system composed by a carbon-oxygen (CO) core and a neutron star (NS) companion. The explosion of the SN leads to hypercritical accretion onto the NS companion which reaches the critical mass, hence inducing its gravitational collapse to a black hole (BH) with consequent emission of the GRB. The first estimates of this process were based on a simplified model of the binary parameters and the Bondi-Hoyle-Lyttleton accretion rate. We present here the first full numerical simulations of the IGC phenomenon. We simulate the core-collapse and SN explosion of CO stars to obtain the density and ejection velocity of the SN ejecta. We follow the hydrodynamic evolution of the accreting material falling into the Bondi-Hoyle surface of the NS all the way up to its incorporation to the NS surface. The simulations go up to BH formation when the NS reaches the critical mass. For appropriate binary parameters the IGC occurs in short timescales (100-1000s) owing to the combined effective action of the photon trapping and the neutrino cooling near the NS surface. We also show that the IGC scenario leads to a natural explanation for why GRBs are associated only to SN Ic with totally absent or very little helium.