The first minutes of a binary-driven hypernova

TL;DR

This study simulates the initial minutes of binary-driven hypernovae, focusing on accretion processes and rotational evolution of the neutron stars, revealing distinctive double-peak and single-peak power structures relevant to gamma-ray burst observations.

Contribution

It provides a detailed simulation of early hypernova evolution including relativistic effects and realistic accretion rates, highlighting novel rotational power features of neutron stars.

Findings

Neutron star rotational power exhibits a double-peak structure.

Competing peaks can occur simultaneously depending on system parameters.

Results have implications for early gamma-ray burst emission features.

Abstract

We simulate the first minutes of the evolution of a binary-driven hypernova (BdHN) event, with a special focus on the associated accretion processes of supernova (SN) ejecta onto the newborn neutron star ($\nu$NS) and the NS companion. We calculate the rotational evolution of the $\nu$NS and the NS under the torques exerted by the accreted matter and the magnetic field. We take into account general relativistic effects and use realistic hypercritical accretion rates obtained from three-dimensional smoothed-particle-hydrodynamics (SPH) numerical simulations of the BdHN for a variety of orbital periods. We show that the rotation power of the $\nu$NS has a unique double-peak structure while that of the NS has a single peak. These peaks are of comparable intensity and can occur very close in time or even simultaneously depending on the orbital period and the initial angular momentum of the stars. We outline the consequences of the above features in the early emission and their consequent observation in long gamma-ray bursts (GRBs).