Jet-environment interplay in magnetized binary neutron star mergers

TL;DR

This paper presents the first 3D special-relativistic magnetohydrodynamic simulation of a magnetized short gamma-ray burst jet propagating through a realistic, magnetized post-merger environment derived from a binary neutron star merger simulation, advancing understanding of jet-environment interactions.

Contribution

It introduces the first 3D special-relativistic MHD simulation of a magnetized sGRB jet in a realistic post-merger environment, incorporating magnetic fields from a previous GRMHD BNS merger simulation.

Findings

First 3D special-relativistic MHD simulation of magnetized sGRB jet.

Realistic environment from previous GRMHD BNS merger simulation.

Insights into jet propagation in magnetized post-merger environments.

Abstract

GRB 170817A, the first short gamma-ray burst (sGRB) to be detected in coincidence with a gravitational wave signal, demonstrated that merging binary neutron star (BNS) systems can power collimated ultra-relativistic jets and, in turn, produce sGRBs. Moreover, it revealed that sGRB jets possess an intrinsic angular structure that is imprinted in the observable prompt and afterglow emission. Advanced numerical simulations represent the leading approach to investigate the physical processes underlying the evolution of sGRB jets breaking out of post-merger environments, and thus connect the final angular structure and energetics with specific jet launching conditions. In a previous paper, we carried out the first three-dimensional (3D) special-relativistic hydrodynamic simulations of incipient (top-hat) sGRB jets propagating across the realistic environment resulting from a general-relativistic (GR) hydrodynamic BNS merger simulation. While the above work marked an important step toward a consistent end-to-end description of sGRB jets from BNS mergers, those simulations did not account for the presence of magnetic fields, which are expected to play a key role. Here, we overcome this limitation, reporting the first 3D special-relativistic magnetohydrodynamic (MHD) simulation of a magnetized (structured and rotating) sGRB jet piercing through a realistic magnetized post-merger environment, wherein the initial conditions of the latter are directly imported from the outcome of a previous GRMHD BNS merger simulation.