Jet-environment interplay in magnetized binary neutron star mergers by Andrea Pavan et al. on Monday 21 November

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 GR-MHD BNS merger

simulation.

arXiv: http://arxiv.org/abs/http://arxiv.org/abs/2211.10135v1