Date: 25 Feb 2022    arXiv:2202.12901

Abstract

We perform general relativistic, magnetohydrodynamic (GRMHD) simulations of binary neutron stars in quasi-circular orbit incorporating neutrino transport. Our new radiative transport module for neutrinos adopts a general relativistic, truncated-moment (M1) formalism. The binaries consist of two identical, irrotational stars supported by the SLy nuclear equation of state (EOS) and initially threaded with a poloidal magnetic field that extends from the stellar interior into the exterior, as in typical pulsars. We insert neutrinos processes shortly after the merger and focus on the role of neutrinos in launching a jet following the collapse of the hypermassive neutron star (HMNS) remnant to a spinning black hole (BH). We treat two microphysics versions, one (a ``warm-up”) evolving single neutrino species and considering only the charged-current processes and the other evolving three species $(\nu_e, \bar{\nu}e, \nu{\rm x})$ with all related processes. We trace the evolution until the system reaches a quasi-equilibrium state after BH formation. We find that after $t\sim 5.5 \, \rm ms$ the BH + disk remnant launches an incipient jet. The electromagnetic Poynting luminosity is $\sim 10^{53} \rm \, erg/s$, consistent with that of typical short gamma-ray bursts (sGRBs). The effect of neutrino cooling shortens the lifetime of the HMNS, which lowers the amplitude of the major peak of the gravitational wave (GW) spectrum. After BH formation, neutrinos help clear out the matter near the BH poles resulting in a stronger force-free environment. The neutrino luminosity resides in the range $\sim 10^{52-53} \rm \, erg/s$ once quasiequilibrium is achieved. Comparing with the neutrino-free models, we observe that the inclusion of neutrinos yields similar ejecta masses and is inefficient in transporting angular momentum.

Case C: Magnetized

Gravitational Waveforms for Case C

Case E: Magnetized and Neutrinos (Full)