On the jet-ejecta interaction in 3D GRMHD simulations of binary neutron star merger aftermath

Abstract

Short $\gamma$-ray burst (sGRB) jets form in the aftermath of a neutron star merger, drill through disk winds and dynamical ejecta, and extend over four to five orders of magnitude in distance before breaking out of the ejecta. We present the first 3D general-relativistic magnetohydrodynamic sGRB simulations to span this enormous scale separation. They feature three possible outcomes: jet+cocoon, cocoon, and neither. Typical sGRB jets break out of the dynamical ejecta if (i) the bound ejecta's isotropic equivalent mass along the pole at the time of the BH formation is $\lesssim 10^{-4}{\mathrm{M}}_{\odot }$, setting a limit on the delay time between the merger and BH formation, otherwise, the jets perish inside the ejecta and leave the jet-inflated cocoon to power a low-luminosity sGRB; (ii) the post-merger remnant disk contains strong large-scale vertical magnetic field, $\gtrsim 10^{15}$ G; and (iii) if the jets are weak ($\lesssim 10^{50}$ erg), the ejecta's isotropic equivalent mass along the pole must be small ($\lesssim 10^{-2}{\mathrm{M}}_{\odot }$). Generally, the jet structure is shaped by the early interaction with disk winds rather than the dynamical ejecta. As long as our jets break out of the ejecta, they retain a significant magnetization ($\lesssim 1$), suggesting that magnetic reconnection is a fundamental property of sGRB emission. The angular structure of the outflow isotropic equivalent energy after breakout consistently features a flat core followed by a steep power-law distribution (slope $\gtrsim 3$), similar to hydrodynamic jets. In the cocoon-only outcome, the dynamical ejecta broadens the outflow angular distribution and flattens it (slope $\sim 1.5$).

For movies of the simulation, see http://www.oregottlieb.com/NSM_GRMHD.html

References in corpus (12)

• Origin of the heavy elements in binary neutron-star mergers from a gravitational wave event
• Illuminating Gravitational Waves: A Concordant Picture of Photons from a Neutron Star Merger
• The rate, luminosity function and time delay of non-Collapsar short GRBs
• Off-axis short GRBs from structured jets as counterparts to GW events
• The structure of weakly-magnetized $\gamma$-ray burst jets
• Propagation of a Short GRB Jet in the Ejecta: Jet Launching Delay Time, Jet Structure, and GW170817/GRB 170817A
• The Effect of Neutrino Radiation on Magnetorotational Instability in Proto-Neutron Stars
• Testing the neutrino annihilation model for launching GRB jets
• The Effect of Jet-Ejecta Interaction on the Viewing Angle Dependence of Kilonova Light Curves
• The role of jet-cocoon mixing, magnetization and shock breakout in neutrino and cosmic-ray emission from short GRBs
• Electromagnetic signals from the decay of free neutrons in the first hours of neutron star mergers
• Are Interactions with Neutron Star Merger Winds Shaping the Jets?

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