Emission of magnetar bursts and precursors of neutron star mergers

Abstract

Magnetar bursts can be emitted by Alfvén waves growing in the outer magnetosphere to nonlinear amplitudes, $\delta B/B\sim 1$, and triggering magnetic reconnection. Similar magnetic flares should occur quasi-periodically in a magnetized neutron star binary nearing merger. In both cases, fast dissipation in the magnetic flare creates optically thick $e^{\pm }$ plasma, whose heat capacity is negligible compared with the generated radiation energy. Magnetic dissipation then involves photon viscosity and acts through Compton drag on the plasma bulk motions in the reconnection region. The effective temperature of the resulting Comptonization process is self-regulated to tens of keV. The generated X-ray emission is calculated using time-dependent radiative transfer simulations, which follow the creation of $e^{\pm }$ pairs and the production, Comptonization, and escape of photons. The simulations show how the dissipation region becomes dressed in an $e^{\pm }$ coat, and how the escaping spectrum is shaped by radiative transfer through the coat. The results are compared with observed magnetar bursts, including the recent activity of SGR 1935+2154 accompanied by a fast radio burst. Predictions are made for X-ray precursors of magnetized neutron star mergers.

14 pages, accepted to ApJ

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Cited by in corpus (18)

• Electromagnetic fireworks: Fast radio bursts from rapid reconnection in the compressed magnetar wind
• Shock-powered radio precursors of neutron star mergers from accelerating relativistic binary winds
• Radiative Particle-in-Cell Simulations of Turbulent Comptonization in Magnetized Black-Hole Coronae
• Dynamic alignment and plasmoid formation in relativistic magnetohydrodynamic turbulence
• Modeling general-relativistic plasmas with collisionless moments and dissipative two-fluid magnetohydrodynamics
• Reconnection-powered fast radio transients from coalescing neutron star binaries
• Magnetar bursts due to Alfvén wave nonlinear breakout
• Electromagnetic precursor flares from the late inspiral of neutron star binaries
• Resonant Shattering Flares in Black Hole-Neutron Star and Binary Neutron Star Mergers
• Comptonization by Reconnection Plasmoids in Black Hole Coronae II: Electron-Ion Plasma
• Pulsar revival in neutron star mergers: multi-messenger prospects for the discovery of pre-merger coherent radio emission
• Direct Emission of Strong Radio Pulses During Magnetar Flares
• Relativistic Alfvén Waves Entering Charge Starvation in the Magnetospheres of Neutron Stars
• Synchrotron Pair Production Equilibrium in Relativistic Magnetic Reconnection
• Fast dissipation of Colliding Alfvén Waves in a Magnetically Dominated Plasma
• Fundamental physics with neutron stars
• Exact nonlinear solutions for three-dimensional Alfvén-wave packets in relativistic magnetohydrodynamics
• Heating of Magnetically Dominated Plasma by Alfvén-Wave Turbulence