Modelling magnetized neutron stars using resistive magnetohydrodynamics

Abstract

This work presents an implementation of the resistive MHD equations for a generic algebraic Ohm's law which includes the effects of finite resistivity within full General Relativity. The implementation naturally accounts for magnetic-field-induced anisotropies and, by adopting a phenomenological current, is able to accurately describe electromagnetic fields in the star and in its magnetosphere. We illustrate the application of this approach in interesting systems with astrophysical implications; the aligned rotator solution and the collapse of a magnetized rotating neutron star to a black hole.

Interaction of misaligned magnetospheres in the coalescence of binary neutron stars

“…Inside the star, the magnetic field is modeled within the ideal MHD limit, transitioning to the forcefree limit outside the stars. This transition is achieved, in our resistive MHD framework, by a prescription for the (anisotropic) conductivity tensor that depends on the fluid density (see [33] for details). We adopt the BSSN formulation [35,36] of the Einstein equations as described in [37].…”

Electromagnetic Precursors to Gravitational-wave Events: Numerical Simulations of Flaring in Pre-merger Binary Neutron Star Magnetospheres

“…In addition this scenario has also been invoked to drive powerful fireballs (Metzger & Zivancev 2016) and Fast Radio Bursts (FRBs) (Wang et al 2016). Since the highly dynamical electromagnetic field configurations present in the inspiraling binary are too involved to be studied using purely analytical approaches a few numerical studies have been performed in order to study force-free magnetospheric interactions, either in binary black hole mergers (Alic et al 2012;Palenzuela et al 2010), in neutron star binaries (Palenzuela et al 2013b,a;Ponce et al 2014), in mixed binaries (Paschalidis et al 2013) and in collapsing neutron stars (Lehner et al 2012;Palenzuela 2013) (see also Most et al (2018a);Nathanail et al (2017) for electrovacuum simulations). While these studies have been performed self-consistently in full general relativity they have not studied the main source of energy dissipation in current sheets, which are important sources of broad-band electromagnetic emission.…”

Electromagnetic and Gravitational Outputs from Binary-Neutron-Star Coalescence

“…Details of our implementation are given in Refs. [25,[29][30][31][32][33][34][35]. Our numerical domain extends up to L ¼ 320 km and contains five nested fixed mesh refinement grids, each finer grid with twice the resolution of its parent grid.…”