Time-Dependent 3D Magnetohydrodynamic Pulsar Magnetospheres: Oblique Rotators

TL;DR

This paper presents time-dependent 3D relativistic MHD simulations of oblique pulsar magnetospheres, revealing low dissipation levels and significant quantitative differences from force-free models, especially in wind luminosity and flow velocity.

Contribution

It advances pulsar magnetosphere modeling by including plasma inertia and heating, providing more realistic insights beyond force-free approximations.

Findings

Less than 10% of spindown energy dissipated within a few light cylinder radii.

Pulsar wind luminosity is more equatorially concentrated at high obliquities.

Reconnection flows modify the flow velocity in the current sheet.

Abstract

The current state of the art in pulsar magnetosphere modeling assumes the force-free limit of magnetospheric plasma. This limit retains only partial information about plasma velocity and neglects plasma inertia and temperature. We carried out time-dependent 3D relativistic magnetohydrodynamic (MHD) simulations of oblique pulsar magnetospheres that improve upon force-free by retaining the full plasma velocity information and capturing plasma heating in strong current layers. We find rather low levels of magnetospheric dissipation, with less than 10% of pulsar spindown energy dissipated within a few light cylinder radii, and the MHD spindown that is consistent with that in force-free. While oblique magnetospheres are qualitatively similar to the rotating split-monopole force-free solution at large radii, we find substantial quantitative differences with the split-monopole, e.g., the luminosity of the pulsar wind is more equatorially concentrated than the split-monopole at high obliquities, and the flow velocity is modified by the emergence of reconnection flow directed into the current sheet.