Multi-wavelength emission in resistive pulsar magnetospheres

TL;DR

This study models neutron star magnetospheres across different regimes using resistive plasma physics, revealing how resistivity influences multi-wavelength emission profiles and aiding interpretation of pulsar observations.

Contribution

It provides a comprehensive resistive magnetosphere model from vacuum to force-free regimes, linking plasma resistivity to observable multi-wavelength emission features in pulsars.

Findings

Magnetosphere geometry near the star is unaffected by resistivity.

Poynting flux and magnetic field sweep-back vary with resistivity.

Resistivity significantly alters gamma-ray and X-ray pulse profiles.

Abstract

In this paper, we compute a full set of neutron star magnetosphere structures from the basic vacuum regime to the dissipation-less force-free regime by implementing a resistive prescription for the plasma. A comparison to the radiation reaction limit is also discussed. We investigated the impact of these resistive magnetospheres onto the multi-wavelength emission properties based on the polar cap model for radio wavelengths, on the slot gap model for X-rays and on the striped wind model for $\gamma$-rays.} % methods heading (mandatory) {We performed time-dependent pseudo-spectral simulations of the full Maxwell equations including a resistive Ohm's law. We deduced the polar cap shape and size, the Poynting flux, the magnetic field structure and the current sheet surface, depending on the magnetic obliquity~$\chi$ and on the conductivity~$\sigma$. We found that the geometry of the magnetosphere close to the stellar surface is not impacted by the amount of resistivity. Polar cap rims remain very similar in shape and size. However the Poynting flux varies significantly as well as the magnetic field sweep-back in the vicinity of the light-cylinder. This bending of field lines reflects into the $\gamma$-ray pulse profiles, changing the $\gamma$-ray peak separation~$\Delta$ as well as the time lag~$\delta$ between the radio pulse and $\gamma$-ray peaks. X-ray pulse profiles are also drastically affected by the resistivity. A full set of multi-wavelength light-curves can be compiled for future comparison with the third $\gamma$-ray pulsar catalogue. This systematic study will help to constrain the amount of magnetic energy flowing into particle kinetic energy and shared by radiation.