A corrugated termination shock in pulsar wind nebulae?

TL;DR

This paper proposes that non-linear corrugation of the pulsar wind nebula termination shock can facilitate magnetic energy dissipation and particle acceleration, explaining observed nebular phenomena.

Contribution

It introduces the idea that shock corrugation leads to turbulence and dissipation, providing a new mechanism for energy conversion and particle acceleration in pulsar wind nebulae.

Findings

Corrugation of the termination shock can convert magnetic energy into turbulence.

Turbulence can accelerate particles near the radiation reaction limit.

Shock corrugation may explain observed nebular emission features.

Abstract

Successful phenomenological models of pulsar wind nebulae assume efficient dissipation of the Poynting flux of the magnetized electron-positron wind as well as efficient acceleration of the pairs in the vicinity of the termination shock, but how this is realized is not yet well understood. The present paper suggests that the corrugation of the termination shock, at the onset of non-linearity, may lead towards the desired phenomenology. Non-linear corrugation of the termination shock would convert a fraction of order unity of the incoming ordered magnetic field into downstream turbulence, slowing down the flow to sub-relativistic velocities. The dissipation of turbulence would further preheat the pair population on short length scales, close to equipartition with the magnetic field, thereby reducing the initial high magnetization to values of order unity. Furthermore, it is speculated that the turbulence generated by the corrugation pattern may sustain a relativistic Fermi process, accelerating particles close to the radiation reaction limit, as observed in the Crab nebula. The required corrugation could be induced by the fast magnetosonic modes of downstream nebular turbulence; but it could also be produced by upstream turbulence, either carried by the wind or seeded in the precursor by the accelerated particles themselves.