Observations of "wisps" in magnetohydrodynamic simulations of the Crab Nebula

TL;DR

This paper presents high-resolution relativistic MHD simulations of the Crab Nebula that replicate observed structures and variability, revealing insights into the nebula's dynamic behavior and turbulence.

Contribution

The study introduces advanced simulation techniques and synthetic imaging that accurately reproduce the Crab Nebula's observed features and variability patterns.

Findings

Simulations reproduce Crab's jet-torus structure and wisps.

Wisp variability shows quasi-periodic behavior with 1.5-3 year cycles.

Evidence of MHD turbulence on sub-year scales.

Abstract

In this letter, we describe results of new high-resolution axisymmetric relativistic MHD simulations of Pulsar Wind Nebulae. The simulations reveal strong breakdown of the equatorial symmetry and highly variable structure of the pulsar wind termination shock. The synthetic synchrotron maps, constructed using a new more accurate approach, show striking similarity with the well known images of the Crab Nebula obtained by Chandra, and the Hubble Space Telescope. In addition to the jet-torus structure, these maps reproduce the Crab's famous moving wisps whose speed and rateof production agree with the observations. The variability is then analyzed using various statistical methods, including the method of structure function and wavelet transform. The results point towards the quasi-periodic behaviour with the periods of 1.5-3yr and MHD turbulence on scales below 1yr. The full account of this study will be presented in a follow up paper.