Magnetic dissipation in the Crab nebula

• Published in: Monthly notices of the Royal Astronomical Society Vol. 428; no. 3; pp. 2459 - 2466
• Main Author: Komissarov, Serguei S.
• Format: Journal Article
• Language: English
• Published: London Oxford University Press 01.01.2013
• Subjects: Astrophysics; Energy dissipation; Gamma ray astronomy; Magnetic fields; Mathematical models; Nebulae; Simulation; radiation mechanisms: non-thermal; MHD; pulsars: individual: Crab; ISM: supernova remnants; magnetic fields
• ISSN: 0035-8711; 1365-2966
• DOI: 10.1093/mnras/sts214

Magnetic dissipation is frequently invoked as a way of powering the observed emission of relativistic flows in Gamma-ray bursts and active galactic nuclei. Pulsar Wind Nebulae provide closer to home cosmic laboratories which can be used to test the hypothesis. To this end, we reanalyze the observational data on the spindown power of the Crab pulsar, energetics of the Crab nebula and its magnetic field. We show that unless the magnetic inclination angle of the Crab pulsar is very close to 90 degrees the overall magnetization of the striped wind after total dissipation of its stripes is significantly higher than that deduced in the Kennel-Coroniti model and recent axisymmetric simulations of Pulsar Wind Nebulae. On the other hand, higher wind magnetization is in conflict with the observed low magnetic field of the Crab nebula, unless it is subject to efficient dissipation inside the nebula as well. For the likely inclination angle of 45 degrees the data require magnetic dissipation on the time-scale of about 80 years, which is short compared to the lifetime of the nebula but long compared to the time-scale of Crab's gamma-ray flares.