Properties of magnetic turbulence in GRB afterglows

Abstract

We present a model-independent way to characterise properties of the magnetic-field turbulence in the emitting regions of Gamma-Ray Burst afterglows. Our only assumption is that afterglows' synchrotron radiation is efficient. It turns out that the gyroradius of plasma particles must be smaller (with a good margin) than the correlation length of the magnetic-field fluctuations. Such turbulence is essentially non-linear and therefore must be produced by some kind of MHD instability, likely acting on top of kinetic Weibel instability. We also find that the emitting particles are loosely confined to local magnetic-field structures and diffusion allows them to sample the entire distribution of local magnetization values. This means that one-zone approach to modelling the afterglow spectra is still valid despite the non-linear nature of the magnetic turbulence. However, the non-linear turbulence may (and likely will) change the synchrotron spectrum of individual electrons.

Largely extended Implications section. 5 pages, accepted for publication in PASA

References in corpus (6)

• Teraelectronvolt emission from the $\gamma$-ray burst GRB 190114C
• Klein-Nishina Effects on Optically Thin Synchrotron and Synchrotron Self-Compton Spectrum
• Long Term Evolution of Magnetic Turbulence in Relativistic Collisionless Shocks: Electron-Positron Plasmas
• Revealing x-ray and gamma ray temporal and spectral similarities in the GRB 190829A afterglow
• GRB afterglow parameters in the era of TeV observations: the case of GRB~190114C
• Probing Particle Acceleration through Broadband Early Afterglow Emission of MAGIC Gamma-Ray Burst GRB 190114C

Cited by in corpus (1)

• Property of downstream turbulence driven by the special relativistic shock-clump interaction