Spatial evidence for transition radiation in a solar radio burst

Document Type

Article

Publication Date

8-10-2005

Abstract

Microturbulence, i.e., enhanced fluctuations of plasma density and electric and magnetic fields, is of great interest in astrophysical plasmas, but occurs on spatial scales far too small to resolve by remote sensing, e.g., at ∼ 1-100 cm in the solar corona. This Letter reports spatially resolved observations that offer strong support for the presence in solar flares of a suspected radio emission mechanism, resonant transition radiation, which is tightly coupled to the level of microturbulence and provides direct diagnostics of the existence and level of fluctuations on decimeter spatial scales. Although the level of the microturbulence derived from the radio data is not particularly high, (Δn2)/n2 ∼ 10-5, it is large enough to affect the charged particle diffusion and give rise to effective stochastic acceleration. This finding has exceptionally broad astrophysical implications, since modern sophisticated numerical models predict generation of much stronger turbulence in relativistic objects, e.g., in gamma-ray burst sources. © 2005. The American Astronomical Society. All rights reserved.

Identifier

28144451608 (Scopus)

Publication Title

Astrophysical Journal

External Full Text Location

https://doi.org/10.1086/444375

e-ISSN

15384357

ISSN

0004637X

First Page

L65

Last Page

L68

Issue

1 II

Volume

629

Grant

0307670

Fund Ref

National Science Foundation

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