Millisecond microwave spikes: Statistical study and application for plasma diagnostics

Document Type

Article

Publication Date

7-10-2008

Abstract

We analyze a dense cluster of solar radio spikes registered at 4.5-6 GHz by the Purple Mountain Observatory spectrometer (Nanjing, China), operating in the 4.5-7.5 GHz range with 5 ms temporal resolution. To handle the data from the spectrometer, we developed a new technique that uses a nonlinear multi-Gaussian spectral fit based on χ2 criteria to extract individual spikes from the originally recorded spectra. Applying this method to the experimental raw data, we eventually identified about 3000 spikes for this event, which allows us to make a detailed statistical analysis. Various statistical characteristics of the spikes have been evaluated, including the intensity distributions, the spectral bandwidth distributions, and the distribution of the spike mean frequencies. The most striking finding of this analysis is the distributions of the spike bandwidth, which are remarkably asymmetric. To reveal the underlaying microphysics, we explore the local-trap model with the renormalized theory of spectral profiles of the electron cyclotron maser (ECM) emission peak in a source with random magnetic irregularities. The distribution of the solar spike relative bandwidths calculated within the local-trap model represents an excellent fit to the experimental data. Accordingly, the developed technique may offer a new tool with which to study very low levels of magnetic turbulence in the spike sources, when the ECM mechanism of the spike cluster is confirmed. © 2008. The American Astronomical Society. All rights reserved.

Identifier

53549110791 (Scopus)

Publication Title

Astrophysical Journal

External Full Text Location

https://doi.org/10.1086/588380

e-ISSN

15384357

ISSN

0004637X

First Page

1688

Last Page

1697

Issue

2

Volume

681

Grant

0607544

Fund Ref

National Science Foundation

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