The spatial distribution of the hard X-ray spectral index and the local magnetic reconnection rate

Document Type

Article

Publication Date

1-1-2008

Abstract

The rare phenomenon of ribbon-like hard X-ray (HXR) sources up to 100 keV found in the 2005 May 13 M8.0 flare observed with the Reuven Ramaty High Energy Solar Spectroscopic Imager provides detailed information on the spatial distribution of flare HXR emission. In this Letter, we further investigate the characteristics of HXR emission in this event using imaging spectroscopy, from which we obtain spatially resolved HXR spectral maps during the flare impulsive phase. As a result we found, along a flare ribbon, an anticorrelation relationship between the local HXR flux and the local HXR spectral index. We suggest that this can be regarded as a spatial analog of the well-known temporal soft-hard-soft spectral evolution pattern of the integrated HXR flux. We also found an anticorrelation between the HXR spectral index and the local electric field along the ribbon, which suggests electron acceleration by the electric field during flares. © 2008. Trie American Astronomical. Society. All rights reserved.

Identifier

64849101526 (Scopus)

Publication Title

Astrophysical Journal

External Full Text Location

https://doi.org/10.1086/525849

e-ISSN

15384357

ISSN

0004637X

First Page

L69

Last Page

L72

Issue

1 PART 2

Volume

672

Grant

0607544

Fund Ref

National Science Foundation

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