Volume 529, May 2011
|Number of page(s)||8|
|Published online||04 April 2011|
Characteristics of the flare acceleration region derived from simultaneous hard X-ray and radio observations
1 Department of Physics and Astronomy, University of Glasgow, G12 8QQ, UK
2 LESIA, Observatoire de Paris, CNRS, UPMC, Université Paris-Diderot, 5 place Jules Janssen, 92195 Meudon Cedex, France
Received: 22 November 2010
Accepted: 8 February 2011
We investigate the type III radio bursts and X-ray signatures of accelerated electrons in a well-observed solar flare in order to find the spatial properties of the acceleration region. Combining simultaneous RHESSI hard X-ray flare data and radio data from Phoenix-2 and the Nançay radioheliograph, the outward transport of flare accelerated electrons is analysed. The observations show that the starting frequencies of type III bursts are anti-correlated with the HXR spectral index of solar flare accelerated electrons. We demonstrate both analytically and numerically that the type III burst starting location is dependent upon the accelerated electron spectral index and the spatial acceleration region size, but weakly dependent on the density of energetic electrons for relatively intense electron beams. Using this relationship and the observed anti-correlation, we estimate the height and vertical extent of the acceleration region, giving values of around 50 Mm and 10 Mm, respectively. The inferred acceleration height and size suggest that electrons are accelerated well above the soft X-ray loop-top, which could be consistent with the electron acceleration between 40 Mm and 60 Mm above the flaring loop.
Key words: Sun: flares / Sun: radio radiation / Sun: X-rays, gamma rays / Sun: particle emission
© ESO, 2011
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.