Elementary energy release events in flaring loops: effects of chromospheric evaporation on x-rays

Liu, S.M., Han, F.R. and Fletcher, L. (2010) Elementary energy release events in flaring loops: effects of chromospheric evaporation on x-rays. Astrophysical Journal, 709(1), pp. 58-66. (doi: 10.1088/0004-637X/709/1/58)

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With the elementary energy release events introduced in a previous paper, we model the chromospheric evaporation in flaring loops. The thick-target hard X-ray (HXR) emission produced by electrons escaping from the acceleration region dominates the impulsive phase, and the thin-target emission from the acceleration region dominates the low-energy thermal component in the gradual phase, as observed in early impulsive flares. Quantitative details depend on properties of the thermal background, which leads to variations in the correlation between HXR flux and spectral index. For lower temperature and/or higher density of the background electrons, the HXRs both rise and decay more quickly with a plateau near the peak. The plateau is less prominent at higher energies. Given the complexity of transport of mass, momentum, and energy along loops in the impulsive phase, we propose a strategy to apply this single-zone energy release and electron acceleration model to observations of flares associated with single loops so that the energy release, electron acceleration, and evaporation processes may be studied quantitatively.

Item Type:Articles
Glasgow Author(s) Enlighten ID:Fletcher, Professor Lyndsay
Authors: Liu, S.M., Han, F.R., and Fletcher, L.
College/School:College of Science and Engineering > School of Physics and Astronomy
Journal Name:Astrophysical Journal
ISSN (Online):1538-4357
Published Online:24 December 2009

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
465931Solar, stellar and cosmological plasmas: a synthesis of data, modelling and theory.Declan DiverScience & Technologies Facilities Council (STFC)ST/F002149/1Physics and Astronomy