Where is the chromospheric response to conductive energy input from a hot pre-flare coronal loop?

Battaglia, M., Fletcher, L. and Simões, P. J. A. (2014) Where is the chromospheric response to conductive energy input from a hot pre-flare coronal loop? Astrophysical Journal, 789(1), p. 47. (doi:10.1088/0004-637X/789/1/47)

Battaglia, M., Fletcher, L. and Simões, P. J. A. (2014) Where is the chromospheric response to conductive energy input from a hot pre-flare coronal loop? Astrophysical Journal, 789(1), p. 47. (doi:10.1088/0004-637X/789/1/47)

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Abstract

Before the onset of a flare is observed in hard X-rays there is often a pro- longed pre-flare or pre-heating phase with no detectable hard X-ray emission but pronounced soft X-ray emission suggesting that energy is being released and deposited into the corona and chromosphere already at this stage. This work analyses the temporal evolution of coronal source heating and the chromospheric response during this pre-heating phase to investigate the origin and nature of early energy release and transport during a solar flare. Simultaneous X-ray, EUV, and microwave observations of a well observed flare with a prolonged pre-heating phase are analysed to study the time evolution of the thermal emission and to determine the onset of particle acceleration. During the 20 minutes duration of the pre-heating phase we find no hint of accelerated electrons, neither in hard X-rays nor in microwave emission. However, the total energy budget during the pre-heating phase suggests that energy must be supplied to the flaring loop to sustain the observed temperature and emission measure. Under the assumption of this energy being transported toward the chromosphere via thermal conduc- tion, significant energy deposition at the chromosphere is expected. However, no detectable increase of the emission in the AIA wavelength channels sensitive to chromospheric temperatures is observed. The observations suggest energy release and deposition in the flaring loop before the onset of particle acceleration, yet a model in which energy is conducted to the chromosphere and subsequent heating of the chromosphere is not supported by the observations.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Simoes, Dr Paulo and Fletcher, Professor Lyndsay and Battaglia, Dr Marina
Authors: Battaglia, M., Fletcher, L., and Simões, P. J. A.
Subjects:Q Science > QB Astronomy
Q Science > QC Physics
College/School:College of Science and Engineering > School of Physics and Astronomy
Research Group:Astronomy and Astrophysics
Journal Name:Astrophysical Journal
Journal Abbr.:ApJ
Publisher:American Astronomical Society
ISSN:0004-637X
ISSN (Online):1538-4357
Copyright Holders:Copyright © 2014 The American Astronomical Society
First Published:First published in Astrophysical Journal 789(1):47
Publisher Policy:Reproduced in accordance with the copyright policy of the publisher

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
537641High Energy Solar Physics Data in Europe HESPELyndsay FletcherEuropean Commission (EC)UNSPECIFIEDP&A - PHYSICS & ASTRONOMY
542081Rolling Programme in Solar and Plasma AstrophysicsLyndsay FletcherScience & Technologies Facilities Council (STFC)ST/I001808/1P&A - PHYSICS & ASTRONOMY