Coronal Hard X-ray Sources in Solar Flares
Yohkoh observations of the Masuda flare of 1992 January 13. Left, soft X-ray whole-Sun image; Right, magnified soft X-ray image with hard X-ray contours and a sketch of the common interpretation of the observed features.
The final version of the review paper is on line here.
1) Krucker Säm, Battaglia M., Cargill P.J., Fletcher L., Hudson H.S, MacKinnon, A.L., Masuda S., Sui L., Tomczak T., Veronig A.M., Vlahos l., White S.M.; Hard X-ray emission from the solar Corona, A&A Rev, 2008, in press
2) Tomczak, M.; Ciborski, T.: Footpoint versus loop-top hard X-ray emission sources in solar flares, A&A, 461, 315, 2007
3) Krucker, Säm; White, S. M.; Lin, R. P.: Solar Flare Hard X-Ray Emission from the High Corona, ApJL, 669, L49, 2007
4) Krucker Säm, & Lin R.P., 'Hard X-Ray Emissions from Partially Occulted Solar Flares', ApJ, 673, 1181, 2008
5) Battaglia, M.; Benz, A.O.: Observational evidence for return currents in solar flare loops, A&A, 487, 337, 2008
6) Krucker, Säm; Hurford, G.J.; MacKinnon, A.L.; Shih, A.Y.; Lin, R.P., 'Coronal Gamma-Ray Bremsstrahlung from Solar Flare-accelerated Electrons', ApJL, 678, L63, 2008
7) Krucker, Säm; Saint-Hilaire, P.; Christe, S.; White, S. M.; Chavier, A. D.; Bale, S. D.; Lin, R. P.: Coronal Hard X-Ray Emission Associated with Radio Type III Bursts, ApJ, 681, 644, 2008
Coronal hard (>20~keV) X-rays differ fundamentally from the 'footpoint' emission normally seen in solar flares and exhibit a wider array of properties. The corona should not generally be a strong bremsstrahlung source because of its low plasma density, but the observation of limb-occulted events such as that of 30~March 1969 (Frost & Dennis 1971) contradicted this expectation. While hard X-ray footpoint emissions show where flare-accelerated electrons lose their energy, coronal hard X-ray sources might reveal emission from the acceleration site itself. Coronal hard X-ray observations therefore provide a great diagnostic tool for particle acceleration in solar flares. Now we can image these sources and also determine their spectra in some detail, using the RHESSI (Reuven Ramaty High Energy Solar Spectroscopic Imager) observations. Neither these data nor those of the earlier Yohkoh observations have been treated systematically in the literature. Accordingly we plan to write one overview paper setting out the range of observations and interpretations derived from our discussions. Furthermore, we will relate these observations to each other, discuss their relationship and implications.
First: October 3-6, 2006 (see below for links to presentations)
Second: May 8-11, 2007 (Tue - Fri)
Second meeting (draft schedule):
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AM1 9:00 - 10:30 | AM2 11:00 - 12:30 | PM1 2:00 - 3:30 | PM2 4:00 - 5:30 |
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Tuesday |
Alec MacKinnon: Mechanisms for generating HXRs | New RHESSI results: Marina Battaglia (ETH Zurich), Sui, Veronig, Krucker | New Yokhoh results Masuda, Tomczak update: Radio observations (White) update: multi-wavelength observations (Fletcher) | update: theory (Cargill/Vlahos) |
Wednesday |
discussion of first draft of review paper | |
discussion & editing of first draft | |
Thursday |
discussion & editing of first draft | |
Discussion of future data analyses | finishing second draft by the end of the day |
Friday |
discussion of second draft | discussion on how to finish paper |
Some pretty pictures: