Group manifesto: The group will unite theorists and observers working to discuss several recent developments in the interpretation of high-energy radiation, such as:
a) what role does bound-free emission play at energies less than ~20 keV?
b) why is the 511 keV line so broad?
c) what can be learned from the Fe/Ni lines near 7-8 keV?
d) what are the SXR and HXR source sizes and heights?
e) what is the role of albedo in the overall HXR emission, and to what extent does it explain certain spectral features?
f) what can we gather from hard X-ray polarization and directivity measurements?
g) how are gamma-ray and hard X-ray source positions related?
h) to what extent does electron-electron bremsstrahlung account for spectral flattening at high energies?
i) do accelerated electrons have enough energy to produce white light flares?
The actual list of topics will be determined by the group participants. Please indicate which topic(s) you would like to see discussed.
Session 1 (Thursday 11:00): Chromosphere/photosphere/corona response
R. Milligan, Impact of Electron Beams on the Ambient Material in the Chromosphere and Corona
Z. Ning, Radio and hard X-ray evidence of chromospheric evaporation
L Kashapova, RHESSI data vs. data simultaneously obtained with the other HXR instruments
W. Gan, Modified Neupert Effect
J. Oliveros, Flare Accelerated Particles and Photospheric Response
Session 2 (Friday 9:00): Dips/Cutoffs/transport/ and electron spectra
E. Dickson, Observations of dips/cutoffs in the electron spectra
C. Alexander, Photospheric backscatter & directivity
G. Emslie, Why do we expect monotonically decreasing electron spectra in flares?
I. Hannah, Should we see dips/humps in the mean electron spectra?
J. Brown, Recombination in HXR continuum spectra
Session 3 (Friday 11:00): Electron fluxes and spectra
Y. Li, Reconnection Region and Accelerated Electron Numbers in Solar Flares
V. Zharkova, HXR emission, directivity/polarization, and electron precipitation
G. Holman, The Impact of Nonuniform Ionization and Return Current Losses on Hard X-Ray Spectra
Session 4 (Saturday 9:00): Summary
E. Kontar, Working Group 4 Report