Compelling Theoretical Issues Driven by Observations / Theoretical Wish List of

Observations

WG5Hamish Reid

General Session• Guangli Huang focussed on HXR and radio spectral index. He

found energy dependent spectral index with increasing energies which agreed better with incoherent radio spectral index.

• Jörg Büchner found that lower energy particles (< 50 keV) can be accelerated by parallel electric fields in solar flares.

• Alexei Struminski analysed large flares in cycle 23 finding (amongst other things) similar behaviour after ~4 mins when relativistic protons are accelerated.

• Valentina Zharkova examined how electrons and protons are accelerated differently with electron clouds forming.

White Light Focussed Session

• Joel Allred demonstrated an atmospheric response model for an injected electron beam into the chromosphere.

– Finds increased visible emission is primarily from the Paschen and Balmer recombination radiation.

– Emission heights are at the top of the chromosphere, co-spatial with where the RHESSI HXR emission would be.

White Light Focussed Session

• Juan Carlos Martinez found co-spatial white light and RHESSI HXR emission for a specific flare

– Study raised uncertainties for the RHESSI pointing near the limb of the flare.

White Light Focussed Session

• Alexander Warmuth analysed the total radiated energy of flares with a variety of different GOES class.

Not enough energy in the non-thermal particles to explain all the emission in both visible and UV wavelengths

Future Obs Required for Theory

• Visible/UV Spectroscopy– A significant fraction of the radiated energy in

flares is in visible and UV emission yet we have no reliable spectroscopy measurements.

• High Frequency Radio Data– Explore the increased emission in the THz range– Understand the discrepancy of HXR and

incoherent radio spectral index

Future Obs Required for Theory• Sensitive X-ray Observations

– Increased detection of coronal sources.– Detection of possible HXR ribbons along UV ribbons.– Analyse fainter events in active regions and the quiet Sun.– Increased temporal resolution for time-of-flight analysis.

• Nature of the Coronal Magnetic Field– Likely energy source for flares yet we do not have regular, reliable

measurements.

• Neutral Particle Emission– Understand the behaviour of accelerated ions– Neutron detection closer to the Sun

Future Theory Required for Obs• Obs Constraints on the Acceleration of Particles

– Account for the total radiated photon energy for all wavelengths in flares. (Woods et al 2006, Kretzschmar 2011)

– Correlation between gamma ray and relativistic electron data. (Shih et al 2009)

– Number of electrons required to explain the HXR observations.– Displacement in gamma ray and HXR sources. (Hurford et al. 2003)– Displacement of decimetric spikes and coronal sources (Battaglia Benz

2009)

• Separating the acceleration signatures from the transport signatures– Understand the differences between the electron fluence deduced from X-

ray photons and the actual accelerated electron spectrum.

Thanks to the Local Organising Committee