In-depth studies of solar
flares emissions and energy releases include analyses of polarization data. Polarization
gives clear information about mechanisms and processes leading to electron acceleration
and photon production. Despite of many past attempts, the key energy range of
hard X-rays was only rarely explored and results were inconclusive. To large extend
it was due to greater instrumental complications. Currently several novel
polarimeters are either to be employed or under constructions for both balloon
and satellite based observations. The novel hard X-ray polarimeter POLAR is an
instrument developed by a collaboration between Switzerland, China and Poland.
It is primarily designed for high accuracy polarization measurements from the
prompt photon emissions of the gamma-ray bursts. The satellite orientation and
instrument pointing direction make it also capable for precise measurements of
polarization in solar flares. The instrument should fly in near future onboard
of the Chinese Space Station TG2.
References
[1]
Jeffrey, N.L.S. and Kontar, E.P. (2011) Spatially Resolved Hard X-Ray Polarization in Solar Flares: Effects of Compton Scattering and Bremsstrahlung. A&A, 536, 1-15.
[2]
Boggs, S.E., Coburn, W. and Kalemci, E. (2006) Gamma-Ray Polarimetry of Two X-Class Solar Flares. Astrophys. J. 638, 1129-1139. http://dx.doi.org/10.1086/498930
[3]
Suarez-Garcia, E., et al. (2006) X-Ray Polarization of Solar Flares Measured with Rhessi. Solar Phys., 239, 149-172.
http://dx.doi.org/10.1007/s11207-006-0268-1
[4]
Hajdas, W. and Suarez-Garcia, E. (2013) Polarimetry at High Energies. In: Huber, M.C.E., et al., Eds., Observing Photons in Space, 2nd Edition, 599-617. http://dx.doi.org/10.1007/978-1-4614-7804-1_34
[5]
Kanbach, G. and The MEGA Collaboration (2005) Development and Calibration of the Tracking Compton/Pair Telescope MEGA. NIM-A, 541, 310-322. http://dx.doi.org/10.1016/j.nima.2005.01.071
[6]
Pearce, M., et al. (2011) PoGOLite—A Balloon-Borne X-Ray Polarimeter. 13th ICATPP Conference on Astroparticle, Particle, Space Physics and Detectors for Physics Applications, VillaOlma, Como, 6 October 2011.
[7]
Produit, N., et al. (2005) POLAR, a Compact Detector for Gamma-Ray Bursts Photon Polarization Measurements. NIM, A550, 616-625. http://dx.doi.org/10.1016/j.nima.2005.05.066
[8]
Suarez Garcia, E. (2010) X-Ray Polarization: RHESSI Results and POLAR Prospects. Ph.D. Thesis, Universitte de Geneve.