caa a22 4500 445816341 CHVBK 20180317145229.0 cr unu---uuuuu 170323e20110901xx s 000 0 eng 10.1007/s11214-011-9804-x doi (NATIONALLICENCE)springer-10.1007/s11214-011-9804-x Deducing Electron Properties from Hard X-ray Observations [Elektronische Daten] [E. Kontar, J. Brown, A. Emslie, W. Hajdas, G. Holman, G. Hurford, J. Kašparová, P. Mallik, A. Massone, M. McConnell, M. Piana, M. Prato, E. Schmahl, E. Suarez-Garcia] X-radiation from energetic electrons is the prime diagnostic of flare-accelerated electrons. The observed X-ray flux (and polarization state) is fundamentally a convolution of the cross-section for the hard X-ray emission process(es) in question with the electron distribution function, which is in turn a function of energy, direction, spatial location and time. To address the problems of particle propagation and acceleration one needs to infer as much information as possible on this electron distribution function, through a deconvolution of this fundamental relationship. This review presents recent progress toward this goal using spectroscopic, imaging and polarization measurements, primarily from the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI). Previous conclusions regarding the energy, angular (pitch angle) and spatial distributions of energetic electrons in solar flares are critically reviewed. We discuss the role and the observational evidence of several radiation processes: free-free electron-ion, free-free electron-electron, free-bound electron-ion, photoelectric absorption and Compton backscatter (albedo), using both spectroscopic and imaging techniques. This unprecedented quality of data allows for the first time inference of the angular distributions of the X-ray-emitting electrons and improved model-independent inference of electron energy spectra and emission measures of thermal plasma. Moreover, imaging spectroscopy has revealed hitherto unknown details of solar flare morphology and detailed spectroscopy of coronal, footpoint and extended sources in flaring regions. Additional attempts to measure hard X-ray polarization were not sufficient to put constraints on the degree of anisotropy of electrons, but point to the importance of obtaining good quality polarization data in the future. Springer Science+Business Media B.V., 2011 Sun: flares nationallicence Sun: X-rays nationallicence Sun: acceleration nationallicence Sun: energetic particles nationallicence Kontar E. Department of Physics and Astronomy, University of Glasgow, Kelvin Building, G12 8QQ, Glasgow, UK aut Brown J. Department of Physics and Astronomy, University of Glasgow, Kelvin Building, G12 8QQ, Glasgow, UK aut Emslie A. Department of Physics, Oklahoma State University, 74078, Stillwater, OK, USA aut Hajdas W. Paul Scherrer Institut, Villigen PSI, Switzerland aut Holman G. NASA Goddard Space Flight Center, Code 671, 20771, Greenbelt, MD, USA aut Hurford G. Space Sciences Laboratory, University of California, 94720, Berkeley, CA, USA aut Kašparová J. Astronomický ústav AV ČR, v.v.i., Fričova 298, 251 65, Ondřejov, Czech Republic aut Mallik P. Department of Physics and Astronomy, University of Glasgow, Kelvin Building, G12 8QQ, Glasgow, UK aut Massone A. CNR-SPIN, Via Dodecaneso 33, 16146, Genova, Italy aut McConnell M. Space Science Center, University of New Hampshire, 03824, Durham, NH, USA aut Piana M. Dipartimento di Matematica, Universita di Genova, Via Dodecaneso 35, 16146, Genova, Italy aut Prato M. CNR-SPIN, Via Dodecaneso 33, 16146, Genova, Italy aut Schmahl E. NWRA/CoRA, 80301, Boulder, CO, USA aut Suarez-Garcia E. Department of Nuclear and Particle Physics, University of Geneva, Quai Ernest Ansermet 24, 1212, Geneva, Switzerland aut Space Science Reviews Springer Netherlands 159/1-4(2011-09-01), 301-355 0038-6308 159:1-4<301 2011 159 11214 https://doi.org/10.1007/s11214-011-9804-x text/html Onlinezugriff via DOI 1 review-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s11214-011-9804-x text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Kontar E. Department of Physics and Astronomy, University of Glasgow, Kelvin Building, G12 8QQ, Glasgow, UK aut NATIONALLICENCE 700 1- Brown J. Department of Physics and Astronomy, University of Glasgow, Kelvin Building, G12 8QQ, Glasgow, UK aut NATIONALLICENCE 700 1- Emslie A. Department of Physics, Oklahoma State University, 74078, Stillwater, OK, USA aut NATIONALLICENCE 700 1- Hajdas W. Paul Scherrer Institut, Villigen PSI, Switzerland aut NATIONALLICENCE 700 1- Holman G. NASA Goddard Space Flight Center, Code 671, 20771, Greenbelt, MD, USA aut NATIONALLICENCE 700 1- Hurford G. Space Sciences Laboratory, University of California, 94720, Berkeley, CA, USA aut NATIONALLICENCE 700 1- Kašparová J. Astronomický ústav AV ČR, v.v.i., Fričova 298, 251 65, Ondřejov, Czech Republic aut NATIONALLICENCE 700 1- Mallik P. Department of Physics and Astronomy, University of Glasgow, Kelvin Building, G12 8QQ, Glasgow, UK aut NATIONALLICENCE 700 1- Massone A. CNR-SPIN, Via Dodecaneso 33, 16146, Genova, Italy aut NATIONALLICENCE 700 1- McConnell M. Space Science Center, University of New Hampshire, 03824, Durham, NH, USA aut NATIONALLICENCE 700 1- Piana M. Dipartimento di Matematica, Universita di Genova, Via Dodecaneso 35, 16146, Genova, Italy aut NATIONALLICENCE 700 1- Prato M. CNR-SPIN, Via Dodecaneso 33, 16146, Genova, Italy aut NATIONALLICENCE 700 1- Schmahl E. NWRA/CoRA, 80301, Boulder, CO, USA aut NATIONALLICENCE 700 1- Suarez-Garcia E. Department of Nuclear and Particle Physics, University of Geneva, Quai Ernest Ansermet 24, 1212, Geneva, Switzerland aut NATIONALLICENCE 773 0- Space Science Reviews Springer Netherlands 159/1-4(2011-09-01), 301-355 0038-6308 159:1-4<301 2011 159 11214 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer