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Radio Diagnostics of Energetic Electrons from Solar Flares , CMEs and Shocks :

Radio Diagnostics of Energetic Electrons from Solar Flares , CMEs and Shocks :. Nicole Vilmer LESIA Observatoire de Paris UMR 8109 CNRS, UPMC, Université Paris-Diderot ESPM 14 8-12 SEPTEMBER 2014 TRINITY COLLEGE DUBLIN DUBLIN. Electromagnetic radiation from energetic electrons.

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Radio Diagnostics of Energetic Electrons from Solar Flares , CMEs and Shocks :

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  1. Radio Diagnostics of Energetic Electrons from Solar Flares, CMEs and Shocks: Nicole Vilmer LESIA Observatoire de Paris UMR 8109 CNRS, UPMC, Université Paris-Diderot ESPM 14 8-12 SEPTEMBER 2014TRINITY COLLEGE DUBLIN DUBLIN

  2. Electromagnetic radiation fromenergeticelectrons X-rays Energeticelectronsfrom the active Sun produceelectromagnetic radiation in a veryextendeddomain : X-ray and Gamma-ray emissions Radio emissions in the 10 kHz to >500 GHz domain Microwaves Gyrosynchrotron Emissions fb(Hz)= 2.8 1B (G) Meterwaves Plasma emissions Im I fp(kHz)=9ne cm- 3 Dauphin et al., 2005

  3. INPUT of RADIO OBSERVATIONS in the GHz-MHz range to SOLAR and HELIOSPHERIC PHYSICS 1 MHz 10 MHz 100 MHz 1 GHz - Whatare the physicalmechanismsleading to particleacceleration? - What are the physical mechanisms leading to instabilities and eruptive activity in the coronal plasma?

  4. INPUT of RADIO OBSERVATIONS in the 1 GHz-1 MHz range to SOLAR and HELIOSPHERIC PHYSICS Plasma radio emissionsfrom « non-thermal » electrons predominantbelow 1 GHz Particleacceleration in flares and CMEs Propagation of particlesfrom the acceleration site to the interplanetary medium Triggering and evolution of coronal mass ejectionsand shocksin the low corona Radio emissions are TRACERS of dynamicalprocesses (e.g. shocks) and of electron propagation in the corona and interplanetary medium. Type III ( e beams) Wind/WAVES (satellite) Nançay DAM Type II (shock) Nançay ORFEES Spectral identification of imaged radio sources Nançay NRH 150 MHz Positions (2X1D) of radio sources http://radio-monitoring.obspm.fr/index.php

  5. Radio emissions in the corona VLA, OVSA fp= 9 √ Ne (kHz) cm-3 CSRH NRH 327 MHz 237 MHz 164 MHz LOFAR 2 Rs

  6. Radio diagnostics of electronbeams acceleration sites? propagation in the corona, in the interplanetary medium? Injection from the flare site to the IP medium? Radio diagnostics of shocks and CMEs acceleration sites? origin of the shockwave?

  7. Statisticalstudies on « coronal » type III bursts: flux distributions Number of type III events in 3 months (with NRH observations) Blue: f 10.7 index (SFU) Red: Sunspotnumber ~10000 types III « bursts » observed by the NRH in the frequency range 450-150 MHz from 1998 to 2008 (Saint-Hilaire, et al. , 2013)

  8. Statisticalstudies on « coronal » type III bursts: Very close to results for radio burstsat higherfrequencies (above 1GHz)slope of (-1.8) (Nita et al., 2002) Variation of radio flux withfrequency (Seealsoresultson a type III burstbetween3-50 MHz (Dulk et al., 2001) Constraints to type III emissionmodels? dN/dS= 0.34 ν−2:9S−1.7sfu-1 day-1 (( sfu−1 day−1

  9. Coronal and Interplanetary type III bursts? What about interplanetary type III bursts?? • 156 interplanetary Type III burstswithStereo Peak at 1 MHz for 156 type III burstsobservedwith STEREO (seeKrupar et al., 2014)

  10. Electron acceleration sites? ARE THE TYPE III GENERATING ELECTRONS A PART OF THE SAME POPULATION AS HXR GENERATING ELECTRONS? A question debated for many years: (e.g. Kane, 1971; 1981; Raoult et al., 1985, Hamilton, et al., 1995; Aschwanden et al., 1995; Benz et al., 2005; 2007) Some Recent Results!

  11. Radio and X-ray diagnostics of flareenergeticelectrons X-RAYS One of the cartoon (how common?) Electrons travelling downwards into the chromosphere radiate X-rays in dense (ne=1012 cm-3) plasma via Bremsstrahlung. Detected X-rays are usually in the 6-100 keV energy range Electrons travelling upwards can induce Langmuir waves which in turn produce coherent radio emission (type III) in the rarefied (ne<109 cm-3) coronal and interplanetary plasma. Detected radio frequencies are from around 400 MHz down to 2 MHZ RADIO Standard picture? Electron acceleration in the corona Propagation both upwards and downwards. Vilmer et al. 2002 NRH and RHESSI observations

  12. ARE THE TYPE III GENERATING ELECTRONS A PART OF THE SAME POPULATION AS HXR GENERATING ELECTRONS? For some events : YES See correlations between type III starting frequencies and HXR spectral index Startingfrequency of the radio type III burst(red) and HXR spectral index (green) Reid, et al. 2011 Seealso Raoult et al., 1985

  13. ARE THE TYPE III GENERATING • ELECTRONS A PART OF THE SAME POPULATION AS HXR GENERATING ELECTRONS? • For some events : YES • Is it the common rule? • SystematicsearchusingRHESSI flarelist and PHOENIX 2 catalogue of type III bursts • 30 eventsbetween 2002 and 2009 • 17/30 events (50% ) withcorrelations • Use of a density model (exponential model derived from Saint Hilaire et al., 2013) to change frequency to height and thick target model to go from HXR spectral index to electron spectral index. • Conclusion: For half of the events type III generatingelectrons are part of the same population as HXR generatingelectrons- • CC=-0.86 CC=0.85 Reid et al., 2014

  14. What are the characteristics of the acceleration region? Deducing the characteristics of accelerationregion: height and size d usingcombined radio and X-ray observations and numerical simulations (Reid et al., 2011, 2014) Need of future imaging spectroscopy < 500 MHz (e.g. Chinese Solar RadioHeliograph, FASR,…) • FromX-rays time of flight • measurementsH~ 20 Mm • (seeAschwanden et al. , 1998)) • 10 events: • h (accelerationheight) in the 25Mm to 180 Mm range • d (acceleration size) in the 2.1 to 16 Mm • Conclusion: Extended accelerationregion «high » in the corona • BUT flareswith open fieldlines (metric type III burts)

  15. Tracingelectronbeams in the corona with radio dynamicsimagingspectroscopy First observations of type IIIdm bursts 1-2 GHz With the new technique of radio dynamic imaging spectroscopy recently upgraded Karl G. Jansky Very Large Array (VLA). (Chen et al., 2013) Energy release height < 15 Mm Note the spread of Positions at a given f injection of electronbeams in a fibrous corona D<100 km More to belearnt with the CSRH…

  16. Tracing the path of electronbeams in the corona to the IP medium Radio spectrum NRH flux Do all coronal type III bursts have X-ray counterparts? 30% to 50% of type III events (only type III emissions) haveassociatedhard X-ray flares. Do all coronal type III bursts have an interplanetary counterpart? 50% of events have emission < 14 MHz Bias for the more intense events having interplanetary emission Study based on >1000 type III bursts over 10 years of data See poster by Reid,Vilmer RHESSI flux

  17. Flare Morphology The “ standard” flare model is very simplified. The reality is more complicated Particles can be injected into different magnetic structures during the course of a flare. This can influence whether the electron beam makes it into interplanetary space.

  18. Tracing radio emittingelectronbeams in the corona to the IP medium LOFAR observations of type III radio burts at 50-55 MHz, 40-45 MHz and 30-35 MHz (tied-array mode) seeMorosan et al., 2014 and talk Type III sources at the flank of the CME Another site of electronacceleration … Alsoseen at lowerfrequencies…

  19. Radio diagnostics of electronbeams acceleration sites? propagation in the corona, in the interplanetary medium? Injection from the flare site to the IP medium? Radio diagnostics of energeticelectronsfromCMEs and shocks acceleration sites? origin of the shockwave?

  20. Where are the electronaccelerationsites in the corona? Role of the Coronal Mass Ejection CME development and propagation CME interaction withothermagnetic structures (open B lines, streamers) for the production of energeticelectrons Relatedto the shockwave?? (1) In the reconnectionsheetformedbelowthe CME?? (2) In the interaction regionsduring the evolution of the magneticfeatures?? (3) INPUT OF RADIO IMAGES… 2 1 1 3 AdaptedfromDémoulin et al., 2012

  21. Electron acceleration in currentSheets in flares and CMEs Evidence fromSpectrography Kliem, et al. 2000, Karlicky et al., 2002, 2004 Quasi periodicepisodes frommagneticreconnection in CS S M Reconnection Multifrequencyimaging Pick, Démoulin et al., 2005

  22. Evidence for electronacceleration due to CME interaction Electron acceleration (type III bursts) due to reconnection at the lateralflanks of CMEs Electron acceleration (herringbones) due to shock acceleration at the lateralflank of the CME Carley et al., 2013 Démoulin et al., 2012 Positions of the bursty source at 150 MHz Type III position at 164 MHz and movement Radio CME

  23. Klein et al., 1999 • Shock in flares and CMEs Coronal type II bursts: signature of MHD shockwaves (Wild & Smerd, 1972; Mann, 1995; Cairns 2011,…) Origin of the coronal shockwave? Flare blast wave Piston drivenshock(eruptivemagnetoplasma) structure A lot of discussions(Aurass 1997; Cliver et al., 1999; Vrsnak & Cliver 2008,…) Need to study the relative positions of radio type II sources and eruptive plasma But very few observations of type II burstsstarting at high enoughfrequencies to compare positions of radio type II sources (e.g. with the NRH) with the positions of eruptive plasmas (seen in X-ray, EUV) A few studied cases of type II burstsstarting at HF (~ 500 MHz) Gopalswamyet al., 1997; Klein et al., 1999; Dauphin et al., 2006, Magdalenic et al., 2010, Magdalenic et al., 2012; Bain et al., 2012; Zimovets et al;, 2012; Zucca et al., 2014 & posters

  24. Origin of the shock in the low corona Positions of radio sources at the beginning of the type II emission at eachfrequency Source at 432 MHz above the LE of hot plasma Increase of the distance between the LE and the type II positions at lowerfrequencies Type II 1500- 2000km/s 3 Hot Hot plasma centroid /leading edge 500 km/s Warm plasma 1100 km/s Zimovets et al., 2012

  25. Origin of the shock in the low corona Flareblast wave or piston driven? Two strong evidences in favour of the piston-driven shockwavescenario for this case: -location of the type-II burst source above the apex of the eruptive plasma leading edge -similar propagation direction of the type II and LE of the eruptive plasma But: how to explain the difference between the velocity of Leading edge of the eruptive plasma and the velocity of the shock (type II sources)? See e.g. numerical simulations of the propagation of a shock wave in a gravitationally stratified corona the shock wave (once created) can propagate faster through the corona than its driver . (piston driven and then freely propagating blast wave) See also very recent Type II/CME/ejecta observations by Carley, Pick (posters) Pomoell et al., 2008 shock FR

  26. Origin of the shock in the interplanetary medium • General agreement on the origin of InterplanetaryShocks (IP shocks): CME driven (Cane et al. 1987; Gopalswamy et al., 2000) • Where are the radio type II sources in the IP Medium?? • Positions derivedthrough triangulation of emissionsobserved by 2 spacecrafts ( STEREO B and WIND ) from 625 to 425 kHz • 3D reconstruction of the CME (SOHO, STEREO) The source of the type II burstis at the southernflank of the CME! Close to the location of the interaction of the CME/shock and nearby coronal streamer!! Observations of type II sources with LOFAR?? Magdalenic et al., 2014 Magdalenic et al., 2014 Seealso talk by Susino

  27. Radio Diagnostics of Energetic Electrons from Solar Flares, CMEs and Shocks Radio emissions(1GHz-100 kHz) are TRACERS of dynamicalprocesses (e.g. shocks) and of electron propagation in the corona and interplanetarymedium Electron acceleration sites? Accelerationregionsdeducedfrom x-rays, radio imaging at 1 GHz<15 Mm, Combined X-ray/ radio observations (25 -200 Mm) BUT NO Images yet of the acceleration sites Input of radio images and spectrabelow 500 MHz! CSRH, FASR, otherdecimetricradioheliographs?) Roleof the CME development and interaction with ambient magnetic structure Differentsites for electronacceleration (in extended CS below the CME flux rope, in interaction regionswithsurrounding B fields? Formation of the shock ? Input of radio images below 100 MHz (LOFAR observations) Combinationwithspace missions

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