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Nicole Vilmer LESIA Observatoire de Paris

Radio diagnostics of electron acceleration in the corona and in the IP medium Radio observations of the late/gradual/second phase of flares: implications for solar electron (ion) acceleration. Nicole Vilmer LESIA Observatoire de Paris. SHINE Workshop August 2009.

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Nicole Vilmer LESIA Observatoire de Paris

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  1. Radio diagnostics of electron acceleration in the corona and in the IP mediumRadio observations of the late/gradual/second phase of flares:implications for solar electron (ion) acceleration Nicole Vilmer LESIA Observatoire de Paris SHINE Workshop August 2009

  2. Radio emissions in the corona and the interplanetary medium fp= 9 √ Ne kHz cm-3 in IP space f≈ R-1 Frequency-distance ranging

  3. A few definitions andsome historical overview… • Impulsive/gradual • Flares (time profiles, radio and X-ray spectra…) • -CMEs (acceleration profile, velocity ,…) • -SEPs (particle energy, proton-rich, abundances, • charge state,…) • ARE THEY RELATED?? • Input of radio observations • A lot of material from: • Pick, Vilmer Astron. Astrophys. Rev., (2008) • 65 years of solar radioastronomy: • flares, CMEs, sun-Earth connections (I) (I) (G) (Wild et al., 73), ground-based observations Wild et al., 1954) A type II burst 0.25 MHz/s MHD shock associated (Uchida, 1960)

  4. Radio emissions in the « gradual phase » … Continuum storm or stationary type IV Type IV emissions Flare continuum At cm wavelengths : microwave type IV Long duration, high intensity (Kakinuma and Tanaka, 1961) See also Kundu (1959) At dm/m/dam wavelengths… From Pick-Gutmann, 1961 Observations from 1958 events

  5. Radio emissions in the « gradual phase » … Extended radio sources as seen with the Culgoora radioheliograph at 80 MHz (from Kai, 1970) Advancing shock fronts or Radiation from electrons trapped in an expanding magnetic arch Before the first detection of a CME by OSO-7 (Tousey ,1973)

  6. Radio emissions in the « gradual phase » and first association with solar cosmic rays… Strong association between the flux of cosmic rays (>100 MeV protons) and the continuum storm at decameter wavelengths association between PCA effects (10-100 MeV protons) and type IV emissions: Radio importance of a flare: High intensity at microwave And long duration event at metric wavelengths + magnetic connection (flare on the west) (see e.g. Avignon and Pick,1959, Pick-Gutmann, 1961,..) August, 22, 1958 from Boischot and Warwick 1959

  7. Role of the shock (type II) in the production of high energy particles and SEPs?? Frost and Dennis, 1971 Wild et al., 1963 Also type II (shock associated) emission Are high energy particles were accelerated by the shock in the second phase? Are there 2 acceleration phases with 2 different acceleration mechanisms (one related to impulsive events and one to gradual events?) Harder spectrum

  8. Role of time extended particle acceleration in the corona ?? I Continuous acceleration of >10 kev electrons in the corona on time scales of hours Radio images provide evidence for many acceleration/interaction sites of energetic electrons not related to the type II shock but to the coronal « loop transient » observed by SMM/CP G Longer production of electrons above a few keV No images Klein et al., 1983

  9. Role of time extended acceleration in the corona GOES+NRH GOES 150 MHZ RHESSI 236 MHZ RHESSI 3-12 keV contours on EIT 327 MHZ WIND/WAVES 432 MHZ NRH 150 MHz on EIT C7.3 flare associated with a faint CME continous acceleration in the corona linked to large scale reconnection?

  10. Role of time extended electron acceleration in the corona? Eruptive prominences Extended metric radio sources (no type II) but IP II Continous electron production (3 arrows) Trapping in an expanding magnetic arch after 11:59 UT Bruggmann, Vilmer, Klein, Kane 1994 Microwave rich gradual phase. Delays in the time profile. Spectral hardening

  11. Role of time extended electron acceleration in the corona? • Examination of 10 Gradual Hard X-ray Bursts • Systematic hardening of the X-ray emission • Association with a CME • - Microwave rich • Poor association with metric type II burst • But strong association with type IV or continua… • - Acceleration of electrons not by shock wave but by electrons • accelerated in post-flare loop systems following CMEs. Cliver et al., 1986

  12. Role of time extended particle acceleration in the corona? (I) Moving type IV 400 km/s No type II Evolution of acceleration(emission) sites during the event Several phases= different particle Populations produced in different Magnetic configurations No evidence for large scale coronal shock Trottet, Chupp et al., 1994 NRH 169 MHz positions

  13. Time extended particle acceleration in the corona and SEP events X10 flare CME and GLE associated Klein, Chupp et al., 1999

  14. Time extended particle acceleration in the corona and SEP events • Kiplinger (1995): strong association between gradual HXR flares exhibiting spectral hardening and SEP events • No proton event if no spectral hardening • Also a few examples with RHESSI( Saldanah, Krucker, Lin, 2008)

  15. Time extended particle acceleration in the corona and SEP events 20 January 2005 event (Masson et al., 2009) X7.1 event One of the largest GLE event Spectral hardening observed with RHESSI (Saldanha et al., 2008) Extended phase at high energies observed with SONG/KORONAS (pions) Time extended coronal electron and ion acceleration

  16. Electron acceleration in connection with Coronal mass ejections (CMEs), flares,shocks

  17. Where are the acceleration sites in the corona? From Mac Neice et al., 2004 Snapshots of selected field lines from the numerical simulation of the break-out model for Coronal Mass Ejections Where are the possible acceleration sites?? Related to the shock wave?? (1) In the reconnection sheet forming below the CME?? (2) In the interaction regions during the evolution of The magnetic features at different scales?? (3) INPUT OF RADIO IMAGES… 3 1 2

  18. Electron acceleration related to CME lift-off Electron acceleration in successive magnetic interactions at larger distances from the flare Note the comparable extent of the radio source and of the CME. Maia et al., 1999

  19. Electron acceleration behind CME eruptive flux ropes Pick et al., 2002 Long duration drifting type IV burst Radio modulations and HXR peaks 2 radio sources: A quasi- stationary one and a fast moving source (400 km/s) located on ascending EIT arches Common acceleration sites for HXR and radio emitting electrons in the CS formed below the eruptive flux rope No radio emission above the ascending loop X-rays RHESSI Radio NRH OSRA WIND

  20. Electron acceleration behind CME eruptive flux ropes Broad band modulations in the late phase Simultaneously observed at X-rays and in radio From 300 MHz to 10’s of GHZ Particle acceleration at the reconnection sites triggered in the current sheets behind the eruptive flux rope X-rays Microwaves Meter waves Dauphin et al., 2005 Dauphin, Vilmer, Krucker, 2006

  21. A piston driven coronal shock (with type II emission) ty 1st type II branch Type II SXI 09:52:20 UT NRH (432) 09:51:50 UT SXI 09:54:18 UT NRH (236) 09:54:05 UT SXI 09:52:20 UT NRH (432) 09:52:20 UT Detection of a rising SXR loop GOES/SXI linked to the CME (Dauphin et al, 2006) Shock wave associated with the rising loop Type II

  22. Comparison of the X-ray rising loop position with the positions of the radio sources Rising loop and shock front above the radio sources of the second part CME + shock Post CME Production sites The shock cannot accelerate the particles in the second part of the flare Particles accelerated during the modulations might be due to instabilities in the tail of the CME

  23. Shock wave associated radio emissions in the corona and in the IP medium • Coronal shocks: metric and decametric type II bursts • IP type II bursts: hectometric to kilometric type II bursts associated with CMEs (Sheeley et al., 1985) believed to be CME driven shocks formed above 1 solar radius and to be associated with efficient particle acceleration in the IP medium • Coronal types II associated with flares blast waves or piston-driven? still controversial (see a few examples of driven shocks in the corona) No efficient electron acceleration upper limit less than flare produced electrons (Klein et al., 2003) Cane and Erickson (2005) Example of coronal type II burst from 300 to 10 MHz

  24. Shock wave associated radio emissions in the corona Faint metric radio type II like emissions associated in the low corona with the CME leading edge Very rare events due to the presence of strong radio sources due to accelerated particles in the flare.

  25. Shock waves in the corona and in the IP medium • From 1998 observations , WIND/WAVES provide observations in the D-H domain (1-14 MHz) • Causal relationship between metric and IP • type II burst? • Coronal type II bursts generally vanish before reaching the IP medium (Gopalswamy et al., 1998; Cane and Erickson 2005) • For some events, good association between DH and metric type II burst (Reiner et al., 2003) • Systematic study of D-H type II burst observed by Wind (Cane and Erickson 2005) • -extension of coronal metric bursts • -narrow band intermittent events (70%) • strong IP type II bursts (<25%) • 2 shock-like phenomena for m and D-H type II bursts Reiner et al 2003 Cane and Erickson 2005

  26. Role of the shock or of time extended coronal electron acceleration in the production of energetic electrons in the IP medium? Reiner et al., 2001 Observations in the14-1 MHZ with Wind/Waves Association between hm/km emissions in the IP medium and the higher frequency coronal emissions Close association between 3 GhZ and in the 13-1 MHz range (Reiner et al., 2001 Complex type III like emissions originate from electrons accelerated in the corona (see Kundu and Stone, 1984) Usually associated with major flare/CME events of wide angular extent Cane et al, 1981 No data in the 20-2 MHz range

  27. Role of the shock or of time extended coronal electron acceleration in the production of energetic electrons in the IP medium? From Reiner et al., 2007 Good temporal relationship (duration) between complex type III like burst and HXR /microwave fluxes Extended coronal electron acceleration (in the aftermath of CMEs) Another example of two shock waves

  28. Energetic electrons in the corona and injection in the IP space during a large SEP event • Nançay RH : synchrotron radiation of relativistic electrons (1 MeV) in CME-related loops, while CME still occulted • Energetic electrons accelerated in the aftermath of CME (post-CME current sheets?) Maia et al 2007 ApJ 660, 874 : large SEP event of 2001 April 15

  29. Injection time profile : Energetic electrons in the corona and injection in the IP space during a large SEP event • Injection time profile of the escaping electrons very similar to that of the synchrotron emitting electrons in the corona. • Release starts some min after the first radiative signatures of particle acceleration in the corona (together with relativistic p; Bieber et al 2004 ApJ 601, L103). • Particle acceleration in the magnetically stressed corona in the aftermath of a CME ACE : e (178-290) keV Maia et al 2007 ApJ 660, 874

  30. Conclusions and further questions • Radio observations of the late/gradual/second phase of flares show that the energy release sites (particle acceleration regions) are not limited to the flaring active regions but imply structures far away from the flaring site and different layers of the solar atmosphere. • Long duration coronal emissions (type IV radiation) seems to be a good indicator for large SEP events • Radio observations provide information about the different possible acceleration sites in the corona (flaring active region, but also current sheets formed below eruptive flux ropes and CMEs. • SEP electron events are associated with long duration kilometric type III like associated with wide CMEs. Radio observations show that electrons are likely accelerated in the corona in the aftermath of CMEs; • High energy protons and relativistic electrons measured in situ may also originate in the low corona and be produced by the same acceleration process as the relativistic electrons radiating in the CME magnetic loops. • Coronal shocks usually do not reach the interplanetary medium • Origin of coronal shocks? • Consistency with observations of in situ particles?

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