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Karl-Ludwig Klein ludwig.klein@obspm.fr

Karl-Ludwig Klein ludwig.klein@obspm.fr. High-energy particles at and from the Sun. High-energy particles at and from the Sun. 0.1. 1. 10. 100. During the largest solar events measurements by particle detectors :

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Karl-Ludwig Klein ludwig.klein@obspm.fr

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  1. Karl-Ludwig Klein ludwig.klein@obspm.fr High-energy particles at and from the Sun

  2. High-energy particles at and from the Sun 0.1 1 10 100 During the largest solar events • measurements by particle detectors : • e -> 100 MeV (Moses et al 1989), maybe higher • p -> several GeV (neutron monitors on ground) • EM emissions / interacting particles : • Gamma-rays from e : h -> 100 MeV, E>100 MeV • Gamma-rays from pion decay : p> 300 MeV • Time scales of flares : fraction of s to tens of s, evidence that acceleration time scales are that short ! Vilmer et al 1999 AA Count rate [s-1] Vilmer et al 2003 AA 412, 865 Photon energy [MeV]

  3. Particle acceleration in solar flares

  4. Particle acceleration associated with magnetic reconnection ? A simple flare. • HXR from the low atmosphere (chromosphere) - e precipitated downward to ne > 1012 cm-3, bremsstrahlung with ambient p, h<energy(e) • Radio emission (type III) from outward propagating e beams, =2pene, start < 400 MHz : ne < 109 cm-3, energy some keV  Acceleration region in the corona, injects particles downward (chromosphere) & upward (high corona, IP space) Vilmer et al. 2002 Solar Phys

  5. Dauphin et al. 2007 AA 468, 273 Particle acceleration associated with magnetic reconnection ? A simple scenario. Particle acceleration region in a reconnecting coronal current sheet : • Fragmented energy release regions (multiple CS). • Acceleration processes : direct E, turbulence, termination shock of reconnection jet. • Huge fluxes of NT particles, rapid acceleration to relativistic energies ? Vilmer et al. 2002 Solar Phys

  6. 1 min Supporting evidence : energy transport from the corona to the chromosphere • Time profiles : thermal response of the chromosphere (H), HXR &  waves from NT electrons • Fast energy transport; NT particles carry major fraction of flare energy Trottet et al. 2000 A&A 356, 1067

  7. Supporting evidence : polarisation of optical line emission • Linear polarisation of optical lines by the impact of NT particles (or their return current) • THEMIS H, H: excitation by particle beams (directly or through return current) Map of linear polari-sation (colour) on top of H intensity and mag field (contours) : Hénoux & Karlicky 2003 ; Karlicky & Hénoux 2002 ; Xu et al. 2005 ApJ 631, 618

  8. Coronal mass ejections (CMEs), flares, and the origin of large solar energetic particle events in space

  9. Count rate [s-1] 0 400 800 1200 High-energy particles at and from the Sun : gamma-ray analysis of a large flare • INTEGRAL/SPI measurements of R line & continuum emission : • evolving CONT/line ratio => e & ions accelerated together, but proportions vary during event • Evolving 12C/16O line ratio : diff. target abundances at diff. times => flare may comprise time-extended (min - tens of min - hours) particle acceleration in different regions. h>150 keV (e bremsstr.) h>500 keV (e bremsstr.) h=(7-15) MeV (e bremsstr.) h=4.4 & 6.1 MeV (12C, 16O) h=2.2 MeV (n+p-> 2H) Time [s] Kiener et al. 2006 A&A 445, 725

  10. CME, shock waves, magnetic reconnection, and large SEP events • CME and particle acceleration : shock wave, reconnection in the post-eruptive corona • Numerical resistive MHD (2.5 D) model • Bright emission from a “plasma sheet”, repeated plasmoid formation, in-ward and outward motion : plasmoids at O-type points, X-type points in between Riley et al. 2007 ApJ 655, 591 Site(s) for SEP acceleration in the magnetically stressed post-CME corona ?

  11. Do fast CMEs produce SEP in the absence of « flares » ? • Attempt to isolate pure CME-shock-events : • Fast (>700 km/s) west-limb CME (SoHO) : likely to drive shock. • EUV manifestations on disk, but no metric radio emission : no evidence for particle acceleration related to a flare (3 events 1996-98). • SEP from the CME shock ? Marqué et al. 2006 ApJ 642, 1222

  12. Do fast CMEs produce SEP in the absence of « flares » ? • Attempt to isolate pure CME-shock-events : • Fast (>700 km/s) west-limb CME (SoHO) : likely to drive shock. • EUV manifestations on disk, but no metric radio emission : no evidence for particle acceleration related to a flare (3 events 1996-98). • SEP from the CME shock ? • None detected at GOES. • SoHO/COSTEP & ACE/EPAM: weak (deka-MeV protons, hecto-keV electrons). • Indication that CME shock alone is NOT an efficient SEP accelerator at these energies ! Marqué et al. 2006 ApJ 642, 1222

  13. Energetic particles in the corona and 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

  14. Injection time profile : Energetic particles in the corona and IP space during a large SEP event ACE : e (178-290) keV • 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). • Hint to particle acceleration in the magnetically stressed corona in the aftermath of a CME (see also Klein et al 1999 AA 348, 271; Laitinen et al 2000 AA, 360, 729; Klein & Trottet 2001, Spa Sci Rev 95, 215). Maia et al 2007 ApJ 660, 874

  15. Open questions - outlook • Assess the respective role of CME and flares in energetic particle acceleration: acceleration, transport in the corona and IP space. • Investigate the high-energy limit of accelerated particle spectra in the corona and IP space. • Investigate acceleration processes and seed populations by in situ measurements. • The tools : • STEREO : bidirectional view on CME (longitudinal extent), shocks, SEP • SMESE : FIR, R of HE particles & energy transport in flares, CME • Spectral imaging cm-to-m- : energetic particles, localisation of their acceleration sites (dm-, never imaged before) and their synchrotron emitting regions : FASR, CnRH(, NRH) • Solar Orbiter / Sentinels : SEP, shocks & seed populations in the inner heliosphere (to minimise distorsion of SEP profiles by IP transport) • Crucial : accompanying observations (HXR, radio) of energetic particles in the solar atmosphere to ensure a close coupling between in situ and remote sensing measurements.

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