Karl-Ludwig Klein & Rositsa Miteva Solar Energetic Particle Events and their Parent Activity : a Re-assessment of Statistical Relationships Karl-Ludwig Klein & Rositsa Miteva (ludwig.klein@obspm.fr) (F-92195 Meudon) Universités P&M Curie, Diderot Collaborators: Olga Malandraki & Garreth Dorrian, National Observatory of Athens, Greece

Correlation SEP intensity - solar activity Past work, motivation of this study Intensities of protons>10 MeV in SEP events correlate with CME speed (VCME) and SXR peak flux (ISXR) All correlations are noisy: Kahler (2001, JGR 106, 20947): pre-event particle intensity (=seed population for CME shock acceleration ?) Garcia (2004, Spa Wea 2, S0202): combination of SXR parameters (ISXR, EM, duration) Problem: SEP measured in a single point, after a long IP travel (scattering, … ): IP transport, magnetic connection Present study: influence of the IMF configuration ? Kahler 2001 JGR 106, 20947

SEP events and IMF configuration The IP path of SEP Standard picture: Parker spiral IMF connection Alternative: ICME  SEP released onto field lines of an earlier CME whose front has reached the Earth Present study: Identification of ICMEs: from Richardson & Cane catalogue (2010 SP 264, 189) SEPs: all events 1996-2006 (GOES; Cane et al. 2010 JGR(A) 115, A08101) with M or X class flares, western solar hemisphere. GOES protons (15-40 MeV) from ONERA/Toulouse database (81 events), ACE/EPAM electrons 40-300 keV (96). Earth From Zurbuchen & Richardson 2006 SSR

SEP events and IMF configuration The IP path of SEP Result (Miteva et al. 2012 SP, in press): the IMF configuration of SEP events 20% of SEP events associated with well-defined western flares (M, X) within ICMEs (« ICME events »), about 50 % within standard solar wind (« SoWi events »), rest in an intermediate IMF configuration Transient IMF configurations important even for SEP with activity in W hemisphere ! Fraction of ICME events increases with importance of associated solar activity: 14-18% SEP associated with M class, 29% SEP associated with X class; Masson et al. 2012 A&A: 7/10 GLEs (>X5 class) in the vicinity of an ICME Earth From Zurbuchen & Richardson 2006 SSR

J(SEP)-ISXR-VCME correlation SEPs in the solar wind (SoWi events) and in ICMEs All SEP events: J(p)/VCME= 0.630.05 J(e)/VCME= 0.530.07 J(p)/ISXR = 0.590.07 J(e)/ISXR = 0.400.08 ICME events: J(SEP) /VCME unchanged J(p)/ISXR = 0.670.13 J(e)/ISXR = 0.730.10 SoWi events: J(p)/ISXR = 0.360.13 J(e)/ISXR = 0.120.11

J(SEP)-ISXR correlation SEPs in the solar wind (SoWi events) and in ICMEs Result: J(SEP)/VCME correlation independent of IMF configuration. J(SEP)/ISXR correlation very weak in SoWi events, both for e and p. Why is the J(SEP)/ISXR correlation so much weaker in SoWi events than in ICME events (and in the entire event sample) ? What distinguishes ICME events from SoWi events ? SEP transport in two different IMF configurations.

J(SEP)-ISXR correlation Blurring of the correlation by particle transport Time profile at injection (source surface) Any relationship J(SEP)ISXRb is blurred by SEP transport in the turbulent IMF log(intensity) Time profile at s/c (1 AU) time log(intensity) time Does varying IP transport affect SEP more in the solar wind than in ICMEs ? Measure: fastest rise time during the rise of the SEP profile Protons: yes (earlier work: Tranquille et al. 1987; Torsti et al. 2004; Malandraki et al. 2005) Electrons: no

J(SEP)-ISXR correlation SEPs in the solar wind (SoWi events) and in ICMEs Why is the J(SEP)/ISXR correlation so much weaker in SoWi events than in ICME events (and in the entire event sample) ? What distinguishes ICME events from SoWi events ? SEP transport in two different IMF configurations. Connection between solar activity (flare) and observer (s/c).

J(SEP)-ISXR correlation SEPs in the solar wind (SoWi events) and in ICMEs Why is the J(SEP)/ISXR correlation so much weaker in SoWi events than in ICME events (and in the entire event sample) ? What distinguishes ICME events from SoWi events ? SEP transport in two different IMF configurations. Connection between solar activity (flare) and observer (s/c): super-radial expansion of open flux tubes in AR (Wang & Sheeley 2003 ApJ; Klein et al. 2008 A&A), concentrated flux in the legs of ICMEs.. AR AR

J(SEP)-ISXR correlation Blurring of the correlation by the connection distance Range of coronal field lines f Flare f IMF Range of IMF lines, width IMF IMF through s/c (cf. Lario et al. 2006 ApJ) The relationship J(SEP)ISXRb is blurred by (1) differences between longitudes of the flare and the Parker spiral (2) div. of flare-connected coronal field lines around flare direction: 0=f+f (3) scattering of the root of the IMF around the Parker spiral: =PS+IMF

J(SEP)-ISXR-VCME correlation Summary and conclusion Empirical findings SEPs often observed in transient IMF configurations (ICMEs) J(SEP)/VCME correlation independent of configuration (e, p alike) J(SEP)/ISXR correlation weak/absent when SEP propagate in standard solar wind, high when in ICMEs (e, p alike) Interpretation: a correlation between J(SEP) and ISXR is blurred by IP particle transport: but rise time distributions of p and e behave differently varying connection distances: not strong enough to be the exclusive interpretation Absence of a strict J(SEP)/ISXR correlation for flare-accelerated SEP + contribution of CME shock-accelerated particles Strong J(SEP) - ISXR correlation in ICME events consistent with a contribution of flare-acceleration (protons10 MeV, electrons  30 keV) to early SEPs if magnetic connection exists. Necessity of a vantage point nearer to the Sun to reduce IP transport and provide a closer look at injection time profiles - Solar Orbiter.