1. Evidence of Thick Reconnection Layers in Solar Flares John Raymond Work with A. Ciaravella, Y.-K. Ko and J. Lin White Light and UV Observations Apparent Thickness >> Classically expected thickness Not just projection effect Non-thermal line widths Petschek Exhaust or Thick Turbulent CS?

2. Overview J. Lin Tsuneta et al

3. Direct Observation of a CS Innes & Wang 1000 km/s 10 7 K plasma Reeves et al. Fan seen in Fe XXIV – 20 MK

4. Hard X-ray Sui & Holman: RHESSI X-rays above and below X-line

5. White Light: Morphology Straight ray to the base of a disconnection event [Fe XVIII] Lower T lines UV: High temperature feature between flare loops and CME CME Core Post-flare Arcade Ko et al. Ciaravella et al.

6. Current Sheet Models Petschek Turbulent Lazarian & Vishniac Tajima & Shibata Vršnak

7. Predicted Thickness  SP = (  H /V A ) 1/2 ~ 100 m Anomalous resistivity~ 100 km Observed Widths ~ 10 5 km Power = (B 2 /8  ) LHV IN Heat, Particles, Kinetic Energy Projection Effects Vršnak et al

8. Unknown Energy Partition due to rapid conversion Particles rapidly heat chromosphere. Heat drives bulk flows. Shocks heat plasma and accelerate particles. Turbulence accelerates particles. Energetic particle beams generate turbulence. Shiota et al

9. November 4, 2003 CME Current Sheet Ciaravella & Raymond 302° 262° 228° 1.66 R ☼ Current Sheet

10. 2003 November 4 CS: Images [Fe XVIII] emission begins ~ 8 min after the CME “ “ peak move by ~ 4° south in 2.5 h narrows and becomes constant Si XII emission starts about 2h later: implies cooling OVI and CIII are patchy: cold plasmoids are detected CS in MLSO-MK4 provides N e

11. time (UT) PA Fe XVIII Si XII logT EM N e n e d ph/(cm 2 sec sr) 10 25 cm -5 10 17 cm -2 10 7 cm -3 R ¤ 17:20-19:09 251.6-261.9 1.39 11.0 6.61 2.4 20:27-21:00 251.6-261.9 5.13 6.83 6.81 3.1 21:06-21:28 251.6-258.9 6.44 6.59 6.90 4.4 4.5 9.8 0.07 22:03-22:35 251.6-257.5 5.74 6.95 6.79 3.4 4.9 7.0 0.10 23:19-00:02 251.6-256.0 4.06 9.95 6.72 3.4 5.0 6.8 0.11 00:42-01:38 251.6-254.5 1.46 9.61 6.62 2.4 5.9 4.1* 0.21* 03:29-04:57 250.2-257.5 1.10 7.72 6.62 1.8 MLSO Mark IV pB [Fe XVIII] Temperature and density in the CS decrease with time

12. 2003 November 4 CS: Reconnection UVCS was observing the reconnection region Cross sectional Area of CS Apparent Thickness of CS is constant above ~ 2 R ¤

13. 2003 November 4 CS: Line Width Thermal width Measured width Shiota et al. 2005 Turbulence, Bulk Flow, Shock ? Plasmoids crossing Line width hard to explain as bulk flow Turbulence Lazarian & Vishniac, 1999 Si Line widths support estimate of thermal width

14. Outward moving Blobs 480 – 870 km/s for Nov. 4 event Sort of associated with cool gas CS Instability or puffs from later reconnection events triggered by main flare restructuring? Accelerate or decelerate V ~ V A (?) Riley et al.

15. 2003 November 4 CS: B, V A magnetic field B Alfven speed V A, Petschek Interpretation 2.5 compression factor for slow mode shock B = 2.2 G V A = 800 km/sec similar to the early plasmoid speed

16. 2003 November 4 CS: Summary The actual thickness of the CS much larger than the expected thickness: Petschek reconnection mechanism hyperdiffusion – van Ballegooijen & Cranmer turbulence – Lazarian & Vishniac Temperature decreases with time 8 – 4 × 10 6 K Density 7 – 10 × 10 7 cm -3 Line width non- thermal 380 km/sec beginning bulk flow, turbulence, shock 50 – 100 km/sec most of the observation turbulence likely

17. 6 Events Vršnak et al.

18. Bemporad 2008 Line Width vs. Time

19. Current Sheet Parameters Thickness 0.1 Rsun ( >> classical expectation) Height Several Rsun Length 0.3 Rsun Density 10 7 – 10 8 cm -3 Temperature 10 7 K or more, but cool CS would not be recognized, hot CS invisible Outflow speed 500 -1000 km/s; Assumed to be ~ V A Inflow Mach number Measured at ~ 0.05 V out Turbulence 100 km/s seems common (Bemporad) turbulent nature open to question Time scales hours to a day RESISTIVITY IF l =  /v i then  eff is huge (Lin et al.)

20. Thick CS or Petschek Exhaust? Turbulent CS - many tiny Diffusion Regions - colliding exhaust flows - nature of turbulence (what modes?) - stochastic particle acceleration Exhaust - Slow mode shocks dissipate magnetic energy - compress plasma by a factor of 2.5 - how much electron heating in shocks? - particle acceleration by Diffusive Shock Mechanism? Either is consistent with observed thickness due to lack of constraints on other parameters, e.g. turbulence scale or location of diffusion region: Look at other factors.

21. Petschek Interpretation Most of Energy Dissipated in Slow Mode Shocks No obvious source of turbulence Particle acceleration not obvious No electron heating in IP exhausts – Gosling No actual slow mode shocks in IP exhausts -- Gosling Factor of 2.5 compression for low  slow mode shocks looks OK Thickness depends on distance from diffusion region N e W implies acceleration: V A increases with height? Time-dependent ionization

22. Width increases with height, but not in a consistent manner. Product of area times height is not constant Vršnak et al. Width Mass Density

23. Petschek Interpretation Kuen Ko: time-dependent ionization Various empirical density and B vs height

24. Turbulent CS Interpretation Lazarian & Vishniac Thickness ~ L X (v l /V A ) 1.5 to L X (v l /V A ) 2 = 0.004 to 0.02 L X Not bad agreement for L X ~ few R SUN J. Lin: effective resistivity is very large  eff = v in x thickness No problem with mass conservation or N e W Few solid predictions: T e, n e, V ?

25. Predicted properties of micro CS within turbulent layer Ion Acoustic or Lower Hybrid Turbulence A. Bemporad

26. THE END Thickness is Large Density is Modest Turbulence is probably ~ 100 km/s Theoretical predictions are badly needed CPEX

28. 2003 November 4 CS: Thickness The actual thickness is 2.5 -5 times narrower than the apparent thickness Petschek – Anomalous Resistivity - Hyperdiffusion

29. Reconnection is Supposed to… Release Tether to allow CME escape Reduce Magnetic Free Energy while preserving Magnetic Helicity Create or Enhance Flux Rope Gosling, Birn & Hesse Lin et al

30. Ionization State Time-dependent Ionization Predicted FeXVIII, Si XII line fluxes, Ne, Te vs DR Height D-M,1MK, D-M 2MK, Mann 1MK, Mann 2MK models Ko et al 2008 Petschek Picture Input n(R), B(R) and Diffusion Region R

31. Overall Energetics E FLARE ~ E powerlaw ~ E CME WHY??? Log E Apr 21, 2002 Flare/CME Magnetic 32.3 Emslie et al. Electrons 31.3 Ions <31.6 Thermal 32.2 CME 32.3 SEPs 31.5 E CME ~ E KIN + E HEAT and E KIN ~ E HEAT ~ E SEP WHY??? P IMPULSIVE ~ 10 28 erg/s V A ~ 1000 km/s, V IN ~ 0.1 V A, B ~ 10 G A ~ 10 20 cm 2, L ~ 10 10 Akmal et al; Filippov & Koutchmy; Rakowski et al.

32. TIMING Zhang et al. 2004 CME Acceleration Coincides with Impulsive X-rays (most of the time; Maričić et al 2007) Does Reconnection accelerate CME? Does Reconfiguration of B field by CME drive Reconnection?

33. Shock Waves and Radio Emission 1 h Aurass et al. 2002 Type II emission At constant frequency Constant density ~10 9

34. Particle Acceleration Rapid (seconds) Efficient (A large fraction of energy) Selective ( e.g., 3 He) Power Law spectrum Attributed to: Turbulence 1 st order Fermi Deceleration in expanding flow?? Electric Field Shocks Liu et al. 2008