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?
Overview
J. LinTsuneta et al
Direct Observation of a CS
Innes & Wang
1000 km/s 107 K plasma
Reeves et al.
Fan seen in Fe XXIV – 20 MK
Hard X-ray
Sui & Holman: RHESSI
X-rays above and below X-line
White Light: Morphology
Straight ray to the baseof a disconnection event
[Fe XVIII]
Lower T lines
UV: High temperature featurebetween flare loops and CME
CME Core
Post-flare Arcade
Ko et al.
Ciaravella et al.
Current Sheet Models
Petschek Turbulent
D R
S M S
P E L p h o to sp h e re
o c c u lt in g d isc
c u s p
ra y Lazarian &Vishniac
Tajima &Shibata
Vršnak
Predicted Thickness
SP = (H /VA)1/2 ~ 100 m
Anomalous resistivity~ 100 km
Observed Widths ~ 105 km
Power = (B2/8) LHVIN
Heat, Particles, Kinetic Energy
Projection Effects
Vršnak et al
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
November 4, 2003 CME Current Sheet
Ciaravella & Raymond
302°
262°
228°
1.66 R☼
Current Sheet
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 Ne
e
e
n
Nd
ee N
EMn eN
time (UT) PA Fe XVIII Si XII logT EM Ne ne d ph/(cm2 sec sr) 1025 cm-5 1017 cm-2 107 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] EM
Temperature and density in the CS decrease with time
2003 November 4 CS: Reconnection
A
h
UVCS was observing the reconnection region
Cross sectional Area of CS
Apparent Thickness of CS
hNAn ee
Ane is constant above ~ 2 R¤
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 widthssupport estimateof thermal width
Outward moving Blobs
480 – 870 km/s for Nov. 4 event
Sort of associated with cool gas
CS Instability or puffs fromlater reconnection events triggeredby main flare restructuring?
Accelerate or decelerate
V ~ VA (?)
Riley et al.
2003 November 4 CS: B, VA
CSen
8
2BPCS magnetic field B
CSeT
Alfven speed VA
,
coren
Petschek Interpretation2.5 compression factor for slow mode shock
B = 2.2 GVA = 800 km/sec similar to the early plasmoid speed
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 × 106 K
Density 7 – 10 × 107 cm-3
Line width non- thermal 380 km/sec beginning bulk flow , turbulence, shock 50 – 100 km/sec most of the observation turbulence likely
6 Events
Vršnak et al.
Bemporad 2008
Line Width vs. Time
Current Sheet Parameters
Thickness 0.1 Rsun ( >> classical expectation)
Height Several Rsun
Length 0.3 Rsun
Density 107 – 108 cm -3
Temperature 107 K or more, but cool CS would not be recognized, hot CS invisible
Outflow speed 500 -1000 km/s; Assumed to be ~ VA
Inflow Mach number Measured at ~ 0.05 Vout
Turbulence 100 km/s seems common (Bemporad) turbulent nature open to question
Time scales hours to a day RESISTIVITY IF l = /vi then eff is huge (Lin et al.)
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.
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
NeW implies acceleration: VA increases with height?
Time-dependent ionization
Width increases with height, but not in a consistent manner.
Product of area times height is not constant
Vršnak et al. Width Mass Density
Petschek Interpretation
Kuen Ko: time-dependent ionization
Various empirical density and B vs height
Turbulent CS Interpretation
Lazarian & Vishniac
Thickness ~ LX (vl/VA)1.5 to LX (vl/VA)2
= 0.004 to 0.02 LX
Not bad agreement for LX ~ few RSUN
J. Lin: effective resistivity is very large
eff = vin x thickness
No problem with mass conservation or NeW
Few solid predictions: Te, ne, V ?
Predicted properties of micro CS within turbulent layer
Ion Acoustic or Lower Hybrid Turbulence
A. Bemporad
THE END
Thickness is Large
Density is Modest
Turbulence is probably ~ 100 km/s
Theoretical predictions are badly needed
CPEX
2003 November 4 CS: Thickness
)90cos(
)90sin()90cos(
dw
wLl
sunRw 08.004.0
2535
sun
sun
sun
RL
Rd
Rl
3.0
2.007.0
2.0
The actual thickness is 2.5 -5 times narrower than the apparent thickness
Petschek – Anomalous Resistivity - Hyperdiffusion
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
Ionization State
Time-dependentIonization
dni
dt
ni
t (niui ) ne[ni 1Ci 1 ni (Ci Ri ) ni1Ri1]
Predicted FeXVIII, Si XII line fluxes, Ne, Te vs DR HeightD-M,1MK, D-M 2MK, Mann 1MK, Mann 2MK models
Ko et al 2008
Petschek PictureInput n(R), B(R) and Diffusion Region R
Overall Energetics
EFLARE ~ Epowerlaw ~ ECME WHY???
Log EApr 21, 2002 Flare/CME Magnetic 32.3Emslie et al. Electrons 31.3 Ions <31.6 Thermal 32.2 CME 32.3 SEPs 31.5
ECME ~ EKIN + EHEAT and EKIN ~ EHEAT ~ ESEP WHY???
PIMPULSIVE ~ 1028 erg/s
VA ~ 1000 km/s, VIN ~ 0.1 VA, B ~ 10 G A ~ 1020 cm2, L ~ 1010
Akmal et al; Filippov & Koutchmy; Rakowski et al.
TIMING
Zhang et al. 2004
CME Acceleration Coincides withImpulsive X-rays
(most of the time; Maričić et al 2007)
Does Reconnection accelerate CME?
Does Reconfiguration of B field byCME drive Reconnection?
Shock Waves and Radio Emission
1 h
Aurass et al. 2002
Type II emissionAt constant frequencyConstant density ~109
Particle Acceleration
Rapid (seconds)
Efficient (A large fraction of energy)
Selective ( e.g., 3He)
Power Law spectrum
Attributed to:
Turbulence 1st order Fermi Deceleration in expanding flow??
Electric Field
Shocks Liu et al. 2008