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