Magnetic Reconnection Rate and RHESSI Hard X-Ray

Imaging Spectroscopy of Well Resolved X-class Flares

Yan Xu, Ju Jing, Wenda Cao, and Yan Xu, Ju Jing, Wenda Cao, and Haimin Wang Haimin Wang

2003 Oct. 29 X10

Red: NIR flare ribbonsRed: NIR flare ribbonsBlue: RHESSI HXR contours correspond to the 50 – 100 keVBlue: RHESSI HXR contours correspond to the 50 – 100 keV

NIR/OpticalEmission

From Under Photosphere?

OrUpper Layers?

Photosphere

Direct Heating

Lower Chromosphere

Back-warming?

Enough power?

Low-NMagnetic field? Hard spectrum

Low Contrast

Few %Delay

NIR/OpticalEmission

From Under Photosphere?

OrUpper Layers?

Photosphere

Direct Heating

Lower Chromosphere

Back-warming?

Enough power?

Low-NMagnetic field? Hard spectrum

Low Contrast

Few %Delay

Ding et al. 2003

According to Brown et al. 2002

Therefore, electrons with energy greater than 200 could reach 1022 cm-2

2220 )20

(10)(keV

cmzN

Loop length ~ 109 cm, number density in corona ~ 1011 cm-3 ==> Ncorona~ 1020

cm-2

Brown et al. 2002

More complicate treatment: N ~ , b…

We need more events…

Date Contrast Enhancement (G-band)

Peak HXR Flux

(25 ~ 50 keV)

Peak HXR Flux

(50 ~ 100 keV)

Position (Cosθ)

2003-Oct-29 118% 15260 12800 0.92

2003-Nov-02 230%* 23380 7500 0.49

2006-Dec-06 336% 4460 3200 0.45

2006-Dec-13 104% 3400 1200 0.89

2006-Dec-14 84.5% 2000 540 0.69

G-band Observations

Footpoint Asymmetrice

e

α

Footpoint Asymmetrice

e

α

α ?

RHESSI Visibility + Forward-fit

Footpoint Asymmetric

B0 B0 B1 B2

B ?

Magnetic/Mirror Effect?

= -2.80

= -2.53

= -2.72

Magnetic/Mirror Effect?

= -2.74

= -2.50

= -2.60

Magnetic/Mirror Effect?

Magnetic/Mirror Effect?

B (Gauss)

Po

wer In

dex

Shear Angle

20:40:54 20:41:32 20:41:46 20:41:52

20:41:58 20:42:02 20:42:08 20:42:18

Shear Angle

20:40:54 20:41:32 20:41:46 20:41:52

20:41:58 20:42:02 20:42:08 20:42:18

Shear Angle

20:41:32 20:42:02

Shear Angle

20:41:32 20:42:02

Change Rate vs. ???

G-band ~ E field ~ Power-index

G-band ~ E field ~ Power-index

Electric Field (V/cm)

Contras

t

G-band ~ E field ~ Power-index

Electric Field (V/cm)

Contras

t

 RHESSI Observations: Total Number of particles inside the acceleration region   Rate of acceleration of electrons (from spatially-integrated HXR intensity)     Specific Acceleration Rate 

Electron Acceleration Rate

 

LnrLrnnVN 4)2( ) 2( 22

)20(]

21

,2[

)2(1031.9)(

]21

,2[

)2(4 332

keVIB

IB

KRN

BH

N

Nspecific

Super-Dreicer Electric Field Acceleration

/// 13.0~ BBspecific (Somov 1991)

B//

B//

BE

RHESSI observations ~ Vector Magnetograms