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
