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Spatially Resolved Spectral Analysis of Gradual Hardening Flare. Takasaki H. , Kiyohara J. (Kyoto Univ.), Asai A., Nakajima H. (NRO) , Yokoyama T. (Univ. of Tokyo), Sato J. ( STEL/Nagoya-U.), Kosugi T. (JAXA). Oct, 27, 2004 Nobeyama. Introduction.
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Takasaki H. , Kiyohara J. (Kyoto Univ.), Asai A., Nakajima H. (NRO) , Yokoyama T. (Univ. of Tokyo), Sato J. ( STEL/Nagoya-U.), Kosugi T. (JAXA)
Oct, 27, 2004 Nobeyama
gradual hardening flares (Kosugi et al. 1985)
Tsuneta et al. (1984) reported that the gradual hardening HXR source located on apex of coronal loop.
It is suggested that the magnetic trapping of energetic electrons plays significant role in this type of flares!!!
Really??
How is gradual hard flare seen in microwave?
E
Spectral
δHXR≠δMicrowave
There is a breakup in the energy spectrum of the electrons.
Implies “not single population” !!!?
However, previous works (of the light curves / of the spectral) are performed without spatial resolution.
“spatially resolved” spectral distribution (imaging spectroscopy) is needed.
NoRH + HXT : use images in both wavelengths
This is calculated by M2 and H-band
temporal variation of spectral index
NOT imaging spectroscopy
In HXR, a soft-hard-harder temporal variation of electron spectral index.
Temporal behavior and value of microwave spectral index is different from those of HXR.
This is calculated by 1, 2, 3.75, 9.4, 17, 34 GHz
NOT imaging spectroscopy
±0
±0
＋2
＋4
±0
＋4
＋8
＋2
Energy dependence of HXR time profiles
L-band (14-23 keV)
M1-band (23-33keV）
M2-band (33-53 keV)
H-band (53-93 keV)
Time delay of HXR peak emission
τ= 9.5×107 E1.5/ N
(Spitzer, Physics of Fully Ionized Gases)
In this flare, HXR is emitted from precipitating electrons which are once trapped in coronal loops!
Identification of hardening HXR source
Hard X-ray contour on Ha image
HXR is emitted at footpoint.
the dominant hard X-ray source appears as a single source located above the Habright point in eastern-ribbon and the temporal and spatial variation of this HXR source is correspond with the variation of this Habright point.
For the impulsive phase of each peak, the microwave emission from the western footpoint was considerably larger than that from the looptop. After peak, on the contrary, the emission of loop top is larger than that of footpoint.
Spatial distribution of microwave sources
at valleys of time profile
at peaks of time profile
microwave is dominantly emitted at western footpoint.
microwave is dominantly emitted at looptop.
→direct precipitation component
→precipitation after trap component
→Mirroring component
In the microwave, we can also see the trapped component.
Brief summary of flare configuration
Microwave
×
HXR
-70 gauss
HXR
+800 gauss
trapped electrons
－70 Gauss
＋ 800 Gauss
SoHO/MDI
Ha ribbon
Spatially resolved spectral index (footpoint)
Electron spectral index (HXR)
δHXR
A
δrectangleA
Electron spectral index (Microwave)
Total emission (from rectangle A)
NoRH (17GHz)
※HXR is emitted at only rectangle C
Total emission (from rectangle C)
HXR; δ＝γ＋1.0(thick target)
Microwave; δ＝（1.22 – α）/0.9
(Dulk, 1985)
Spectral indeces of microwave (A) and HXR (C) show quit similar evolution.
A
C
B
Peak times of microwave (A) delay for ～15 sec from those of HXR (C).
Spatially resolved spectral index (looptop)
Electron spectral index (HXR)
δHXR
δmicrowave
C
Electron spectral index (Microwave)
B
NoRH (17GHz)
Total emission (rectangle B)
※HXR is emitted at only rectangle C
Total emission (rectangle C)
HXR; δ＝γ＋1.0 (thick target)
Microwave; δ＝（1.22 – α）/0.9
(Dulk, 1985)
Spectral indeces of microwave (B) and HXR (C) show quit different evolution.
C
B
