1. Nonthermal Electrons in an Ejecta Associated with a Solar Flare
Satoshi Masuda　(STEL, Nagoya Univ. )
What happens there？
Any high-energy phnomenon？
(Shibata et al. 1995)

2. X-class flare on September 30, 2000
Yohkoh Soft X-ray／Hard X-ray Observations
GOES 1-8A
HXT L-band
HXT H-band
23: : : :30
　　　　　　　　　　　(UT)

3. Coronal Hard X-ray source during the second HXR spikeM1 M2
Hard X-ray source is located at the same place as the SXR ejecta.
It doesn’t show any significant motion during its lifetime (~1minute).
Color: SXT Be-filter
Contours: HXT M1-band

4. W W E E Time series of 1-D slice images SXR HXR M1 (23 -33 keV) Ejecta
provided by
T. Minoshima
Time series of 1-D slice images
SXR
HXR M1 ( keV)
HXR peaktime
Ejecta
HXR coronal Source W W
Height
Height
Flare Loop
Looptop E E
Footpoint
680 seconds
280 seconds

5. but shows a little gradual (long) decay in the M1-band.
(3) Its time profile is almost similar to that of the footpoint sources,
but shows a little gradual (long) decay in the M1-band.
M1-band ( keV) during the HXR second spike
double footpoint sources
coronal source
23: : : :21 (UT)

6. (4) Its hard X-ray spectrum is softer than that of the footpoint sources.
M1/L
M2/M1
H/M2
Footpoint
north
N/A
4.6
4.3
south
4.5
High-altitude
coronal source
> 6.0
55MK

7. (5) An intense (probably nonthermal) microwave source is observed at the same location with the NoRH.
17GHz
flare loop
coronal source
34GHz

8. Characteristics of the coronal HXR source
Hard X-ray source is located at the same place as the SXR ejecta.
It doesn’t show any significant motion during its lifetime (~1 minute).
Its time profile is almost similar to that of the footpoint sources, but shows a little gradual (long) decay in the M1-band.
(4) Its hard X-ray spectrum is a little softer than that of the footpoint sources.
(5) An intense (probably nonthermal) microwave source is observed at the same location with NoRH.

9. ? Increase in thermal energy: 3 × 10^30 ergs
Gradual increase in SXR intensity of the ejecta after the impulsive phase
SXR intensity
flare loop
ejecta
thermal energy of the ejecta
thermal energy
increase rate x 100
End of the HXR nonthermal emission
assuming T = 5MK and L (thickness) = 1 x 109 cm
normalized version
ejecta only
Increase in thermal energy: 3 × 10^30 ergs

10. Model
Electrons accelerated in the impulsive phase are trapped in the magnetic field of the soft X-ray ejecta.
(We assume that the same amount of electrons are injected into the upper part of the reconnection site as those precipitating to footpoints.)
Trapped electrons gradually precipitate. Then, a hot-plasma with high density are supplied from chromosphere.
Trapped electrons lose their energy in the corona.
Can nonthermal electrons trapped in the ejecta
produce such a SXR brightening of the ejecta in the later phase?
Time scale (trapping)
total energy (nonthermal vs thermal)

11. Lifetime of nonthermal electrons in the ejecta derived from the NoRH
Thermal free-free emission at 34 GHz estimated from SXR (T, EM)
34GHz thermal free-free 1
34GHz thermal free-free 2
34GHz Observation
obs.(red) とcalc. (blue, green)
Nonthermal
provided by
K. Kobayashi

12. about 300 seconds after the end of nonthermal HXR emission

13. time scale (trapping) and total energy (nonthermal vs thermal)
From observations,
after the impulsive phase,
　　　 (1) SXR intensity of the ejecta increases for about 500 seconds.
　　　 (Nonthermal emissions around the ejecta are
observed for about 300 seconds.)
(2) total thermal energy of the ejecta = 3 × 10^30 ergs
Lifetime of nonthermal electrons
(collision loss-cone)
E=50 keV －　70 seconds
E=100 keV　－　200 seconds
E=200 keV　－　560 seconds
Density of the ejecta 　~　109 cm-3
Total energy of nonthermal electrons trapped in the ejecta
Energy of electrons above >200 keV　　~ 6× 10^27 ergs
For 3 × 10^30 ergs, all nonthermal electrons above 30 keV are needed.　　

14. summary
We analyzed an X-class flare occurred at the west limb on Sep. 30, 2000, using hard X-ray, soft X-ray, and microwave data.
A HXR source and a nonthermal microwave source are located
at the same place where a SXR ejecta is located.
If this SXR ejecta is really ejected by magnetic reconnection occurring above the flaring loop, this observation indicates that HXR emissions (even in the 33 – 53 keV range) exist above the reconnection point.
Sui and Holman (2003)
HXR source above the reconnetion point
(8-10, 10-12, and keV)
thermal source?
Hudson et al. (2001)
Moving HXR source
(M1-band and 17GHz)

15. Problem:
The SXR intensity increase of the ejecta lasts for about 500 seconds after the impulsive phase.
Can this phenomenon be explained by nonthermal electrons trapped in the ejecta and their gradual precipitation into chromosphere?
It’s difficult. Some additional energy input after the impulsive phase is needed into the ejecta.
Or, we need more only high-energy (~500 keV) electrons emitting microwave.
(We estimate the energy of high-energy (> 100 keV) electrons by using the information derived from the HXR observations.
Is this a problem?)

16. Relationship between nonthermal electrons emitting HXRs
and nonthermal electrons emitting microwave
The Nobeyama radio heliograph still can contribute to solve this problem with Yohkoh/HXT and RHESSI.

17. End

19. than that where the M1-band (23-33 keV) source is located.
(3) The M2-band (33-53 keV) source is located at a little higher altitude
than that where the M1-band (23-33 keV) source is located.
red: M2, black: M1

20. (But, the time resolution is very low, it’s about 10 seconds.)
(3) Its time profile is almost similar to that of the footpoint sources.
(But, the time resolution is very low, it’s about 10 seconds.)
First spike
Second spike

21. 23: : : :20 UT
(10^28 ergs/s)
nonthermal energy
spectral index (gamma)