1. Flare-Associated Oscillations Observed with NoRH
Nobeyama Symposium 2004 : 2004/10/26
Flare-Associated Oscillations Observed with NoRH
Ayumi Asai
(NSRO)

2. Flare-Associated Oscillations
Quasi-Periodic Pulsation (QPP)
flare
Nakajima et al. 1983
Kiplinger et al. 1983
Kane et al. 1983
Both m-wave and HXR show quisi-periodic oscillation (QPP)
oscillation period : ~8sec
typical time scale : ~Alfven transit time
X-rays
microwave
17GHz

3. What are These? QPP nonthermal emission (in microwave and HXR)
efficiency of particle acceleration is modulated periodically
QPP period : ~ Alfven transit time scale
physical parameters should be determined from observation!
Which mode determines the periodicity?
Loop oscillation (sausage, kink, …)
Particle acceleration process?

4. 1998 November 10 Flare 1998-11-10 Flare (C7.9) @NOAA8375
Asai et al. 2001/Grechnev et al. 2002
QPP!
NOAA 8375
Flare (C7.9) @NOAA8375
Multi-wavelength observation :
NoRH, NoRP, SXT, HXT, MDI

5. QPP in Microwave (only) source A shows QPP
Oscillation period ~ 6.6 sec
source A
source B
total
NoRH 17GHz
source A
source B

6. Geometrical Properties
Loop-loop interaction
Flare site = source B A B
source A
Flare Loop
negative image
source B

7. QPP in Microwave and HXR
HXR light curves also show QPP
m-wave peak slightly delay from HXR peak (~0.6s)
~ traveling time of nonthermal electrons
Length of faint loop : 50,000 km
velocity of nonthermal particle ~100,000 km/s
traveling time :
50,000 / 100,000 = 0.5 s

8. Physical Values SXT temperature analysis (source B)
T : 9.4 MK
n : 4.5×1010 cm-3
MDI + potential field approx.
B : 300 G A B
negative image
source A
Flare Loop
source B

9. Physical Parameters (1) flare loop / flare kernel ~ length : 16,000 km
~ width : 6,000 km
temperature : 9.4MK
density : 4.5×1010 cm-3
magnetic field : 300 G
sound velocity : 360 km/s
Alfven velocity : 3,100 km/s
(2)
(1)
c.f. (2) faint loop : ~50,000 km

10. Physical Parameters (1) flare loop / flare kernel ~ length : 16,000 km
~ width : 6,000 km
sound velocity : 360 km/s
Alfven velocity : 3,100 km/s
Alfven transit time:
Along the loop : 5.1 s
Across the loop : 1.9 s
Acoustic transit time :
Along the loop : 44 s
Across the loop : 17 s
(2)
(1)
observed period ~ 6.6 s
Alfven transit time along the loop (5.1 s) is the most similar

11. Alfven transit time (s)
Statistical Study
Kamio et al. 2004
Period ~ Alfven transit time scale along the loop
Date
velocity (km/s)
Alfven transit time (s)
Sound transit time (s)
Obs. P(sec) VA VS L W
3100
360 5 2 44 17 6
1200
430 10 - 23
2500
410 8
0.8 49
4.9
1600 13
1.9 7 16

12. 2000-01-12 Event Melnikov, et al. 2002 Foot 1 Loop top 14 – 17 s
image : 17 GHz
orange cont. : 34GHz
brown cont. : HXT M2
Foot 2
loop length : 25,000 km
Fourier power spectra
Radio flux variation

13. Which Mode Determines QPP?
Period of QPP ~ Alfven transit time scale
MHD fast mode
kink mode
sausage mode

14. Kink Mode Oscillation TRACE P ~ 300 sec tkink ~ L/CA
- Aschwanden et al. 1999
- Nakariakov et al. 1999
P ~ 300 sec
tkink ~ L/CA

15. Kink Mode?? In the case of m-wave QPP : tkink ~ 5 s
L : 16,000 km
CA : 3,100 km
~observation (P ~ 6 s)
Is it possible for flare loop in high pressure? A B
negative image

16. Sausage Mode Oscillation
- Nakariakov et al. 2003
- Aschwanden et al. 2004
Previous estimations:
External medium, finite wave length  or
k=kc

17. Radio Pulsation (no imaging)
Aschwanden et al. 1987, 2002, etc…
clearer oscillation in radio
oscillation periods : P = 0.01  1000 s
Culgoora radio spectograph
1972/05/16 flare
McLean & Sheridan (1973)
Pulsations at 230 MHz,
period = 4.28 ± 0.01 s

18. Sausage Mode?? Parameters of loop CA0 = 440 km/s CAe = 3,500 km/s
L = 25,000 km 
PGSM = 2L/Cp ~ 2L/CAe
P~15 s
~ observation !
Melnikov et al. 2002
Nakariakov et al. 2003

19. Sausage Mode?? L : 16,000 km T : 9.4 MK n : 4.5×1010 cm-3 B : 300 G
CA0 = 3,100 km/s
CAe = ?? km/s
PGSM < 2L/CA0 ~ 10 s
OK for the case that k is large enough A B
negative image

20. Loop OscillationParticle Acceleration
Loop oscillation modulates the efficiency of particle acceleration?
reconnection region (energy release site) as itself oscillates!?

21. Loop OscillationParticle Acceleration
Tsuneta and Naito (1998)
Shock acceleration (Tsuneta and Naito 1998)
Coalescence instability (Tajima et al. 1987)
How loop oscillation modulates particle acceleration?
flare-loop
Loop oscillation

22. Summary & Conclusions
Flare-associated oscillations are observed with NoRH
Oscillation period ~ Alfven transit time scale
Oscillation period is also explained with kink-mode or sausage-mode (not fixed)
Coronal Seismology
Loop oscillation modulates the efficiency of particle acceleration How?

23. Thank you!

24. Oscillation Period (Auto-Correlation)
using NoRP 9.4GHz data, we determined the oscillation period (auto-correlation function)
~ 6.6 sec
6.6 sec

25. Cross Correlation
Cross-correlation function between HXR and m-wave light curves
m-wave peaks delay ~0.6 sec
~0.6 sec
source A
HXT
source B

26. QPP in microwave and HXR
HXR light curves also show QPP
m-wave peak slightly delay from HXR peak (~0.6s)
~ traveling time of nonthermal electrons
Length of faint loop : 50,000 km
Time delay : 0.6 s
length of effective electron path: 150,000 km

27. Coronal Magnetic Field
MDI
SOHO/MDI
potential field approximation (MDI data of 1998/11/06)
 ~ 350 G
flare loop
rotation

28. No m-wave QPP at Source B
No QPP in microwave at source B
Emission from thermal plasma (thermal-Bremsstrahlung) is dominant
caused by 1st burst

29. Kink Mode?? In the case of m-wave QPP : tkink ~ 5 s
L : 16,000 km
CA : 3,100 km
~observation (P ~ 6 s)
Is it possible for flare loop in high pressure?

30. Slow Mode Oscillation by SUMER
Wang et al. 2002
Ofman et al. 2002
event (not flare)
SUMER slit
SUMER slit
200 arcsec
Yohkoh/SXT
TRACE 195A
Fe XIX
(6  106 K)