FlareAssociated Oscillations Observed with NoRH

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Flare-Associated Oscillations Observed with NoRH
Nobeyama Symposium 2004 2004/10/26

• Ayumi Asai
• (NSRO)

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Flare-Associated Oscillations
Quasi-Periodic Pulsation (QPP)

• 1980-06-07 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
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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?

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1998 November 10 Flare
Asai et al. 2001/Grechnev et al. 2002
QPP!
NOAA 8375

• 1998-11-10 Flare (C7.9) _at_NOAA8375
• Multi-wavelength observation
• NoRH, NoRP, SXT, HXT, MDI

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QPP in Microwave

• (only) source A shows QPP
• Oscillation period 6.6 sec

source A
source B
total
NoRH 17GHz
source A
source B
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Geometrical Properties

• Loop-loop interaction
• Flare site source B

A
B
source A
Flare Loop
negative image
source B
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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

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Physical Values

• SXT temperature analysis (source B)
• T 9.4 MK
• n 4.51010 cm-3
• MDI potential field approx.
• B 300 G

A
B
negative image
source A
Flare Loop
source B
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Physical Parameters

• (1) flare loop / flare kernel
• length 16,000 km
• width 6,000 km
• temperature 9.4MK
• density 4.51010 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
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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
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Statistical Study

• Kamio et al. 2004
• Period Alfven transit time scale along the loop

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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
Radio flux variation
Fourier power spectra
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Which Mode Determines QPP?

• Period of QPP Alfven transit time scale
• ?MHD fast mode
• kink mode
• sausage mode

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Kink Mode Oscillation

• TRACE
• - Aschwanden et al. 1999
• - Nakariakov et al. 1999
• P 300 sec
• tkink L/CA

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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
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Sausage Mode Oscillation

• - Nakariakov et al. 2003
• - Aschwanden et al. 2004

Previous estimations
External medium, finite wave length ?
or
kkc
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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
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Sausage Mode??

• Parameters of loop
• CA0 440 km/s
• CAe 3,500 km/s
• L 25,000 km
• ?
• PGSM 2L/Cp 2L/CAe
• ?P15 s
• observation !

Melnikov et al. 2002 Nakariakov et al. 2003
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Sausage Mode??

• L 16,000 km
• T 9.4 MK
• n 4.51010 cm-3
• B 300 G
• CA0 3,100 km/s
• CAe ?? km/s
• PGSM lt 2L/CA0 10 s
• ?OK for the case that k is large enough

A
B
negative image
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Loop Oscillation??Particle Acceleration

• Loop oscillation modulates the efficiency of
  particle acceleration?
• ?reconnection region (energy release site) as
  itself oscillates!?

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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
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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?

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Thank you!
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Oscillation Period (Auto-Correlation)

• using NoRP 9.4GHz data, we determined the
  oscillation period (auto-correlation function)
• ? 6.6 sec

6.6 sec
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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
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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

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Coronal Magnetic Field
MDI 1998-11-06

• SOHO/MDI
• potential field approximation (MDI data of
  1998/11/06)
• ? 350 G

flare loop
rotation
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No m-wave QPP at Source B

• No QPP in microwave at source B
• Emission from thermal plasma (thermal-Bremsstrahlu
  ng) is dominant
• ?caused by 1st burst

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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?

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Slow Mode Oscillation by SUMER

• Wang et al. 2002
• Ofman et al. 2002

2001-03-09 event (not flare)
SUMER slit
SUMER slit
200 arcsec
Yohkoh/SXT
TRACE 195A
Fe XIX (6 ? 106 K)