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

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

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?

1998 November 10 Flare Flare Multi-wavelength observation : –NoRH, NoRP, SXT, HXT, MDI NOAA 8375 QPP! Asai et al. 2001/Grechnev et al. 2002

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

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

QPP in Microwave and HXR HXR light curves also show QPP  -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

Physical Values SXT temperature analysis (source B) –T : 9.4 MK –n : 4.5×10 10 cm -3 MDI + potential field approx. –B : 300 G negative image A B Flare Loop source A source B

Physical Parameters (1) flare loop / flare kernel ~ length : 16,000 km ~ width : 6,000 km temperature : 9.4MK density : 4.5×10 10 cm -3 magnetic field : 300 G sound velocity : 360 km/s Alfven velocity : 3,100 km/s (1) (2) c.f. (2) faint loop : ~50,000 km

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 (1) (2)  observed period ~ 6.6 s Alfven transit time along the loop (5.1 s) is the most similar

Statistical Study Kamio et al Period ~ Alfven transit time scale along the loop Datevelocity (km/s) Alfven transit time (s) Sound transit time (s) Obs. P (sec) VAVA VSVS LWLW

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

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

Kink Mode Oscillation TRACE - Aschwanden et al Nakariakov et al P ~ 300 sec  kink ~ L/C A

Kink Mode?? In the case of  -wave QPP :  kink ~ 5 s –L : 16,000 km –C A : 3,100 km ~observation (P ~ 6 s) Is it possible for flare loop in high pressure? negative image A B

Sausage Mode Oscillation - Nakariakov et al Aschwanden et al Previous estimations: or External medium, finite wave length  k=k c

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

Sausage Mode?? Parameters of loop C A0 = 440 km/s C Ae = 3,500 km/s L = 25,000 km  P GSM = 2L/C p ~ 2L/C Ae  P~15 s ~ observation ! Melnikov et al Nakariakov et al. 2003

Sausage Mode?? L : 16,000 km T : 9.4 MK n : 4.5×10 10 cm -3 B : 300 G C A0 = 3,100 km/s C Ae = ?? km/s  P GSM < 2L/C A0 ~ 10 s  OK for the case that k is large enough negative image A B

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

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

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?

Thank you!

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

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

QPP in microwave and HXR HXR light curves also show QPP  -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

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

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

Kink Mode?? In the case of  -wave QPP :  kink ~ 5 s –L : 16,000 km –C A : 3,100 km ~observation (P ~ 6 s) Is it possible for flare loop in high pressure?

Slow Mode Oscillation by SUMER Wang et al Ofman et al SUMER slit Yohkoh/SXT TRACE 195A SUMER slit event (not flare) Fe XIX (6  10 6 K) 200 arcsec