Radio and Hard X-ray Quasi-Periodic Pulsations during the 2004 July 13 Flare
Abstract
Quasi-periodic pulsations QPPs in radio and hard X-ray emissions have been observed in association with solar flares Typical pulsation periods of QPPs range from a few seconds to several minutes Possible causes of the intensity variations in radio emission are i fluctuation in the number of particles created by the acceleration process ii modulation in the whole structure in which the radiation takes place MHD oscillations and iii modulation in spatial and energy distributions of the radiating particles Trottet et al 1979 Among them the fast sausage-mode MHD oscillation has been preferably interpreted as a cause of QPPs which is manifested in coronal loops by symmetric cross-sectional variations and plasma compression This compressive mode is nearly transversal and the perturbations of plasma velocity in the radial direction are stronger than those along the field Nakariakov and Verwichte 2006 Recently Asai et al 2001 detected spatially resolved microwave QPPs for the first time with the Nobeyama Radioheliograph NoRH NoRH can provide microwave images with a time resolution up to 0 1 sec and thus suitable for the study of spatially resolved QPPs Asai et al 2001 investigated the oscillation with a periodicity of 6 6s in the context of the fast kink-mode rather than the fast sausage-mode In their interpretation the QPPs can be due to the modulation of the electron acceleration by a global kink oscillation of the flaring loop or by an interaction of the flaring loops with another loop which performs kink
- Publication:
-
36th COSPAR Scientific Assembly
- Pub Date:
- 2006
- Bibcode:
- 2006cosp...36..720H