Modulation of Gyrosynchrotron Emission of Flare Loops by Fast and Slow MHD Oscillations

V.F. Melnikov$^1$, V.M. Nakariakov$^2$, V.E. Reznikova$^1$

$^1$Radiophysical Research Institute (NIRFI), Nizhny Novgorod, 603950, Russia
$^2$University of Warwick, Coventry, UK

Gyrosynchrotron emission generated by non-thermal electrons can be efficiently modulated by fast and slow MHD oscillations of flaring magnetic loops. The modulation is caused by variations of magnetic field strength and direction as well as by perturbations of plasma density. Importance of Razin suppression for the modulation of gyrosynchrotron emission in solar flaring loops is shown. Theoretical modeling demonstrates differences between observational properties of microwave oscillations caused by different harmonics of the sausage and acoustic modes of MHD standing waves. Observations with spatial resolution, together with analysis of the modulation frequency, are shown to be sufficient for providing the information needed to identify the modes.