Perturbations of gyrosynchrotron emission polarization from solar flares by sausage modes: forward modeling

¹ CmPA, Department of Mathematics, KU Leuven, 3001 Leuven, Belgium
e-mail: Veronika.Reznikova@wis.kuleuven.be
² Radiophysical Research Institute (NIRFI), 603950 Nizhny Novgorod, Russia
³ Institute of Solar-Terrestrial Physics, 664033 Irkutsk, Russia

Received: 7 July 2014
Accepted: 16 December 2014

Abstract

We examined the polarization of the microwave flaring emission and its modulation by the fast sausage standing wave using a linear 3D magnetohydrodynamic model of a plasma cylinder. We analyzed the effects of the line-of-sight angle on the perturbations of the gyrosynchrotron intensity for two models: a base model with strong Razin suppression and a low-density model in which the Razin effect was negligible. The circular polarization (Stokes V) oscillation is in phase with the intensity oscillation, and the polarization degree (Stokes V/I) oscillates in phase with the magnetic field at the examined frequencies in both models. The two quantities experience a periodical reversal of their signs with a period equal to half of the sausage wave period when seen at a 90° viewing angle, in this case, their modulation depth reaches 100%.