Speaker
Description
Type II radio bursts are solar radio emissions associated with coronal shock waves and are believed to be produced by electrons accelerated by these shocks. As radio signatures of coronal shocks, they are typically found near the expanding edges of coronal mass ejections (CMEs), making them valuable for studying the dynamics of CME-related shocks in the solar corona. Here, we aim to determine the regions in the solar corona and their properties where the CME-driven shock waves accelerate electrons. To do this, we combine radio observations with magneto-hydrodynamic (MHD) simulations of the solar corona. We conduct an analysis of ten type II radio bursts exhibiting emissions in the 20--300 MHz frequency range from Solar Cycle 25. We used a combination of observatories to obtain images and dynamic spectra of type II radio bursts, including spectra recorded by LOFAR IDOLS for some of these events. The novelty of this study lies in the use of radio imaging data for all type II bursts considered to examine the positions of the radio sources. The radio source positions, combined with a geometrical fitting of the CME shock are used to determine essential shock parameters at the acceleration region such as the Alfvénic Mach number and shock normal angle, in the context of the MHD simulations. The shock parameters are then combined in a comprehensive statistical study with the properties of the radio emission observed, electron energies estimated from herringbone radio bursts, CME speeds in both the lateral and radial directions and the presence of open/closed magnetic field regions and other radio emissions.
