EGU General Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Metric-Decametric Gyrosynchrotron Radio Emission From the Quiet Solar Corona

Kamen Kozarev1, Peijin Zhang1, and Pietro Zucca2
Kamen Kozarev et al.
  • 1Institute of Astronomy, Bulgarian Academy of Sciences, Sofia, Bulgaria (
  • 2ASTRON, The Netherlands Institute of Radio Astronomy

The radio emission of the quiet Sun in the metric and decametric bands has not been well studied historically due to limitations of existing instruments. It is nominally dominated by thermal brehmsstrahlung of the solar corona, but may also include significant gyrosynchrotron emission, usually assumed to be weak under quiet conditions. In this work, we investigate the expected gyrosynchrotron contribution to solar radio emission in the lowest radio frequencies observable by ground instruments, for different regions of the low and middle corona. We approximate the coronal conditions by a synoptic magnetohydrodynamic (MHD) model. The thermal emission is estimated from a forward model based on the simulated corona. We calculate the expected gyrosynchrotron emission with the Fast Gyrosynchrotron Codes framework by Fleishman and Kuznetsov (2010). The model emissions of different coronal regions are compared with quiet-time imaging observations between 20-90 MHz by the LOw Frequency ARray (LOFAR) radio telescope. The contribution of gyrosynchrotron radiation to low frequency solar radio emission may shed light on effects such as the hitherto unexplained brightness variation observed in decametric coronal hole emission, and help constrain measurements of the coronal magnetic fields. It can also improve our understanding of electron populations in the middle corona and their relation to the formation of the solar wind.

How to cite: Kozarev, K., Zhang, P., and Zucca, P.: Metric-Decametric Gyrosynchrotron Radio Emission From the Quiet Solar Corona, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5067,, 2022.