Spectropolarimetric radio imaging of faint Gyrosynchrotron emission from a CME: A possible indication of the insufficiency of homogeneous models

The geo-effectiveness of coronal mass ejections (CMEs) is determined primarily by their magnetic fields. Modeling of gyrosynchrotron (GS) emission is a promising remote sensing technique to measure the CME magnetic field at coronal heights. However, faint GS emission from CME flux ropes is hard to detect in the presence of bright solar emission from the solar corona. With high dynamic-range spectropolarimetric meter wavelength solar images provided by the Murchison Widefield Array, we have detected faint GS emission from a CME out to similar to 8.3 R circle dot, the largest heliocentric distance reported to date. High-fidelity polarimetric calibration also allowed us to robustly detect circularly polarized emission from GS emission. For the first time in the literature, Stokes V detection has jointly been used with Stokes I spectra to constrain GS models. One expects that the inclusion of polarimetric measurement will provide tighter constraints on the GS model parameters. Instead, we found that homogeneous GS models, which have been used in all prior works, are unable to model both the total intensity and circular polarized emission simultaneously. This strongly suggests the need for using inhomogeneous GS models to robustly estimate the CME magnetic field and plasma parameters.

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Related Software #1 : Ultimate fast gyrosynchrotron codes: the first release

Related Software #2 : P-AIRCARS (Polarimetry using Automated Imaging Routine for Compact Arrays of the Radio Sun)

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Author Kansabanik, Devojyoti
Mondal, S.
Oberoi, D.
Publisher UCAR/NCAR - Library
Publication Date 2024-06-01T00:00:00
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Topic Category geoscientificInformation
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Metadata Date 2025-07-10T20:01:26.072687
Metadata Record Identifier edu.ucar.opensky::articles:27291
Metadata Language eng; USA
Suggested Citation Kansabanik, Devojyoti, Mondal, S., Oberoi, D.. (2024). Spectropolarimetric radio imaging of faint Gyrosynchrotron emission from a CME: A possible indication of the insufficiency of homogeneous models. UCAR/NCAR - Library. https://n2t.org/ark:/85065/d75t3qq6. Accessed 01 August 2025.

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