Direct Radio Synchrotron Emission Imaging of a CME with the Murchison Widefield Array
Abstract
Recent space-borne missions with optical remote instruments have returned a wealth of information and new understanding of coronal mass ejections (CMEs) and their early evolution. However, these observations follow the bulk or thermal plasma, and thus only provide one part of the picture of solar eruptions. There are also EUV and X-ray observations, which are very useful, but only provide information about the flare energized plasma close to the photospheric surface. Solar radio observations allow us to constrain the dynamics of high energy electron beams accelerated in both flares and CMEs. In particular, the synchrotron emission from erupting flux ropes should give important information about the distributions of energetic electrons trapped in the cores of CMEs. Such measurements are very difficult to make, and until recently, there have been only very few, the observations by Bastian et al. (2001) being a notable example. Over the last few years, several new radio interferometric instruments have been brought online. The Murchison Widefield Array is one of them, and is particularly well-suited to imaging the Sun and solar transients at frequencies between 80 and 300 MHz. This instrument holds great promise for improving the status of direct CME imaging in the radio. Here we present imaging observations with high frequency and time resolution of an erupting flux rope, part of a CME which occurred on November 4, 2015. The observations allow us to obtain detailed frequency spectra of the synchrotron emission, and thus to constrain the energy distributions of the emitting nonthermal electron populations. In addition, such observations provide independent information about the thermal electron density, as well as the magnetic field strength in the CME flux rope. Finally, these observations provide information about the detailed evolution and kinematics of the CME flux rope in its early stages. The new observations demonstrate the capability of the MWA to improve the status of the field through high sensitivity, high dynamic range radio imaging.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFMSH22B..01K
- Keywords:
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- 4305 Space weather;
- NATURAL HAZARDSDE: 7594 Instruments and techniques;
- SOLAR PHYSICS;
- ASTROPHYSICS;
- AND ASTRONOMYDE: 7924 Forecasting;
- SPACE WEATHERDE: 7999 General or miscellaneous;
- SPACE WEATHER