Quantifying weak non-thermal meterwave solar emission using non-imaging techniques
Abstract
An improved understanding of the solar corona is crucial for making progress on long-standing problems like coronal heating and the origin of the solar wind. Metrewave radio emissions arise in the coronal regions and form a unique diagnostic probe of this, otherwise hard to study region. The background radio emission at these wavelengths comes from the slowly varying thermal free-free emission and on it are superposed a variety of nonthermal emissions arising from a range of plasma emission processes. The latter are coherent in nature and hence lead to a much larger observational contrast, as compared to that in EUV or X-ray, for emissions involving similar energetics. One of the prevalent hypotheses for explaining coronal heating is based on the presence of an energetically weak population of `nanoflares' (Parker 1988). A necessary requirement for nanoflares based coronal heating to be effective is that their occurrence rate slopes must be <-2 (Hudson 1991). There is hence a lot of interest in studies of weak nonthermal emissions. Existing studies in EUV and X-ray bands have detected `microflares' with slopes >-2 (e.g. Hannah et al. 2011). Some of the weak meterwave emissions detected are, however, believed to correspond to energies in the `picoflare' range (Ramesh et al. 2013). It is hence, very interesting to study weak nonthermal emissions at metric wavelengths.
- Publication:
-
Long-term Datasets for the Understanding of Solar and Stellar Magnetic Cycles
- Pub Date:
- February 2018
- DOI:
- 10.1017/S1743921318002004
- Bibcode:
- 2018IAUS..340..181S