Centimeter-wave radio and X-ray emission from the sun

Abstract

The generation of solar radio waves on centimeter wavelengths appears to be closely associated with the production of X-rays during both quiet and disturbed periods of the Sun. The theory of solar X-rays shows that the temperature of the corona as deduced, among other methods, from radio observations can adequately account for the quiet X-radiation from the Sun. The dense hot regions (sources of slowly varying component on centimeter and decimeter waves) can be identified with the localized regions of X-radiation of increased intensity and of higher quantum energy and are consequently the sources of slowly varying X-radiation. Both the quiet and the slowly varying radio and X-ray emissions can be explained by thermal Bremsstrahlung mechanism. During solar flares bursts of centimeter-wave radio emission and X-rays of high and low energy occur simultaneously. The high energy X-ray bursts are due to non-thermal Bremsstrahlung, while the associated cm-2 radio bursts can be due to synchrotron radiation of the high-energy electrons. In this review, we shall discuss the various relationships existing between solar radio emission and X-radiation.