RADIO-EMISSION FROM 3 FACE-ON SPIRAL GALAXIES

Maps of NGC 1566, 2442 and 5236 (M83) at 843 MHz have been made with the Molonglo Observatory Synthesis Telescope. Emission extends over the nuclei and discs of the three galaxies. M83 has a significant thermal component in its emission at 10 GHz; this enabled the electron density and mass of H II to be estimated. The radial distributions of non-thermal emission from NGC 1566 and M83 show an exponential dependence similar to that of the blue light distributions. Scale lengths of non-thermal emission are used to investigate the distributions of cosmic ray electrons and magnetic fields in NGC 1566 and M83. © 1984 Royal Astronomical Society. Provided by the NASA Astrophysics Data System.