Radio continuum observations of four edge-on spiral galaxies

Abstract

We present maps of the three edge-on galaxies NGC 55, 4945 and 7090 made at 843 MHz with the Molonglo Observatory Synthesis Telescope, and complete some previous analysis of the 843-MHz emission from NGC 253. Emission extends along the plane of each galaxy; the component perpendicular to the plane is resolved with a mean scale height of 0.55 kpc. The 85-MHz flux density of NGC 4945 suggests a low-frequency spectral turn-over similar to that seen for NGC 253. Scale heights of the non-thermal emission are used to investigate the z-distributions of magnetic fields and relativistic electrons and the associated diffusion rates of the electrons in NGC 55, 253 and 4945.