Evidence for a dynamical halo around the edge-on galaxy NGC 4631

Radio continuum observations at five frequencies between 327 MHz and 10.7 GHz of the edge on galaxy NGC 4631 confirm the prediction concerning the frequency dependence of the halo extent and the spatial variations of the radio spectral indices in the dynamical halo model made by Lerche and Schlickeiser. The measurements are presented, and a detailed comparison with theoretical predictions is made.