Deceleration of supernovae in the circumstellar wind and their radio emission

A model for the deceleration of a supernova shell in the circumstellar wind in the thin-layer approximation is used to analyze the evolution of the radio emission of the supernovae SN 1980K, SN 1979C, and SN 1987A. Spectroscopic data on the expansion velocities of the outer boundary of the shell are also used. No significant differences were found between a description of the evolution of SN 1980K based on the standard self-similar solution and the numerical model considered here. In the case of SN 1979C, the self-similar solution cannot fit the evolution of the expansion velocity, whereas the numerical model for this supernova satisfactorily describes the dynamics of the shell expansion. The numerical model cannot reproduce the radio evolution of SN 1979C over a timespan of 12 years simultaneously at all frequencies if the wind parameters are constant along the radius. In 1987A, the early evolution of the radio emission and expansion velocity cannot be accounted for by free-free absorption in the wind, but a model with synchrotron self-absorption is consistent with both the radio data and the expansion velocity.