Supernova remnants of known age and X-radiation

When X-ray observations and the age of a SNR are known, basic physical parameters can be found either for an adiabatic phase model or an early phase (free expansion) model. The results obtained for the 3 objects SN185, SN1006 and SN1054 show that, in each case, the early phase models agree with ancient observations. For SN185 and SN1006, the early phase model gives a low medium density and much smaller distance than previously, suggesting a much lower radio luminosity-the correlated presence of these two features is favourable to the view that radio emission arises from the interaction between shock waves and the interstellar medium.