A new look at the birthrate of supernova remnants

Abstract

We have reanalysed a homogeneous catalogue of shell-type supernova remnants and we find that the radio data are consistent with a birthrate of one in 22 ± 3 yr. Our approach is based on the secular decrease of surface brightness of the historical remnants whose ages are precisely known. The above-mentioned birthrate is significantly higher than most previous estimates which range from one in 50-150 yr, and is consistent with the supernova rate in our galaxy derived from 'historical - observations, as well as with recent estimates of the pulsar birthrate.