Updated radio Σ-D relation for galactic supernova remnants-ii

Abstract

In this paper we present the updated empirical radio surface-brightness-to-diameter Σ-D relation for Galactic supernova remnants (SNRs) calibrated using 110 SNRs with reliable distances. We apply orthogonal fitting procedure and kernel density smoothing in the Σ-D plane and compare the re-sults with the latest theoretical Σ-D relations derived from simulations of radio evolution of SNRs. We argue that the best agreement between the empirical and simulated Σ-D relations is achieved if the mixed-morphology SNRs and SNRs of both, low brightness and small diameter, are ltered out from the calibration sample. The distances to 5 newly discovered remnants and 27 new candidates for shell SNRs are estimated from our full and ltered calibration samples.