Some statistics of Galactic SNRs

TL;DR

This paper discusses the selection biases in identifying Galactic supernova remnants at radio wavelengths and evaluates the limitations of the Sigma-D relation for estimating their properties.

Contribution

It analyzes the impact of observational selection effects on the statistical properties of Galactic SNRs, highlighting the limited utility of the Sigma-D relation.

Findings

Low surface brightness remnants are underrepresented

Small angular size remnants are often missed

The Sigma-D relation has limited applicability for distance estimation

Abstract

The selection effects applicable to the identification of Galactic supernova remnants (SNRs) at radio wavelengths are discussed. Low surface brightness remnants are missing, as are those with small angular sizes (including young but distant SNRs). Several statistical properties of Galactic SNRs are discussed, including the surface-brightness/diameter (Sigma-D) relation. The wide range of intrinsic properties of Galactic remnants with known distances, and the observational selection effects, means that the Sigma-D relation is of limited use to derive diameters and hence distances for individual SNRs, or for statistical studies.