Galactic and Extragalactic Samples of Supernova Remnants: How They Are Identified and What They Tell Us

TL;DR

This paper reviews methods for identifying and studying supernova remnants in our galaxy and beyond, emphasizing the importance of multi-wavelength data and large samples to understand their properties and origins.

Contribution

It provides a comprehensive overview of techniques used to identify and characterize thousands of SNRs and discusses strategies for interpreting their properties across different environments.

Findings

Large samples of SNRs are essential for understanding their overall properties.

Multi-wavelength comparisons help classify SNRs and infer explosion types.

Studying SNRs in galaxies with existing data is more effective than expanding to new galaxies.

Abstract

Supernova remnants (SNRs) arise from the interaction between the ejecta of a supernova (SN) explosion and the surrounding circumstellar and interstellar medium. Some SNRs, mostly nearby SNRs, can be studied in great detail. However, to understand SNRs as a whole, large samples of SNRs must be assembled and studied. Here, we describe the radio, optical, and X-ray techniques which have been used to identify and characterize almost 300 Galactic SNRs and more than 1200 extragalactic SNRs. We then discuss which types of SNRs are being found and which are not. We examine the degree to which the luminosity functions, surface-brightness distributions and multi-wavelength comparisons of the samples can be interpreted to determine the class properties of SNRs and describe efforts to establish the type of SN explosion associated with a SNR. We conclude that in order to better understand the class properties of SNRs, it is more important to study (and obtain additional data on) the SNRs in galaxies with extant samples at multiple wavelength bands than it is to obtain samples of SNRs in other galaxies