An Exploration of X-ray Supernova Remnants in the Milky Way and Nearby Galaxies

TL;DR

This study analyzes the environmental properties and evolutionary stages of X-ray supernova remnants in the Milky Way, LMC, and SMC, comparing observational data with theoretical models to understand their development and ambient conditions.

Contribution

It provides a comprehensive catalog of SNR sizes and X-ray luminosities, and compares these with Sedov-Taylor phase models to infer environmental densities and evolutionary states.

Findings

Small, young remnants are mainly Type Ia or high-luminosity core-collapse SNRs.

LMC SNRs evolve in a less dense medium than Milky Way SNRs.

Many core-collapse SNRs are detected only after emerging from progenitor wind bubbles.

Abstract

We probe the environmental properties of X-ray supernova remnants (SNRs) at various points along their evolutionary journey, especially the S-T phase, and their conformance with theoretically derived models of SNR evolution. The remnant size is used as a proxy for the age of the remnant. Our data set includes 34 Milky Way, 59 Large Magellanic Cloud (LMC), and 5 Small Magellanic Cloud (SMC) SNRs. We select remnants that have been definitively typed as either core-collapse (CC) or Type Ia supernovae, with well-defined size estimates, and a thermal X-ray flux measured over the entire remnant. A catalog of SNR size and X-ray luminosity is presented and plotted, with ambient density and age estimates from the literature. Model remnants with a given density, in the Sedov-Taylor (S-T) phase, are overplotted on the diameter-vs-luminosity plot, allowing the evolutionary state and physical properties of SNRs to be compared to each other, and to theoretical models. We find that small, young remnants are predominantly Type Ia remnants or high luminosity CCs, suggesting that many CC SNRs are not detected until after they have emerged from the progenitor's wind-blown bubble. An examination of the distribution of SNR diameters in the Milky Way and LMC reveals that LMC SNRs must be evolving in an ambient medium which is 30% as dense as that in the Milky Way. This is consistent with ambient density estimates for the Galaxy and LMC.