A Systematic Study of Evolved Supernova Remnants in the Large and Small Magellanic Clouds with Suzaku

TL;DR

This study uses Suzaku's high energy resolution to identify supernova types in evolved remnants of the Magellanic Clouds by analyzing emission lines, despite limited spatial resolution.

Contribution

It demonstrates that spatially-integrated X-ray spectra can reliably determine supernova progenitor types in old remnants, expanding methods for extragalactic SNR studies.

Findings

Ejecta emission remains significant in the spectra of ~10^4 yr old SNRs.

Fe/Ne mass ratios effectively distinguish Type Ia from core-collapse SNRs.

Suzaku's spectral resolution compensates for its lack of spatial resolution in SNR typing.

Abstract

Typing the origin (i.e., Type Ia or core-collapse) of supernova remnants (SNRs) is crucial to determine the rates of supernova (SN) explosions in a galaxy, which is a key to understand its recent chemical evolution. However, evolved SNRs in the so-called Sedov phase are dominated by the swept-up interstellar medium (ISM), making it difficult to determine their ejecta composition and thus SN type. Here we present a systematic X-ray study of nine evolved SNRs in the Magellanic Clouds, DEM L238, DEM L249, 0534-69.9, 0548-70.4, B0532-71.0, B0532-67.5, 0103-72.6, 0049-73.6, and 0104-72.3, using archival data of the Suzaku satellite. Although Suzaku does not spatially resolve the SN ejecta from the swept-up ISM due to the limited angular resolution, its excellent energy resolution has enabled clear separation of emission lines in the soft X-ray band. This leads to the finding that the `spatially-integrated' spectra of the evolved (~10^4 yr) SNRs are still significantly contributed by emission from the ejecta at the energies around 1 keV. The Fe/Ne mass ratios, determined mainly from the well-resolved Fe L-shell and Ne K-shell lines, clearly divide the observed SNRs into the Type Ia and core-collapse groups, confirming some previous typing made by Chandra observations that had utilized its extremely high angular resolution. This demonstrates that spatially-integrated X-ray spectra of old SNRs can also be used to discriminate their progenitor type, which would be helpful for future systematic studies of extragalactic SNRs with ASTRO-H and beyond.