A Deep Chandra Observation of the Oxygen-Rich Supernova Remnant 0540-69.3 in the Large Magellanic Cloud

TL;DR

This deep Chandra X-ray study of SNR 0540-69.3 reveals nonthermal shock features, suggests possible Fe ejecta presence, and discusses implications for nucleosynthesis and ejecta mixing in this young supernova remnant.

Contribution

First spatially-resolved X-ray spectral analysis of SNR 0540-69.3, confirming cosmic-ray acceleration and exploring ejecta composition with tentative Fe overabundance evidence.

Findings

Confirmed nonthermal nature of boundary arcs

Evidence suggests possible Fe overabundance near outer boundary

No X-ray counterparts for optical ejecta in the center

Abstract

Using our deep ~120 ks Chandra observation, we report on the results from our spatially-resolved X-ray spectral analysis of the "oxygen-rich" supernova remnant (SNR) 0540-69.3 in the Large Magellanic Cloud. We conclusively establish the nonthermal nature of the "arcs" in the east and west boundaries of the SNR, which confirms the cosmic-ray electron acceleration in the supernova shock (B ~ 20-140 microG). We report tentative evidence for Fe overabundance in the southern region close to the outer boundary of the SNR. While such a detection would be intriguing, the existence of Fe ejecta is not conclusive with the current data because of poor photon statistics and limited plasma models. If it is verified using deeper X-ray observations and improved plasma models, the presence of Fe ejecta, which was produced in the core of the supernova, near the SNR's outer boundary would provide an intriguing opportunity to study the explosive nucleosynthesis and the ejecta mixing in this young core-collapse SNR. There is no evidence of X-ray counterparts for the optical O-rich ejecta in the central regions of the SNR.