Spectral Identification of an Ancient Supernova using Light Echoes in the LMC

TL;DR

This study successfully identifies the type of ancient supernova in the LMC by analyzing light echoes, demonstrating a novel method to classify historical supernovae and improve understanding of supernova diversity.

Contribution

The paper introduces a spectral classification method for centuries-old supernovae using light echoes and a comprehensive spectral library, enabling identification of supernova types from historical remnants.

Findings

Overluminous 91T-like SNe Ia best match the light echo spectrum.

Spectral fitting techniques effectively classify ancient supernovae.

Method provides new insights into historical supernovae in the LMC.

Abstract

We report the successful identification of the type of the supernova responsible for the supernova remnant SNR 0509-675 in the Large Magellanic Cloud (LMC) using Gemini spectra of surrounding light echoes. The ability to classify outbursts associated with centuries-old remnants provides a new window into several aspects of supernova research and is likely to be successful in providing new constraints on additional LMC supernovae as well as their historical counterparts in the Milky Way Galaxy (MWG). The combined spectrum of echo light from SNR 0509-675 shows broad emission and absorption lines consistent with a supernova (SN) spectrum. We create a spectral library consisting of 26 SNe Ia and 6 SN Ib/c that are time-integrated, dust-scattered by LMC dust, and reddened by the LMC and MWG. We fit these SN templates to the observed light echo spectrum using $\chi^2$ minimization as well as correlation techniques, and we find that overluminous 91T-like SNe Ia with $\dm15<0.9$ match the observed spectrum best.