A Newly Recognized Very Young Supernova Remnant in M83

TL;DR

This paper reports the discovery of a very young supernova remnant in M83 with spectral features indicating a recent type II supernova, potentially missed in historical observations, supported by multi-wavelength data.

Contribution

It identifies a new supernova remnant in M83 with spectral and imaging evidence suggesting a recent, possibly century-old, supernova event that was previously unrecorded.

Findings

Spectroscopic detection of broad emission lines characteristic of late-time supernovae.

Multi-wavelength data confirming the presence of a supernova remnant with X-ray and radio sources.

Estimated progenitor star mass of at least 17 solar masses.

Abstract

As part of a spectroscopic survey of supernova remnant candidates in M83 using the Gemini-South telescope and GMOS, we have discovered one object whose spectrum shows very broad lines at H$\alpha$, [O~I] 6300,6363, and [O~III] 4959,5007, similar to those from other objects classified as `late time supernovae.' Although six historical supernovae have been observed in M83 since 1923, none were seen at the location of this object. Hubble Space Telescope Wide Field Camera 3 images show a nearly unresolved emission source, while Chandra and ATCA data reveal a bright X-ray source and nonthermal radio source at the position. Objects in other galaxies showing similar spectra are only decades post-supernova, which raises the possibility that the supernova that created this object occurred during the last century but was missed. Using photometry of nearby stars from the HST data, we suggest the precursor was at least 17 $\rm M_{sun}$, and the presence of broad H$\alpha$ in the spectrum makes a type II supernova likely. The supernova must predate the 1983 VLA radio detection of the object. We suggest examination of archival images of M83 to search for evidence of the supernova event that gave rise to this object, and thus provide a precise age.