Spitzer Observations of the Type Ia Supernova Remnant N103B: Kepler's Older Cousin?

TL;DR

This study uses Spitzer IR observations to analyze the dense circumstellar environment of the Type Ia supernova remnant N103B, revealing similarities to Kepler's SNR and suggesting a progenitor with circumstellar material.

Contribution

It provides the first detailed IR analysis of N103B, proposing that dense circumstellar material influences its evolution, similar to Kepler's supernova remnant.

Findings

N103B exhibits strong IR emission from warm dust in the post-shock region.

Derived gas density in N103B is 45 cm$^{-3}$, higher than other Type Ia remnants.

The dust is silicate, with a peak at 17.3 μm instead of 18 μm.

Abstract

We report results from Spitzer observations of SNR 0509-68.7, also known as N103B, a young Type Ia supernova remnant in the Large Magellanic Cloud that shows interaction with a dense medium in its western hemisphere. Our images show that N103B has strong IR emission from warm dust in the post-shock environment. The post-shock gas density we derive, 45 cm$^{-3}$, is much higher than in other Type Ia remnants in the LMC, though a lack of spatial resolution may bias measurements towards regions of higher than average density. This density is similar to that in Kepler's SNR, a Type Ia interacting with a circumstellar medium. Optical images show H$\alpha$ emission along the entire periphery of the western portion of the shock, with [O III] and [S II] lines emitted from a few dense clumps of material where the shock has become radiative. The dust is silicate in nature, though standard silicate dust models fail to reproduce the "18 $\mu$m" silicate feature that peaks instead at 17.3 $\mu$m. We propose that the dense material is circumstellar material lost from the progenitor system, as with Kepler. If the CSM interpretation is correct, this remnant would become the second member, along with Kepler, of a class of Type Ia remnants characterized by interaction with a dense CSM hundreds of years post-explosion. A lack of N enhancement eliminates symbiotic AGB progenitors. The white dwarf companion must have been relatively unevolved at the time of the explosion.