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arXiv · 1502.00646

Constraining the Progenitor Companion of the Nearby Type Ia SN 2011fe with a Nebular Spectrum at +981 Days

Melissa L. Graham·Peter E. Nugent·Mark Sullivan·Alexei V. Filippenko·S. Bradley Cenko·Jeffrey M. Silverman·Kelsey I. Clubb·Weikang Zheng
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Abstract

We present an optical nebular spectrum of the nearby Type Ia supernova 2011fe, obtained 981 days after explosion. SN 2011fe exhibits little evolution since the +593 day optical spectrum, but there are several curious aspects in this new extremely late-time regime. We suggest that the persistence of the $\sim5800$~Å feature is due to Na I D, and that a new emission feature at $\sim7300$~Å may be [Ca II]. Also, we discuss whether the new emission feature at $\sim6400$~Å might be [Fe I] or the high-velocity hydrogen predicted by Mazzali et al. The nebular feature at 5200~Å exhibits a linear velocity evolution of $\sim350$ $\rm km\ s^{-1}$ per 100 days from at least +220 to +980 days, but the line's shape also changes in this time, suggesting that line blending contributes to the evolution. At $\sim 1000$ days after explosion, flux from the SN has declined to a point where contribution from a luminous secondary could be detected. In this work we make the first observational tests for a post-impact remnant star and constrain its temperature and luminosity to $T \gtrsim 10^4$ $\rm K$ and $L \lesssim 10^4$ $\rm L_{\odot}$. Additionally, we do not see any evidence for narrow H$α$ emission in our spectrum. We conclude that observations continue to strongly exclude many single-degenerate scenarios for SN 2011fe.

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Melissa L. Graham, Peter E. Nugent, Mark Sullivan, Alexei V. Filippenko, S. Bradley Cenko, Jeffrey M. Silverman, Kelsey I. Clubb, Weikang Zheng. 2015-11-12. Constraining the Progenitor Companion of the Nearby Type Ia SN 2011fe with a Nebular Spectrum at +981 Days. https://doi.org/10.1093/mnras%2Fstv1888

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