http://arxiv.org/abs/1610.07601
Even though SN 2012cg is one of the best-studied Type Ia Supernovae to date, the nature of its progenitor system has been debated in numerous studies. Specifically, it is difficult to reconcile the claims of the detection of a $\sim 6 \rm{M}_\odot$ main-sequence companion by Marion et al. 2016 with the deep, late-time H$\alpha{}$ flux limits from \citet{maguire16}. In this study we add three new constraints: 1) We analyze a high-signal-to-noise, nebular-phase, LBT/MODS spectrum of SN 2012cg and place an upper limit on the amount of low-velocity, solar-abundance material removed from a possible companion of $ < 7.8 \times 10^{-3} \rm{M}_\odot$. 2) We use Swift X-ray observations to constrain the preexplosion mass-loss rate to be $\dot M<10^{-6}$ $\rm{M}_\odot \rm{yr}^{-1}$ for $v_\textrm{w}=100\,\rm{km\,s^{-1}}$. 3) We carefully reanalyze a prediscovery MASTER image and, with published light curves of SN 2012cg, we estimate the time of first light and conservatively constrain the radius of a Roche-lobe overflowing companion to be $< 0.23 \rm{R}_\odot$ . These observations strongly disagree with Marion et al. 2016, and, when considered with other studies of SN 2012cg’s progenitor system, essentially rule out a non-degenerate companion.
B. Shappee, A. Piro, K. Stanek, et. al.
Wed, 26 Oct 16
38/63
Comments: 10 pages, 6 figures, 1 Table. Submitted to ApJ
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