학술논문
Carnegie Supernova Project: The First Homogeneous Sample of Super-Chandrasekhar-mass/2003fg-like Type Ia Supernovae
Document Type
article
Author
Ashall, C; Lu, J; Hsiao, EY; Hoeflich, P; Phillips, MM; Galbany, L; Burns, CR; Contreras, C; Krisciunas, K; Morrell, N; Stritzinger, MD; Suntzeff, NB; Taddia, F; Anais, J; Baron, E; Brown, PJ; Busta, L; Campillay, A; Castellón, S; Corco, C; Davis, S; Folatelli, G; Förster, F; Freedman, WL; Gonzaléz, C; Hamuy, M; Holmbo, S; Kirshner, RP; Kumar, S; Marion, GH; Mazzali, P; Morokuma, T; Nugent, PE; Persson, SE; Piro, AL; Roth, M; Salgado, F; Sand, DJ; Seron, J; Shahbandeh, M; Shappee, BJ
Source
The Astrophysical Journal. 922(2)
Subject
Language
Abstract
We present a multiwavelength photometric and spectroscopic analysis of 13 super-Chandrasekhar-mass/2003fg-like Type Ia supernovae (SNe Ia). Nine of these objects were observed by the Carnegie Supernova Project. The 2003fg-like SNe have slowly declining light curves (Δm 15(B) < 1.3 mag), and peak absolute B-band magnitudes of -19 < M B < -21 mag. Many of the 2003fg-like SNe are located in the same part of the luminosity-width relation as normal SNe Ia. In the optical B and V bands, the 2003fg-like SNe look like normal SNe Ia, but at redder wavelengths they diverge. Unlike other luminous SNe Ia, the 2003fg-like SNe generally have only one i-band maximum, which peaks after the epoch of the B-band maximum, while their near-IR (NIR) light-curve rise times can be ⪆40 days longer than those of normal SNe Ia. They are also at least 1 mag brighter in the NIR bands than normal SNe Ia, peaking above M H = -19 mag, and generally have negative Hubble residuals, which may be the cause of some systematics in dark-energy experiments. Spectroscopically, the 2003fg-like SNe exhibit peculiarities such as unburnt carbon well past maximum light, a large spread (8000-12,000 km s-1) in Si ii λ6355 velocities at maximum light with no rapid early velocity decline, and no clear H-band break at +10 days. We find that SNe with a larger pseudo-equivalent width of C ii at maximum light have lower Si ii λ6355 velocities and more slowly declining light curves. There are also multiple factors that contribute to the peak luminosity of 2003fg-like SNe. The explosion of a C-O degenerate core inside a carbon-rich envelope is consistent with these observations. Such a configuration may come from the core-degenerate scenario.