Carnegie Supernova Project: The First Homogeneous Sample of Super-Chandrasekhar-mass/2003fg-like Type Ia Supernovae Academic Article uri icon

abstract

  • 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 (m 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 luminositywidth 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 (800012,000 km s1) in Si ii 6355 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 6355 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 CO degenerate core inside a carbon-rich envelope is consistent with these observations. Such a configuration may come from the core-degenerate scenario.

published proceedings

  • ASTROPHYSICAL JOURNAL

altmetric score

  • 7.33

author list (cited authors)

  • Ashall, C., Lu, J., Hsiao, E. Y., Hoeflich, P., Phillips, M. M., Galbany, L., ... Shappee, B. J.

citation count

  • 11

complete list of authors

  • 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||Castellon, S||Corco, C||Davis, S||Folatelli, G||Forster, F||Freedman, WL||Gonzalez, 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

publication date

  • December 2021