Carnegie Supernova Project II: The Slowest Rising Type Ia Supernova LSQ14fmg and Clues to the Origin of Super-Chandrasekhar/03fg-like Events Academic Article uri icon

abstract

  • Abstract The Type Ia supernova (SN Ia) LSQ14fmg exhibits exaggerated properties that may help to reveal the origin of the super-Chandrasekhar (or 03fg-like) group. The optical spectrum is typical of a 03fg-like SN Ia, but the light curves are unlike those of any SNe Ia observed. The light curves of LSQ14fmg rise extremely slowly. At 23 rest-frame days relative to B-band maximum, LSQ14fmg is already brighter than mag before host extinction correction. The observed color curves show a flat evolution from the earliest observation to approximately 1 week after maximum. The near-infrared light curves peak brighter than 20.5 mag in the J and H bands, far more luminous than any 03fg-like SNe Ia with near-infrared observations. At 1 month past maximum, the optical light curves decline rapidly. The early, slow rise and flat color evolution are interpreted to result from an additional excess flux from a power source other than the radioactive decay of the synthesized 56Ni. The excess flux matches the interaction with a typical superwind of an asymptotic giant branch (AGB) star in density structure, mass-loss rate, and duration. The rapid decline starting at around 1 month past B-band maximum may be an indication of rapid cooling by active carbon monoxide (CO) formation, which requires a low-temperature and high-density environment. These peculiarities point to an AGB progenitor near the end of its evolution and the core degenerate scenario as the likely explosion mechanism for LSQ14fmg.

published proceedings

  • ASTROPHYSICAL JOURNAL

altmetric score

  • 214.646

author list (cited authors)

  • Hsiao, E. Y., Hoeflich, P., Ashall, C., Lu, J., Contreras, C., Burns, C. R., ... Uddin, S. A.

citation count

  • 27

complete list of authors

  • Hsiao, EY||Hoeflich, P||Ashall, C||Lu, J||Contreras, C||Burns, CR||Phillips, MM||Galbany, L||Anderson, JP||Baltay, C||Baron, E||Castellon, S||Davis, S||Freedman, Wendy L||Gall, C||Gonzalez, C||Graham, ML||Hamuy, M||Holoien, TW-S||Karamehmetoglu, E||Krisciunas, K||Kumar, S||Kuncarayakti, H||Morrell, N||Moriya, TJ||Nugent, PE||Perlmutter, S||Persson, SE||Piro, AL||Rabinowitz, D||Roth, M||Shahbandeh, M||Shappee, BJ||Stritzinger, MD||Suntzeff, NB||Taddia, F||Uddin, SA

publication date

  • September 2020