Optical studies of two stripped-envelope supernovae – SN 2015ap (Type Ib) and SN 2016P (Type Ic)
Anjasha Gangopadhyay, Kuntal Misra, D. K. Sahu, Shan-Qin Wang, Brajesh Kumar, Long Li, G. C. Anupama, Raya Dastidar, N. Elias–Rosa, Brijesh Kumar, Mridweeka Singh, S. B. Pandey, Pankaj Sanwal, Avinash Singh, Shubham Srivastav, L. Tartaglia, L. Tomasella
Abstract
ABSTRACT We present the photometric and spectroscopic studies of a Type Ib SN 2015ap and a Type Ic SN 2016P. SN 2015ap is one of the bright (MV = −18.04 mag) Type Ib while SN 2016P lies at an average value among the Type Ic SNe (MV = −17.53 mag). Bolometric light-curve modelling of SNe 2015ap and 2016P indicates that both the SNe are powered by 56Ni + magnetar model with 56Ni masses of 0.01 and 0.002 M⊙, ejecta masses of 3.75 and 4.66 M⊙, spin period P0 of 25.8 and 36.5 ms, and magnetic field Bp of 28.39 × 1014 and 35.3 × 1014 G, respectively. The early spectra of SN 2015ap show prominent lines of He with a ‘W’ feature due to Fe complexes while other lines of Mg ii, Na i, and Si ii are present in both SNe 2015ap and 2016P. Nebular phase [O i] profile indicates an asymmetric profile in SN 2015ap. The [O i]/[Ca ii] ratio and nebular spectral modelling of SN 2015ap hint towards a progenitor mass between 12 and 20 M⊙.