Optical studies of two stripped envelope supernovae SN 2015ap (Type Ib) and SN 2016P (Type Ic)

TL;DR

This study presents detailed optical analyses of two stripped-envelope supernovae, SN 2015ap (Type Ib) and SN 2016P (Type Ic), revealing their physical properties, spectral features, and progenitor characteristics through photometric and spectroscopic data.

Contribution

It provides new insights into the physical parameters and progenitor masses of these supernovae using bolometric light curve modeling and spectral analysis.

Findings

SN 2015ap is a bright Type Ib supernova with M_V = -18.04 mag.

SN 2016P is an average luminosity Type Ic supernova with M_V = -17.53 mag.

Both SNe are powered by a combined $^{56}$Ni and magnetar model, with specific ejecta masses, spin periods, and magnetic fields.

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 (M$_{V}$ = $-$18.04 mag) Type Ib while SN 2016P lies at an average value among the Type Ic SNe (M$_{V}$ = $-$17.53 mag). Bolometric light curve modelling of SNe 2015ap and 2016P indicates that both the SNe are powered by $^{56}$Ni + magnetar model with $^{56}$Ni masses of 0.01 M$_{\odot}$ and 0.002 M$_{\odot}$, ejecta masses of 3.75 M$_{\odot}$ and 4.66 M$_{\odot}$, spin period P$_{0}$ of 25.8 ms and 36.5 ms and magnetic field B$_{p}$ of 28.39 $\times$ 10$^{14}$ Gauss and 35.3 $\times$ 10$^{14}$ Gauss respectively. The early spectra of SN 2015ap shows 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 hints towards a progenitor mass between 12 $-$ 20 M$_{\odot}$.