Progenitor mass constraints for the type Ib intermediate-luminosity SN 2015ap and the highly extinguished SN 2016bau

TL;DR

This study constrains the progenitor masses of two Type Ib supernovae, 2015ap and 2016bau, through photometric, spectroscopic analysis, and stellar evolution modeling, suggesting a 12 solar mass progenitor for 2015ap and a slightly less massive progenitor for 2016bau.

Contribution

It combines observational data with stellar evolution and explosion modeling to estimate progenitor masses of intermediate-luminosity Type Ib supernovae, providing new insights into their origins.

Findings

Progenitor of SN 2015ap likely a 12 M_sun ZAMS star.

Progenitor of SN 2016bau is near the boundary between SN and non-SN.

Modeling results closely match observed properties, supporting progenitor mass estimates.

Abstract

Photometric and spectroscopic analyses of the intermediate-luminosity Type Ib supernova (SN) 2015ap and of the heavily reddened Type Ib SN~2016bau are discussed. Photometric properties of the two SNe, such as colour evolution, bolometric luminosity, photospheric radius, temperature, and velocity evolution, are also constrained. The ejecta mass, synthesised nickel mass, and kinetic energy of the ejecta are calculated from their light-curve analysis. We also model and compare the spectra of SN~2015ap and SN~2016bau at various stages of their evolution. The P~Cygni profiles of various lines present in the spectra are used to determine the velocity evolution of the ejecta. To account for the observed photometric and spectroscopic properties of the two SNe, we have computed 12\,$M_\odot$ zero-age main sequence (ZAMS) star models and evolved them until the onset of core collapse using the publicly available stellar-evolution code {\tt MESA}. Synthetic explosions were produced using the public version of {\tt STELLA} and another publicly available code, {\tt SNEC}, utilising the {\tt MESA} models. {\tt SNEC} and {\tt STELLA} provide various observable properties such as the bolometric luminosity and velocity evolution. The parameters produced by {\tt SNEC}/{\tt STELLA} and our observations show close agreement with each other, thus supporting a 12\,$M_\odot$ ZAMS star as the possible progenitor for SN~2015ap, while the progenitor of SN~2016bau is slightly less massive, being close to the boundary between SN and non-SN as the final product.