Excavating the Explosion and Progenitor Properties of Type IIP Supernovae via Modelling of their Optical Lightcurves

Abstract

The progenitors of Type IIP supernovae (SNe) are known to be red supergiants, but their properties are not well determined. We employ hydrodynamical modelling to investigate the explosion characteristics of eight Type IIP supernovae, and the properties of their progenitor stars. We create evolutionary models using the {\sc MESA} stellar evolution code, explode these models, and simulate the optical lightcurves using the {\sc STELLA} code. We fit the optical lightcurves, Fe II 5169\AA\ velocity, and photospheric velocity, to the observational data. Recent research has suggested that the progenitors of Type IIP SNe have a zero age main sequence (ZAMS) mass not exceeding $\sim18$ M$_{\odot}$. Our fits give a progenitor ZAMS mass $\leq18$ M$_{\odot}$ for seven of the supernovae. Where previous progenitor mass estimates exist, from various sources such as hydrodynamical modelling, multi-wavelength observations, or semi-analytic calculations, our modelling generally tends towards the lower mass values. This result is in contrast to results from previous hydrodynamical modelling, but is consistent with those obtained using general-relativistic radiation-hydrodynamical codes. We do find that one event, SN 2015ba, has a progenitor whose mass is closer to 24 M$_{\odot}$ , although we are unable to fit it well. We also derive the amount of $^{56}$Ni required to reproduce the tail of the lightcurve, and find values generally larger than previous estimates. Overall, we find that it is difficult to characterize the explosion by a single parameter, and that a range of parameters is needed.