iPTF14hls in the circumstellar medium interaction model: A promising candidate for a pulsational pair-instability supernova

TL;DR

This paper investigates iPTF14hls as a potential pulsational pair-instability supernova, modeling its light curve with circumstellar medium interaction and inferring significant mass loss episodes over centuries.

Contribution

It presents an analytic model fitting the supernova's light curve with wind-like circumstellar material, suggesting multiple mass loss episodes and supporting its classification as a pulsational pair-instability supernova.

Findings

iPTF14hls's light curve can be explained by CSM interaction.

The supernova experienced six mass loss episodes over 200 years.

Total ejecta and CSM mass estimated around 245 solar masses.

Abstract

iPTF14hls is a luminous Type II supernova (SN) with a bumpy light curve that remains debated for its origin. It maintains roughly a constant effective temperature and luminosity since discovery for about 600 days, followed by a slow decay. On $\sim 1000$\ days post discovery the light curve transitions to a very steep decline. A spectrum taken during this steep decline phase shows clear signatures of shock interaction with dense circumstellar medium (CSM). Here we explore the possibility of iPTF14hls as an interaction-powered SN. The light curve of iPTF14hls can be fitted with wind-like CSMs. Analytic modeling indicates that iPTF14hls may have undertaken six episodes of mass loss during the last $\sim 200\mathrm{yr}$. Assuming that the 1954 eruption triggered the last mass-loss episode, the stellar-wind velocity is determined to be $40-70\mathrm{km}\mathrm{s}^{-1}$, depending on different models. Mass loss rates are in the range $% 0.4-3.3M_{\odot }\mathrm{yr}^{-1}$. The inferred total mass of ejecta and CSMs ($M_{\mathrm{ej}}+M_{\mathrm{CSMs}}\simeq 245M_{\odot }$) supports the idea that iPTF14hls may be a candidate for a (pulsational) pair-instability SN. Discovery and observations of more similar stellar explosions will help understand these peculiar SNe.