Possible Signatures of Ejecta-Companion Interaction in iPTF 13bvn

TL;DR

This paper explores how supernova ejecta interacting with a binary companion in iPTF 13bvn could produce observable signatures, predicting the companion's post-explosion appearance to aid future detection efforts.

Contribution

It combines hydrodynamical and evolutionary simulations to predict the observable effects of ejecta-companion interaction in a specific supernova, guiding future observational searches.

Findings

Companion star will be heated and expand, resembling a red supergiant.

Post-supernova companion will have increased luminosity and lower surface temperature.

Predicted observable signatures can help identify the binary companion in future observations.

Abstract

We investigate the possible effects of the supernova ejecta hitting the companion star in iPTF 13bvn, focusing on the observable features when it becomes visible. iPTF 13bvn is a type Ib supernova that may become the first case that its progenitor is identified as a binary by near future observations. According to calculations by Bersten et al. (2014), the progenitor should have a mass $\approx3.5M_\odot$ to reproduce the supernova light curve, and such compact stars could only be produced via binary evolution. This is one of the reasons that we expect the progenitor to be a binary, but it should be confirmed by observing the remaining companion after the supernova. Their evolutionary calculations suggest that the companion star will be an overluminous OB star at the moment of supernova. With a combination of hydrodynamical and evolutionary simulations, we find that the secondary star will be heated by the supernova ejecta and expand to have larger luminosities and lower surface effective temperatures. The star will look rather like a red super giant, and this should be taken into account when searching for the companion star in the supernova ejecta in future observations.