Comprehensive study of ejecta-companion interaction for core-collapse supernovae in massive binaries

TL;DR

This study comprehensively simulates supernova ejecta-companion interactions in massive binaries, revealing deviations from classical models and providing a new simplified model to predict impact velocities and post-supernova companion evolution.

Contribution

It introduces a new simple model for ejecta-companion impact velocities and explores the long-term evolution of the companion star after supernovae in massive binaries.

Findings

Classical models often deviate significantly from simulation results.

The companion star can become over a magnitude more luminous immediately after supernova.

The companion's luminosity returns to normal within about 10 years.

Abstract

We carry out a comprehensive study of supernova ejecta-companion interaction in massive binary systems. We aim to physically understand the kinematics of the interaction and predict observational signatures. To do this we perform simulations over a vast parameter space of binary configurations, varying the masses of the progenitor and companion, structure of the companion, explosion energy, and orbital separation. Our results were not so consistent with classical models by Wheeler et al. 1975, sometimes deviating by an order of magnitude. We construct an alternative simple model which explains the simulated results reasonably well and can be used to estimate impact velocities for arbitrary explosion profiles and companion star structures. We then investigate the long term evolution after the supernova, where the companion can be inflated by the energy injected into the star. We find that the companion can become more than an order of magnitude overluminous straight after the supernova, but quickly fades away after $\sim10$ years and returns to its original luminosity in about a thermal timescale of the star. Finally, we also discuss the possible surface contamination of heavy elements from the slower ejecta.