The CO White Dwarf + Intermediate Mass/Massive Star Binary Evolution: Possible Merger Origins for Peculiar Type Ia and II Supernovae

TL;DR

This study explores binary star evolution, focusing on mergers during the common envelope phase as potential origins for peculiar Type Ia and II supernovae, including superluminous variants, through detailed modeling.

Contribution

It introduces new binary evolution pathways involving CO white dwarfs and various stellar companions that could explain peculiar supernovae phenomena.

Findings

CO WD + intermediate star mergers can trigger SNe Ia with circumstellar interaction.

Rare CO WD + helium star core mergers may produce super-Chandrasekhar SNe Ia.

CO WD + massive star mergers could lead to superluminous Type II SNe like SN 2006gy.

Abstract

Binary stellar evolution has been studied as important pathway to initiate various transient events like supernovae (SNe). Although the common envelope (CE) in a binary, outcomes of the CE and conditions for the SN explosion during the CE phase are uncertain, it has been suggested that SN explosions can be triggered during the CE phase. In this work, we explore formation and evolution routes of carbon/oxygen (CO) WDs binaries in order to investigate mergers of CO WDs and cores of non-degenerate stars during the CE phase as possible origins for SNe under the core merger detonation (CMD) scenario by considering several binary physical models. Evolution of CO WD + intermediate mass normal (non-degenerate and hydrogen-rich) star binaries lead to mergers during the CE phases still may trigger type Ia SNe (SNe Ia) interacting with circumstellar material under different models. Mergers between CO WDs and cores of He (non-degenerate and helium-rich) stars within the CE phases are rare comparing to other CE merger events. These two channels may produce peculiar SNe Ia such as over-luminous/super-chandrasekhar mass SNe Ia as certain fraction of them have combined core masses $\geq2M_\odot$. In the channel of CO WD + massive star ($\geq8M_\odot$) CE events, we find that rates of mergers between CO WDs and He cores of massive stars are (0.85 - 12.18)$\times10^{-5}{M_\odot}^{-1}$ which may initiate type II superluminous SNe like SN 2006gy, and delay times from this scenario are in the range of 34 - 120 Myr. Our results based on the CMD model are comparable with observational results of peculiar SNe.