Type Ia Supernovae from wide white-dwarfs triples

TL;DR

This paper explores how ultra-wide triple white-dwarf systems in the galactic field can become dynamically unstable due to stellar flybys, leading to collisions that produce Type Ia supernovae, with estimated galactic rates of 0.1%-36%.

Contribution

It introduces a new channel for Type Ia supernovae involving dynamical instability and resonant encounters in ultra-wide triple white-dwarf systems.

Findings

Galactic rate of Type Ia SN from direct collisions: 0.1%-4%.

Galactic rate from double-degenerate scenario: 2%-36%.

Ultra-wide triples can become unstable and produce supernovae via stellar flybys.

Abstract

For ultra-wide systems (with outer orbit >$10^{3}{\rm AU})$ the galactic field is collisional. Hence, ultra-wide triple white-dwarfs (TWDs) can be perturbed, by flyby stars, to sufficiently high outer eccentricity such that the triple becomes dynamically unstable. An unstable triple undergoes multiple binary-single resonant encounters between all three WDs. These encounters might result in a direct collision between any random two WDs and lead to a Type Ia supernova (SN) event. In case where the multiple resonant encounters did not produce a collision a compact binary is formed (while the third WD is ejected), this binary either collides or merges via gravitational wave emission, similar to the classic double-degenerate (DD) channel. In this research study we estimate the galactic rates of Type Ia SN from the direct collision channel is to be $0.1\%-4\%$ and primarily $2\%-36\%$ from the DD scenario.