Type Ia supernovae from wide white dwarfs triples

Abstract

ABSTRACT For ultra-wide systems (with outer orbit >103 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 Ia) 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 SN Ia from the direct collision channel is to be $0.11\!-\!3.76{{\ \rm per\ cent}}$ and primarily $1\!-\!36{{\ \rm per\ cent}}$ from the DD scenario. The spread in the range is due to uncertainty in the underlying population and two types of galaxies, where elliptical galaxies host higher fraction. and primarily $2\!-\!36{{\ \rm per\ cent}}$ from the DD scenario.