# Companion-driven evolution of massive stellar binaries

## TL;DR

This study investigates how a third star influences the evolution of massive binary systems through the EKL mechanism, revealing that initial conditions significantly shape their final orbital properties, consistent with observations.

## Contribution

The paper introduces a comprehensive analysis of the EKL mechanism's impact on massive binaries, incorporating tidal and relativistic effects, and uses large-scale simulations to connect birth conditions with observed orbital distributions.

## Key findings

- Final eccentricity distribution reflects birth conditions.
- Period distributions are similarly indicative of initial states.
- Observed period distribution aligns with EKL evolution predictions.

## Abstract

At least $70\%$ of massive OBA-type stars reside in binary or higher-order systems. The dynamical evolution of these systems can lend insight into the origins of extreme phenomena such as X-ray binaries and gravitational wave sources. In one such dynamical process, the Eccentric Kozai-Lidov (EKL) Mechanism, a third companion star alters the secular evolution of a binary system. For dynamical stability, these triple systems must have a hierarchical configuration. We explore the effects of a distant third companion's gravitational perturbations on a massive binary's orbital configuration before significant stellar evolution has taken place ($\leq 10$ Myr). We include tidal dissipation and general relativistic precession. With large ($38,000$ total) Monte-Carlo realizations of massive hierarchical triples, we characterize imprints of the birth conditions on the final orbital distributions. Specifically, we find that the final eccentricity distribution over the range $0.1-0.7$ is an excellent indicator of its birth distribution. Furthermore, we find that the period distributions have a similar mapping for wide orbits. Finally, we demonstrate that the observed period distribution for approximately $10$ Myr-old massive stars is consistent with EKL evolution.