The Energy Sharing Timescale in an Analytic Framework for Common Envelope Hydrodynamics

TL;DR

This paper introduces an analytical framework with new parameters to predict the energy sharing timescale in common envelope events, aligning well with hydrodynamical models and aiding binary evolution predictions.

Contribution

It presents a novel analytical model incorporating parameters that describe the energetics and hydrodynamics of envelope ejection during common envelope phases.

Findings

Parameters ξ and β effectively characterize CE ejection conditions.

The framework aligns with 3D hydrodynamical simulations.

Potential to improve binary population synthesis models.

Abstract

We propose a new predictive theory for the analysis of common envelope (CE) events which incorporates the effects of relevant hydrodynamical processes into a simple analytical framework. We introduce the ejection and dynamical parameters $\xi$ and $\beta$, which define if envelope ejection is energetically or hydrodynamically favorable, respectively, during CE inspiral. When combined, these parameters offer a detailed narrative of how inspiral begins, proceeds, and ends that is consistent with preliminary comparisons to 3D hydrodynamical models. This physically-motivated framework impacts predictions for CE outcomes, especially for systems that have energy excess, and offers promise as a potential alternative for the treatment of CE in binary population synthesis.