Angular Momentum Loss During Stable Mass Transfer onto a Compact object: the Effect of Mass Loss via Accretion Disk Winds

TL;DR

This paper develops an analytic model to quantify how winds from accretion disks around compact objects cause greater angular momentum loss during stable mass transfer, significantly affecting binary orbit evolution.

Contribution

It introduces a physically-motivated prescription for disk wind angular momentum loss, showing it exceeds standard models and impacts orbital evolution calculations.

Findings

Disk wind angular momentum loss is 3-40 times greater than standard models.

Accounting for disk winds can reduce orbital separations by up to 60%.

The effect is significant for mass ratios between 2 and 10.

Abstract

We use an analytic framework to calculate the evolution of binary orbits under a physically-motivated model that accounts for angular momentum loss associated with winds from an accretion disk around the compact objected accretor. Our prescription considers wind mass ejection from the surface of an accretion disk, accounting for a radial mass-loss dependence across the disk surface. We compare this to the standard prescription of angular momentum loss associated with isotropic mass loss from the vicinity of the accretor. The angular momentum loss from a disk-wind is always larger. For mass ratios, $q$, between $2$--$10$, angular momentum loss via a disk wind is $\simeq3$--$40$ times greater than the standard prescription. For the majority of mass ratios and disk properties, accounting for the disk wind can result in considerably smaller orbital separations compared to the standard formalism; the differences being $\simeq 60\%$ depending on how long the effect is integrated for. We conclude that it is important to consider the effects of angular momentum loss from a disk wind when evolving binary orbits.