Dynamical Friction and Tidal Interactions

TL;DR

This paper develops a linear perturbation method to analyze how tidal interactions influence dynamical friction in stellar systems, extending classical formulas and providing initial estimates of tidal effects.

Contribution

It introduces a perturbation scheme that incorporates tidal effects into dynamical friction calculations, aligning with Chandrasekhar's formula when tides are absent.

Findings

Dynamical friction force derived with tidal effects included

Agreement with Chandrasekhar's formula in the no-tide limit

Preliminary estimates of tidal contributions to dynamical friction

Abstract

We discuss dynamical friction in an $N$-body system in the presence of tidal interactions caused by a distant external source. Using the distant tide approximation, we develop a perturbation scheme for the calculation of dynamical friction that takes tidal effects into account to linear order. In this initial analytic approach to the problem, we neglect the influence of tides on the distribution function of stars in the background stellar system. Our result for the dynamical friction force in the appropriate limit is in agreement with Chandrasekhar's formula in the absence of tides. We provide preliminary estimates for the tidal contributions to the dynamical friction force. The astrophysical implications of our results are briefly discussed.