On the Motion of Compact Objects in Relativistic Viscous Fluids

TL;DR

This paper develops an effective field theory framework to describe the motion of compact objects in relativistic viscous fluids, simplifying the analysis by converting fluid-object interactions into source terms in the action.

Contribution

It introduces a world-line effective field theory approach for relativistic compact objects in viscous fluids, avoiding boundary value problems and deriving equations of motion in curved spacetime.

Findings

Derived relativistic equations of motion for objects in viscous fluids.

Presented a method to incorporate fluid interactions as source terms in the action.

Applicable in regimes with small velocity gradients relative to object size.

Abstract

We present a world-line effective field theory of compact objects moving relativistically through a viscous fluid. The theory is valid when velocity gradients are small compared to the inverse size of the object. Working within the EFT eliminates the need to solve a boundary value problem by turning all interactions between the fluid and the object into a source term in the action. We use the EFT to derive the relativistic equations of motion for a compact object immersed in a viscous fluid in a curved background.