Acoustic geometry for general relativistic barotropic irrotational fluid flow

TL;DR

This paper develops a framework using differential geometry to describe sound propagation in general relativistic barotropic irrotational fluids within arbitrary curved spacetimes, extending previous non-relativistic models.

Contribution

It provides a pedagogical derivation of the acoustic spacetime for relativistic fluids in arbitrary curved backgrounds, broadening the scope of acoustic geometry models.

Findings

Derivation of the relativistic acoustic spacetime in curved backgrounds

Extension of non-relativistic models to general relativistic fluids

Framework applicable to arbitrary (d+1) dimensional spacetimes

Abstract

"Acoustic spacetimes", in which techniques of differential geometry are used to investigate sound propagation in moving fluids, have attracted considerable attention over the last few decades. Most of the models currently considered in the literature are based on non-relativistic barotropic irrotational fluids, defined in a flat Newtonian background. The extension, first to special relativistic barotropic fluid flow, and then to general relativistic barotropic fluid flow in an arbitrary background, is less straightforward than it might at first appear. In this article we provide a pedagogical and simple derivation of the general relativistic "acoustic spacetime" in an arbitrary (d+1) dimensional curved-space background.