On the existence of solutions and causality for relativistic viscous conformal fluids

TL;DR

This paper demonstrates the causality and well-posedness of equations describing relativistic viscous conformal fluids, both in flat spacetime and when coupled to gravity, ensuring physical consistency of such models.

Contribution

It proves causality and solves the initial-value problem for a specific viscous conformal fluid model in relativistic settings.

Findings

Equations are causal in Minkowski spacetime.

Solutions exist when coupled to Einstein's equations.

The initial-value problem is well-posed.

Abstract

We consider a stress-energy tensor describing a pure radiation viscous fluid with conformal symmetry introduced in arXiv:1708.06255. We show that the corresponding equations of motions are causal in Minkowski background and also when coupled to Einstein's equations, and solve the associated initial-value problem.