Thermodynamics formalism for singular flows

TL;DR

This paper proves that smooth three-dimensional flows with positive entropy have finitely many maximal entropy measures, all rapidly mixing, using a new symbolic coding system for flows with singularities.

Contribution

It introduces a novel symbolic coding framework for singular flows and establishes properties like finiteness and rapid mixing of maximal entropy measures.

Findings

Finitely many ergodic measures of maximal entropy exist.

All such measures are rapidly mixing within a dense open set.

The coding system extends to other singular flows and equilibrium states.

Abstract

We establish that $C^\infty$ three-dimensional flows with positive topological entropy admit only finitely many ergodic measures of maximal entropy, even when singularities (zero-velocity points) are present. Furthermore, every ergodic measure of maximal entropy is rapid mixing for such flows within a $C^\infty$ open and dense subset. To prove this, we develop a novel symbolic coding system for flows with singularities, which serves as a fundamental tool in this work. We also define the strong positive recurrence (SPR) property for singular flows and verify that SPR flows can be coded by suspension flows of SPR symbolic systems. This framework extends to other singular flows, including star flows, and to equilibrium states.