Properties of the maximal entropy measure and geometry of Hénon attractors

Abstract

We consider an abundant class of non-uniformly hyperbolic $C^2$-Hénon like diffeomorphisms called strongly regular and which corresponds to Benedicks–Carleson parameters. We prove the existence of $m>0$ such that for any such diffeomorphism $f$, every invariant probability measure of $f$ has a Lyapunov exponent greater than $m$, answering a question of L. Carleson. Moreover, we show the existence and uniqueness of a measure of maximal entropy, which answers a question of M. Lyubich and Y. Pesin. We also prove that the maximal entropy measure is equidistributed on the periodic points and is finitarily Bernoulli, which gives an answer to a question of J.-P. Thouvenot. Finally, we show that the maximal entropy measure is exponentially mixing and satisfies the central limit theorem. The proof is based on a new construction of a Young tower for which the first return time coincides with the symbolic return time, and whose orbit is conjugate to a strongly positive recurrent Markov shift.