The measure of maximal entropy for random skew products on compact complex surfaces

Abstract

Let $X$ be a compact complex surface. We prove that the skew product associated to a Borel probability measure $μ$ on $\operatorname{Aut}(X)$ admits a unique invariant measure of maximal fiber entropy, assuming that $μ$ satisfies a logarithmic integrability condition and that $\operatorname{supp}(μ)$ generates a non-elementary subgroup of $\operatorname{Aut}(X)$. We describe this measure canonically in terms of the random limit currents constructed by Cantat and Dujardin, and show that its fiber entropy is equal to the Furstenberg exponent of the associated random action on cohomology. Under an exponential moment assumption, we prove that it is mixing.