On the number of invariant measures for random expanding maps in higher dimensions

TL;DR

This paper extends the understanding of invariant measures for random multidimensional expanding maps, showing that such systems have finitely many ergodic absolutely continuous invariant measures with bounds on their number.

Contribution

It generalizes previous results to the quenched setting of random Jab extl{}onski maps, establishing finiteness and bounds on the number of ergodic ACIPs.

Findings

Finite number of ergodic ACIPs for the system.

Provided upper bounds on the number of mutually singular ergodic ACIPs.

Extended results to the quenched random setting in higher dimensions.

Abstract

In \cite{J}, Jab\l o\'{n}ski proved that a piecewise expanding $C^{2}$ multidimensional Jab\l o\'{n}ski map admits an absolutely continuous invariant probability measure (ACIP). In \cite{BL}, Boyarsky and Lou extended this result to the case of i.i.d. compositions of the above maps, with an on average expanding condition. We generalize these results to the (quenched) setting of random Jab\l o\'{n}ski maps, where the randomness is governed by an ergodic, invertible and measure preserving transformation. We prove that the skew product associated to this random dynamical system admits a finite number of ergodic ACIPs. Furthermore, we provide two different upper bounds on the number of mutually singular ergodic ACIP's, motivated by the works of Buzzi \cite{B} in one dimension and Gora, Boyarsky and Proppe \cite{GBP} in higher dimensions.