Adapted random perturbations for non-uniformly expanding maps

Abstract

We obtain stochastic stability of C2 non-uniformly expanding one-dimensional endomorphisms, requiring only that the first hyperbolic time map be L^{p}-integrable for p>3. We show that, under this condition (which depends only on the unperturbed dynamics), we can construct a random perturbation that preserves the original hyperbolic times of the unperturbed map and, therefore, to obtain non-uniform expansion for random orbits. This ensures that the first hyperbolic time map is uniformly integrable for all small enough noise levels, which is known to imply stochastic stability. The method enables us to obtain stochastic stability for a class of maps with infinitely many critical points. For higher dimensional endomorphisms, a similar result is obtained, but under stronger assumptions.Comment: 25 pages; 1 figure; many typos corrected. Keywords: stochastic stability, additive perturbation, non-uniform expansion, slow recurrence, adapted random perturbation, stationary measures, physical measures, first hyperbolic time map. To be published in Stochastics and Dynamic