Degenerations of Complex Dynamical Systems II: Analytic and Algebraic Stability

Abstract

We study pairs $(f, Γ)$ consisting of a non-Archimedean rational function $f$ and a finite set of vertices $Γ$ in the Berkovich projective line, under a certain stability hypothesis. We prove that stability can always be attained by enlarging the vertex set $Γ$. As a byproduct, we deduce that meromorphic maps preserving the fibers of a rationally-fibered complex surface are algebraically stable after a proper modification. The first article in this series examined the limit of the equilibrium measures for a degenerating 1-parameter family of rational functions on the Riemann sphere. Here we construct a convergent countable-state Markov chain that computes the limit measure. A classification of the periodic Fatou components for non-Archimedean rational functions, due to Rivera-Letelier, plays a key role in the proofs of our main theorems. The appendix contains a proof of this classification for all tame rational functions.

* Added appendix by Jan Kiwi on classification of periodic Fatou components (due to Rivera-Letelier) * To appear in Mathematische Annalen: The final publication is available at Springer via http://dx.doi.org/10.1007/s00208-015-1331-8