Hostname: page-component-7b7567c8c-fvjsw Total loading time: 0 Render date: 2026-11-15T22:58:14.344Z Has data issue: false hasContentIssue false

Natural boundary for the susceptibility function of generic piecewise expanding unimodal maps

Published online by Cambridge University Press:  25 January 2013

V. BALADI
Affiliation:
D.M.A., UMR 8553, École Normale Supérieure, 75005 Paris, France (email: baladi@math.ku.dk)
S. MARMI
Affiliation:
Scuola Normale Superiore, CNRS–UMI 3483 Fibonacci, 56126 Pisa, Italy (email: s.marmi@sns.it)
D. SAUZIN
Affiliation:
Scuola Normale Superiore, CNRS–UMI 3483 Fibonacci, 56126 Pisa, Italy (email: david.sauzin@sns.it)
Rights & Permissions [Opens in a new window]

Abstract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the 'Save PDF' action button.

For a piecewise expanding unimodal interval map $f$ with unique absolutely continuous invariant probability measure $\mu $, a perturbation $X$, and an observable $\varphi $, the susceptibility function is $\Psi _\varphi (z)= \sum _{k=0}^\infty z^k \int X(x) \varphi '( f^k)(x) (f^k)'(x) \, d\mu $. Combining previous results [V. Baladi, On the susceptibility function of piecewise expanding interval maps. Comm. Math. Phys.275 (2007), 839–859; V. Baladi and D. Smania, Linear response for piecewise expanding unimodal maps. Nonlinearity21 (2008), 677–711] (deduced from spectral properties of Ruelle transfer operators) with recent work of Breuer–Simon [Natural boundaries and spectral theory. Adv. Math.226 (2011), 4902–4920] (based on techniques from the spectral theory of Jacobi matrices and a classical paper of Agmon [Sur les séries de Dirichlet. Ann. Sci. Éc. Norm. Supér. (3) 66 (1949), 263–310]), we show that density of the postcritical orbit (a generic condition) implies that $\Psi _\varphi (z)$ has a strong natural boundary on the unit circle. The Breuer–Simon method provides uncountably many candidates for the outer functions of $\Psi _\varphi (z)$, associated with precritical orbits. If the perturbation $X$ is horizontal, a generic condition (Birkhoff typicality of the postcritical orbit) implies that the non-tangential limit of $\Psi _\varphi (z)$ as $z\to 1$ exists and coincides with the derivative of the absolutely continuous invariant probability measure with respect to the map (‘linear response formula’). Applying the Wiener–Wintner theorem, we study the singularity type of non-tangential limits of $\Psi _\varphi (z)$ as $z\to e^{i\omega }$ for real $\omega $. An additional ‘law of the iterated logarithm’ typicality assumption on the postcritical orbit gives stronger results.

Information

Type
Research Article
Copyright
©2013 Cambridge University Press