A Dynamical Fekete-Szegő Theorem

Fuente: arXiv
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Autori principali: Bayraktar, Turgay, Efe, Melike
Natura: Preprint
Pubblicazione: 2026
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author Bayraktar, Turgay
Efe, Melike
author_facet Bayraktar, Turgay
Efe, Melike
contents Let $E\subset\Bbb{C}$ be a compact set symmetric with respect to the real axis. A classical theorem of Fekete-Szegő asserts that such a compact set is of logarithmic capacity at least one if and only if it admits approximation by algebraic integers whose Galois conjugates lie arbitrarily close to $E$. In this note we prove a dynamical analogue of this phenomenon. When $\mathrm{cap}(E)=1$, we also show that the algebraic polynomials arising from the Fekete-Szegő theorem generate filled Julia sets $K_{P_n}$ which converge to the polynomially convex hull $Pc(E)$ in the Klimek topology, while their Brolin measures converge to the equilibrium measure $μ_E$. In particular, when $E\subset\Bbb{R}$, this provides a genuine approximation of $E$ by algebraic filled Julia sets. As an arithmetic application, we prove that the Rumely height associated to $E$ arises as a limit of canonical dynamical heights in the sense of Call and Silverman, giving a dynamical counterpart to the equidistribution theorems of Bilu and Rumely.
format Preprint
id arxiv_https___arxiv_org_abs_2603_01684
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle A Dynamical Fekete-Szegő Theorem
Bayraktar, Turgay
Efe, Melike
Dynamical Systems
Complex Variables
Number Theory
37F50, 11G50, 31A15
Let $E\subset\Bbb{C}$ be a compact set symmetric with respect to the real axis. A classical theorem of Fekete-Szegő asserts that such a compact set is of logarithmic capacity at least one if and only if it admits approximation by algebraic integers whose Galois conjugates lie arbitrarily close to $E$. In this note we prove a dynamical analogue of this phenomenon. When $\mathrm{cap}(E)=1$, we also show that the algebraic polynomials arising from the Fekete-Szegő theorem generate filled Julia sets $K_{P_n}$ which converge to the polynomially convex hull $Pc(E)$ in the Klimek topology, while their Brolin measures converge to the equilibrium measure $μ_E$. In particular, when $E\subset\Bbb{R}$, this provides a genuine approximation of $E$ by algebraic filled Julia sets. As an arithmetic application, we prove that the Rumely height associated to $E$ arises as a limit of canonical dynamical heights in the sense of Call and Silverman, giving a dynamical counterpart to the equidistribution theorems of Bilu and Rumely.
title A Dynamical Fekete-Szegő Theorem
topic Dynamical Systems
Complex Variables
Number Theory
37F50, 11G50, 31A15
url https://arxiv.org/abs/2603.01684