English

Bogomolov property for Galois representations with big local image

Number Theory 2025-10-24 v3

Abstract

An algebraic extension of the rational numbers is said to have the Bogomolov property\textit{Bogomolov property} (B) if the absolute logarithmic Weil height of its non-torsion elements is uniformly bounded from below. Given a continuous representation ρ\rho of the absolute Galois group GKG_{\mathbb{K}} of a number field K{\mathbb{K}}, one says that ρ\rho has (B) if the subfield of Q\overline{\mathbb{Q}} fixed by kerρ\mathrm{ker}\,\rho has (B). We prove that, if ρ:GKGLd(Zp)\rho:G_{\mathbb{K}} \to \mathrm{GL}_d({\mathbb{Z}}_p) maps an inertia subgroup at a prime above pp surjectively onto an open subgroup of GLd(Zp)\mathrm{GL}_d({\mathbb{Z}}_p), then ρ\rho has (B). More generally, we show that if the image of inertia is open in the image of the decomposition group, the normal closure of the local image is sufficiently large in the global one, and a certain condition on the center of ρ(GK)\rho(G_{\mathbb{K}}) satisfied, then ρ\rho has (B). In particular, no assumption on the modularity of ρ\rho is needed, contrary to previous work of Habegger and Amoroso--Terracini. We provide several examples both in modular and non-modular cases. Our methods rely on a result of Sen comparing the ramification and Lie filtrations on the pp-adic Lie group ρ(GK)\rho(G_{\mathbb{K}}).

Keywords

Cite

@article{arxiv.2503.14052,
  title  = {Bogomolov property for Galois representations with big local image},
  author = {Andrea Conti and Lea Terracini},
  journal= {arXiv preprint arXiv:2503.14052},
  year   = {2025}
}

Comments

38 pages. Weakened the hypothesis of potential total ramifiedness to local potential total ramifiedness together with a normal closure assumption. Included some applications to elliptic curves over number fields and abelian varieties