English

Counting surface subgroups in cusped hyperbolic 3-manifolds

Geometric Topology 2026-03-06 v2 Differential Geometry Group Theory

Abstract

Let M=H3/ΓM =\mathbb{H}^3/\Gamma be a finite-volume, noncompact hyperbolic 3-manifold. We show that the number of quasi-Fuchsian surface subgroups of Γ\Gamma (up to conjugacy and commensurability) of genus at most gg is bounded both above and below by functions of the form (cg)2g(cg)^{2g}. As a corollary, for all h4h\geq 4, the number of purely pseudo-Anosov closed surface subgroups of genus at most gg of the mapping class group Mod(Sh,0)\mathrm{Mod}(S_{h,0}) is bounded below by (Cg)2g(Cg)^{2g} for a universal constant CC. In contrast, for some g2g \geq 2, we construct infinitely many conjugacy classes of genus-gg surface subgroups of Γ\Gamma with accidental parabolics.

Keywords

Cite

@article{arxiv.2602.20098,
  title  = {Counting surface subgroups in cusped hyperbolic 3-manifolds},
  author = {Xiaolong Hans Han and Zhenghao Rao and Jia Wan},
  journal= {arXiv preprint arXiv:2602.20098},
  year   = {2026}
}

Comments

25 pages, 3 figures

R2 v1 2026-07-01T10:48:17.696Z