English

On the Gauss map of equivariant immersions in hyperbolic space

Differential Geometry 2024-10-25 v2 Geometric Topology Symplectic Geometry

Abstract

Given an oriented immersed hypersurface in hyperbolic space Hn+1\mathbb{H}^{n+1}, its Gauss map is defined with values in the space of oriented geodesics of Hn+1\mathbb{H}^{n+1}, which is endowed with a natural para-K\"ahler structure. In this paper we address the question of whether an immersion GG of the universal cover of an nn-manifold MM, equivariant for some group representation of π1(M)\pi_1(M) in Isom(Hn+1)\mathrm{Isom}(\mathbb{H}^{n+1}), is the Gauss map of an equivariant immersion in Hn+1\mathbb{H}^{n+1}. We fully answer this question for immersions with principal curvatures in (1,1)(-1,1): while the only local obstructions are the conditions that GG is Lagrangian and Riemannian, the global obstruction is more subtle, and we provide two characterizations, the first in terms of the Maslov class, and the second (for MM compact) in terms of the action of the group of compactly supported Hamiltonian symplectomorphisms.

Keywords

Cite

@article{arxiv.2008.07390,
  title  = {On the Gauss map of equivariant immersions in hyperbolic space},
  author = {Christian El Emam and Andrea Seppi},
  journal= {arXiv preprint arXiv:2008.07390},
  year   = {2024}
}

Comments

55 pages, 12 figures. Minor improvements with respect to the previous version