Domain of Discontinuity of Anosov Subgroups Acting on Bundles

Abstract: Let $\rho: \Gamma \to G$ be an Anosov representation, with $\Gamma$ a word hyperbolic group and $G$ a semisimple Lie group. Previous works (by Guichard--Wienhard, Kapovich--Leeb--Porti, and recently Carvajales--Stecker) constructed an open domain of discontinuity $\Omega_\rho \subset G/H$, where $H$ is a parabolic or symmetric subgroup. In this paper, we extend the properly discontinuous $\Gamma$-action (via $\rho$) to the space of connections on the pullback of the tangent bundle over $\Omega_\rho$. When $\Omega_\rho$ is a complex surface, we show that the $\Gamma$-action is properly discontinuous on the union of the Higgs bundle structures of the $(1,0)$ part of the complexification of these pullback bundles. We further construct a topological free group $F$ generated by these holomorphic line bundles and show that $\rho(\Gamma)$ acts properly discontinuously on $F \setminus {\mathrm{id}}$. This free group is shown to be well-defined up to isomorphism over the character variety of Zariski dense Anosov representations. Finally, we endow the space of Anosov representations with a categorical structure and construct a natural functor to the category of free groups.