Azumaya algebras and once-punctured torus bundles

Abstract

Recent work of Chinburg, Reid, and Stover has shown that certain arithmetic and algebro-geometric properties of the character variety of a hyperbolic knot complement in the 3-sphere $M=S^3\setminus K$ yields topological and number theoretic information about Dehn fillings of M. Specifically, they show how the study of a certain extension problem for quaternion Azumaya algebras is related to topological invariants associated to these fillings. In this paper, we extend their work to the setting of hyperbolic once punctured torus bundles. Along the way, we exhibit new phenomenon in the relevant extension problem not visible in the case of a hyperbolic knot complement, which is related to the more complicated non-abelian reducible representation theory of hyperbolic once punctured torus bundles. We then apply these results to a series of examples from the literature and list some remaining questions from both works.