Hodge classes and the Jacquet–Langlands correspondence

Abstract

Abstract We prove that the Jacquet–Langlands correspondence for cohomological automorphic forms on quaternionic Shimura varieties is realized by a Hodge class. Conditional on Kottwitz’s conjecture for Shimura varieties attached to unitary similitude groups, we also show that the image of this Hodge class in $\ell $ -adic cohomology is Galois invariant for all $\ell $ .