Cohomological Weight Shiftings for Automorphic Forms on Definite Quaternion Algebras

Abstract

Let F/Q be a totally real field extension of degree g and let D be a definite quaternion algebra with center F. Fix an odd prime p which is unramified in F and D. We produce weight shiftings between (mod p) automorphic forms on the multiplicative group of D having fixed level. When the starting weight does not contain any (2,...,2)-block, we obtain these shiftings via maps induced in cohomology by intertwining operators acting on F_{p}-representations of GL(2,O_{F}/pO_{F}). Shiftings by (p-1,...,p-1) for weights containing (2,...,2)-blocks are obtained following the methods of Edixhoven-Khare, as half of our intertwining operators becomes trivial in this case.