Suppose that $G$ is a simple adjoint reductive group over $\mathbf{ Q}$, with an exceptional Dynkin type, and with $G(\mathbf{ R})$ quaternionic (in the sense of Gross-Wallach). Then there is a notion of modular forms for $G$, anchored on the so-called quaternionic discrete series representations of $G(\mathbf{ R})$. The purpose of this paper is to give an explicit form of the Fourier expansion of modular forms on $G$, along the unipotent radical $N$ of the Heisenberg parabolic $P = MN$ of $G$.
Categories: math.NT math.RT