Perfectoid overconvergent Siegel modular forms and the overconvergent Eichler-Shimura morphism

Abstract: The aim of this paper is twofold. We first present a construction of overconvergent automorphic sheaves for Siegel modular forms by generalising the perfectoid method, originally introduced by Chojecki-Hansen-Johansson for automorphic forms on compact Shimura curves over $\mathbf{Q}$. These sheaves are then verified to be isomorphic to the ones introduced by Andreatta-Iovita-Pilloni. Secondly, we establish an overconvergent Eichler-Shimura morphism for Siegel modular forms, generalising the result of Andreatta-Iovita-Stevens for elliptic modular forms.