Arithmetic compactifications of integral models of Shimura varieties of abelian type
Abstract
In this paper, we construct good toroidal and minimal compactifications in the sense of Lan-Stroh for integral models of abelian-type Shimura varieties. We start with finding suitable types of cusp labels and cone decompositions which are compatible with those of the associated Hodge-type Shimura varieties. We then study the action of -points of the adjoint group on boundary charts and toroidal compactifications of Hodge-type integral models. In particular, we extend the twisting construction of Kisin and Pappas to boundary charts. Finally, up to taking refinements of cone decompositions, we construct an abelian-type toroidal compactification as an open and closed algebraic subspace of a quotient from a disjoint union of Hodge-type toroidal compactifications and construct minimal compactifications with a similar method. Furthermore, we show results on nearby cycles of these compactifications and verify Pink's formula when the level at is an intersection of quasi-parahoric subgroups.
Keywords
Cite
@article{arxiv.2505.09135,
title = {Arithmetic compactifications of integral models of Shimura varieties of abelian type},
author = {Peihang Wu},
journal= {arXiv preprint arXiv:2505.09135},
year = {2025}
}
Comments
v2: 151 pages. minor changes on typos. Added: A workflow diagram; Section 5.5 on nearby cycles