Hecke orbits on Shimura varieties of Hodge type

Fuente: arXiv
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Autores principales: D'Addezio, Marco, van Hoften, Pol
Formato: Preprint
Publicado: 2022
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_version_ 1866929758615371776
author D'Addezio, Marco
van Hoften, Pol
author_facet D'Addezio, Marco
van Hoften, Pol
contents We prove the Hecke orbit conjecture of Chai--Oort for Shimura varieties of Hodge type at odd primes of good reduction. We use a novel result for the local monodromy groups of $F$-isocrystals "coming from geometry", which refines Crew's parabolicity conjecture. In the course of the proof, we also introduce a noncommutative generalisation of Serre--Tate coordinates for formal neighbourhoods of central leaves, built upon the previous work of Caraiani--Scholze and Kim. Using these coordinates, we reinterpret Chai--Oort's notion of strongly Tate-linear subspaces and we establish upper bounds for their monodromy groups. For this step, we employ the notion of Cartier--Witt stacks, as introduced by Drinfeld and Bhatt--Lurie. Another crucial ingredient in the proof is a rigidity result proved by Chai--Oort, which shows that the relevant subspaces are strongly Tate-linear. On the way, we generalise de Jong's full faithfulness theorem for $F$-isocrystals.
format Preprint
id arxiv_https___arxiv_org_abs_2205_10344
institution arXiv
publishDate 2022
record_format arxiv
spellingShingle Hecke orbits on Shimura varieties of Hodge type
D'Addezio, Marco
van Hoften, Pol
Algebraic Geometry
Number Theory
11G18 (Primary) 14G35 (Secondary)
We prove the Hecke orbit conjecture of Chai--Oort for Shimura varieties of Hodge type at odd primes of good reduction. We use a novel result for the local monodromy groups of $F$-isocrystals "coming from geometry", which refines Crew's parabolicity conjecture. In the course of the proof, we also introduce a noncommutative generalisation of Serre--Tate coordinates for formal neighbourhoods of central leaves, built upon the previous work of Caraiani--Scholze and Kim. Using these coordinates, we reinterpret Chai--Oort's notion of strongly Tate-linear subspaces and we establish upper bounds for their monodromy groups. For this step, we employ the notion of Cartier--Witt stacks, as introduced by Drinfeld and Bhatt--Lurie. Another crucial ingredient in the proof is a rigidity result proved by Chai--Oort, which shows that the relevant subspaces are strongly Tate-linear. On the way, we generalise de Jong's full faithfulness theorem for $F$-isocrystals.
title Hecke orbits on Shimura varieties of Hodge type
topic Algebraic Geometry
Number Theory
11G18 (Primary) 14G35 (Secondary)
url https://arxiv.org/abs/2205.10344