On the Boundary and Intersection Motives of Genus 2 Hilbert-Siegel Varieties
Documenta mathematica, Tome 24 (2019), pp. 1033-1098
We study genus 2 Hilbert-Siegel varieties, i.e. Shimura varieties SK corresponding to the group GSp4,F over a totally real field F, along with the relative Chow motives λV of abelian type over SK obtained from irreducible representations Vλ of GSp4,F. We analyse the weight filtration on the degeneration of such motives at the boundary of the Baily-Borel compactification and we find a criterion on the highest weight λ, potentially generalisable to other families of Shimura varieties, which characterizes the absence of the middle weights 0 and 1 in the corresponding degeneration. Thanks to Wildeshaus' theory, the absence of these weights allows us to construct Hecke-equivariant Chow motives over Q, whose realizations equal interior (or intersection) cohomology of SK with Vλ-coefficients. We give applications to the construction of homological motives associated to automorphic representations.
Classification :
11F46, 11F70, 11G18, 14G35
Mots-clés : Shimura varieties, Hilbert-Siegel varieties, boundary motive, intersection motive, weight structures, motives for Hilbert-Siegel modular forms
Mots-clés : Shimura varieties, Hilbert-Siegel varieties, boundary motive, intersection motive, weight structures, motives for Hilbert-Siegel modular forms
@article{10_4171_dm_699,
author = {Mattia Cavicchi},
title = {On the {Boundary} and {Intersection} {Motives} of {Genus} 2 {Hilbert-Siegel} {Varieties}},
journal = {Documenta mathematica},
pages = {1033--1098},
year = {2019},
volume = {24},
doi = {10.4171/dm/699},
url = {http://geodesic.mathdoc.fr/articles/10.4171/dm/699/}
}
Mattia Cavicchi. On the Boundary and Intersection Motives of Genus 2 Hilbert-Siegel Varieties. Documenta mathematica, Tome 24 (2019), pp. 1033-1098. doi: 10.4171/dm/699
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