Displaying similar documents to “Galois actions on Néron models of Jacobians”

Equivariant Euler characteristics and sheaf resolvents

Ph. Cassou-Noguès, M.J. Taylor (2012)

Annales de l’institut Fourier

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For certain tame abelian covers of arithmetic surfaces we obtain formulas, involving a quadratic form derived from intersection numbers, for the equivariant Euler characteristics of both the canonical sheaf and also its square root. These formulas allow us to carry out explicit calculations; in particular, we are able to exhibit examples where these two Euler characteristics and that of the structure sheaf are all different and non-trivial. Our results are obtained by using resolvent...

Integral models for moduli spaces of G -torsors

Martin Olsson (2012)

Annales de l’institut Fourier

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Given a finite tame group scheme G , we construct compactifications of moduli spaces of G -torsors on algebraic varieties, based on a higher-dimensional version of the theory of twisted stable maps to classifying stacks.

Canonical integral structures on the de Rham cohomology of curves

Bryden Cais (2009)

Annales de l’institut Fourier

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For a smooth and proper curve X K over the fraction field K of a discrete valuation ring R , we explain (under very mild hypotheses) how to equip the de Rham cohomology H dR 1 ( X K / K ) with a : an R -lattice which is functorial in finite (generically étale) K -morphisms of X K and which is preserved by the cup-product auto-duality on H dR 1 ( X K / K ) . Our construction of this lattice uses a certain class of normal proper models of X K and relative dualizing sheaves. We show that our lattice naturally contains the lattice...

The Drinfeld Modular Jacobian J 1 ( n ) has connected fibers

Sreekar M. Shastry (2007)

Annales de l’institut Fourier

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We study the integral model of the Drinfeld modular curve X 1 ( n ) for a prime n ∈ 𝔽 q [ T ] . A function field analogue of the theory of Igusa curves is introduced to describe its reduction mod n . A result describing the universal deformation ring of a pair consisting of a supersingular Drinfeld module and a point of order n in terms of the Hasse invariant of that Drinfeld module is proved. We then apply Jung-Hirzebruch resolution for arithmetic surfaces to produce a regular model of X 1 ( n ) which, after contractions...

Smooth components of Springer fibers

William Graham, R. Zierau (2011)

Annales de l’institut Fourier

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This article studies components of Springer fibers for 𝔤𝔩 ( n ) that are associated to closed orbits of G L ( p ) × G L ( q ) on the flag variety of G L ( n ) , n = p + q . These components occur in any Springer fiber. In contrast to the case of arbitrary components, these components are smooth varieties. Using results of Barchini and Zierau we show these components are iterated bundles and are stable under the action of a maximal torus of G L ( n ) . We prove that if ℒ is a line bundle on the flag variety associated to a dominant weight,...