Browsing by Author "Viray, Bianca"

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    Abelian n -Division Fields of Elliptic Curves and Brauer Groups of Product Kummer & Abelian Surfaces
    (Cambridge University Press, 2017) Várilly-Alvarado, Anthony; Viray, Bianca
    Let Y be a principal homogeneous space of an abelian surface, or a K3 surface, over a finitely generated extension of Q. In 2008, Skorobogatov and Zarhin showed that the Brauer group modulo algebraic classes BrY/Br1Y is finite. We study this quotient for the family of surfaces that are geometrically isomorphic to a product of isogenous non-CM elliptic curves, as well as the related family of geometrically Kummer surfaces; both families can be characterized by their geometric Néron–Severi lattices. Over a field of characteristic 0, we prove that the existence of a strong uniform bound on the size of the odd torsion of BrY/Br1Y is equivalent to the existence of a strong uniform bound on integers n for which there exist non-CM elliptic curves with abelian n-division fields. Using the same methods we show that, for a fixed prime ℓ, a number field k of fixed degree r, and a fixed discriminant of the geometric Néron–Severi lattice, #(BrY/Br1Y)[ℓ∞] is bounded by a constant that depends only on ℓ, r, and the discriminant.
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    Arithmetic of del Pezzo surfaces of degree 4 and vertical Brauer groups
    (Elsevier, 2014) Varilly-Alvarado, Anthony; Viray, Bianca