Genus 1 Curves in Severi--Brauer Surfaces
Abstract
In a talk at the Banff International Research Station in 2015 Asher Auel asked questions about genus one curves in Severi-Brauer varieties $SB(A)$. More specifically he asked about the smooth cubic curves in Severi-Brauer surfaces, that is in $SB(D)$ where $D/F$ is a degree three division algebra. Even more specifically, he asked about the Jacobian, $E$, of these curves. In this paper we give a version of an answer to both these questions, describing the surprising connection between these curves and properties of the algebra $A$. Let $F$ contain $\rho$, a primitive third root of one. Since $D/F$ is cyclic, it is generated over $F$ by $x,y$ such that $xy = \rho{yx}$ and we call $x,y$ a skew commuting pairs. The connection mentioned above is between the Galois structure of the three torsion points $E[3]$ and the Galois structure of skew commuting pairs in extensions $D \otimes_F K$. Given a description of which $E$ arise, we then describe, via Galois cohomology, which $C$ arise.
- Publication:
-
arXiv e-prints
- Pub Date:
- May 2021
- DOI:
- 10.48550/arXiv.2105.09986
- arXiv:
- arXiv:2105.09986
- Bibcode:
- 2021arXiv210509986S
- Keywords:
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- Mathematics - Algebraic Geometry;
- Mathematics - Rings and Algebras