English

Abelian surfaces good away from 2

Number Theory 2015-04-14 v1

Abstract

Fix a number field kk and a rational prime \ell. We consider abelian varieties whose \ell-power torsion generates a pro-\ell extension of k(μ)k(\mu_{\ell^\infty}) which is unramified away from \ell. It is a necessary, but not generally sufficient, condition that such varieties have good reduction away from \ell. In the special case of =2\ell = 2, we demonstrate that for abelian surfaces A/QA/\mathbb{Q}, good reduction away from \ell does suffice. The result is extended to elliptic curves and abelian surfaces over certain number fields unramified away from {2,}\{2,\infty\}. An explicit example is constructed to demonstrate that good reduction is not sufficient, at =2\ell = 2, for abelian varieties of sufficiently high dimension.

Keywords

Cite

@article{arxiv.1504.03047,
  title  = {Abelian surfaces good away from 2},
  author = {Christopher Rasmussen and Akio Tamagawa},
  journal= {arXiv preprint arXiv:1504.03047},
  year   = {2015}
}

Comments

9 pages, 1 table

R2 v1 2026-06-22T09:14:50.875Z