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Divisibility of torsion subgroups of abelian surfaces over number fields
- Source :
- Can. J. Math.-J. Can. Math. 74 (2022) 266-298
- Publication Year :
- 2019
-
Abstract
- Let $A$ be a 2-dimensional abelian variety defined over a number field $K$. Fix a prime number $\ell$ and suppose $\#A(\mathbb{F}_p) \equiv 0 \pmod{\ell^2}$ for a set of primes $\mathfrak{p} \subset \mathcal{O}_K$ of density 1. When $\ell=2$ Serre has shown that there does not necessarily exist a $K$-isogenous $A'$ such that $\#A'(K)_{\mathrm{tors}} \equiv 0 \pmod{4}$. We extend those results to all odd $\ell$ and classify the abelian varieties that fail this divisibility principle for torsion in terms of the image of the mod-$\ell^2$ representation.<br />Comment: 31 pages, 5 sections. Numerous changes in exposition have been made since the last version and section 6 has been removed, but all main results are the same. This is the version that will appear in the Canadian Journal of Mathematics
- Subjects :
- Mathematics - Number Theory
11G10, 11R32, 20G25
Subjects
Details
- Database :
- arXiv
- Journal :
- Can. J. Math.-J. Can. Math. 74 (2022) 266-298
- Publication Type :
- Report
- Accession number :
- edsarx.1912.02356
- Document Type :
- Working Paper
- Full Text :
- https://doi.org/10.4153/S0008414X20000759