English

Bielliptic intermediate modular curves

Number Theory 2019-08-19 v2 Algebraic Geometry

Abstract

We determine which of the modular curves XΔ(N)X_\Delta(N), that is, curves lying between X0(N)X_0(N) and X1(N)X_1(N), are bielliptic. Somewhat surprisingly, we find that one of these curves has exceptional automorphisms. Finally we find all XΔ(N)X_\Delta(N) that have infinitely many quadratic points over Q\mathbb{Q}.

Keywords

Cite

@article{arxiv.1709.00510,
  title  = {Bielliptic intermediate modular curves},
  author = {Daeyeol Jeon and Chang Heon Kim and Andreas Schweizer},
  journal= {arXiv preprint arXiv:1709.00510},
  year   = {2019}
}

Comments

35 pages, published version, improved exposition, added many details