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Quadratic Chabauty Experiments on Genus 2 Bielliptic Modular Curves in the LMFDB

Number Theory 2025-09-29 v2

Abstract

We present results of quadratic Chabauty experiments on genus 2 bielliptic modular curves of Jacobian rank 2 that have recently been added to the LMFDB. We apply quadratic Chabauty methods over both the rationals and quadratic imaginary fields. In a number of cases, the experiments yielded algebraic irrational points among the set of mock rational points. We highlight specific notable examples, including the non-split Cartan modular curve Xns+(15)X^+_{ns}(15). Lastly, we offer a conjecture relating the level of the modular curve to the potential number fields over which points can arise.

Keywords

Cite

@article{arxiv.2507.03784,
  title  = {Quadratic Chabauty Experiments on Genus 2 Bielliptic Modular Curves in the LMFDB},
  author = {Kate Finnerty},
  journal= {arXiv preprint arXiv:2507.03784},
  year   = {2025}
}

Comments

17 pages, accepted to LuCaNT 2025 conference proceedings. Version 2 addresses referee comments