English

Rational torsion of generalised modular Jacobians of odd level

Number Theory 2022-10-21 v3

Abstract

We consider the generalised Jacobian J0(N)mJ_{0}(N)_{\mathbf{m}} of the modular curve X0(N)X_{0}(N) of level NN, with respect to the modulus m\mathbf{m} consisting of all cusps on the modular curve. When NN is odd, we determine the group structure of the rational torsion J0(N)m(Q)torJ_{0}(N)_{\mathbf{m}}(\mathbb{Q})_{tor} up to 22-primary and ll-primary parts for any prime ll dividing NN. Our results extend those of Wei--Yamazaki for squarefree levels and Yamazaki--Yang for prime-power levels.

Keywords

Cite

@article{arxiv.2112.03741,
  title  = {Rational torsion of generalised modular Jacobians of odd level},
  author = {Mar Curcó Iranzo},
  journal= {arXiv preprint arXiv:2112.03741},
  year   = {2022}
}

Comments

56 pages; major changes including new, more general results superseeding previous versions; comments welcome!