English

Congruences between modular forms and related modules

Number Theory 2007-10-26 v1

Abstract

We fix \ell a prime and let MM be an integer such that ∤M\ell\not|M; let fS2(Γ1(M2))f\in S_2(\Gamma_1(M\ell^2)) be a newform supercuspidal of fixed type related to the nebentypus, at \ell and special at a finite set of primes. Let \TTψ\TT^\psi be the local quaternionic Hecke algebra associated to ff. The algebra \TTψ\TT^\psi acts on a module Mfψ\mathcal M^\psi_f coming from the cohomology of a Shimura curve. Applying the Taylor-Wiles criterion and a recent Savitt's theorem, \TTψ\TT^\psi is the universal deformation ring of a global Galois deformation problem associated to \orhof\orho_f. Moreover Mfψ\mathcal M^\psi_f is free of rank 2 over \TTψ\TT^\psi. If ff occurs at minimal level, by a generalization of a Conrad, Diamond and Taylor's result and by the classical Ihara's lemma, we prove a theorem of raising the level and a result about congruence ideals. The extension of this results to the non minimal case is an open problem.

Keywords

Cite

@article{arxiv.0710.4677,
  title  = {Congruences between modular forms and related modules},
  author = {Miriam Ciavarella},
  journal= {arXiv preprint arXiv:0710.4677},
  year   = {2007}
}
R2 v1 2026-06-21T09:35:58.368Z