Higher congruences between newforms and Eisenstein series of squarefree level

Cathy Hsu

Research output: Contribution to journalArticle (Academic Journal)peer-review

1 Citation (Scopus)
52 Downloads (Pure)


Let p≥5 be prime. For elliptic modular forms of weight 2 and level Γ0(N) where N>6 is squarefree, we bound the depth of Eisenstein congruences modulo p (from below) by a generalized Bernoulli number with correction factors and show how this depth detects the local non-principality of the Eisenstein ideal. We then use admissibility results of Ribet and Yoo to give an infinite class of examples where the Eisenstein ideal is not locally principal. Lastly, we illustrate these results with explicit computations and give an interesting commutative algebra application related to Hilbert--Samuel multiplicities.
Original languageEnglish
Pages (from-to)503-525
Number of pages24
JournalJournal de théorie des nombres de Bordeaux
Issue number2
Publication statusPublished - 29 Oct 2019


  • Congruences between modular forms
  • Eisenstein ideal


Dive into the research topics of 'Higher congruences between newforms and Eisenstein series of squarefree level'. Together they form a unique fingerprint.

Cite this