RESIDUAL GALOIS REPRESENTATIONS OF ELLIPTIC CURVES WITH IMAGE CONTAINED IN THE NORMALISER OF A NON-SPLIT CARTAN - Université Grenoble Alpes
Article Dans Une Revue Algebra & Number Theory Année : 2021

RESIDUAL GALOIS REPRESENTATIONS OF ELLIPTIC CURVES WITH IMAGE CONTAINED IN THE NORMALISER OF A NON-SPLIT CARTAN

Pedro Lemos
  • Fonction : Auteur

Résumé

It is known that if p > 37 is a prime number and E/Q is an elliptic curve without complex multiplication, then the image of the mod p Galois representation ρE,p :

of E is either the whole of GL2(Fp), or is contained in the normaliser of a non-split Cartan subgroup of GL2(Fp). In this paper, we build on work of Zywina and show that when p > 1.4 × 10 7 , the image of ρE,p is either GL2(Fp), or is the normaliser of a non-split Cartan subgroup. We use this to show the following result, partially settling a question of Najman. For d ≥ 1, let I(d) denote the set of primes p for which there exists an elliptic curve defined over Q and without complex multiplication admitting a degree p isogeny defined over a number field of degree ≤ d. We show that, for d ≥ 1.4 × 10 7 , we have

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Dates et versions

hal-04767393 , version 1 (05-11-2024)

Identifiants

Citer

Samuel Le Fourn, Pedro Lemos. RESIDUAL GALOIS REPRESENTATIONS OF ELLIPTIC CURVES WITH IMAGE CONTAINED IN THE NORMALISER OF A NON-SPLIT CARTAN. Algebra & Number Theory, 2021, 15 (3), pp.747-771. ⟨10.2140/ant.2021.15.747⟩. ⟨hal-04767393⟩
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