Constructing Galois representations with large Iwasawa $λ$-Invariant

Fuente: arXiv
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Auteur principal: Ray, Anwesh
Format: Preprint
Publié: 2021
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author Ray, Anwesh
author_facet Ray, Anwesh
contents Let $p\geq 5$ be a prime. We construct modular Galois representations for which the $\mathbb{Z}_p$-corank of the $p$-primary Selmer group (i.e., $λ$-invariant) over the cyclotomic $\mathbb{Z}_p$-extension is large. More precisely, for any natural number $n$, one constructs a modular Galois representation such that the associated $λ$-invariant is $\geq n$. The method is based on the study of congruences between modular forms, and leverages results of Greenberg and Vatsal. Given a modular form $f_1$ satisfying suitable conditions, one constructs a congruent modular form $f_2$ for which the $λ$-invariant of the Selmer group is large. A key ingredient in acheiving this is the Galois theoretic lifting result of Fakruddin-Khare-Patrikis, which extends previous work of Ramakrishna. The results are subject to certain additional hypotheses, and are illustrated by explicit examples.
format Preprint
id arxiv_https___arxiv_org_abs_2105_00147
institution arXiv
publishDate 2021
record_format arxiv
spellingShingle Constructing Galois representations with large Iwasawa $λ$-Invariant
Ray, Anwesh
Number Theory
11F80, 11F11, 11R23
Let $p\geq 5$ be a prime. We construct modular Galois representations for which the $\mathbb{Z}_p$-corank of the $p$-primary Selmer group (i.e., $λ$-invariant) over the cyclotomic $\mathbb{Z}_p$-extension is large. More precisely, for any natural number $n$, one constructs a modular Galois representation such that the associated $λ$-invariant is $\geq n$. The method is based on the study of congruences between modular forms, and leverages results of Greenberg and Vatsal. Given a modular form $f_1$ satisfying suitable conditions, one constructs a congruent modular form $f_2$ for which the $λ$-invariant of the Selmer group is large. A key ingredient in acheiving this is the Galois theoretic lifting result of Fakruddin-Khare-Patrikis, which extends previous work of Ramakrishna. The results are subject to certain additional hypotheses, and are illustrated by explicit examples.
title Constructing Galois representations with large Iwasawa $λ$-Invariant
topic Number Theory
11F80, 11F11, 11R23
url https://arxiv.org/abs/2105.00147