scholarly journals Wild Galois representations: Elliptic curves over a 2-adic field with non-abelian inertia action

2020 ◽  
Vol 16 (06) ◽  
pp. 1199-1208
Author(s):  
Nirvana Coppola
Keyword(s):  
Elliptic Curve ◽  
Elliptic Curves ◽  
Galois Representations ◽  
Galois Representation

In this paper, we present a description of the [Formula: see text]-adic Galois representation attached to an elliptic curve defined over a [Formula: see text]-adic field [Formula: see text], in the case where the image of inertia is non-abelian. There are two possibilities for the image of inertia, namely [Formula: see text] and [Formula: see text], and in each case, we need to distinguish whether the inertia degree of [Formula: see text] over [Formula: see text] is even or odd. The results presented here are being implemented in an algorithm to compute explicitly the Galois representation in these four cases.

On the Surjectivity of the Galois Representations Associated to Non-CM Elliptic Curves

2005 ◽  
Vol 48 (1) ◽  
pp. 16-31 ◽  
Author(s):  
Alina Carmen Cojocaru ◽  
Ernst Kani
Keyword(s):  
Positive Integer ◽  
Elliptic Curve ◽  
Elliptic Curves ◽  
Galois Representations ◽  
Complex Multiplication ◽  
Galois Representation ◽  
Upper Bounds

AbstractLet E be an elliptic curve defined over ℚ, of conductor N and without complex multiplication. For any positive integer l, let ϕl be the Galois representation associated to the l-division points of E. From a celebrated 1972 result of Serre we know that ϕl is surjective for any sufficiently large prime l. In this paper we find conditional and unconditional upper bounds in terms of N for the primes l for which ϕl is not surjective.

scholarly journals Irreducibility of mod p Galois representations of elliptic curves with multiplicative reduction over number fields

2021 ◽  
pp. 1-10
Author(s):  
Filip Najman ◽  
George C. Ţurcaş
Keyword(s):  
Elliptic Curve ◽  
Elliptic Curves ◽  
Number Field ◽  
Galois Representations ◽  
Galois Representation ◽  
Number Fields ◽  
Fermat's Last Theorem ◽  
Modular Method ◽  
Explicit Constant ◽  
Mod P

In this paper we prove that for every integer [Formula: see text], there exists an explicit constant [Formula: see text] such that the following holds. Let [Formula: see text] be a number field of degree [Formula: see text], let [Formula: see text] be any rational prime that is totally inert in [Formula: see text] and [Formula: see text] any elliptic curve defined over [Formula: see text] such that [Formula: see text] has potentially multiplicative reduction at the prime [Formula: see text] above [Formula: see text]. Then for every rational prime [Formula: see text], [Formula: see text] has an irreducible mod [Formula: see text] Galois representation. This result has Diophantine applications within the “modular method”. We present one such application in the form of an Asymptotic version of Fermat’s Last Theorem that has not been covered in the existing literature.

scholarly journals Constructing elliptic curves from Galois representations

2018 ◽  
Vol 154 (10) ◽  
pp. 2045-2054
Author(s):  
Andrew Snowden ◽  
Jacob Tsimerman
Keyword(s):  
Elliptic Curve ◽  
Elliptic Curves ◽  
Galois Representations ◽  
Good Reduction ◽  
Arithmetic Surface

Given a non-isotrivial elliptic curve over an arithmetic surface, one obtains a lisse $\ell$-adic sheaf of rank two over the surface. This lisse sheaf has a number of straightforward properties: cyclotomic determinant, finite ramification, rational traces of Frobenius elements, and somewhere not potentially good reduction. We prove that any lisse sheaf of rank two possessing these properties comes from an elliptic curve.

EXPLICIT SURJECTIVITY RESULTS FOR DRINFELD MODULES OF RANK 2

2017 ◽  
Vol 234 ◽  
pp. 17-45 ◽  
Author(s):  
IMIN CHEN ◽  
YOONJIN LEE
Keyword(s):  
Elliptic Curves ◽  
Upper Bound ◽  
Riemann Hypothesis ◽  
Galois Representations ◽  
Complex Multiplication ◽  
Galois Representation ◽  
Drinfeld Module ◽  
Torsion Points ◽  
Rank 2 ◽  
Invent Math

Let $K=\mathbb{F}_{q}(T)$ and $A=\mathbb{F}_{q}[T]$. Suppose that $\unicode[STIX]{x1D719}$ is a Drinfeld $A$-module of rank $2$ over $K$ which does not have complex multiplication. We obtain an explicit upper bound (dependent on $\unicode[STIX]{x1D719}$) on the degree of primes ${\wp}$ of $K$ such that the image of the Galois representation on the ${\wp}$-torsion points of $\unicode[STIX]{x1D719}$ is not surjective, in the case of $q$ odd. Our results are a Drinfeld module analogue of Serre’s explicit large image results for the Galois representations on $p$-torsion points of elliptic curves (Serre, Propriétés galoisiennes des points d’ordre fini des courbes elliptiques, Invent. Math. 15 (1972), 259–331; Serre, Quelques applications du théorème de densité de Chebotarev, Inst. Hautes Etudes Sci. Publ. Math. 54 (1981), 323–401.) and are unconditional because the generalized Riemann hypothesis for function fields holds. An explicit isogeny theorem for Drinfeld $A$-modules of rank $2$ over $K$ is also proven.

scholarly journals COMPUTING IMAGES OF GALOIS REPRESENTATIONS ATTACHED TO ELLIPTIC CURVES

2016 ◽  
Vol 4 ◽  
Author(s):  
ANDREW V. SUTHERLAND
Keyword(s):  
Monte Carlo ◽  
Elliptic Curve ◽  
Elliptic Curves ◽  
Galois Representations ◽  
Complex Multiplication ◽  
Monte Carlo Algorithm ◽  
Quadratic Fields ◽  
Complete List ◽  
Torsion Subgroup ◽  
Probabilistic Algorithms

Let $E$ be an elliptic curve without complex multiplication (CM) over a number field $K$, and let $G_{E}(\ell )$ be the image of the Galois representation induced by the action of the absolute Galois group of $K$ on the $\ell$-torsion subgroup of $E$. We present two probabilistic algorithms to simultaneously determine $G_{E}(\ell )$ up to local conjugacy for all primes $\ell$ by sampling images of Frobenius elements; one is of Las Vegas type and the other is a Monte Carlo algorithm. They determine $G_{E}(\ell )$ up to one of at most two isomorphic conjugacy classes of subgroups of $\mathbf{GL}_{2}(\mathbf{Z}/\ell \mathbf{Z})$ that have the same semisimplification, each of which occurs for an elliptic curve isogenous to $E$. Under the GRH, their running times are polynomial in the bit-size $n$ of an integral Weierstrass equation for $E$, and for our Monte Carlo algorithm, quasilinear in $n$. We have applied our algorithms to the non-CM elliptic curves in Cremona’s tables and the Stein–Watkins database, some 140 million curves of conductor up to $10^{10}$, thereby obtaining a conjecturally complete list of 63 exceptional Galois images $G_{E}(\ell )$ that arise for $E/\mathbf{Q}$ without CM. Under this conjecture, we determine a complete list of 160 exceptional Galois images $G_{E}(\ell )$ that arise for non-CM elliptic curves over quadratic fields with rational $j$-invariants. We also give examples of exceptional Galois images that arise for non-CM elliptic curves over quadratic fields only when the $j$-invariant is irrational.

scholarly journals Non-openness of v-adic Galois representation for A-motives

2020 ◽  
pp. 1-21
Author(s):  
Maike Ella Elisabeth Frantzen
Keyword(s):  
Elliptic Curves ◽  
Function Field ◽  
Galois Representations ◽  
Abelian Varieties ◽  
Galois Representation ◽  
Drinfeld Modules ◽  
Ground Field ◽  
Rank One

Drinfeld modules and [Formula: see text]-motives are the function field analogs of elliptic curves and abelian varieties. For both Drinfeld modules and [Formula: see text]-motives, one can construct their [Formula: see text]-adic Galois representations and ask whether the images are open. For Drinfeld modules, this question has been answered by Richard Pink and his co-authors; however, this question has not been addressed for [Formula: see text]-motives. Here, we clarify the rank-one case for [Formula: see text]-motives and show that the image of Galois is open if and only if the virtual dimension is prime to the characteristic of the ground field.

scholarly journals Density of odd order reductions for elliptic curves with a rational point of order 2

2019 ◽  
Vol 15 (08) ◽  
pp. 1547-1563
Author(s):  
Ke Liang ◽  
Jeremy Rouse
Keyword(s):  
Elliptic Curve ◽  
Elliptic Curves ◽  
Infinite Order ◽  
Rational Point ◽  
Representation Formula ◽  
Galois Representation ◽  
Odd Order

Suppose that [Formula: see text] is an elliptic curve with a rational point [Formula: see text] of order [Formula: see text] and [Formula: see text] is a point of infinite order. We consider the problem of determining the density of primes [Formula: see text] for which [Formula: see text] has odd order. This density is determined by the image of the arboreal Galois representation [Formula: see text]. Assuming that [Formula: see text] is primitive (that is neither [Formula: see text] nor [Formula: see text] is twice a point over [Formula: see text]) and that the image of the ordinary [Formula: see text]-adic Galois representation is as large as possible (subject to [Formula: see text] having a rational point of order [Formula: see text]), we determine that there are [Formula: see text] possibilities for the image of [Formula: see text]. As a consequence, the density of primes [Formula: see text] for which the order of [Formula: see text] is odd is between 1/14 and [Formula: see text].

scholarly journals Integral Tate modules and splitting of primes in torsion fields of elliptic curves

2016 ◽  
Vol 12 (01) ◽  
pp. 237-248 ◽  
Author(s):  
Tommaso Giorgio Centeleghe
Keyword(s):  
Finite Field ◽  
Elliptic Curve ◽  
Elliptic Curves ◽  
Prime Number ◽  
Galois Representations ◽  
Number Fields ◽  
Tate Module ◽  
Explicit Procedure ◽  
Polynomial Formula ◽  
Class Polynomials

Let [Formula: see text] be an elliptic curve over a finite field [Formula: see text], and [Formula: see text] a prime number different from the characteristic of [Formula: see text]. In this paper, we consider the problem of finding the structure of the Tate module [Formula: see text] as an integral Galois representations of [Formula: see text]. We indicate an explicit procedure to solve this problem starting from the characteristic polynomial [Formula: see text] and the [Formula: see text]-invariant [Formula: see text] of [Formula: see text]. Hilbert Class Polynomials of imaginary quadratic orders play an important role here. We give a global application to the study of prime-splitting in torsion fields of elliptic curves over number fields.

scholarly journals FINDING GALOIS REPRESENTATIONS CORRESPONDING TO CERTAIN HECKE EIGENCLASSES

2009 ◽  
Vol 05 (01) ◽  
pp. 1-11
Author(s):  
MEGHAN DEWITT ◽  
DARRIN DOUD
Keyword(s):  
Field Theory ◽  
Elliptic Curves ◽  
Strong Evidence ◽  
Galois Representations ◽  
Three Dimensional ◽  
Galois Representation ◽  
Class Field Theory ◽  
Class Field

In 1992, Ash and McConnell presented computational evidence of a connection between three-dimensional Galois representations and certain arithmetic cohomology classes. For some examples, they were unable to determine the attached representation. For several Hecke eigenclasses (including one for which Ash and McConnell did not find the Galois representation), we find a Galois representation which appears to be attached and show strong evidence for the uniqueness of this representation. The techniques that we use to find defining polynomials for the Galois representations include a targeted Hunter search, class field theory and elliptic curves.

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