Properties

Label 4.4.19821.1-21.1-a1
Base field 4.4.19821.1
Conductor norm \( 21 \)
CM no
Base change no
Q-curve no
Torsion order \( 6 \)
Rank \( 0 \)

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Base field 4.4.19821.1

Generator \(a\), with minimal polynomial \( x^{4} - x^{3} - 8 x^{2} + 6 x + 3 \); class number \(1\).

sage: R.<x> = PolynomialRing(QQ); K.<a> = NumberField(R([3, 6, -8, -1, 1]))
 
gp: K = nfinit(Polrev([3, 6, -8, -1, 1]));
 
magma: R<x> := PolynomialRing(Rationals()); K<a> := NumberField(R![3, 6, -8, -1, 1]);
 

Weierstrass equation

\({y}^2+\left(\frac{1}{3}a^{3}+\frac{1}{3}a^{2}-3a\right){x}{y}+\left(a^{2}-a-3\right){y}={x}^{3}+\left(\frac{1}{3}a^{3}+\frac{1}{3}a^{2}-3a-2\right){x}^{2}+\left(-\frac{1}{3}a^{3}-\frac{4}{3}a^{2}+1\right){x}+\frac{2}{3}a^{3}+\frac{2}{3}a^{2}-2a-2\)
sage: E = EllipticCurve([K([0,-3,1/3,1/3]),K([-2,-3,1/3,1/3]),K([-3,-1,1,0]),K([1,0,-4/3,-1/3]),K([-2,-2,2/3,2/3])])
 
gp: E = ellinit([Polrev([0,-3,1/3,1/3]),Polrev([-2,-3,1/3,1/3]),Polrev([-3,-1,1,0]),Polrev([1,0,-4/3,-1/3]),Polrev([-2,-2,2/3,2/3])], K);
 
magma: E := EllipticCurve([K![0,-3,1/3,1/3],K![-2,-3,1/3,1/3],K![-3,-1,1,0],K![1,0,-4/3,-1/3],K![-2,-2,2/3,2/3]]);
 

This is a global minimal model.

sage: E.is_global_minimal_model()
 

Invariants

Conductor: \((-1/3a^3-1/3a^2+4a-1)\) = \((-1/3a^3-1/3a^2+3a+2)\cdot(-1/3a^3-1/3a^2+2a)\)
sage: E.conductor()
 
gp: ellglobalred(E)[1]
 
magma: Conductor(E);
 
Conductor norm: \( 21 \) = \(3\cdot7\)
sage: E.conductor().norm()
 
gp: idealnorm(ellglobalred(E)[1])
 
magma: Norm(Conductor(E));
 
Discriminant: \((2/3a^3-1/3a^2-7a-7)\) = \((-1/3a^3-1/3a^2+3a+2)^{2}\cdot(-1/3a^3-1/3a^2+2a)^{3}\)
sage: E.discriminant()
 
gp: E.disc
 
magma: Discriminant(E);
 
Discriminant norm: \( -3087 \) = \(-3^{2}\cdot7^{3}\)
sage: E.discriminant().norm()
 
gp: norm(E.disc)
 
magma: Norm(Discriminant(E));
 
j-invariant: \( -\frac{45668663}{343} a^{3} - \frac{10461181}{1029} a^{2} + \frac{362255132}{343} a + \frac{367286758}{1029} \)
sage: E.j_invariant()
 
gp: E.j
 
magma: jInvariant(E);
 
Endomorphism ring: \(\Z\)
Geometric endomorphism ring: \(\Z\) (no potential complex multiplication)
sage: E.has_cm(), E.cm_discriminant()
 
magma: HasComplexMultiplication(E);
 
Sato-Tate group: $\mathrm{SU}(2)$

Mordell-Weil group

Rank: \(0\)
Torsion structure: \(\Z/6\Z\)
sage: T = E.torsion_subgroup(); T.invariants()
 
gp: T = elltors(E); T[2]
 
magma: T,piT := TorsionSubgroup(E); Invariants(T);
 
Torsion generator: $\left(1 : -\frac{1}{3} a^{3} - \frac{1}{3} a^{2} + 2 a + 1 : 1\right)$
sage: T.gens()
 
gp: T[3]
 
magma: [piT(P) : P in Generators(T)];
 

BSD invariants

Analytic rank: \( 0 \)
sage: E.rank()
 
magma: Rank(E);
 
Mordell-Weil rank: \(0\)
Regulator: \( 1 \)
Period: \( 2775.2341315986191602360511886094125625 \)
Tamagawa product: \( 6 \)  =  \(2\cdot3\)
Torsion order: \(6\)
Leading coefficient: \( 3.28537990874532 \)
Analytic order of Ш: \( 1 \) (rounded)

Local data at primes of bad reduction

sage: E.local_data()
 
magma: LocalInformation(E);
 
prime Norm Tamagawa number Kodaira symbol Reduction type Root number ord(\(\mathfrak{N}\)) ord(\(\mathfrak{D}\)) ord\((j)_{-}\)
\((-1/3a^3-1/3a^2+3a+2)\) \(3\) \(2\) \(I_{2}\) Split multiplicative \(-1\) \(1\) \(2\) \(2\)
\((-1/3a^3-1/3a^2+2a)\) \(7\) \(3\) \(I_{3}\) Split multiplicative \(-1\) \(1\) \(3\) \(3\)

Galois Representations

The mod \( p \) Galois Representation has maximal image for all primes \( p < 1000 \) except those listed.

prime Image of Galois Representation
\(2\) 2B
\(3\) 3B.1.1

Isogenies and isogeny class

This curve has non-trivial cyclic isogenies of degree \(d\) for \(d=\) 2, 3 and 6.
Its isogeny class 21.1-a consists of curves linked by isogenies of degrees dividing 6.

Base change

This elliptic curve is not a \(\Q\)-curve.

It is not the base change of an elliptic curve defined over any subfield.