Properties

Base field 4.4.9909.1
Label 4.4.9909.1-21.1-b2
Conductor \((21,-a^{2} + 2 a + 3)\)
Conductor norm \( 21 \)
CM no
base-change no
Q-curve no
Torsion order \( 4 \)
Rank not available

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Base field 4.4.9909.1

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

magma: R<x> := PolynomialRing(Rationals()); K<a> := NumberField(R![3, -3, -6, 0, 1]);
 
sage: x = polygen(QQ); K.<a> = NumberField(x^4 - 6*x^2 - 3*x + 3)
 
gp (2.8): K = nfinit(a^4 - 6*a^2 - 3*a + 3);
 

Weierstrass equation

\( y^2 + \left(a^{2} - a - 2\right) x y + \left(a^{3} - a^{2} - 3 a + 1\right) y = x^{3} + \left(a^{3} - 5 a - 2\right) x^{2} + \left(34 a^{3} + 12 a^{2} - 188 a - 186\right) x + 183 a^{3} + 62 a^{2} - 1009 a - 987 \)
magma: E := ChangeRing(EllipticCurve([a^2 - a - 2, a^3 - 5*a - 2, a^3 - a^2 - 3*a + 1, 34*a^3 + 12*a^2 - 188*a - 186, 183*a^3 + 62*a^2 - 1009*a - 987]),K);
 
sage: E = EllipticCurve(K, [a^2 - a - 2, a^3 - 5*a - 2, a^3 - a^2 - 3*a + 1, 34*a^3 + 12*a^2 - 188*a - 186, 183*a^3 + 62*a^2 - 1009*a - 987])
 
gp (2.8): E = ellinit([a^2 - a - 2, a^3 - 5*a - 2, a^3 - a^2 - 3*a + 1, 34*a^3 + 12*a^2 - 188*a - 186, 183*a^3 + 62*a^2 - 1009*a - 987],K)
 

This is a global minimal model.

sage: E.is_global_minimal_model()
 

Invariants

\(\mathfrak{N} \) = \((21,-a^{2} + 2 a + 3)\) = \( \left(-a^{3} + a^{2} + 4 a\right) \cdot \left(a^{3} - a^{2} - 4 a + 1\right) \)
magma: Conductor(E);
 
sage: E.conductor()
 
\(N(\mathfrak{N}) \) = \( 21 \) = \( 3 \cdot 7 \)
magma: Norm(Conductor(E));
 
sage: E.conductor().norm()
 
\(\mathfrak{D}\) = \((441,9 a + 225,9 a^{3} - 9 a^{2} - 36 a + 261,9 a^{2} - 9 a + 324)\) = \( \left(-a^{3} + a^{2} + 4 a\right)^{8} \cdot \left(a^{3} - a^{2} - 4 a + 1\right)^{2} \)
magma: Discriminant(E);
 
sage: E.discriminant()
 
gp (2.8): E.disc
 
\(N(\mathfrak{D})\) = \( 321489 \) = \( 3^{8} \cdot 7^{2} \)
magma: Norm(Discriminant(E));
 
sage: E.discriminant().norm()
 
gp (2.8): norm(E.disc)
 
\(j\) = \( -\frac{2514435768239}{147} a^{3} + \frac{14274453830897}{441} a^{2} + \frac{2028661440026}{49} a - \frac{11951649907706}{441} \)
magma: jInvariant(E);
 
sage: E.j_invariant()
 
gp (2.8): E.j
 
\( \text{End} (E) \) = \(\Z\)   (no Complex Multiplication )
magma: HasComplexMultiplication(E);
 
sage: E.has_cm(), E.cm_discriminant()
 
\( \text{ST} (E) \) = $\mathrm{SU}(2)$

Mordell-Weil group

Rank not available.
magma: Rank(E);
 
sage: E.rank()
 
magma: Generators(E); // includes torsion
 
sage: E.gens()
 

Regulator: not available

magma: Regulator(Generators(E));
 
sage: E.regulator_of_points(E.gens())
 

Torsion subgroup

Structure: \(\Z/2\Z\times\Z/2\Z\)
magma: TorsionSubgroup(E);
 
sage: E.torsion_subgroup().gens()
 
gp (2.8): elltors(E)[2]
 
magma: Order(TorsionSubgroup(E));
 
sage: E.torsion_order()
 
gp (2.8): elltors(E)[1]
 
Generators: $\left(\frac{3}{2} a^{3} - \frac{3}{4} a^{2} - \frac{27}{4} a - \frac{17}{4} : -\frac{1}{2} a^{3} + 3 a^{2} - \frac{7}{4} a - \frac{65}{8} : 1\right)$,$\left(a^{3} - 5 a - 7 : 3 a^{2} - 4 a - 9 : 1\right)$
magma: [f(P): P in Generators(T)] where T,f:=TorsionSubgroup(E);
 
sage: E.torsion_subgroup().gens()
 
gp (2.8): elltors(E)[3]
 

Local data at primes of bad reduction

magma: LocalInformation(E);
 
sage: E.local_data()
 
prime Norm Tamagawa number Kodaira symbol Reduction type Root number ord(\(\mathfrak{N}\)) ord(\(\mathfrak{D}\)) ord\((j)_{-}\)
\( \left(-a^{3} + a^{2} + 4 a\right) \) \(3\) \(2\) \(I_{8}\) Non-split multiplicative \(1\) \(1\) \(8\) \(8\)
\( \left(a^{3} - a^{2} - 4 a + 1\right) \) \(7\) \(2\) \(I_{2}\) Split multiplicative \(-1\) \(1\) \(2\) \(2\)

Galois Representations

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

prime Image of Galois Representation
\(2\) 2Cs

Isogenies and isogeny class

This curve has non-trivial cyclic isogenies of degree \(d\) for \(d=\) 2.
Its isogeny class 21.1-b consists of curves linked by isogenies of degrees dividing 4.

Base change

This curve is not the base-change of an elliptic curve defined over \(\Q\). It is not a \(\Q\)-curve.