Properties

Label 2.0.7.1-28672.7-m4
Base field \(\Q(\sqrt{-7}) \)
Conductor norm \( 28672 \)
CM no
Base change yes
Q-curve yes
Torsion order \( 4 \)
Rank \( 2 \)

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Show commands: Magma / PariGP / SageMath

Base field \(\Q(\sqrt{-7}) \)

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

sage: R.<x> = PolynomialRing(QQ); K.<a> = NumberField(R([2, -1, 1]))
 
gp: K = nfinit(Polrev([2, -1, 1]));
 
magma: R<x> := PolynomialRing(Rationals()); K<a> := NumberField(R![2, -1, 1]);
 

Weierstrass equation

\({y}^2={x}^{3}-76{x}-240\)
sage: E = EllipticCurve([K([0,0]),K([0,0]),K([0,0]),K([-76,0]),K([-240,0])])
 
gp: E = ellinit([Polrev([0,0]),Polrev([0,0]),Polrev([0,0]),Polrev([-76,0]),Polrev([-240,0])], K);
 
magma: E := EllipticCurve([K![0,0],K![0,0],K![0,0],K![-76,0],K![-240,0]]);
 

This is a global minimal model.

sage: E.is_global_minimal_model()
 

Invariants

Conductor: \((-128a+64)\) = \((a)^{6}\cdot(-a+1)^{6}\cdot(-2a+1)\)
sage: E.conductor()
 
gp: ellglobalred(E)[1]
 
magma: Conductor(E);
 
Conductor norm: \( 28672 \) = \(2^{6}\cdot2^{6}\cdot7\)
sage: E.conductor().norm()
 
gp: idealnorm(ellglobalred(E)[1])
 
magma: Norm(Conductor(E));
 
Discriminant: \((3211264)\) = \((a)^{16}\cdot(-a+1)^{16}\cdot(-2a+1)^{4}\)
sage: E.discriminant()
 
gp: E.disc
 
magma: Discriminant(E);
 
Discriminant norm: \( 10312216477696 \) = \(2^{16}\cdot2^{16}\cdot7^{4}\)
sage: E.discriminant().norm()
 
gp: norm(E.disc)
 
magma: Norm(Discriminant(E));
 
j-invariant: \( \frac{740772}{49} \)
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: \(2\)
Generators $\left(-2 a - 10 : -20 a + 24 : 1\right)$ $\left(10 a - 2 : 40 a - 48 : 1\right)$
Heights \(0.53455428839861278029628268140944256340\) \(0.96652861666989373325834270388896421508\)
Torsion structure: \(\Z/2\Z\oplus\Z/2\Z\)
sage: T = E.torsion_subgroup(); T.invariants()
 
gp: T = elltors(E); T[2]
 
magma: T,piT := TorsionSubgroup(E); Invariants(T);
 
Torsion generators: $\left(-6 : 0 : 1\right)$ $\left(-4 : 0 : 1\right)$
sage: T.gens()
 
gp: T[3]
 
magma: [piT(P) : P in Generators(T)];
 

BSD invariants

Analytic rank: \( 2 \)
sage: E.rank()
 
magma: Rank(E);
 
Mordell-Weil rank: \(2\)
Regulator: \( 0.51666201690087063474428167766196190212 \)
Period: \( 1.0040739295787181528074062214376360766 \)
Tamagawa product: \( 64 \)  =  \(2^{2}\cdot2^{2}\cdot2^{2}\)
Torsion order: \(4\)
Leading coefficient: \( 6.2744141903796174726086344435173742279 \)
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\((j)_{-}\)
\((a)\) \(2\) \(4\) \(I_{6}^{*}\) Additive \(-1\) \(6\) \(16\) \(0\)
\((-a+1)\) \(2\) \(4\) \(I_{6}^{*}\) Additive \(-1\) \(6\) \(16\) \(0\)
\((-2a+1)\) \(7\) \(4\) \(I_{4}\) Split multiplicative \(-1\) \(1\) \(4\) \(4\)

Galois Representations

The mod \( p \) Galois Representation has maximal image for all primes \( p < 1000 \) 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 and 4.
Its isogeny class 28672.7-m consists of curves linked by isogenies of degrees dividing 8.

Base change

This elliptic curve is a \(\Q\)-curve. It is the base change of the following 2 elliptic curves:

Base field Curve
\(\Q\) 448.e3
\(\Q\) 3136.p3