Properties

Base field \(\Q(\sqrt{-1}) \)
Label 2.0.4.1-64.1-CMa2
Conductor \((8)\)
Conductor norm \( 64 \)
CM yes (\(-16\))
base-change yes: 32.a1,32.a2
Q-curve yes
Torsion order \( 4 \)
Rank not available

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Base field \(\Q(\sqrt{-1}) \)

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

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

Weierstrass equation

\( y^2 + \left(i + 1\right) x y = x^{3} + i x^{2} + 2 x + 3 i \)
magma: E := ChangeRing(EllipticCurve([i + 1, i, 0, 2, 3*i]),K);
 
sage: E = EllipticCurve(K, [i + 1, i, 0, 2, 3*i])
 
gp (2.8): E = ellinit([i + 1, i, 0, 2, 3*i],K)
 

This is a global minimal model.

sage: E.is_global_minimal_model()
 

Invariants

\(\mathfrak{N} \) = \((8)\) = \( \left(i + 1\right)^{6} \)
magma: Conductor(E);
 
sage: E.conductor()
 
\(N(\mathfrak{N}) \) = \( 64 \) = \( 2^{6} \)
magma: Norm(Conductor(E));
 
sage: E.conductor().norm()
 
\(\mathfrak{D}\) = \((8)\) = \( \left(i + 1\right)^{6} \)
magma: Discriminant(E);
 
sage: E.discriminant()
 
gp (2.8): E.disc
 
\(N(\mathfrak{D})\) = \( 64 \) = \( 2^{6} \)
magma: Norm(Discriminant(E));
 
sage: E.discriminant().norm()
 
gp (2.8): norm(E.disc)
 
\(j\) = \( 287496 \)
magma: jInvariant(E);
 
sage: E.j_invariant()
 
gp (2.8): E.j
 
\( \text{End} (E) \) = \(\Z[\sqrt{-4}]\)   ( Complex Multiplication )
magma: HasComplexMultiplication(E);
 
sage: E.has_cm(), E.cm_discriminant()
 
\( \text{ST} (E) \) = $\mathrm{U}(1)$

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: \(\Z/4\Z\)
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]
 
Generator: $\left(-i : -1 : 1\right)$
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\((j)_{-}\)
\( \left(i + 1\right) \) \(2\) \(1\) \(II\) Additive \(-1\) \(6\) \(6\) \(0\)

Galois Representations

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

The image is a Borel subgroup if \(p=2\), a split Cartan subgroup if \(\left(\frac{ -1 }{p}\right)=+1\) or a nonsplit Cartan subgroup if \(\left(\frac{ -1 }{p}\right)=-1\).

Isogenies and isogeny class

This curve has non-trivial cyclic isogenies (excluding endomorphisms) of degree \(d\) for \(d=\) 2.
Its isogeny class 64.1-CMa consists of curves linked by isogenies of degree 2.

Base change

This curve is the base-change of elliptic curves 32.a1, 32.a2, defined over \(\Q\), so it is also a \(\Q\)-curve.