# Properties

 Label 4.4.2048.1-32.1-a2 Base field $$\Q(\zeta_{16})^+$$ Conductor norm $$32$$ CM yes ($$-16$$) Base change yes Q-curve yes Torsion order $$16$$ Rank $$0$$

# Related objects

Show commands: Magma / Pari/GP / SageMath

## Base field$$\Q(\zeta_{16})^+$$

Generator $$a$$, with minimal polynomial $$x^{4} - 4 x^{2} + 2$$; class number $$1$$.

sage: R.<x> = PolynomialRing(QQ); K.<a> = NumberField(R([2, 0, -4, 0, 1]))

gp: K = nfinit(Pol(Vecrev([2, 0, -4, 0, 1])));

magma: R<x> := PolynomialRing(Rationals()); K<a> := NumberField(R![2, 0, -4, 0, 1]);

## Weierstrass equation

$${y}^2+\left(a^{2}-2\right){x}{y}+\left(a^{2}-2\right){y}={x}^{3}+{x}^{2}-3{x}$$
sage: E = EllipticCurve([K([-2,0,1,0]),K([1,0,0,0]),K([-2,0,1,0]),K([-3,0,0,0]),K([0,0,0,0])])

gp: E = ellinit([Pol(Vecrev([-2,0,1,0])),Pol(Vecrev([1,0,0,0])),Pol(Vecrev([-2,0,1,0])),Pol(Vecrev([-3,0,0,0])),Pol(Vecrev([0,0,0,0]))], K);

magma: E := EllipticCurve([K![-2,0,1,0],K![1,0,0,0],K![-2,0,1,0],K![-3,0,0,0],K![0,0,0,0]]);

This is a global minimal model.

sage: E.is_global_minimal_model()

## Invariants

 Conductor: $$(2a)$$ = $$(a)^{5}$$ sage: E.conductor()  gp: ellglobalred(E)[1]  magma: Conductor(E); Conductor norm: $$32$$ = $$2^{5}$$ sage: E.conductor().norm()  gp: idealnorm(ellglobalred(E)[1])  magma: Norm(Conductor(E)); Discriminant: $$(8)$$ = $$(a)^{12}$$ sage: E.discriminant()  gp: E.disc  magma: Discriminant(E); Discriminant norm: $$4096$$ = $$2^{12}$$ sage: E.discriminant().norm()  gp: norm(E.disc)  magma: Norm(Discriminant(E)); j-invariant: $$287496$$ sage: E.j_invariant()  gp: E.j  magma: jInvariant(E); Endomorphism ring: $$\Z$$ Geometric endomorphism ring: $$\Z[\sqrt{-4}]$$ (potential complex multiplication) sage: E.has_cm(), E.cm_discriminant()  magma: HasComplexMultiplication(E); Sato-Tate group: $N(\mathrm{U}(1))$

## Mordell-Weil group

 Rank: $$0$$ Torsion structure: $$\Z/2\Z\oplus\Z/8\Z$$ sage: T = E.torsion_subgroup(); T.invariants()  gp: T = elltors(E); T[2]  magma: T,piT := TorsionSubgroup(E); Invariants(T); Torsion generators: $\left(a^{2} - 3 : -1 : 1\right)$ $\left(a^{2} + a - 1 : a^{2} + 2 a - 1 : 1\right)$ 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: $$3025.16352206774$$ Tamagawa product: $$4$$ Torsion order: $$16$$ Leading coefficient: $$1.04448908234975$$ 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$$(j)_{-}$$
$$(a)$$ $$2$$ $$4$$ $$I_{3}^{*}$$ Additive $$1$$ $$5$$ $$12$$ $$0$$

## 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

For all other primes $$p$$, the image is the normalizer of a split Cartan subgroup if $$\left(\frac{ -1 }{p}\right)=+1$$ or the normalizer of a nonsplit Cartan subgroup if $$\left(\frac{ -1 }{p}\right)=-1$$.

## Isogenies and isogeny class

This curve has non-trivial cyclic isogenies of degree $$d$$ for $$d=$$ 2, 4 and 8.
Its isogeny class 32.1-a consists of curves linked by isogenies of degrees dividing 16.

## Base change

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

Base field Curve
$$\Q$$ 32.a2
$$\Q$$ 64.a2