# Properties

 Label 27a4 Conductor $27$ Discriminant $-243$ j-invariant $$-12288000$$ CM yes ($$D=-27$$) Rank $0$ Torsion structure $$\Z/{3}\Z$$

# Related objects

Show commands for: Magma / Pari/GP / SageMath

## Minimal Weierstrass equation

sage: E = EllipticCurve([0, 0, 1, -30, 63])

gp: E = ellinit([0, 0, 1, -30, 63])

magma: E := EllipticCurve([0, 0, 1, -30, 63]);

$$y^2+y=x^3-30x+63$$

## Mordell-Weil group structure

$$\Z/{3}\Z$$

## Torsion generators

sage: E.torsion_subgroup().gens()

gp: elltors(E)

magma: TorsionSubgroup(E);

$$\left(3, 0\right)$$

## Integral points

sage: E.integral_points()

magma: IntegralPoints(E);

$$\left(3, 0\right)$$, $$\left(3, -1\right)$$

## Invariants

 sage: E.conductor().factor()  gp: ellglobalred(E)[1]  magma: Conductor(E); Conductor: $$27$$ = $$3^{3}$$ sage: E.discriminant().factor()  gp: E.disc  magma: Discriminant(E); Discriminant: $$-243$$ = $$-1 \cdot 3^{5}$$ sage: E.j_invariant().factor()  gp: E.j  magma: jInvariant(E); j-invariant: $$-12288000$$ = $$-1 \cdot 2^{15} \cdot 3 \cdot 5^{3}$$ Endomorphism ring: $$\Z$$ Geometric endomorphism ring: $$\Z[(1+\sqrt{-27})/2]$$ (potential complex multiplication) Sato-Tate group: $N(\mathrm{U}(1))$ Faltings height: $$-0.49715821192695564644343526816\dots$$ Stable Faltings height: $$-0.95491333220533468452478745021\dots$$

## BSD invariants

 sage: E.rank()  magma: Rank(E); Analytic rank: $$0$$ sage: E.regulator()  magma: Regulator(E); Regulator: $$1$$ sage: E.period_lattice().omega()  gp: E.omega[1]  magma: RealPeriod(E); Real period: $$5.2999162508563498719410684989\dots$$ sage: E.tamagawa_numbers()  gp: gr=ellglobalred(E); [[gr[4][i,1],gr[5][i][4]] | i<-[1..#gr[4][,1]]]  magma: TamagawaNumbers(E); Tamagawa product: $$1$$ sage: E.torsion_order()  gp: elltors(E)[1]  magma: Order(TorsionSubgroup(E)); Torsion order: $$3$$ sage: E.sha().an_numerical()  magma: MordellWeilShaInformation(E); Analytic order of Ш: $$1$$ (exact)

## Modular invariants

sage: E.q_eigenform(20)

gp: xy = elltaniyama(E);

gp: x*deriv(xy[1])/(2*xy[2]+E.a1*xy[1]+E.a3)

magma: ModularForm(E);

$$q - 2q^{4} - q^{7} + 5q^{13} + 4q^{16} - 7q^{19} + O(q^{20})$$

 sage: E.modular_degree()  magma: ModularDegree(E); Modular degree: 9 $$\Gamma_0(N)$$-optimal: no Manin constant: 3

#### Special L-value

sage: r = E.rank();

sage: E.lseries().dokchitser().derivative(1,r)/r.factorial()

gp: ar = ellanalyticrank(E);

gp: ar[2]/factorial(ar[1])

magma: Lr1 where r,Lr1 := AnalyticRank(E: Precision:=12);

$$L(E,1)$$ ≈ $$0.58887958342848331910456316654932546833$$

## Local data

This elliptic curve is not semistable. There is only one prime of bad reduction:

sage: E.local_data()

gp: ellglobalred(E)[5]

magma: [LocalInformation(E,p) : p in BadPrimes(E)];

prime Tamagawa number Kodaira symbol Reduction type Root number ord($$N$$) ord($$\Delta$$) ord$$(j)_{-}$$
$$3$$ $$1$$ $$IV$$ Additive -1 3 5 0

## Galois representations

sage: rho = E.galois_representation();

sage: [rho.image_type(p) for p in rho.non_surjective()]

magma: [GaloisRepresentation(E,p): p in PrimesUpTo(20)];

The mod $$p$$ Galois representation has maximal image for all primes $$p < 1000$$ except those listed.

prime Image of Galois representation
$$3$$ B.1.1

For all other primes $$p$$, the image is the normalizer of a split Cartan subgroup if $$\left(\frac{ -3 }{p}\right)=+1$$ or the normalizer of a nonsplit Cartan subgroup if $$\left(\frac{ -3 }{p}\right)=-1$$.

## $p$-adic data

### $p$-adic regulators

sage: [E.padic_regulator(p) for p in primes(5,20) if E.conductor().valuation(p)<2]

All $$p$$-adic regulators are identically $$1$$ since the rank is $$0$$.

## Iwasawa invariants

$p$ Reduction type 2 3 ss add 0,5 - 0,0 -

All Iwasawa $\lambda$ and $\mu$-invariants for primes $p\ge 5$ of good reduction are zero.

An entry - indicates that the invariants are not computed because the reduction is additive.

## Isogenies

This curve has non-trivial cyclic isogenies of degree $$d$$ for $$d=$$ 3, 9 and 27.
Its isogeny class 27a consists of 4 curves linked by isogenies of degrees dividing 27.

## Growth of torsion in number fields

The number fields $K$ of degree less than 24 such that $E(K)_{\rm tors}$ is strictly larger than $E(\Q)_{\rm tors}$ $\cong \Z/{3}\Z$ are as follows:

 $[K:\Q]$ $E(K)_{\rm tors}$ Base change curve $K$ $3$ 3.1.108.1 $$\Z/6\Z$$ Not in database $3$ $$\Q(\zeta_{9})^+$$ $$\Z/9\Z$$ 3.3.81.1-27.1-a3 $6$ 6.0.34992.1 $$\Z/2\Z \times \Z/6\Z$$ Not in database $6$ 6.0.177147.2 $$\Z/3\Z \times \Z/3\Z$$ Not in database $6$ 6.0.177147.1 $$\Z/9\Z$$ Not in database $9$ $$\Q(\zeta_{27})^+$$ $$\Z/27\Z$$ Not in database $9$ 9.3.918330048.1 $$\Z/18\Z$$ Not in database $12$ 12.2.15045919506432.1 $$\Z/12\Z$$ Not in database $12$ 12.0.241162079949.1 $$\Z/21\Z$$ Not in database $18$ 18.0.4052555153018976267.1 $$\Z/3\Z \times \Z/9\Z$$ Not in database $18$ 18.0.2954312706550833698643.2 $$\Z/27\Z$$ Not in database $18$ 18.0.1844362878529525198848.1 $$\Z/6\Z \times \Z/6\Z$$ Not in database $18$ 18.0.1844362878529525198848.2 $$\Z/2\Z \times \Z/18\Z$$ Not in database $18$ 18.0.2529990231179046912.1 $$\Z/2\Z \times \Z/18\Z$$ Not in database

We only show fields where the torsion growth is primitive.