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

Related objects


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Show commands: Magma / Oscar / PariGP / SageMath

Minimal Weierstrass equation

Minimal Weierstrass equation

Simplified equation

\(y^2+y=x^3-30x+63\) Copy content Toggle raw display (homogenize, simplify)
\(y^2z+yz^2=x^3-30xz^2+63z^3\) Copy content Toggle raw display (dehomogenize, simplify)
\(y^2=x^3-480x+4048\) Copy content Toggle raw display (homogenize, minimize)

comment: Define the curve
sage: E = EllipticCurve([0, 0, 1, -30, 63])
gp: E = ellinit([0, 0, 1, -30, 63])
magma: E := EllipticCurve([0, 0, 1, -30, 63]);
oscar: E = EllipticCurve([0, 0, 1, -30, 63])
sage: E.short_weierstrass_model()
magma: WeierstrassModel(E);
oscar: short_weierstrass_model(E)

Mordell-Weil group structure


magma: MordellWeilGroup(E);

Torsion generators

\( \left(3, 0\right) \) Copy content Toggle raw display

comment: Torsion subgroup
sage: E.torsion_subgroup().gens()
gp: elltors(E)
magma: TorsionSubgroup(E);
oscar: torsion_structure(E)

Integral points

\( \left(3, 0\right) \), \( \left(3, -1\right) \) Copy content Toggle raw display

comment: Integral points
sage: E.integral_points()
magma: IntegralPoints(E);


Conductor: \( 27 \)  =  $3^{3}$
comment: Conductor
sage: E.conductor().factor()
gp: ellglobalred(E)[1]
magma: Conductor(E);
oscar: conductor(E)
Discriminant: $-243 $  =  $-1 \cdot 3^{5} $
comment: Discriminant
sage: E.discriminant().factor()
gp: E.disc
magma: Discriminant(E);
oscar: discriminant(E)
j-invariant: \( -12288000 \)  =  $-1 \cdot 2^{15} \cdot 3 \cdot 5^{3}$
comment: j-invariant
sage: E.j_invariant().factor()
gp: E.j
magma: jInvariant(E);
oscar: j_invariant(E)
Endomorphism ring: $\Z$
Geometric endomorphism ring: \(\Z[(1+\sqrt{-27})/2]\) (potential complex multiplication)
sage: E.has_cm()
magma: HasComplexMultiplication(E);
Sato-Tate group: $N(\mathrm{U}(1))$
Faltings height: $-0.49715821192695564644343526816\dots$
gp: ellheight(E)
magma: FaltingsHeight(E);
oscar: faltings_height(E)
Stable Faltings height: $-0.95491333220533468452478745021\dots$
magma: StableFaltingsHeight(E);
oscar: stable_faltings_height(E)
$abc$ quality: $1.23864473399791\dots$
Szpiro ratio: $6.619664953039187\dots$

BSD invariants

Analytic rank: $0$
sage: E.analytic_rank()
gp: ellanalyticrank(E)
magma: AnalyticRank(E);
Regulator: $1$
comment: Regulator
sage: E.regulator()
G = E.gen \\ if available
magma: Regulator(E);
Real period: $5.2999162508563498719410684989\dots$
comment: Real Period
sage: E.period_lattice().omega()
gp: if(E.disc>0,2,1)*[1]
magma: (Discriminant(E) gt 0 select 2 else 1) * RealPeriod(E);
Tamagawa product: $ 1 $
comment: Tamagawa numbers
sage: E.tamagawa_numbers()
gp: gr=ellglobalred(E); [[gr[4][i,1],gr[5][i][4]] | i<-[1..#gr[4][,1]]]
magma: TamagawaNumbers(E);
oscar: tamagawa_numbers(E)
Torsion order: $3$
comment: Torsion order
sage: E.torsion_order()
gp: elltors(E)[1]
magma: Order(TorsionSubgroup(E));
oscar: prod(torsion_structure(E)[1])
Analytic order of Ш: $1$ ( exact)
comment: Order of Sha
sage: E.sha().an_numerical()
magma: MordellWeilShaInformation(E);
Special value: $ L(E,1) $ ≈ $ 0.58887958342848331910456316655 $
comment: Special L-value
r = E.rank();
gp: [r,L1r] = ellanalyticrank(E); L1r/r!
magma: Lr1 where r,Lr1 := AnalyticRank(E: Precision:=12);

BSD formula

$\displaystyle 0.588879583 \approx L(E,1) = \frac{\# Ш(E/\Q)\cdot \Omega_E \cdot \mathrm{Reg}(E/\Q) \cdot \prod_p c_p}{\#E(\Q)_{\rm tor}^2} \approx \frac{1 \cdot 5.299916 \cdot 1.000000 \cdot 1}{3^2} \approx 0.588879583$

# self-contained SageMath code snippet for the BSD formula (checks rank, computes analytic sha)
E = EllipticCurve(%s); r = E.rank(); ar = E.analytic_rank(); assert r == ar;
Lr1 = E.lseries().dokchitser().derivative(1,r)/r.factorial(); sha = E.sha().an_numerical();
omega = E.period_lattice().omega(); reg = E.regulator(); tam = E.tamagawa_product(); tor = E.torsion_order();
assert r == ar; print("analytic sha: " + str(RR(Lr1) * tor^2 / (omega * reg * tam)))
/* self-contained Magma code snippet for the BSD formula (checks rank, computes analyiic sha) */
E := EllipticCurve(%s); r := Rank(E); ar,Lr1 := AnalyticRank(E: Precision := 12); assert r eq ar;
sha := MordellWeilShaInformation(E); omega := RealPeriod(E) * (Discriminant(E) gt 0 select 2 else 1);
reg := Regulator(E); tam := &*TamagawaNumbers(E); tor := #TorsionSubgroup(E);
assert r eq ar; print "analytic sha:", Lr1 * tor^2 / (omega * reg * tam);

Modular invariants

Modular form   27.2.a.a

\( q - 2 q^{4} - q^{7} + 5 q^{13} + 4 q^{16} - 7 q^{19} + O(q^{20}) \) Copy content Toggle raw display

comment: q-expansion of modular form
sage: E.q_eigenform(20)
\\ actual modular form, use for small N
[mf,F] = mffromell(E)
\\ or just the series
magma: ModularForm(E);

For more coefficients, see the Downloads section to the right.

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

Local data

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

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

comment: Local data
sage: E.local_data()
gp: ellglobalred(E)[5]
magma: [LocalInformation(E,p) : p in BadPrimes(E)];
oscar: [(p,tamagawa_number(E,p), kodaira_symbol(E,p), reduction_type(E,p)) for p in bad_primes(E)]

Galois representations

The $\ell$-adic Galois representation has maximal image for all primes $\ell$ except those listed in the table below.

prime $\ell$ mod-$\ell$ image $\ell$-adic image
$3$ 3B.1.1 27.648.13.25

comment: mod p Galois image
sage: rho = E.galois_representation(); [rho.image_type(p) for p in rho.non_surjective()]
magma: [GaloisRepresentation(E,p): p in PrimesUpTo(20)];


gp: ellisomat(E)

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.


This elliptic curve is its own minimal quadratic twist.

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:

$[K:\Q]$ $K$ $E(K)_{\rm tors}$ Base change curve
$3$ \(\Z/6\Z\) Not in database
$3$ \(\Q(\zeta_{9})^+\) \(\Z/9\Z\)
$6$ 6.0.34992.1 \(\Z/2\Z \oplus \Z/6\Z\) Not in database
$6$ 6.0.177147.2 \(\Z/3\Z \oplus \Z/3\Z\) 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 \(\Z/3\Z \oplus \Z/9\Z\) Not in database
$18$ 18.0.2954312706550833698643.2 \(\Z/27\Z\) Not in database
$18$ 18.0.1844362878529525198848.1 \(\Z/6\Z \oplus \Z/6\Z\) Not in database
$18$ 18.0.1844362878529525198848.2 \(\Z/2\Z \oplus \Z/18\Z\) Not in database
$18$ 18.0.2529990231179046912.1 \(\Z/2\Z \oplus \Z/18\Z\) Not in database

We only show fields where the torsion growth is primitive.

Iwasawa invariants

$p$ 2 3
Reduction type ss add
$\lambda$-invariant(s) 0,5 -
$\mu$-invariant(s) 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.

$p$-adic regulators

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