Properties

Label 28224.dw4
Conductor $28224$
Discriminant $-65548320768$
j-invariant \( -3375 \)
CM yes (\(D=-7\))
Rank $1$
Torsion structure \(\Z/{2}\Z\)

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Show commands: Magma / Pari/GP / SageMath

Minimal Weierstrass equation

sage: E = EllipticCurve([0, 0, 0, -1260, 21168])
 
gp: E = ellinit([0, 0, 0, -1260, 21168])
 
magma: E := EllipticCurve([0, 0, 0, -1260, 21168]);
 

\(y^2=x^3-1260x+21168\)  Toggle raw display

Mordell-Weil group structure

$\Z\times \Z/{2}\Z$

Infinite order Mordell-Weil generator and height

sage: E.gens()
 
magma: Generators(E);
 

$P$ =  \(\left(21, 63\right)\)  Toggle raw display
$\hat{h}(P)$ ≈  $1.3838174644149674858408056866$

Torsion generators

sage: E.torsion_subgroup().gens()
 
gp: elltors(E)
 
magma: TorsionSubgroup(E);
 

\( \left(-42, 0\right) \)  Toggle raw display

Integral points

sage: E.integral_points()
 
magma: IntegralPoints(E);
 

\( \left(-42, 0\right) \), \((21,\pm 63)\), \((22,\pm 64)\), \((16086,\pm 2040192)\)  Toggle raw display

Invariants

sage: E.conductor().factor()
 
gp: ellglobalred(E)[1]
 
magma: Conductor(E);
 
Conductor: \( 28224 \)  =  $2^{6} \cdot 3^{2} \cdot 7^{2}$
sage: E.discriminant().factor()
 
gp: E.disc
 
magma: Discriminant(E);
 
Discriminant: $-65548320768 $  =  $-1 \cdot 2^{18} \cdot 3^{6} \cdot 7^{3} $
sage: E.j_invariant().factor()
 
gp: E.j
 
magma: jInvariant(E);
 
j-invariant: \( -3375 \)  =  $-1 \cdot 3^{3} \cdot 5^{3}$
Endomorphism ring: $\Z$
Geometric endomorphism ring: \(\Z[(1+\sqrt{-7})/2]\) (potential complex multiplication)
Sato-Tate group: $N(\mathrm{U}(1))$
Faltings height: $0.78988852611835039269915909092\dots$
Stable Faltings height: $-1.2856159263194507434006498956\dots$

BSD invariants

sage: E.rank()
 
magma: Rank(E);
 
Analytic rank: $1$
sage: E.regulator()
 
magma: Regulator(E);
 
Regulator: $1.3838174644149674858408056866\dots$
sage: E.period_lattice().omega()
 
gp: E.omega[1]
 
magma: RealPeriod(E);
 
Real period: $1.0441076544415988952242884345\dots$
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: $ 16 $  = $ 2^{2}\cdot2\cdot2 $
sage: E.torsion_order()
 
gp: elltors(E)[1]
 
magma: Order(TorsionSubgroup(E));
 
Torsion order: $2$
sage: E.sha().an_numerical()
 
magma: MordellWeilShaInformation(E);
 
Analytic order of Ш: $1$ (exact)
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);
 
Special value: $ L'(E,1) $ ≈ $ 5.7794176277825297904209902354670756865 $

Modular invariants

Modular form 28224.2.a.dw

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);
 

\( q + 4q^{11} + O(q^{20}) \)  Toggle raw display

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

sage: E.modular_degree()
 
magma: ModularDegree(E);
 
Modular degree: 16384
$ \Gamma_0(N) $-optimal: yes
Manin constant: 1

Local data

This elliptic curve is not semistable. There are 3 primes 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$(j)_{-}$
$2$ $4$ $I_8^{*}$ Additive 1 6 18 0
$3$ $2$ $I_0^{*}$ Additive -1 2 6 0
$7$ $2$ $III$ Additive -1 2 3 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 $\ell$-adic Galois representation has maximal image for all primes $\ell$.

$p$-adic regulators

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

Note: $p$-adic regulator data only exists for primes $p\ge 5$ of good ordinary reduction.

Iwasawa invariants

$p$ 2 3 5 7 11 13 17 19 23 29 31 37 41 43 47
Reduction type add add ss add ordinary ss ss ss ordinary ordinary ss ordinary ss ordinary ss
$\lambda$-invariant(s) - - 1,1 - 1 1,1 1,1 1,1 1 1 3,1 1 1,1 1 1,1
$\mu$-invariant(s) - - 0,0 - 0 0,0 0,0 0,0 0 0 0,0 0 0,0 0 0,0

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 $d=$ 2, 7 and 14.
Its isogeny class 28224.dw consists of 4 curves linked by isogenies of degrees dividing 14.

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 $E(\Q)_{\rm tors}$ $\cong \Z/{2}\Z$ are as follows:

$[K:\Q]$ $K$ $E(K)_{\rm tors}$ Base change curve
$2$ \(\Q(\sqrt{-7}) \) \(\Z/2\Z \times \Z/2\Z\) Not in database
$4$ 4.2.790272.1 \(\Z/4\Z\) Not in database
$4$ 4.0.197568.2 \(\Z/2\Z \times \Z/4\Z\) Not in database
$6$ 6.6.232339968.1 \(\Z/14\Z\) Not in database
$8$ 8.0.624529833984.16 \(\Z/4\Z \times \Z/4\Z\) Not in database
$8$ 8.0.156132458496.3 \(\Z/2\Z \times \Z/8\Z\) Not in database
$8$ 8.2.1053894094848.2 \(\Z/6\Z\) Not in database
$12$ 12.0.53981860730241024.5 \(\Z/2\Z \times \Z/14\Z\) Not in database
$16$ Deg 16 \(\Z/8\Z\) Not in database
$16$ Deg 16 \(\Z/4\Z \times \Z/8\Z\) Not in database
$16$ Deg 16 \(\Z/2\Z \times \Z/16\Z\) Not in database
$16$ Deg 16 \(\Z/6\Z \times \Z/6\Z\) Not in database
$20$ 20.0.709769256018536283137282494313791488.2 \(\Z/2\Z \times \Z/22\Z\) Not in database

We only show fields where the torsion growth is primitive. For fields not in the database, click on the degree shown to reveal the defining polynomial.