# Properties

 Label 930.b1 Conductor $930$ Discriminant $658986840$ j-invariant $$\frac{32208729120020809}{658986840}$$ CM no Rank $1$ Torsion structure $$\Z/{2}\Z$$

# Related objects

Show commands: Magma / Oscar / PariGP / SageMath

## Simplified equation

 $$y^2+xy=x^3+x^2-6628x+204952$$ y^2+xy=x^3+x^2-6628x+204952 (homogenize, simplify) $$y^2z+xyz=x^3+x^2z-6628xz^2+204952z^3$$ y^2z+xyz=x^3+x^2z-6628xz^2+204952z^3 (dehomogenize, simplify) $$y^2=x^3-8590563x+9691095582$$ y^2=x^3-8590563x+9691095582 (homogenize, minimize)

comment: Define the curve

sage: E = EllipticCurve([1, 1, 0, -6628, 204952])

gp: E = ellinit([1, 1, 0, -6628, 204952])

magma: E := EllipticCurve([1, 1, 0, -6628, 204952]);

oscar: E = EllipticCurve([1, 1, 0, -6628, 204952])

sage: E.short_weierstrass_model()

magma: WeierstrassModel(E);

oscar: short_weierstrass_model(E)

## Mordell-Weil group structure

$$\Z \oplus \Z/{2}\Z$$

magma: MordellWeilGroup(E);

### Infinite order Mordell-Weil generator and height

 $P$ = $$\left(47, -19\right)$$ (47, -19) $\hat{h}(P)$ ≈ $2.0526299529936577857568998294$

sage: E.gens()

magma: Generators(E);

gp: E.gen

## Torsion generators

$$\left(\frac{187}{4}, -\frac{187}{8}\right)$$

comment: Torsion subgroup

sage: E.torsion_subgroup().gens()

gp: elltors(E)

magma: TorsionSubgroup(E);

oscar: torsion_structure(E)

## Integral points

$$\left(47, -19\right)$$, $$\left(47, -28\right)$$, $$\left(229, 3166\right)$$, $$\left(229, -3395\right)$$

comment: Integral points

sage: E.integral_points()

magma: IntegralPoints(E);

## Invariants

 Conductor: $$930$$ = $2 \cdot 3 \cdot 5 \cdot 31$ comment: Conductor  sage: E.conductor().factor()  gp: ellglobalred(E)[1]  magma: Conductor(E);  oscar: conductor(E) Discriminant: $658986840$ = $2^{3} \cdot 3^{12} \cdot 5 \cdot 31$ comment: Discriminant  sage: E.discriminant().factor()  gp: E.disc  magma: Discriminant(E);  oscar: discriminant(E) j-invariant: $$\frac{32208729120020809}{658986840}$$ = $2^{-3} \cdot 3^{-12} \cdot 5^{-1} \cdot 31^{-1} \cdot 373^{3} \cdot 853^{3}$ comment: j-invariant  sage: E.j_invariant().factor()  gp: E.j  magma: jInvariant(E);  oscar: j_invariant(E) Endomorphism ring: $\Z$ Geometric endomorphism ring: $$\Z$$ (no potential complex multiplication) sage: E.has_cm()  magma: HasComplexMultiplication(E); Sato-Tate group: $\mathrm{SU}(2)$ Faltings height: $0.81172727248298071679371672864\dots$ gp: ellheight(E)  magma: FaltingsHeight(E);  oscar: faltings_height(E) Stable Faltings height: $0.81172727248298071679371672864\dots$ magma: StableFaltingsHeight(E);  oscar: stable_faltings_height(E)

## BSD invariants

 Analytic rank: $1$ sage: E.analytic_rank()  gp: ellanalyticrank(E)  magma: AnalyticRank(E); Regulator: $2.0526299529936577857568998294\dots$ comment: Regulator  sage: E.regulator()  G = E.gen \\ if available matdet(ellheightmatrix(E,G))  magma: Regulator(E); Real period: $1.4909281319194464680379456301\dots$ comment: Real Period  sage: E.period_lattice().omega()  gp: if(E.disc>0,2,1)*E.omega[1]  magma: (Discriminant(E) gt 0 select 2 else 1) * RealPeriod(E); Tamagawa product: $2$  = $1\cdot2\cdot1\cdot1$ 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: $2$ 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: $L'(E,1)$ ≈ $1.5301618706693677089205230487$ comment: Special L-value  r = E.rank(); E.lseries().dokchitser().derivative(1,r)/r.factorial()  gp: [r,L1r] = ellanalyticrank(E); L1r/r!  magma: Lr1 where r,Lr1 := AnalyticRank(E: Precision:=12);

## BSD formula

$\displaystyle 1.530161871 \approx L'(E,1) = \frac{\# Ш(E/\Q)\cdot \Omega_E \cdot \mathrm{Reg}(E/\Q) \cdot \prod_p c_p}{\#E(\Q)_{\rm tor}^2} \approx \frac{1 \cdot 1.490928 \cdot 2.052630 \cdot 2}{2^2} \approx 1.530161871$

# 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

$$q - q^{2} - q^{3} + q^{4} - q^{5} + q^{6} - q^{8} + q^{9} + q^{10} - 4 q^{11} - q^{12} + 6 q^{13} + q^{15} + q^{16} + 2 q^{17} - q^{18} - 4 q^{19} + O(q^{20})$$

comment: q-expansion of modular form

sage: E.q_eigenform(20)

\\ actual modular form, use for small N

[mf,F] = mffromell(E)

Ser(mfcoefs(mf,20),q)

\\ or just the series

Ser(ellan(E,20),q)*q

magma: ModularForm(E);

Modular degree: 1152
comment: Modular degree

sage: E.modular_degree()

gp: ellmoddegree(E)

magma: ModularDegree(E);

$\Gamma_0(N)$-optimal: no
Manin constant: 1
comment: Manin constant

magma: ManinConstant(E);

## Local data

This elliptic curve is semistable. There are 4 primes of bad reduction:

prime Tamagawa number Kodaira symbol Reduction type Root number ord($N$) ord($\Delta$) ord$(j)_{-}$
$2$ $1$ $I_{3}$ Non-split multiplicative 1 1 3 3
$3$ $2$ $I_{12}$ Non-split multiplicative 1 1 12 12
$5$ $1$ $I_{1}$ Non-split multiplicative 1 1 1 1
$31$ $1$ $I_{1}$ Non-split multiplicative 1 1 1 1

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
$2$ 2B 8.12.0.8

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)];

gens = [[748, 1, 1511, 6], [1, 0, 8, 1], [1, 8, 0, 1], [1, 4, 4, 17], [3256, 1403, 2329, 2358], [3484, 1, 503, 6], [2328, 473, 2353, 2400], [7, 6, 3714, 3715], [3713, 8, 3712, 9], [1241, 8, 1244, 33]]

GL(2,Integers(3720)).subgroup(gens)

Gens := [[748, 1, 1511, 6], [1, 0, 8, 1], [1, 8, 0, 1], [1, 4, 4, 17], [3256, 1403, 2329, 2358], [3484, 1, 503, 6], [2328, 473, 2353, 2400], [7, 6, 3714, 3715], [3713, 8, 3712, 9], [1241, 8, 1244, 33]];

sub<GL(2,Integers(3720))|Gens>;

The image $H:=\rho_E(\Gal(\overline{\Q}/\Q))$ of the adelic Galois representation has level $$3720 = 2^{3} \cdot 3 \cdot 5 \cdot 31$$, index $48$, genus $0$, and generators

$\left(\begin{array}{rr} 748 & 1 \\ 1511 & 6 \end{array}\right),\left(\begin{array}{rr} 1 & 0 \\ 8 & 1 \end{array}\right),\left(\begin{array}{rr} 1 & 8 \\ 0 & 1 \end{array}\right),\left(\begin{array}{rr} 1 & 4 \\ 4 & 17 \end{array}\right),\left(\begin{array}{rr} 3256 & 1403 \\ 2329 & 2358 \end{array}\right),\left(\begin{array}{rr} 3484 & 1 \\ 503 & 6 \end{array}\right),\left(\begin{array}{rr} 2328 & 473 \\ 2353 & 2400 \end{array}\right),\left(\begin{array}{rr} 7 & 6 \\ 3714 & 3715 \end{array}\right),\left(\begin{array}{rr} 3713 & 8 \\ 3712 & 9 \end{array}\right),\left(\begin{array}{rr} 1241 & 8 \\ 1244 & 33 \end{array}\right)$.

Input positive integer $m$ to see the generators of the reduction of $H$ to $\mathrm{GL}_2(\Z/m\Z)$:

The torsion field $K:=\Q(E[3720])$ is a degree-$658243584000$ Galois extension of $\Q$ with $\Gal(K/\Q)$ isomorphic to the projection of $H$ to $\GL_2(\Z/3720\Z)$.

## Isogenies

gp: ellisomat(E)

This curve has non-trivial cyclic isogenies of degree $d$ for $d=$ 2 and 4.
Its isogeny class 930.b consists of 4 curves linked by isogenies of degrees dividing 4.

## Twists

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

 $[K:\Q]$ $E(K)_{\rm tors}$ Base change curve $K$ $2$ $$\Q(\sqrt{310})$$ $$\Z/2\Z \oplus \Z/2\Z$$ Not in database $2$ $$\Q(\sqrt{155})$$ $$\Z/4\Z$$ Not in database $2$ $$\Q(\sqrt{2})$$ $$\Z/4\Z$$ Not in database $4$ $$\Q(\sqrt{2}, \sqrt{155})$$ $$\Z/2\Z \oplus \Z/4\Z$$ Not in database $8$ deg 8 $$\Z/2\Z \oplus \Z/4\Z$$ Not in database $8$ deg 8 $$\Z/8\Z$$ Not in database $8$ deg 8 $$\Z/8\Z$$ Not in database $8$ 8.2.1262337766875.2 $$\Z/6\Z$$ Not in database $16$ deg 16 $$\Z/4\Z \oplus \Z/4\Z$$ Not in database $16$ deg 16 $$\Z/2\Z \oplus \Z/8\Z$$ Not in database $16$ deg 16 $$\Z/2\Z \oplus \Z/8\Z$$ Not in database $16$ deg 16 $$\Z/2\Z \oplus \Z/6\Z$$ Not in database $16$ deg 16 $$\Z/12\Z$$ Not in database $16$ deg 16 $$\Z/12\Z$$ 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.

## Iwasawa invariants

 $p$ Reduction type $\lambda$-invariant(s) $\mu$-invariant(s) 2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 nonsplit nonsplit nonsplit ss ord ord ord ord ord ord nonsplit ord ord ord ss 8 1 1 1,1 1 1 1 1 1 1 1 1 3 1 1,3 0 0 0 0,0 0 0 0 0 0 0 0 0 0 0 0,0

## $p$-adic regulators

$p$-adic regulators are not yet computed for curves that are not $\Gamma_0$-optimal.