# Properties

 Label 120a4 Conductor $120$ Discriminant $-33592320$ j-invariant $$\frac{54607676}{32805}$$ CM no Rank $0$ Torsion structure $$\Z/{4}\Z$$

# Related objects

Show commands: Magma / Pari/GP / SageMath

## Simplified equation

 $$y^2=x^3+x^2+80x+80$$ y^2=x^3+x^2+80x+80 (homogenize, simplify) $$y^2z=x^3+x^2z+80xz^2+80z^3$$ y^2z=x^3+x^2z+80xz^2+80z^3 (dehomogenize, simplify) $$y^2=x^3+6453x+38934$$ y^2=x^3+6453x+38934 (homogenize, minimize)

sage: E = EllipticCurve([0, 1, 0, 80, 80])

gp: E = ellinit([0, 1, 0, 80, 80])

magma: E := EllipticCurve([0, 1, 0, 80, 80]);

sage: E.short_weierstrass_model()

magma: WeierstrassModel(E);

## Mordell-Weil group structure

$$\Z/{4}\Z$$

## Torsion generators

sage: E.torsion_subgroup().gens()

gp: elltors(E)

magma: TorsionSubgroup(E);

$$\left(8, 36\right)$$

## Integral points

sage: E.integral_points()

magma: IntegralPoints(E);

$$\left(-1, 0\right)$$, $$(8,\pm 36)$$

## Invariants

 sage: E.conductor().factor()  gp: ellglobalred(E)[1]  magma: Conductor(E); Conductor: $$120$$ = $2^{3} \cdot 3 \cdot 5$ sage: E.discriminant().factor()  gp: E.disc  magma: Discriminant(E); Discriminant: $-33592320$ = $-1 \cdot 2^{10} \cdot 3^{8} \cdot 5$ sage: E.j_invariant().factor()  gp: E.j  magma: jInvariant(E); j-invariant: $$\frac{54607676}{32805}$$ = $2^{2} \cdot 3^{-8} \cdot 5^{-1} \cdot 239^{3}$ Endomorphism ring: $\Z$ Geometric endomorphism ring: $$\Z$$ (no potential complex multiplication) Sato-Tate group: $\mathrm{SU}(2)$ Faltings height: $0.13342527478994193668010000701\dots$ Stable Faltings height: $-0.44419737567667915450092676087\dots$

## 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: if(E.disc>0,2,1)*E.omega[1]  magma: (Discriminant(E) gt 0 select 2 else 1) * RealPeriod(E); Real period: $1.2694942779633329898464064271\dots$ 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: $16$  = $2\cdot2^{3}\cdot1$ sage: E.torsion_order()  gp: elltors(E)[1]  magma: Order(TorsionSubgroup(E)); Torsion order: $4$ 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: $L(E,1)$ ≈ $1.2694942779633329898464064271$

## 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);

$$q + q^{3} + q^{5} + q^{9} - 4 q^{11} + 6 q^{13} + q^{15} - 6 q^{17} - 4 q^{19} + O(q^{20})$$

 sage: E.modular_degree()  magma: ModularDegree(E); Modular degree: 32 $\Gamma_0(N)$-optimal: no 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$(j)_{-}$
$2$ $2$ $III^{*}$ Additive -1 3 10 0
$3$ $8$ $I_{8}$ Split multiplicative -1 1 8 8
$5$ $1$ $I_{1}$ Split multiplicative -1 1 1 1

## 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 $\ell$ except those listed in the table below.

prime $\ell$ mod-$\ell$ image $\ell$-adic image
$2$ 2B 8.48.0.160
sage: gens = [[1, 0, 16, 1], [1, 16, 0, 1], [56, 1, 223, 10], [15, 2, 142, 227], [106, 67, 143, 222], [5, 4, 236, 237], [161, 16, 88, 129], [225, 16, 224, 17], [13, 16, 204, 25]]

sage: GL(2,Integers(240)).subgroup(gens)

magma: Gens := [[1, 0, 16, 1], [1, 16, 0, 1], [56, 1, 223, 10], [15, 2, 142, 227], [106, 67, 143, 222], [5, 4, 236, 237], [161, 16, 88, 129], [225, 16, 224, 17], [13, 16, 204, 25]];

magma: sub<GL(2,Integers(240))|Gens>;

The image of the adelic Galois representation has level $240$, index $192$, genus $1$, and generators

$\left(\begin{array}{rr} 1 & 0 \\ 16 & 1 \end{array}\right),\left(\begin{array}{rr} 1 & 16 \\ 0 & 1 \end{array}\right),\left(\begin{array}{rr} 56 & 1 \\ 223 & 10 \end{array}\right),\left(\begin{array}{rr} 15 & 2 \\ 142 & 227 \end{array}\right),\left(\begin{array}{rr} 106 & 67 \\ 143 & 222 \end{array}\right),\left(\begin{array}{rr} 5 & 4 \\ 236 & 237 \end{array}\right),\left(\begin{array}{rr} 161 & 16 \\ 88 & 129 \end{array}\right),\left(\begin{array}{rr} 225 & 16 \\ 224 & 17 \end{array}\right),\left(\begin{array}{rr} 13 & 16 \\ 204 & 25 \end{array}\right)$

## $p$-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 $\lambda$-invariant(s) 2 3 5 add split split - 3 1 - 0 0

All Iwasawa $\lambda$ and $\mu$-invariants for primes $p\ge 3$ 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 $d=$ 2, 4 and 8.
Its isogeny class 120a consists of 6 curves linked by isogenies of degrees dividing 8.

## 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 $E(\Q)_{\rm tors}$ $\cong \Z/{4}\Z$ are as follows:

 $[K:\Q]$ $E(K)_{\rm tors}$ Base change curve $K$ $2$ $$\Q(\sqrt{-5})$$ $$\Z/2\Z \oplus \Z/4\Z$$ Not in database $2$ $$\Q(\sqrt{10})$$ $$\Z/8\Z$$ 2.2.40.1-360.1-p2 $2$ $$\Q(\sqrt{-2})$$ $$\Z/8\Z$$ 2.0.8.1-1800.2-a2 $4$ $$\Q(\sqrt{-2}, \sqrt{-5})$$ $$\Z/2\Z \oplus \Z/8\Z$$ Not in database $8$ 8.0.64000000.3 $$\Z/4\Z \oplus \Z/4\Z$$ Not in database $8$ 8.0.1024000000.6 $$\Z/2\Z \oplus \Z/8\Z$$ Not in database $8$ 8.4.21233664000000.25 $$\Z/16\Z$$ Not in database $8$ 8.0.33973862400.4 $$\Z/16\Z$$ Not in database $8$ 8.2.113374080000.2 $$\Z/12\Z$$ Not in database $16$ deg 16 $$\Z/4\Z \oplus \Z/8\Z$$ Not in database $16$ 16.0.16777216000000000000.3 $$\Z/4\Z \oplus \Z/8\Z$$ Not in database $16$ deg 16 $$\Z/2\Z \oplus \Z/16\Z$$ Not in database $16$ deg 16 $$\Z/2\Z \oplus \Z/16\Z$$ Not in database $16$ deg 16 $$\Z/2\Z \oplus \Z/12\Z$$ Not in database $16$ deg 16 $$\Z/24\Z$$ Not in database $16$ deg 16 $$\Z/24\Z$$ 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.