This is a model for the modular curve $X_0(20)$.
Minimal Weierstrass equation
Minimal Weierstrass equation
Simplified equation
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\(y^2=x^3+x^2+4x+4\)
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(homogenize, simplify) |
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\(y^2z=x^3+x^2z+4xz^2+4z^3\)
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(dehomogenize, simplify) |
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\(y^2=x^3+297x+1998\)
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(homogenize, minimize) |
Mordell-Weil group structure
\(\Z/{6}\Z\)
Mordell-Weil generators
| $P$ | $\hat{h}(P)$ | Order |
|---|---|---|
| \( \left(4, 10\right) \) | $0$ | $6$ |
| $P$ | $\hat{h}(P)$ | Order |
|---|---|---|
| \([4:10:1]\) | $0$ | $6$ |
| $P$ | $\hat{h}(P)$ | Order |
|---|---|---|
| \( \left(39, 270\right) \) | $0$ | $6$ |
Integral points
\( \left(-1, 0\right) \), \((0,\pm 2)\), \((4,\pm 10)\)
\([-1:0:1]\), \([0:\pm 2:1]\), \([4:\pm 10:1]\)
\( \left(-1, 0\right) \), \((0,\pm 2)\), \((4,\pm 10)\)
Invariants
| Conductor: | $N$ | = | \( 20 \) | = | $2^{2} \cdot 5$ |
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| Minimal Discriminant: | $\Delta$ | = | $-6400$ | = | $-1 \cdot 2^{8} \cdot 5^{2} $ |
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| j-invariant: | $j$ | = | \( \frac{21296}{25} \) | = | $2^{4} \cdot 5^{-2} \cdot 11^{3}$ |
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| Endomorphism ring: | $\mathrm{End}(E)$ | = | $\Z$ | |||
| Geometric endomorphism ring: | $\mathrm{End}(E_{\overline{\Q}})$ | = | \(\Z\) (no potential complex multiplication) |
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| Sato-Tate group: | $\mathrm{ST}(E)$ | = | $\mathrm{SU}(2)$ | |||
| Faltings height: | $h_{\mathrm{Faltings}}$ | ≈ | $-0.58337650523554731646541001985$ |
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| Stable Faltings height: | $h_{\mathrm{stable}}$ | ≈ | $-1.0454746256088441894102314342$ |
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| $abc$ quality: | $Q$ | ≈ | $0.8396384887826309$ | |||
| Szpiro ratio: | $\sigma_{m}$ | ≈ | $5.18724658047375$ | |||
| Intrinsic torsion order: | $\#E(\mathbb Q)_\text{tors}^\text{is}$ | = | $1$ | |||
BSD invariants
| Analytic rank: | $r_{\mathrm{an}}$ | = | $ 0$ |
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| Mordell-Weil rank: | $r$ | = | $ 0$ |
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| Regulator: | $\mathrm{Reg}(E/\Q)$ | = | $1$ |
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| Real period: | $\Omega$ | ≈ | $2.8243751419591137994837895490$ |
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| Tamagawa product: | $\prod_{p}c_p$ | = | $ 6 $ = $ 3\cdot2 $ |
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| Torsion order: | $\#E(\Q)_{\mathrm{tor}}$ | = | $6$ |
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| Special value: | $ L(E,1)$ | ≈ | $0.47072919032651896658063159151 $ |
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| Analytic order of Ш: | Ш${}_{\mathrm{an}}$ | = | $1$ (exact) |
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BSD formula
$$\begin{aligned} 0.470729190 \approx L(E,1) & = \frac{\# ะจ(E/\Q)\cdot \Omega_E \cdot \mathrm{Reg}(E/\Q) \cdot \prod_p c_p}{\#E(\Q)_{\rm tor}^2} \\ & \approx \frac{1 \cdot 2.824375 \cdot 1.000000 \cdot 6}{6^2} \\ & \approx 0.470729190\end{aligned}$$
Modular invariants
For more coefficients, see the Downloads section to the right.
| Modular degree: | 1 |
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| $ \Gamma_0(N) $-optimal: | yes | |
| Manin constant: | 1 |
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Local data at primes of bad reduction
This elliptic curve is not semistable. There are 2 primes $p$ of bad reduction:
| $p$ | Tamagawa number | Kodaira symbol | Reduction type | Root number | $\mathrm{ord}_p(N)$ | $\mathrm{ord}_p(\Delta)$ | $\mathrm{ord}_p(\mathrm{den}(j))$ |
|---|---|---|---|---|---|---|---|
| $2$ | $3$ | $IV^{*}$ | additive | -1 | 2 | 8 | 0 |
| $5$ | $2$ | $I_{2}$ | nonsplit multiplicative | 1 | 1 | 2 | 2 |
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 | $\ell$-adic index |
|---|---|---|---|
| $2$ | 2B | 8.12.0.37 | $12$ |
| $3$ | 3B.1.1 | 3.8.0.1 | $8$ |
The image $H:=\rho_E(\Gal(\overline{\Q}/\Q))$ of the adelic Galois representation has level \( 120 = 2^{3} \cdot 3 \cdot 5 \), index $384$, genus $9$, and generators
$\left(\begin{array}{rr} 97 & 24 \\ 96 & 25 \end{array}\right),\left(\begin{array}{rr} 1 & 0 \\ 24 & 1 \end{array}\right),\left(\begin{array}{rr} 99 & 4 \\ 71 & 65 \end{array}\right),\left(\begin{array}{rr} 13 & 24 \\ 12 & 13 \end{array}\right),\left(\begin{array}{rr} 15 & 16 \\ 74 & 95 \end{array}\right),\left(\begin{array}{rr} 61 & 24 \\ 6 & 25 \end{array}\right),\left(\begin{array}{rr} 1 & 24 \\ 0 & 1 \end{array}\right),\left(\begin{array}{rr} 15 & 22 \\ 14 & 83 \end{array}\right),\left(\begin{array}{rr} 99 & 16 \\ 46 & 3 \end{array}\right)$.
The torsion field $K:=\Q(E[120])$ is a degree-$92160$ Galois extension of $\Q$ with $\Gal(K/\Q)$ isomorphic to the projection of $H$ to $\GL_2(\Z/120\Z)$.
The table below list all primes $\ell$ for which the Serre invariants associated to the mod-$\ell$ Galois representation are exceptional.
| $\ell$ | Reduction type | Serre weight | Serre conductor |
|---|---|---|---|
| $2$ | additive | $2$ | \( 1 \) |
| $5$ | nonsplit multiplicative | $6$ | \( 4 = 2^{2} \) |
Isogenies
This curve has non-trivial cyclic isogenies of degree $d$ for $d=$
2, 3 and 6.
Its isogeny class 20a
consists of 4 curves linked by isogenies of
degrees dividing 6.
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 $E(\Q)_{\rm tors}$ $\cong \Z/{6}\Z$ are as follows:
| $[K:\Q]$ | $K$ | $E(K)_{\rm tors}$ | Base change curve |
|---|---|---|---|
| $2$ | \(\Q(\sqrt{-1}) \) | \(\Z/2\Z \oplus \Z/6\Z\) | 2.0.4.1-100.2-a6 |
| $4$ | 4.2.400.1 | \(\Z/12\Z\) | not in database |
| $6$ | 6.0.270000.1 | \(\Z/3\Z \oplus \Z/6\Z\) | not in database |
| $8$ | 8.0.2560000.1 | \(\Z/2\Z \oplus \Z/12\Z\) | not in database |
| $8$ | 8.0.6553600.1 | \(\Z/2\Z \oplus \Z/12\Z\) | not in database |
| $9$ | 9.3.787320000.1 | \(\Z/18\Z\) | not in database |
| $12$ | 12.0.18662400000000.1 | \(\Z/6\Z \oplus \Z/6\Z\) | not in database |
| $16$ | 16.0.26843545600000000.2 | \(\Z/4\Z \oplus \Z/12\Z\) | not in database |
| $16$ | 16.4.16777216000000000000.4 | \(\Z/24\Z\) | not in database |
| $18$ | 18.0.2538998916710400000000.1 | \(\Z/2\Z \oplus \Z/18\Z\) | not in database |
We only show fields where the torsion growth is primitive.
Iwasawa invariants
| $p$ | 2 | 3 | 5 |
|---|---|---|---|
| Reduction type | add | ord | nonsplit |
| $\lambda$-invariant(s) | - | 2 | 0 |
| $\mu$-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 $0$.