Properties

Label 36481.a.36481.1
Conductor $36481$
Discriminant $36481$
Mordell-Weil group \(\Z \times \Z\)
Sato-Tate group $G_{3,3}$
\(\End(J_{\overline{\Q}}) \otimes \R\) \(\R \times \R\)
\(\End(J_{\overline{\Q}}) \otimes \Q\) \(\mathsf{RM}\)
\(\End(J) \otimes \Q\) \(\mathsf{RM}\)
\(\overline{\Q}\)-simple yes
\(\mathrm{GL}_2\)-type yes

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This is a model for the quotient of the modular curve $X_0(191)$ by its Fricke involution involution $w_{191}$. This is the largest level $N \in \mathbb{N}$ such that $X_0(N)/ \langle w_N \rangle$ is of genus $2$.

Minimal equation

Minimal equation

Simplified equation

$y^2 + (x^3 + x + 1)y = x^2 - 2x$ (homogenize, simplify)
$y^2 + (x^3 + xz^2 + z^3)y = x^2z^4 - 2xz^5$ (dehomogenize, simplify)
$y^2 = x^6 + 2x^4 + 2x^3 + 5x^2 - 6x + 1$ (minimize, homogenize)

sage: R.<x> = PolynomialRing(QQ); C = HyperellipticCurve(R([0, -2, 1]), R([1, 1, 0, 1]));
 
magma: R<x> := PolynomialRing(Rationals()); C := HyperellipticCurve(R![0, -2, 1], R![1, 1, 0, 1]);
 
sage: X = HyperellipticCurve(R([1, -6, 5, 2, 2, 0, 1]))
 
magma: X,pi:= SimplifiedModel(C);
 

Invariants

Conductor: \( N \)  \(=\)  \(36481\) \(=\) \( 191^{2} \)
magma: Conductor(LSeries(C)); Factorization($1);
 
Discriminant: \( \Delta \)  \(=\)  \(36481\) \(=\) \( 191^{2} \)
magma: Discriminant(C); Factorization(Integers()!$1);
 

Igusa-Clebsch invariants

Igusa invariants

G2 invariants

\( I_2 \)  \(=\) \(188\) \(=\)  \( 2^{2} \cdot 47 \)
\( I_4 \)  \(=\) \(9409\) \(=\)  \( 97^{2} \)
\( I_6 \)  \(=\) \(508799\) \(=\)  \( 508799 \)
\( I_{10} \)  \(=\) \(-4669568\) \(=\)  \( - 2^{7} \cdot 191^{2} \)
\( J_2 \)  \(=\) \(47\) \(=\)  \( 47 \)
\( J_4 \)  \(=\) \(-300\) \(=\)  \( - 2^{2} \cdot 3 \cdot 5^{2} \)
\( J_6 \)  \(=\) \(-1708\) \(=\)  \( - 2^{2} \cdot 7 \cdot 61 \)
\( J_8 \)  \(=\) \(-42569\) \(=\)  \( -42569 \)
\( J_{10} \)  \(=\) \(-36481\) \(=\)  \( - 191^{2} \)
\( g_1 \)  \(=\) \(-229345007/36481\)
\( g_2 \)  \(=\) \(31146900/36481\)
\( g_3 \)  \(=\) \(3772972/36481\)

sage: C.igusa_clebsch_invariants(); [factor(a) for a in _]
 
magma: IgusaClebschInvariants(C); IgusaInvariants(C); G2Invariants(C);
 

Automorphism group

\(\mathrm{Aut}(X)\)\(\simeq\) $C_2$
magma: AutomorphismGroup(C); IdentifyGroup($1);
 
\(\mathrm{Aut}(X_{\overline{\Q}})\)\(\simeq\) $C_2$
magma: AutomorphismGroup(ChangeRing(C,AlgebraicClosure(Rationals()))); IdentifyGroup($1);
 

Rational points

Known points: \((1 : 0 : 0),\, (1 : -1 : 0),\, (0 : 0 : 1),\, (0 : -1 : 1),\, (2 : 0 : 1),\, (2 : -11 : 1)\)

magma: [C![0,-1,1],C![0,0,1],C![1,-1,0],C![1,0,0],C![2,-11,1],C![2,0,1]];
 

Number of rational Weierstrass points: \(0\)

magma: #Roots(HyperellipticPolynomials(SimplifiedModel(C)));
 

This curve is locally solvable everywhere.

magma: f,h:=HyperellipticPolynomials(C); g:=4*f+h^2; HasPointsEverywhereLocally(g,2) and (#Roots(ChangeRing(g,RealField())) gt 0 or LeadingCoefficient(g) gt 0);
 

Mordell-Weil group of the Jacobian

Group structure: \(\Z \times \Z\)

magma: MordellWeilGroupGenus2(Jacobian(C));
 

Generator $D_0$ Height Order
\((0 : 0 : 1) - (1 : -1 : 0)\) \(z x\) \(=\) \(0,\) \(y\) \(=\) \(0\) \(0.309839\) \(\infty\)
\((0 : -1 : 1) - (1 : -1 : 0)\) \(z x\) \(=\) \(0,\) \(y\) \(=\) \(-z^3\) \(0.210369\) \(\infty\)

2-torsion field: 5.1.2334784.2

BSD invariants

Hasse-Weil conjecture: verified
Analytic rank: \(2\)
Mordell-Weil rank: \(2\)
2-Selmer rank:\(2\)
Regulator: \( 0.055286 \)
Real period: \( 17.35657 \)
Tamagawa product: \( 1 \)
Torsion order:\( 1 \)
Leading coefficient: \( 0.959581 \)
Analytic order of Ш: \( 1 \)   (rounded)
Order of Ш:square

Local invariants

Prime ord(\(N\)) ord(\(\Delta\)) Tamagawa L-factor Cluster picture
\(191\) \(2\) \(2\) \(1\) \(( 1 + T )^{2}\)

Sato-Tate group

\(\mathrm{ST}\)\(\simeq\) $G_{3,3}$
\(\mathrm{ST}^0\)\(\simeq\) \(\mathrm{SU}(2)\times\mathrm{SU}(2)\)

Decomposition of the Jacobian

Simple over \(\overline{\Q}\)

Endomorphisms of the Jacobian

Of \(\GL_2\)-type over \(\Q\)

Endomorphism ring over \(\Q\):

\(\End (J_{})\)\(\simeq\)\(\Z [\frac{1 + \sqrt{5}}{2}]\)
\(\End (J_{}) \otimes \Q \)\(\simeq\)\(\Q(\sqrt{5}) \)
\(\End (J_{}) \otimes \R\)\(\simeq\) \(\R \times \R\)

All \(\overline{\Q}\)-endomorphisms of the Jacobian are defined over \(\Q\).