Properties

Label 976.a.999424.1
Conductor $976$
Discriminant $999424$
Mordell-Weil group \(\Z/{29}\Z\)
Sato-Tate group $\mathrm{USp}(4)$
\(\End(J_{\overline{\Q}}) \otimes \R\) \(\R\)
\(\End(J_{\overline{\Q}}) \otimes \Q\) \(\Q\)
\(\End(J) \otimes \Q\) \(\Q\)
\(\overline{\Q}\)-simple yes
\(\mathrm{GL}_2\)-type no

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Minimal equation

Minimal equation

Simplified equation

$y^2 + (x + 1)y = x^6 - 2x^5 + 2x^3 - x^2$ (homogenize, simplify)
$y^2 + (xz^2 + z^3)y = x^6 - 2x^5z + 2x^3z^3 - x^2z^4$ (dehomogenize, simplify)
$y^2 = 4x^6 - 8x^5 + 8x^3 - 3x^2 + 2x + 1$ (minimize, homogenize)

sage: R.<x> = PolynomialRing(QQ); C = HyperellipticCurve(R([0, 0, -1, 2, 0, -2, 1]), R([1, 1]));
 
magma: R<x> := PolynomialRing(Rationals()); C := HyperellipticCurve(R![0, 0, -1, 2, 0, -2, 1], R![1, 1]);
 
sage: X = HyperellipticCurve(R([1, 2, -3, 8, 0, -8, 4]))
 
magma: X,pi:= SimplifiedModel(C);
 

Invariants

Conductor: \( N \)  \(=\)  \(976\) \(=\) \( 2^{4} \cdot 61 \)
magma: Conductor(LSeries(C: ExcFactors:=[*<2,Valuation(976,2),R![1, -1]>*])); Factorization($1);
 
Discriminant: \( \Delta \)  \(=\)  \(999424\) \(=\) \( 2^{14} \cdot 61 \)
magma: Discriminant(C); Factorization(Integers()!$1);
 

Igusa-Clebsch invariants

Igusa invariants

G2 invariants

\( I_2 \)  \(=\) \(152\) \(=\)  \( 2^{3} \cdot 19 \)
\( I_4 \)  \(=\) \(1012\) \(=\)  \( 2^{2} \cdot 11 \cdot 23 \)
\( I_6 \)  \(=\) \(68714\) \(=\)  \( 2 \cdot 17 \cdot 43 \cdot 47 \)
\( I_{10} \)  \(=\) \(-124928\) \(=\)  \( - 2^{11} \cdot 61 \)
\( J_2 \)  \(=\) \(152\) \(=\)  \( 2^{3} \cdot 19 \)
\( J_4 \)  \(=\) \(288\) \(=\)  \( 2^{5} \cdot 3^{2} \)
\( J_6 \)  \(=\) \(-24464\) \(=\)  \( - 2^{4} \cdot 11 \cdot 139 \)
\( J_8 \)  \(=\) \(-950368\) \(=\)  \( - 2^{5} \cdot 17 \cdot 1747 \)
\( J_{10} \)  \(=\) \(-999424\) \(=\)  \( - 2^{14} \cdot 61 \)
\( g_1 \)  \(=\) \(-4952198/61\)
\( g_2 \)  \(=\) \(-61731/61\)
\( g_3 \)  \(=\) \(551969/976\)

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

All points: \((1 : -1 : 0),\, (1 : 1 : 0),\, (0 : 0 : 1),\, (-1 : 0 : 1),\, (0 : -1 : 1),\, (1 : 0 : 1),\, (1 : -2 : 1)\)

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

Number of rational Weierstrass points: \(1\)

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: \(\Z/{29}\Z\)

magma: MordellWeilGroupGenus2(Jacobian(C));
 

Generator $D_0$ Height Order
\(2 \cdot(0 : 0 : 1) - (1 : -1 : 0) - (1 : 1 : 0)\) \(x^2\) \(=\) \(0,\) \(y\) \(=\) \(0\) \(0\) \(29\)

2-torsion field: 5.1.15616.1

BSD invariants

Hasse-Weil conjecture: unverified
Analytic rank: \(0\)
Mordell-Weil rank: \(0\)
2-Selmer rank:\(0\)
Regulator: \( 1 \)
Real period: \( 12.90036 \)
Tamagawa product: \( 29 \)
Torsion order:\( 29 \)
Leading coefficient: \( 0.444840 \)
Analytic order of Ш: \( 1 \)   (rounded)
Order of Ш:square

Local invariants

Prime ord(\(N\)) ord(\(\Delta\)) Tamagawa L-factor Cluster picture
\(2\) \(4\) \(14\) \(29\) \(1 - T\)
\(61\) \(1\) \(1\) \(1\) \(( 1 - T )( 1 - 4 T + 61 T^{2} )\)

Sato-Tate group

\(\mathrm{ST}\)\(\simeq\) $\mathrm{USp}(4)$
\(\mathrm{ST}^0\)\(\simeq\) \(\mathrm{USp}(4)\)

Decomposition of the Jacobian

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

Endomorphisms of the Jacobian

Not of \(\GL_2\)-type over \(\Q\)

Endomorphism ring over \(\Q\):

\(\End (J_{})\)\(\simeq\)\(\Z\)
\(\End (J_{}) \otimes \Q \)\(\simeq\)\(\Q\)
\(\End (J_{}) \otimes \R\)\(\simeq\) \(\R\)

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

Additional information

The Jacobian of this curve has a rational 29-torsion point. This is the largest known prime factor occurring in the torsion of the Mordell-Weil group of any abelian surface over $\mathbb{Q}$. This example was discovered by Franck Leprévost in 1995: see [MR:1413580].