Properties

Label 847.c.9317.1
Conductor 847
Discriminant 9317
Mordell-Weil group \(\Z/{8}\Z\)
Sato-Tate group $\mathrm{USp}(4)$
\(\End(J_{\overline{\Q}}) \otimes \R\) \(\R\)
\(\End(J_{\overline{\Q}}) \otimes \Q\) \(\Q\)
\(\overline{\Q}\)-simple yes
\(\mathrm{GL}_2\)-type no

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Minimal equation

Minimal equation

Simplified equation

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

sage: R.<x> = PolynomialRing(QQ); C = HyperellipticCurve(R([-2, -1, 0, 1, 1]), R([0, 0, 1, 1]));
 
magma: R<x> := PolynomialRing(Rationals()); C := HyperellipticCurve(R![-2, -1, 0, 1, 1], R![0, 0, 1, 1]);
 
sage: X = HyperellipticCurve(R([-8, -4, 0, 4, 5, 2, 1]))
 
magma: X,pi:= SimplifiedModel(C);
 

Invariants

Conductor: \( N \)  \(=\)  \(847\) \(=\) \( 7 \cdot 11^{2} \)
magma: Conductor(LSeries(C)); Factorization($1);
 
Discriminant: \( \Delta \)  \(=\)  \(9317\) \(=\) \( 7 \cdot 11^{3} \)
magma: Discriminant(C); Factorization(Integers()!$1);
 

Igusa-Clebsch invariants

Igusa invariants

G2 invariants

\( I_2 \)  \(=\) \(1696\) \(=\)  \( 2^{5} \cdot 53 \)
\( I_4 \)  \(=\) \(56320\) \(=\)  \( 2^{10} \cdot 5 \cdot 11 \)
\( I_6 \)  \(=\) \(37211328\) \(=\)  \( 2^{6} \cdot 3^{2} \cdot 7 \cdot 11 \cdot 839 \)
\( I_{10} \)  \(=\) \(38162432\) \(=\)  \( 2^{12} \cdot 7 \cdot 11^{3} \)
\( J_2 \)  \(=\) \(212\) \(=\)  \( 2^{2} \cdot 53 \)
\( J_4 \)  \(=\) \(1286\) \(=\)  \( 2 \cdot 643 \)
\( J_6 \)  \(=\) \(-7999\) \(=\)  \( - 19 \cdot 421 \)
\( J_8 \)  \(=\) \(-837396\) \(=\)  \( - 2^{2} \cdot 3^{2} \cdot 7 \cdot 3323 \)
\( J_{10} \)  \(=\) \(9317\) \(=\)  \( 7 \cdot 11^{3} \)
\( g_1 \)  \(=\) \(428232184832/9317\)
\( g_2 \)  \(=\) \(12253172608/9317\)
\( g_3 \)  \(=\) \(-359507056/9317\)

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: \((1 : 0 : 0),\, (1 : -1 : 0),\, (1 : -1 : 1)\)

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

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: \(\Z/{8}\Z\)

magma: MordellWeilGroupGenus2(Jacobian(C));
 

Generator $D_0$ Height Order
\(D_0 - (1 : -1 : 0) - (1 : 0 : 0)\) \(2x^2 + 3xz + 6z^2\) \(=\) \(0,\) \(4y\) \(=\) \(5xz^2 + 2z^3\) \(0\) \(8\)

2-torsion field: 6.0.664048.1

BSD invariants

Hasse-Weil conjecture: unverified
Analytic rank: \(0\)
Mordell-Weil rank: \(0\)
2-Selmer rank:\(1\)
Regulator: \( 1 \)
Real period: \( 9.983399 \)
Tamagawa product: \( 2 \)
Torsion order:\( 8 \)
Leading coefficient: \( 0.311981 \)
Analytic order of Ш: \( 1 \)   (rounded)
Order of Ш:square

Local invariants

Prime ord(\(N\)) ord(\(\Delta\)) Tamagawa L-factor Cluster picture
\(7\) \(1\) \(1\) \(1\) \(( 1 + T )( 1 - 4 T + 7 T^{2} )\)
\(11\) \(2\) \(3\) \(2\) \(1 + 4 T + 11 T^{2}\)

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 \(\Q\).