Properties

Label 807.a.2421.1
Conductor 807
Discriminant 2421
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

Related objects

Learn more about

Show commands for: Magma / SageMath

Minimal equation

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

$y^2 + (x^3 + x)y = x^5 - 2x^3 - x^2 + 2x - 1$

Invariants

magma: Conductor(LSeries(C)); Factorization($1);
 
\( N \)  =  \( 807 \)  =  \( 3 \cdot 269 \)
magma: Discriminant(C); Factorization(Integers()!$1);
 
\( \Delta \)  =  \(2421\)  =  \( 3^{2} \cdot 269 \)

Igusa-Clebsch invariants

magma: IgusaClebschInvariants(C); [Factorization(Integers()!a): a in $1];
 
sage: C.igusa_clebsch_invariants(); [factor(a) for a in _]
 

Igusa invariants

magma: IgusaInvariants(C); [Factorization(Integers()!a): a in $1];
 

G2 invariants

magma: G2Invariants(C);
 

\( I_2 \)  =  \(2720\)  =  \( 2^{5} \cdot 5 \cdot 17 \)
\( I_4 \)  =  \(10240\)  =  \( 2^{11} \cdot 5 \)
\( I_6 \)  =  \(9795776\)  =  \( 2^{6} \cdot 153059 \)
\( I_{10} \)  =  \(9916416\)  =  \( 2^{12} \cdot 3^{2} \cdot 269 \)
\( J_2 \)  =  \(340\)  =  \( 2^{2} \cdot 5 \cdot 17 \)
\( J_4 \)  =  \(4710\)  =  \( 2 \cdot 3 \cdot 5 \cdot 157 \)
\( J_6 \)  =  \(84049\)  =  \( 7 \cdot 12007 \)
\( J_8 \)  =  \(1598140\)  =  \( 2^{2} \cdot 5 \cdot 79907 \)
\( J_{10} \)  =  \(2421\)  =  \( 3^{2} \cdot 269 \)
\( g_1 \)  =  \(4543542400000/2421\)
\( g_2 \)  =  \(61707280000/807\)
\( g_3 \)  =  \(9716064400/2421\)
Alternative geometric invariants: Igusa-Clebsch, Igusa, G2

Automorphism group

magma: AutomorphismGroup(C); IdentifyGroup($1);
 
\(\mathrm{Aut}(X)\)\(\simeq\) \(C_2 \) (GAP id : [2,1])
magma: AutomorphismGroup(ChangeRing(C,AlgebraicClosure(Rationals()))); IdentifyGroup($1);
 
\(\mathrm{Aut}(X_{\overline{\Q}})\)\(\simeq\) \(C_2 \) (GAP id : [2,1])

Rational points

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);
 

This curve is locally solvable everywhere.

magma: [C![-2,5,1],C![1,-1,0],C![1,-1,1],C![1,0,0]];
 

All rational points: (-2 : 5 : 1), (1 : -1 : 0), (1 : -1 : 1), (1 : 0 : 0)

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

Number of rational Weierstrass points: \(2\)

Invariants of the Jacobian:

Analytic rank: \(0\)

magma: TwoSelmerGroup(Jacobian(C)); NumberOfGenerators($1);
 

2-Selmer rank: \(1\)

magma: HasSquareSha(Jacobian(C));
 

Order of Ш*: square

Regulator: 1.0

Real period: 9.7611402629576132574209053602

Tamagawa numbers: 2 (p = 3), 1 (p = 269)

magma: TorsionSubgroup(Jacobian(SimplifiedModel(C))); AbelianInvariants($1);
 

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

2-torsion field: 4.0.1076.1

Sato-Tate group

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

Decomposition

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

Endomorphisms

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 \(\Q\).