Properties

Label 686.a.686.1
Conductor 686
Discriminant 686
Sato-Tate group $N(G_{1,3})$
\(\End(J_{\overline{\Q}}) \otimes \R\) \(\C \times \R\)
\(\End(J_{\overline{\Q}}) \otimes \Q\) \(\mathrm{CM} \times \Q\)
\(\overline{\Q}\)-simple no
\(\mathrm{GL}_2\)-type yes

Related objects

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Show commands for: Magma / SageMath

Minimal equation

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

$y^2 + (x^2 + x)y = x^5 + x^4 + 2x^3 + x^2 + x$

Invariants

magma: Conductor(LSeries(C)); Factorization($1);
 
\( N \)  =  \( 686 \)  =  \( 2 \cdot 7^{3} \)
magma: Discriminant(C); Factorization(Integers()!$1);
 
\( \Delta \)  =  \(686\)  =  \( 2 \cdot 7^{3} \)

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);
 

\( I_2 \)  =  \(840\)  =  \( 2^{3} \cdot 3 \cdot 5 \cdot 7 \)
\( I_4 \)  =  \(17220\)  =  \( 2^{2} \cdot 3 \cdot 5 \cdot 7 \cdot 41 \)
\( I_6 \)  =  \(5121480\)  =  \( 2^{3} \cdot 3 \cdot 5 \cdot 7^{2} \cdot 13 \cdot 67 \)
\( I_{10} \)  =  \(2809856\)  =  \( 2^{13} \cdot 7^{3} \)
\( J_2 \)  =  \(105\)  =  \( 3 \cdot 5 \cdot 7 \)
\( J_4 \)  =  \(280\)  =  \( 2^{3} \cdot 5 \cdot 7 \)
\( J_6 \)  =  \(-980\)  =  \( -1 \cdot 2^{2} \cdot 5 \cdot 7^{2} \)
\( J_8 \)  =  \(-45325\)  =  \( -1 \cdot 5^{2} \cdot 7^{2} \cdot 37 \)
\( J_{10} \)  =  \(686\)  =  \( 2 \cdot 7^{3} \)
\( g_1 \)  =  \(37209375/2\)
\( g_2 \)  =  \(472500\)
\( g_3 \)  =  \(-15750\)
Alternative geometric invariants: Igusa-Clebsch, Igusa, G2

Automorphism group

magma: AutomorphismGroup(C); IdentifyGroup($1);
 
\(\mathrm{Aut}(X)\)\(\simeq\) \(V_4 \) (GAP id : [4,2])
magma: AutomorphismGroup(ChangeRing(C,AlgebraicClosure(Rationals()))); IdentifyGroup($1);
 
\(\mathrm{Aut}(X_{\overline{\Q}})\)\(\simeq\) \(V_4 \) (GAP id : [4,2])

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![0,0,1],C![1,0,0]];
 

All rational points: (0 : 0 : 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: 11.491654789481447148051129308

Tamagawa numbers: 1 (p = 2), 1 (p = 7)

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

Torsion: \(\Z/{6}\Z\)

2-torsion field: 4.0.2744.1

Sato-Tate group

\(\mathrm{ST}\)\(\simeq\) $N(G_{1,3})$
\(\mathrm{ST}^0\)\(\simeq\) \(\mathrm{U}(1)\times\mathrm{SU}(2)\)

Decomposition

Splits over \(\Q\)

Decomposes up to isogeny as the product of the non-isogenous elliptic curves:
  Elliptic curve 14.a5
  Elliptic curve 49.a4

Endomorphisms

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

Endomorphism ring over \(\Q\):
\(\End (J_{})\)\(\simeq\)an order of index \(2\) in \(\Z \times \Z\)
\(\End (J_{}) \otimes \Q \)\(\simeq\)\(\Q\) \(\times\) \(\Q\)
\(\End (J_{}) \otimes \R\)\(\simeq\) \(\R \times \R\)

Smallest field over which all endomorphisms are defined:
Galois number field \(K = \Q (a) \simeq \) \(\Q(\sqrt{-7}) \) with defining polynomial \(x^{2} - x + 2\)

Not of \(\GL_2\)-type over \(\overline{\Q}\)

Endomorphism ring over \(\overline{\Q}\):
\(\End (J_{\overline{\Q}})\)\(\simeq\)an order of index \(4\) in \(\Z \times \Z [\frac{1 + \sqrt{-7}}{2}]\)
\(\End (J_{\overline{\Q}}) \otimes \Q \)\(\simeq\)\(\Q\) \(\times\) \(\Q(\sqrt{-7}) \)
\(\End (J_{\overline{\Q}}) \otimes \R\)\(\simeq\) \(\R \times \C\)