Genus 2 curve 961.a.961.2

• Label: 961.a.961.2
• Conductor: $961$
• Discriminant: $-961$
• Mordell-Weil group: \(\Z/{5}\Z\)
• Sato-Tate group: $\mathrm{SU}(2)\times\mathrm{SU}(2)$
• \(\End(J_{\overline{\Q}}) \otimes \R\): \(\R \times \R\)
• \(\End(J_{\overline{\Q}}) \otimes \Q\): \(\mathsf{RM}\)
• \(\End(J) \otimes \Q\): \(\mathsf{RM}\)
• \(\overline{\Q}\)-simple: yes
• \(\mathrm{GL}_2\)-type: yes

Minimal equation

$y^2 + (x^3 + x + 1)y = -x^6 + 2x^5 - 8x^4 + 12x^3 - 18x^2 + 12x - 7$

(, )

Invariants

Conductor:	\( N \)	\(=\)	\(961\)	\(=\)	\( 31^{2} \)
Discriminant:	\( \Delta \)	\(=\)	\(-961\)	\(=\)	\( - 31^{2} \)

Igusa-Clebsch invariants

\( I_2 \)	\(=\)	\(11260\)	\(=\)	\( 2^{2} \cdot 5 \cdot 563 \)
\( I_4 \)	\(=\)	\(503521\)	\(=\)	\( 41 \cdot 12281 \)
\( I_6 \)	\(=\)	\(1770579599\)	\(=\)	\( 8627 \cdot 205237 \)
\( I_{10} \)	\(=\)	\(123008\)	\(=\)	\( 2^{7} \cdot 31^{2} \)

Automorphism group

\(\mathrm{Aut}(X)\)	\(\simeq\)	$C_2$
\(\mathrm{Aut}(X_{\overline{\Q}})\)	\(\simeq\)	$C_2$

Rational points

This curve has no rational points.

Number of rational Weierstrass points: \(0\)

This curve is locally solvable except over $\R$.

Mordell-Weil group of the Jacobian

Group structure: \(\Z/{5}\Z\)

Generator	$D_0$						Height	Order
\(D_0 - D_\infty\)	\(x^2 - xz + z^2\)	\(=\)	\(0,\)	\(y\)	\(=\)	\(0\)	\(0\)	\(5\)

2-torsion field: 6.0.61504.1

BSD invariants

Hasse-Weil conjecture:	verified
Analytic rank:	\(0\)
Mordell-Weil rank:	\(0\)
2-Selmer rank:	\(1\)
Regulator:	\( 1 \)
Real period:	\( 5.616096 \)
Tamagawa product:	\( 1 \)
Torsion order:	\( 5 \)
Leading coefficient:	\( 0.449287 \)
Analytic order of Ш:	\( 2 \)   (rounded)
Order of Ш:	twice a square

Local invariants

Prime	ord(\(N\))	ord(\(\Delta\))	Tamagawa	L-factor	Cluster picture
\(31\)	\(2\)	\(2\)	\(1\)	\(( 1 - T )^{2}\)

Galois representations

For primes $\ell \ge 5$ the Galois representation data has not been computed for this curve since it is not generic.

For primes $\ell \le 3$, the image of the mod-$\ell$ Galois representation is listed in the table below, whenever it is not all of $\GSp(4,\F_\ell)$.

Prime \(\ell\)	mod-\(\ell\) image	Is torsion prime?
\(2\)	2.15.2	no
\(3\)	3.72.2	no

Sato-Tate group

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

Decomposition of the Jacobian

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

Endomorphisms of the Jacobian

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

Endomorphism ring over \(\Q\):

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

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