Genus 2 curve 21952.a.21952.1

• Label: 21952.a.21952.1
• Conductor: $21952$
• Discriminant: $21952$
• Mordell-Weil group: \(\Z \oplus \Z/{2}\Z\)
• Sato-Tate group: $N(\mathrm{SU}(2)\times\mathrm{SU}(2))$
• \(\End(J_{\overline{\Q}}) \otimes \R\): \(\R \times \R\)
• \(\End(J_{\overline{\Q}}) \otimes \Q\): \(\Q \times \Q\)
• \(\End(J) \otimes \Q\): \(\Q\)
• \(\overline{\Q}\)-simple: no
• \(\mathrm{GL}_2\)-type: no

Minimal equation

$y^2 + x^3y = -x^4 - 3x^3 - 2x^2 + 2$

(, )

Invariants

Conductor:	\( N \)	\(=\)	\(21952\)	\(=\)	\( 2^{6} \cdot 7^{3} \)
Discriminant:	\( \Delta \)	\(=\)	\(21952\)	\(=\)	\( 2^{6} \cdot 7^{3} \)

Igusa-Clebsch invariants

\( I_2 \)	\(=\)	\(196\)	\(=\)	\( 2^{2} \cdot 7^{2} \)
\( I_4 \)	\(=\)	\(4732\)	\(=\)	\( 2^{2} \cdot 7 \cdot 13^{2} \)
\( I_6 \)	\(=\)	\(197176\)	\(=\)	\( 2^{3} \cdot 7^{2} \cdot 503 \)
\( I_{10} \)	\(=\)	\(-2744\)	\(=\)	\( - 2^{3} \cdot 7^{3} \)

Automorphism group

\(\mathrm{Aut}(X)\)	\(\simeq\)	$C_2$
\(\mathrm{Aut}(X_{\overline{\Q}})\)	\(\simeq\)	$C_2^2$

Rational points

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

Number of rational Weierstrass points: \(0\)

This curve is locally solvable everywhere.

Mordell-Weil group of the Jacobian

Group structure: \(\Z \oplus \Z/{2}\Z\)

Generator	$D_0$						Height	Order
\(D_0 - 2 \cdot(1 : -1 : 0)\)	\(z^2\)	\(=\)	\(0,\)	\(y\)	\(=\)	\(0\)	\(0.310272\)	\(\infty\)
\(D_0 - (1 : -1 : 0) - (1 : 0 : 0)\)	\(x^2 + 2xz + 2z^2\)	\(=\)	\(0,\)	\(y\)	\(=\)	\(-xz^2 - 2z^3\)	\(0\)	\(2\)

2-torsion field: 4.0.1372.1

BSD invariants

Hasse-Weil conjecture:	unverified
Analytic rank:	\(1\)
Mordell-Weil rank:	\(1\)
2-Selmer rank:	\(2\)
Regulator:	\( 0.310272 \)
Real period:	\( 10.95523 \)
Tamagawa product:	\( 1 \)
Torsion order:	\( 2 \)
Leading coefficient:	\( 0.849777 \)
Analytic order of Ш:	\( 1 \)   (rounded)
Order of Ш:	square

Local invariants

Prime	ord(\(N\))	ord(\(\Delta\))	Tamagawa	L-factor	Cluster picture
\(2\)	\(6\)	\(6\)	\(1\)	\(1 + 2 T + 2 T^{2}\)
\(7\)	\(3\)	\(3\)	\(1\)	\(1 + T\)

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?
\(2\)	2.90.4	yes
\(3\)	3.45.1	no

Sato-Tate group

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

Decomposition of the Jacobian

Splits over the number field \(\Q (b) \simeq \) \(\Q(\sqrt{2}) \) with defining polynomial:
  \(x^{2} - 2\)

Decomposes up to isogeny as the product of the non-isogenous elliptic curve isogeny classes:
  Elliptic curve isogeny class 2.2.8.1-343.1-c
  Elliptic curve isogeny class 2.2.8.1-343.2-c

Endomorphisms of the Jacobian

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

Endomorphism ring over \(\Q\):

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

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

Of \(\GL_2\)-type over \(\overline{\Q}\)

Endomorphism ring over \(\overline{\Q}\):

\(\End (J_{\overline{\Q}})\)	\(\simeq\)	an order of index \(2\) in \(\Z \times \Z\)
\(\End (J_{\overline{\Q}}) \otimes \Q \)	\(\simeq\)	\(\Q\) \(\times\) \(\Q\)
\(\End (J_{\overline{\Q}}) \otimes \R\)	\(\simeq\)	\(\R \times \R\)