Genus 2 curve 2080.a.4160.1

• Label: 2080.a.4160.1
• Conductor: $2080$
• Discriminant: $-4160$
• Mordell-Weil group: \(\Z \oplus \Z/{4}\Z\)
• Sato-Tate group: $N(\mathrm{U}(1)\times\mathrm{SU}(2))$
• \(\End(J_{\overline{\Q}}) \otimes \R\): \(\C \times \R\)
• \(\End(J_{\overline{\Q}}) \otimes \Q\): \(\mathsf{CM} \times \Q\)
• \(\End(J) \otimes \Q\): \(\Q \times \Q\)
• \(\overline{\Q}\)-simple: no
• \(\mathrm{GL}_2\)-type: yes

Minimal equation

$y^2 + xy = x^6 + 12x^4 + 48x^2 + 65$

(, )

Invariants

Conductor:	\( N \)	\(=\)	\(2080\)	\(=\)	\( 2^{5} \cdot 5 \cdot 13 \)
Discriminant:	\( \Delta \)	\(=\)	\(-4160\)	\(=\)	\( - 2^{6} \cdot 5 \cdot 13 \)

Igusa-Clebsch invariants

\( I_2 \)	\(=\)	\(49728\)	\(=\)	\( 2^{6} \cdot 3 \cdot 7 \cdot 37 \)
\( I_4 \)	\(=\)	\(2307\)	\(=\)	\( 3 \cdot 769 \)
\( I_6 \)	\(=\)	\(38240328\)	\(=\)	\( 2^{3} \cdot 3 \cdot 7 \cdot 29 \cdot 47 \cdot 167 \)
\( I_{10} \)	\(=\)	\(520\)	\(=\)	\( 2^{3} \cdot 5 \cdot 13 \)

Automorphism group

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

Rational points

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

Number of rational Weierstrass points: \(0\)

This curve is locally solvable everywhere.

Mordell-Weil group of the Jacobian

Group structure: \(\Z \oplus \Z/{4}\Z\)

Generator	$D_0$						Height	Order
\(D_0 - (1 : -1 : 0) - (1 : 1 : 0)\)	\(x^2 + 5z^2\)	\(=\)	\(0,\)	\(y\)	\(=\)	\(0\)	\(0.375514\)	\(\infty\)
\(D_0 - (1 : -1 : 0) - (1 : 1 : 0)\)	\(2x^2 + 7z^2\)	\(=\)	\(0,\)	\(2y\)	\(=\)	\(-xz^2 + z^3\)	\(0\)	\(4\)

2-torsion field: 4.0.1040.2

BSD invariants

Hasse-Weil conjecture:	verified
Analytic rank:	\(1\)
Mordell-Weil rank:	\(1\)
2-Selmer rank:	\(2\)
Regulator:	\( 0.375514 \)
Real period:	\( 7.057075 \)
Tamagawa product:	\( 2 \)
Torsion order:	\( 4 \)
Leading coefficient:	\( 0.331253 \)
Analytic order of Ш:	\( 1 \)   (rounded)
Order of Ш:	square

Local invariants

Prime	ord(\(N\))	ord(\(\Delta\))	Tamagawa	L-factor	Cluster picture
\(2\)	\(5\)	\(6\)	\(2\)	\(1 + T + 2 T^{2}\)
\(5\)	\(1\)	\(1\)	\(1\)	\(( 1 + T )( 1 + 2 T + 5 T^{2} )\)
\(13\)	\(1\)	\(1\)	\(1\)	\(( 1 + T )( 1 - 6 T + 13 T^{2} )\)

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?
\(2\)	2.90.1	yes
\(3\)	3.270.2	no

Sato-Tate group

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

Decomposition of the Jacobian

Splits over \(\Q\)

Decomposes up to isogeny as the product of the non-isogenous elliptic curve isogeny classes:
  Elliptic curve isogeny class 32.a
  Elliptic curve isogeny class 65.a

Endomorphisms of the Jacobian

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 \(K = \Q (a) \simeq \) \(\Q(\sqrt{-1}) \) with defining polynomial \(x^{2} + 1\)

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

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

\(\End (J_{\overline{\Q}})\)	\(\simeq\)	an order of index \(4\) in \(\Z \times \Z [\sqrt{-1}]\)
\(\End (J_{\overline{\Q}}) \otimes \Q \)	\(\simeq\)	\(\Q\) \(\times\) \(\Q(\sqrt{-1}) \)
\(\End (J_{\overline{\Q}}) \otimes \R\)	\(\simeq\)	\(\R \times \C\)