Properties

Label 2.89.a_cj
Base field $\F_{89}$
Dimension $2$
$p$-rank $2$
Ordinary yes
Supersingular no
Simple yes
Geometrically simple no
Primitive yes
Principally polarizable yes
Contains a Jacobian yes

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Invariants

Base field:  $\F_{89}$
Dimension:  $2$
L-polynomial:  $1 + 61 x^{2} + 7921 x^{4}$
Frobenius angles:  $\pm0.305670146422$, $\pm0.694329853578$
Angle rank:  $1$ (numerical)
Number field:  \(\Q(\sqrt{13}, \sqrt{-239})\)
Galois group:  $C_2^2$
Jacobians:  $783$

This isogeny class is simple but not geometrically simple, primitive, ordinary, and not supersingular. It is principally polarizable and contains a Jacobian.

Newton polygon

This isogeny class is ordinary.

$p$-rank:  $2$
Slopes:  $[0, 0, 1, 1]$

Point counts

Point counts of the abelian variety

$r$ $1$ $2$ $3$ $4$ $5$
$A(\F_{q^r})$ $7983$ $63728289$ $496980068400$ $3938110075535769$ $31181719940957580903$

Point counts of the curve

$r$ $1$ $2$ $3$ $4$ $5$ $6$ $7$ $8$ $9$ $10$
$C(\F_{q^r})$ $90$ $8044$ $704970$ $62766484$ $5584059450$ $496978845838$ $44231334895530$ $3936588762833764$ $350356403707485210$ $31181719951948978204$

Jacobians and polarizations

This isogeny class is principally polarizable and contains the Jacobians of 783 curves (of which all are hyperelliptic):

Decomposition and endomorphism algebra

All geometric endomorphisms are defined over $\F_{89^{2}}$.

Endomorphism algebra over $\F_{89}$
The endomorphism algebra of this simple isogeny class is \(\Q(\sqrt{13}, \sqrt{-239})\).
Endomorphism algebra over $\overline{\F}_{89}$
The base change of $A$ to $\F_{89^{2}}$ is 1.7921.cj 2 and its endomorphism algebra is $\mathrm{M}_{2}($\(\Q(\sqrt{-3107}) \)$)$

Base change

This is a primitive isogeny class.

Twists

Below is a list of all twists of this isogeny class.

TwistExtension degreeCommon base change
2.89.a_acj$4$(not in LMFDB)