Properties

Label 2.31.g_be
Base field $\F_{31}$
Dimension $2$
$p$-rank $2$
Ordinary yes
Supersingular no
Simple yes
Geometrically simple yes
Primitive yes
Principally polarizable yes
Contains a Jacobian yes

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Invariants

Base field:  $\F_{31}$
Dimension:  $2$
L-polynomial:  $1 + 6 x + 30 x^{2} + 186 x^{3} + 961 x^{4}$
Frobenius angles:  $\pm0.401139770311$, $\pm0.820057963498$
Angle rank:  $2$ (numerical)
Number field:  \(\Q(\sqrt{-46 -6 \sqrt{41}})\)
Galois group:  $D_{4}$
Jacobians:  $96$
Isomorphism classes:  192
Cyclic group of points:    no
Non-cyclic primes:   $2$

This isogeny class is simple and 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

$r$ $1$ $2$ $3$ $4$ $5$
$A(\F_{q^r})$ $1184$ $947200$ $894522656$ $853449932800$ $819030848182304$

Point counts of the curve

$r$ $1$ $2$ $3$ $4$ $5$ $6$ $7$ $8$ $9$ $10$
$C(\F_{q^r})$ $38$ $986$ $30026$ $924126$ $28608278$ $887544218$ $27512659898$ $852892848766$ $26439622439366$ $819628183497626$

Jacobians and polarizations

This isogeny class is principally polarizable and contains the Jacobians of 96 curves (of which all are hyperelliptic):

Decomposition and endomorphism algebra

All geometric endomorphisms are defined over $\F_{31}$.

Endomorphism algebra over $\F_{31}$
The endomorphism algebra of this simple isogeny class is \(\Q(\sqrt{-46 -6 \sqrt{41}})\).

Base change

This is a primitive isogeny class.

Twists

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

TwistExtension degreeCommon base change
2.31.ag_be$2$(not in LMFDB)