Properties

Label 2.89.ak_by
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:  $1 - 10 x + 50 x^{2} - 890 x^{3} + 7921 x^{4}$
Frobenius angles:  $\pm0.127723103667$, $\pm0.627723103667$
Angle rank:  $1$ (numerical)
Number field:  \(\Q(i, \sqrt{17})\)
Galois group:  $C_2^2$
Jacobians:  $384$
Cyclic group of points:    no
Non-cyclic primes:   $2$

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

$r$ $1$ $2$ $3$ $4$ $5$
$A(\F_{q^r})$ $7072$ $62742784$ $495453860512$ $3936656944070656$ $31182828664681032352$

Point counts of the curve

$r$ $1$ $2$ $3$ $4$ $5$ $6$ $7$ $8$ $9$ $10$
$C(\F_{q^r})$ $80$ $7922$ $702800$ $62743326$ $5584258000$ $496981290962$ $44231343121360$ $3936589056083518$ $350356404227293520$ $31181719929966183602$

Jacobians and polarizations

This isogeny class is principally polarizable and contains the Jacobians of 384 curves (of which all are hyperelliptic):

Decomposition and endomorphism algebra

All geometric endomorphisms are defined over $\F_{89^{4}}$.

Endomorphism algebra over $\F_{89}$
The endomorphism algebra of this simple isogeny class is \(\Q(i, \sqrt{17})\).
Endomorphism algebra over $\overline{\F}_{89}$
The base change of $A$ to $\F_{89^{4}}$ is 1.62742241.uw 2 and its endomorphism algebra is $\mathrm{M}_{2}($\(\Q(\sqrt{-17}) \)$)$
Remainder of endomorphism lattice by field

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.k_by$2$(not in LMFDB)
2.89.a_aey$8$(not in LMFDB)
2.89.a_ey$8$(not in LMFDB)