Properties

Label 2.9.ai_bg
Base field $\F_{3^{2}}$
Dimension $2$
$p$-rank $2$
Ordinary yes
Supersingular no
Simple yes
Geometrically simple no
Primitive yes
Principally polarizable yes
Contains a Jacobian yes

Related objects

Downloads

Learn more

Invariants

Base field:  $\F_{3^{2}}$
Dimension:  $2$
L-polynomial:  $1 - 8 x + 32 x^{2} - 72 x^{3} + 81 x^{4}$
Frobenius angles:  $\pm0.141826552031$, $\pm0.358173447969$
Angle rank:  $1$ (numerical)
Number field:  \(\Q(\zeta_{8})\)
Galois group:  $C_2^2$
Jacobians:  $3$
Isomorphism classes:  3

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

$r$ $1$ $2$ $3$ $4$ $5$
$A(\F_{q^r})$ $34$ $6596$ $561442$ $43507216$ $3481591874$

Point counts of the curve

$r$ $1$ $2$ $3$ $4$ $5$ $6$ $7$ $8$ $9$ $10$
$C(\F_{q^r})$ $2$ $82$ $770$ $6630$ $58962$ $531442$ $4787442$ $43070654$ $387475970$ $3486784402$

Jacobians and polarizations

This isogeny class contains the Jacobians of 3 curves (of which all are hyperelliptic), and hence is principally polarizable:

Decomposition and endomorphism algebra

All geometric endomorphisms are defined over $\F_{3^{8}}$.

Endomorphism algebra over $\F_{3^{2}}$
The endomorphism algebra of this simple isogeny class is \(\Q(\zeta_{8})\).
Endomorphism algebra over $\overline{\F}_{3^{2}}$
The base change of $A$ to $\F_{3^{8}}$ is 1.6561.bi 2 and its endomorphism algebra is $\mathrm{M}_{2}($\(\Q(\sqrt{-2}) \)$)$
Remainder of endomorphism lattice by field

Base change

This is a primitive isogeny class.

Twists

Below are some of the twists of this isogeny class.

TwistExtension degreeCommon base change
2.9.i_bg$2$2.81.a_bi
2.9.i_bg$4$(not in LMFDB)
2.9.ae_w$8$(not in LMFDB)

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

TwistExtension degreeCommon base change
2.9.i_bg$2$2.81.a_bi
2.9.i_bg$4$(not in LMFDB)
2.9.ae_w$8$(not in LMFDB)
2.9.a_ao$8$(not in LMFDB)
2.9.a_o$8$(not in LMFDB)
2.9.e_w$8$(not in LMFDB)
2.9.ac_af$24$(not in LMFDB)
2.9.c_af$24$(not in LMFDB)