Abelian variety isogeny class 1.128.aj over $\F_{2^{7}}$

• Label: 1.128.aj
• Base field: $\F_{2^{7}}$
• Dimension: $1$
• $p$-rank: $1$
• Ordinary: yes
• Supersingular: no
• Simple: yes
• Geometrically simple: yes
• Primitive: yes
• Principally polarizable: yes
• Contains a Jacobian: yes

Invariants

Base field:	$\F_{2^{7}}$
Dimension:	$1$
L-polynomial:	$1 - 9 x + 128 x^{2}$
Frobenius angles:	$\pm0.369791982414$
Angle rank:	$1$ (numerical)
Number field:	\(\Q(\sqrt{-431}) \)
Galois group:	$C_2$
Jacobians:	$21$
Isomorphism classes:	21

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:	$1$
Slopes:	$[0, 1]$

Point counts

Point counts of the abelian variety

$r$	$1$	$2$	$3$	$4$	$5$
$A(\F_{q^r})$	$120$	$16560$	$2099880$	$268437600$	$34359408600$

Point counts of the curve

$r$	$1$	$2$	$3$	$4$	$5$	$6$	$7$	$8$	$9$	$10$
$C(\F_{q^r})$	$120$	$16560$	$2099880$	$268437600$	$34359408600$	$4398043268880$	$562949966451720$	$72057594570206400$	$9223372039977389880$	$1180591620677383186800$

Jacobians and polarizations

This isogeny class contains the Jacobians of 21 curves (of which all are hyperelliptic), and hence is principally polarizable:

Decomposition and endomorphism algebra

All geometric endomorphisms are defined over $\F_{2^{7}}$.

Endomorphism algebra over $\F_{2^{7}}$

The endomorphism algebra of this simple isogeny class is \(\Q(\sqrt{-431}) \).

Base change

This is a primitive isogeny class.

Twists

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

Twist	Extension degree	Common base change
1.128.j	$2$	(not in LMFDB)