Abelian variety isogeny class 1.16.ai over $\F_{2^{4}}$

• Label: 1.16.ai
• Base field: $\F_{2^{4}}$
• Dimension: $1$
• $p$-rank: $0$
• Ordinary: no
• Supersingular: yes
• Simple: yes
• Geometrically simple: yes
• Primitive: no
• Principally polarizable: yes
• Contains a Jacobian: yes

Invariants

Base field:	$\F_{2^{4}}$
Dimension:	$1$
L-polynomial:	$( 1 - 4 x )^{2}$
	$1 - 8 x + 16 x^{2}$
Frobenius angles:	$0$, $0$
Angle rank:	$0$ (numerical)
Number field:	\(\Q\)
Galois group:	Trivial
Jacobians:	$1$

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

Newton polygon

This isogeny class is supersingular.

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

Point counts

Point counts of the abelian variety

$r$	$1$	$2$	$3$	$4$	$5$
$A(\F_{q^r})$	$9$	$225$	$3969$	$65025$	$1046529$

Point counts of the curve

$r$	$1$	$2$	$3$	$4$	$5$	$6$	$7$	$8$	$9$	$10$
$C(\F_{q^r})$	$9$	$225$	$3969$	$65025$	$1046529$	$16769025$	$268402689$	$4294836225$	$68718952449$	$1099509530625$

Jacobians and polarizations

This isogeny class contains the Jacobian of 1 curve (which is hyperelliptic), and hence is principally polarizable:

Decomposition and endomorphism algebra

All geometric endomorphisms are defined over $\F_{2^{4}}$.

Endomorphism algebra over $\F_{2^{4}}$

The endomorphism algebra of this simple isogeny class is the quaternion algebra over \(\Q\) ramified at $2$ and $\infty$.

Base change

This isogeny class is not primitive. It is a base change from the following isogeny classes over subfields of $\F_{2^{4}}$.

Subfield	Primitive Model
$\F_{2}$	1.2.a

Twists

Below are some of the twists of this isogeny class.

Twist	Extension degree	Common base change
1.16.i	$2$	1.256.abg
1.16.e	$3$	(not in LMFDB)
1.16.a	$4$	(not in LMFDB)