Abelian variety isogeny class 1.256.abg over $\F_{2^{8}}$

• Label: 1.256.abg
• Base field: $\F_{2^{8}}$
• 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:	$\F_{2^{8}}$
Dimension:	$1$
L-polynomial:	$( 1 - 16 x )^{2}$
	$1 - 32 x + 256 x^{2}$
Frobenius angles:	$0$, $0$
Angle rank:	$0$ (numerical)
Number field:	\(\Q\)
Galois group:	Trivial
Jacobians:	$1$
Isomorphism classes:	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

$r$	$1$	$2$	$3$	$4$	$5$
$A(\F_{q^r})$	$225$	$65025$	$16769025$	$4294836225$	$1099509530625$

Point counts of the curve

$r$	$1$	$2$	$3$	$4$	$5$	$6$	$7$	$8$	$9$	$10$
$C(\F_{q^r})$	$225$	$65025$	$16769025$	$4294836225$	$1099509530625$	$281474943156225$	$72057593501057025$	$18446744065119617025$	$4722366482732206260225$	$1208925819612430151450625$

Jacobians and polarizations

This isogeny class is principally polarizable and contains the Jacobian of 1 curve (which is not hyperelliptic):

• $y^2+y=x^3$

Decomposition and endomorphism algebra

All geometric endomorphisms are defined over $\F_{2^{8}}$.

Endomorphism algebra over $\F_{2^{8}}$

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 $\F_{2^{8}}$.

Subfield	Primitive Model
$\F_{2}$	1.2.ac
$\F_{2}$	1.2.a
$\F_{2}$	1.2.c
$\F_{2^{2}}$	1.4.ae

Twists

Below are some of the twists of this isogeny class.

Twist	Extension degree	Common base change
1.256.bg	$2$	(not in LMFDB)
1.256.q	$3$	(not in LMFDB)
1.256.a	$4$	(not in LMFDB)