Abelian variety isogeny class 2.31.af_cg over $\F_{31}$

• Label: 2.31.af_cg
• Base field: $\F_{31}$
• Dimension: $2$
• $p$-rank: $2$
• Ordinary: yes
• Supersingular: no
• Simple: yes
• Geometrically simple: yes
• Primitive: yes
• Principally polarizable: yes
• Contains a Jacobian: yes

Invariants

Base field:	$\F_{31}$
Dimension:	$2$
L-polynomial:	$1 - 5 x + 58 x^{2} - 155 x^{3} + 961 x^{4}$
Frobenius angles:	$\pm0.328899069141$, $\pm0.520067493920$
Angle rank:	$2$ (numerical)
Number field:	\(\Q(\sqrt{-430 +10 \sqrt{41}})\)
Galois group:	$D_{4}$
Jacobians:	$32$
Isomorphism classes:	32
Cyclic group of points:	no
Non-cyclic primes:	$2$

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:	$2$
Slopes:	$[0, 0, 1, 1]$

Point counts

Point counts of the abelian variety

$r$	$1$	$2$	$3$	$4$	$5$
$A(\F_{q^r})$	$860$	$1014800$	$895882640$	$852143796800$	$819588963586500$

Point counts of the curve

$r$	$1$	$2$	$3$	$4$	$5$	$6$	$7$	$8$	$9$	$10$
$C(\F_{q^r})$	$27$	$1053$	$30072$	$922713$	$28627777$	$887499678$	$27512279367$	$852890160273$	$26439637890792$	$819628368469573$

Jacobians and polarizations

This isogeny class is principally polarizable and contains the Jacobians of 32 curves (of which all are hyperelliptic):

• $y^2=6 x^5+17 x^4+22 x^3+9 x^2+26 x+27$
• $y^2=7 x^6+3 x^5+19 x^4+25 x^3+21 x^2+2 x+26$
• $y^2=4 x^6+5 x^5+23 x^4+2 x^3+x^2+7 x+4$
• $y^2=13 x^6+17 x^5+29 x^4+20 x^3+8 x^2+25 x+25$
• $y^2=16 x^6+12 x^5+23 x^4+18 x^3+16 x^2+18 x+3$
• $y^2=21 x^6+29 x^5+17 x^4+6 x^3+27 x^2+3$
• $y^2=14 x^6+18 x^5+13 x^4+30 x^3+19 x^2+22 x+19$
• $y^2=10 x^6+21 x^5+16 x^4+24 x^3+5 x^2+18 x+9$
• $y^2=3 x^5+18 x^4+19 x^3+3 x^2+16 x+7$
• $y^2=7 x^6+7 x^5+6 x^4+7 x^3+26 x^2+16 x+20$
• $y^2=22 x^6+16 x^5+4 x^4+x^3+23 x^2+5 x$
• $y^2=6 x^6+29 x^5+26 x^4+2 x^3+21 x^2+22 x+29$
• $y^2=29 x^6+26 x^5+18 x^4+3 x^3+8 x^2+6 x+15$
• $y^2=20 x^6+17 x^5+3 x^4+19 x^3+23 x^2+24 x+4$
• $y^2=14 x^6+28 x^5+12 x^4+23 x^3+14 x^2+19$
• $y^2=6 x^6+9 x^5+17 x^4+14 x^3+13 x^2+11 x+17$
• $y^2=3 x^6+7 x^5+20 x^4+11 x^3+26 x^2+23 x+19$
• $y^2=10 x^6+9 x^5+14 x^4+26 x^3+19 x^2+22 x+27$
• $y^2=30 x^6+9 x^5+23 x^4+12 x^3+14 x^2+24 x+4$
• $y^2=5 x^6+29 x^5+8 x^4+11 x^3+11 x^2+19 x$
• and

• $y^2=10 x^6+29 x^5+15 x^4+5 x^3+24 x^2+13 x+11$
• $y^2=12 x^6+12 x^5+11 x^4+18 x^3+12 x^2+30 x+6$
• $y^2=29 x^6+11 x^5+19 x^3+8 x^2+6 x+17$
• $y^2=10 x^6+10 x^5+26 x^4+24 x^3+26 x^2+29 x+23$
• $y^2=15 x^6+28 x^5+5 x^4+10 x^3+27 x^2+7 x$
• $y^2=11 x^6+10 x^5+x^4+26 x^3+17 x^2+11 x+14$
• $y^2=19 x^6+10 x^5+13 x^4+22 x^3+14 x^2+22 x+29$
• $y^2=15 x^6+12 x^5+11 x^4+2 x^3+16 x^2+15 x$
• $y^2=30 x^6+14 x^5+10 x^4+19 x^3+19 x^2+20 x+5$
• $y^2=24 x^6+20 x^5+2 x^4+18 x^3+14 x^2+6$
• $y^2=17 x^6+20 x^5+3 x^4+8 x^3+24 x^2+22 x+15$
• $y^2=30 x^6+17 x^5+20 x^4+22 x^3+7 x^2+3 x+29$

Decomposition and endomorphism algebra

All geometric endomorphisms are defined over $\F_{31}$.

Endomorphism algebra over $\F_{31}$

The endomorphism algebra of this simple isogeny class is \(\Q(\sqrt{-430 +10 \sqrt{41}})\).

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
2.31.f_cg	$2$	(not in LMFDB)