Abelian variety isogeny class 2.19.am_cs over $\F_{19}$

• Label: 2.19.am_cs
• Base field: $\F_{19}$
• Dimension: $2$
• $p$-rank: $2$
• Ordinary: yes
• Supersingular: no
• Simple: no
• Geometrically simple: no
• Primitive: yes
• Principally polarizable: yes
• Contains a Jacobian: yes

Invariants

Base field:	$\F_{19}$
Dimension:	$2$
L-polynomial:	$( 1 - 8 x + 19 x^{2} )( 1 - 4 x + 19 x^{2} )$
	$1 - 12 x + 70 x^{2} - 228 x^{3} + 361 x^{4}$
Frobenius angles:	$\pm0.130073469147$, $\pm0.348268167089$
Angle rank:	$2$ (numerical)
Jacobians:	$12$

This isogeny class is not 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

$r$	$1$	$2$	$3$	$4$	$5$
$A(\F_{q^r})$	$192$	$129024$	$47791296$	$17020846080$	$6129255605952$

Point counts of the curve

$r$	$1$	$2$	$3$	$4$	$5$	$6$	$7$	$8$	$9$	$10$
$C(\F_{q^r})$	$8$	$358$	$6968$	$130606$	$2475368$	$47043286$	$893917592$	$16984025566$	$322689710792$	$6131069428678$

Jacobians and polarizations

This isogeny class is principally polarizable and contains the Jacobians of 12 curves (of which all are hyperelliptic):

• $y^2=12 x^6+11 x^5+9 x^4+15 x^3+9 x^2+11 x+12$
• $y^2=15 x^6+2 x^5+15 x^4+16 x^3+2 x^2+11 x+5$
• $y^2=11 x^6+3 x^5+x^4+18 x^3+17 x^2+6$
• $y^2=x^6+4 x^5+10 x^4+12 x^3+10 x^2+4 x+1$
• $y^2=17 x^6+15 x^5+7 x^4+13 x^3+9 x^2+8 x+6$
• $y^2=17 x^6+16 x^5+11 x^4+17 x^3+17 x^2+17 x+8$
• $y^2=10 x^6+10 x^5+15 x^4+6 x^3+10 x^2+15 x+10$
• $y^2=11 x^5+3 x^4+5 x^3+3 x^2+11 x$
• $y^2=15 x^6+2 x^5+7 x^4+17 x^3+7 x^2+2 x+15$
• $y^2=7 x^6+13 x^5+11 x^4+9 x^3+x^2+10 x+7$
• $y^2=8 x^6+11 x^5+16 x^4+11 x^3+4 x^2+9 x+12$
• $y^2=8 x^6+4 x^5+5 x^4+8 x^3+6 x^2+5 x+12$

Decomposition and endomorphism algebra

All geometric endomorphisms are defined over $\F_{19}$.

Endomorphism algebra over $\F_{19}$

The isogeny class factors as 1.19.ai $\times$ 1.19.ae and its endomorphism algebra is a direct product of the endomorphism algebras for each isotypic factor. The endomorphism algebra for each factor is:

• 1.19.ai : \(\Q(\sqrt{-3}) \).
• 1.19.ae : \(\Q(\sqrt{-15}) \).

Base change

This is a primitive isogeny class.

Twists

Below are some of the twists of this isogeny class.

Twist	Extension degree	Common base change
2.19.ae_g	$2$	(not in LMFDB)
2.19.e_g	$2$	(not in LMFDB)
2.19.m_cs	$2$	(not in LMFDB)
2.19.ad_bi	$3$	(not in LMFDB)
2.19.d_k	$3$	(not in LMFDB)