Properties

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

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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:  $12$
Isomorphism classes:  60

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 contains the Jacobians of 12 curves (of which all are hyperelliptic), and hence is principally polarizable:

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:

Base change

This is a primitive isogeny class.

Twists

Below are some of the twists of this isogeny class.

TwistExtension degreeCommon 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)

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

TwistExtension degreeCommon 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)
2.19.al_co$6$(not in LMFDB)
2.19.af_bq$6$(not in LMFDB)
2.19.ad_k$6$(not in LMFDB)
2.19.d_bi$6$(not in LMFDB)
2.19.f_bq$6$(not in LMFDB)
2.19.l_co$6$(not in LMFDB)