Properties

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

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Invariants

Base field:  $\F_{19}$
Dimension:  $2$
L-polynomial:  $1 - 3 x + 26 x^{2} - 57 x^{3} + 361 x^{4}$
Frobenius angles:  $\pm0.293143315588$, $\pm0.584036070819$
Angle rank:  $2$ (numerical)
Number field:  4.0.2771397.1
Galois group:  $D_{4}$
Jacobians:  $24$
Isomorphism classes:  24
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

$r$ $1$ $2$ $3$ $4$ $5$
$A(\F_{q^r})$ $328$ $146944$ $47288416$ $17017878528$ $6139458792088$

Point counts of the curve

$r$ $1$ $2$ $3$ $4$ $5$ $6$ $7$ $8$ $9$ $10$
$C(\F_{q^r})$ $17$ $405$ $6896$ $130585$ $2479487$ $47035734$ $893755229$ $16983575473$ $322688963216$ $6131066753205$

Jacobians and polarizations

This isogeny class is principally polarizable and contains the Jacobians of 24 curves (of which all are hyperelliptic):

Decomposition and endomorphism algebra

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

Endomorphism algebra over $\F_{19}$
The endomorphism algebra of this simple isogeny class is 4.0.2771397.1.

Base change

This is a primitive isogeny class.

Twists

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

TwistExtension degreeCommon base change
2.19.d_ba$2$(not in LMFDB)