Properties

Label 2.7.b_g
Base field $\F_{7}$
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:  $\F_{7}$
Dimension:  $2$
L-polynomial:  $1 + x + 6 x^{2} + 7 x^{3} + 49 x^{4}$
Frobenius angles:  $\pm0.352022857153$, $\pm0.719949304674$
Angle rank:  $2$ (numerical)
Number field:  \(\Q(\sqrt{-78 +2 \sqrt{33}})\)
Galois group:  $D_{4}$
Jacobians:  $8$
Isomorphism classes:  8
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

$r$ $1$ $2$ $3$ $4$ $5$
$A(\F_{q^r})$ $64$ $3072$ $118528$ $6057984$ $278002624$

Point counts of the curve

$r$ $1$ $2$ $3$ $4$ $5$ $6$ $7$ $8$ $9$ $10$
$C(\F_{q^r})$ $9$ $61$ $348$ $2521$ $16539$ $116638$ $825141$ $5765329$ $40363764$ $282500341$

Jacobians and polarizations

This isogeny class is principally polarizable and contains the Jacobians of 8 curves (of which all are hyperelliptic):

  • $y^2=3 x^6+2 x^5+4 x^4+3 x^3+2$
  • $y^2=3 x^6+2 x^5+x^4+4 x^3+6 x^2+2 x+1$
  • $y^2=6 x^6+2 x^5+4 x^4+4 x^3+6 x^2+6 x+1$
  • $y^2=6 x^6+x^5+4 x^4+2 x^2+3 x+6$
  • $y^2=5 x^5+2 x^3+4 x^2+6 x+4$
  • $y^2=4 x^5+2 x^4+4 x^3+x^2+5 x+1$
  • $y^2=3 x^5+5 x^4+3 x+1$
  • $y^2=3 x^6+5 x^5+x^4+x^3+4 x^2+4 x+2$

Decomposition and endomorphism algebra

All geometric endomorphisms are defined over $\F_{7}$.

Endomorphism algebra over $\F_{7}$
The endomorphism algebra of this simple isogeny class is \(\Q(\sqrt{-78 +2 \sqrt{33}})\).

Base change

This is a primitive isogeny class.

Twists

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

TwistExtension degreeCommon base change
2.7.ab_g$2$2.49.l_eq