Properties

Label 2.19.af_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:  $1 - 5 x + 26 x^{2} - 95 x^{3} + 361 x^{4}$
Frobenius angles:  $\pm0.216840639262$, $\pm0.565154497481$
Angle rank:  $2$ (numerical)
Number field:  \(\Q(\sqrt{-29 +2 \sqrt{73}})\)
Galois group:  $D_{4}$
Jacobians:  $30$
Cyclic group of points:    no
Non-cyclic primes:   $2, 3$

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

$r$ $1$ $2$ $3$ $4$ $5$
$A(\F_{q^r})$ $288$ $140544$ $46915200$ $17005261824$ $6145255045728$

Point counts of the curve

$r$ $1$ $2$ $3$ $4$ $5$ $6$ $7$ $8$ $9$ $10$
$C(\F_{q^r})$ $15$ $389$ $6840$ $130489$ $2481825$ $47058518$ $893809155$ $16983405169$ $322687669320$ $6131059713029$

Jacobians and polarizations

This isogeny class is principally polarizable and contains the Jacobians of 30 curves (of which all are hyperelliptic):

  • $y^2=6 x^6+x^5+13 x^4+18 x^2+6 x+2$
  • $y^2=5 x^6+6 x^5+13 x^4+18 x^3+9 x^2+12 x+15$
  • $y^2=15 x^6+8 x^5+13 x^4+6 x^3+12 x^2+18 x+11$
  • $y^2=2 x^5+15 x^4+18 x^3+4 x^2+15 x+3$
  • $y^2=13 x^6+x^5+5 x^4+14 x^3+7 x^2+14$
  • $y^2=14 x^6+6 x^5+13 x^4+17 x^3+9 x^2+3 x+13$
  • $y^2=9 x^5+4 x^4+4 x^3+6 x^2+7 x+3$
  • $y^2=15 x^5+14 x^4+10 x^3+6 x^2+11 x+4$
  • $y^2=4 x^6+15 x^5+2 x^4+7 x^3+10 x^2+10 x+12$
  • $y^2=x^6+13 x^4+7 x^3+4 x^2+18 x+10$
  • $y^2=10 x^6+10 x^5+3 x^4+4 x^3+13 x^2+15 x+10$
  • $y^2=11 x^6+12 x^5+14 x^4+12 x^3+8 x^2+16 x+13$
  • $y^2=7 x^6+14 x^5+2 x^4+13 x^3+2 x^2+17 x+3$
  • $y^2=7 x^6+15 x^5+11 x^4+13 x^3+8 x^2+11 x+10$
  • $y^2=3 x^6+18 x^5+5 x^4+2 x^3+x^2+2 x+16$
  • $y^2=13 x^6+16 x^5+8 x^4+14 x^3+7 x^2+13 x+17$
  • $y^2=10 x^6+5 x^5+13 x^4+4 x^3+8 x^2+15 x+15$
  • $y^2=15 x^6+6 x^5+5 x^4+4 x^3+8 x^2+14 x$
  • $y^2=14 x^6+2 x^5+8 x^3+18 x^2+3 x+17$
  • $y^2=16 x^5+8 x^4+7 x^3+10 x^2+7 x$
  • $y^2=13 x^6+2 x^5+3 x^4+14 x^3+13 x^2+12 x+8$
  • $y^2=13 x^6+12 x^5+x^4+2 x^3+16 x^2+9 x$
  • $y^2=11 x^6+15 x^5+18 x^3+3 x^2+14 x+14$
  • $y^2=6 x^5+8 x^4+13 x^3+3 x^2+3$
  • $y^2=4 x^6+4 x^5+6 x^4+8 x^3+9 x^2+x+12$
  • $y^2=7 x^6+4 x^5+16 x^4+14 x^3+2 x^2+11$
  • $y^2=6 x^6+13 x^5+6 x^4+8 x^3+12 x^2+7 x+15$
  • $y^2=4 x^6+x^5+2 x^4+16 x^3+16 x^2+15 x+3$
  • $y^2=9 x^6+12 x^5+12 x^3+4 x^2+x+8$
  • $y^2=14 x^6+16 x^5+3 x^4+16 x^3+18 x^2+x+14$

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 \(\Q(\sqrt{-29 +2 \sqrt{73}})\).

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.f_ba$2$(not in LMFDB)