Properties

Label 2.19.e_w
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:  $1 + 4 x + 22 x^{2} + 76 x^{3} + 361 x^{4}$
Frobenius angles:  $\pm0.408480026548$, $\pm0.766314899703$
Angle rank:  $2$ (numerical)
Number field:  \(\Q(\sqrt{-13 +2 \sqrt{5}})\)
Galois group:  $D_{4}$
Jacobians:  $46$
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

$r$ $1$ $2$ $3$ $4$ $5$
$A(\F_{q^r})$ $464$ $141056$ $47239376$ $17037307904$ $6116629164624$

Point counts of the curve

$r$ $1$ $2$ $3$ $4$ $5$ $6$ $7$ $8$ $9$ $10$
$C(\F_{q^r})$ $24$ $390$ $6888$ $130734$ $2470264$ $47047926$ $893950536$ $16983497694$ $322688177112$ $6131059051750$

Jacobians and polarizations

This isogeny class is principally polarizable and contains the Jacobians of 46 curves (of which all are hyperelliptic):

  • $y^2=9 x^6+14 x^5+12 x^4+17 x^3+18 x^2+4 x+15$
  • $y^2=4 x^6+5 x^5+3 x^4+8 x^3+7 x^2+15 x+16$
  • $y^2=17 x^6+x^5+8 x^4+14 x^3+6 x^2+14 x+17$
  • $y^2=6 x^6+4 x^5+11 x^4+3 x^3+7 x+6$
  • $y^2=6 x^6+13 x^5+12 x^4+4 x^3+9 x^2+7 x+7$
  • $y^2=9 x^5+6 x^4+8 x^3+11 x^2+11 x+11$
  • $y^2=17 x^6+4 x^5+2 x^4+10 x^3+x^2+14 x+5$
  • $y^2=13 x^6+x^5+10 x^4+6 x^3+11 x^2+18 x+18$
  • $y^2=2 x^6+2 x^5+8 x^4+3 x^3+12 x^2+10 x$
  • $y^2=10 x^5+6 x^4+8 x^3+10 x^2+4 x+1$
  • $y^2=11 x^6+9 x^5+17 x^4+6 x^3+10 x^2+12 x+9$
  • $y^2=8 x^6+14 x^5+5 x^4+2 x^3+14 x^2+14 x$
  • $y^2=4 x^5+16 x^4+17 x^2+1$
  • $y^2=x^6+4 x^5+6 x^4+4 x^3+3 x^2+13 x+3$
  • $y^2=4 x^6+16 x^5+17 x^4+14 x^3+3 x^2+4 x+3$
  • $y^2=5 x^6+16 x^5+15 x^4+9 x^3+13 x^2+13 x+3$
  • $y^2=4 x^6+6 x^5+13 x^4+9 x^3+17 x^2+9 x+18$
  • $y^2=18 x^6+16 x^5+3 x^4+2 x^3+15 x^2+3 x+15$
  • $y^2=4 x^6+2 x^5+12 x^4+11 x^3+12 x^2+13 x+15$
  • $y^2=7 x^6+17 x^5+6 x^4+14 x^3+13 x^2+18 x+8$
  • and 26 more

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 \(\Q(\sqrt{-13 +2 \sqrt{5}})\).

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.ae_w$2$(not in LMFDB)