Properties

Label 2.11.b_t
Base field $\F_{11}$
Dimension $2$
$p$-rank $2$
Ordinary yes
Supersingular no
Simple yes
Geometrically simple yes
Primitive yes
Principally polarizable yes
Contains a Jacobian yes

Related objects

Downloads

Learn more

Invariants

Base field:  $\F_{11}$
Dimension:  $2$
L-polynomial:  $1 + x + 19 x^{2} + 11 x^{3} + 121 x^{4}$
Frobenius angles:  $\pm0.437074627469$, $\pm0.612852731135$
Angle rank:  $2$ (numerical)
Number field:  \(\Q(\sqrt{-162 +2 \sqrt{13}})\)
Galois group:  $D_{4}$
Jacobians:  $5$
Cyclic group of points:    yes

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

$r$ $1$ $2$ $3$ $4$ $5$
$A(\F_{q^r})$ $153$ $19737$ $1740987$ $211363533$ $25955901648$

Point counts of the curve

$r$ $1$ $2$ $3$ $4$ $5$ $6$ $7$ $8$ $9$ $10$
$C(\F_{q^r})$ $13$ $159$ $1309$ $14435$ $161168$ $1771155$ $19490435$ $214387123$ $2357847895$ $25937001174$

Jacobians and polarizations

This isogeny class is principally polarizable and contains the Jacobians of 5 curves (of which all are hyperelliptic):

  • $y^2=4 x^6+2 x^5+x^4+10 x^3+10 x^2+4 x+5$
  • $y^2=5 x^6+3 x^5+3 x^4+5 x^3+5 x^2+2 x+5$
  • $y^2=10 x^6+5 x^5+7 x^4+6 x^3+2 x^2+x+4$
  • $y^2=7 x^6+4 x^5+x^4+x^3+8 x^2+6 x+7$
  • $y^2=5 x^6+3 x^5+5 x^4+4 x^3+x^2+10 x+5$

Decomposition and endomorphism algebra

All geometric endomorphisms are defined over $\F_{11}$.

Endomorphism algebra over $\F_{11}$
The endomorphism algebra of this simple isogeny class is \(\Q(\sqrt{-162 +2 \sqrt{13}})\).

Base change

This is a primitive isogeny class.

Twists

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

TwistExtension degreeCommon base change
2.11.ab_t$2$2.121.bl_wj