Properties

Label 2.61.ax_jf
Base field $\F_{61}$
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:  $\F_{61}$
Dimension:  $2$
L-polynomial:  $1 - 23 x + 239 x^{2} - 1403 x^{3} + 3721 x^{4}$
Frobenius angles:  $\pm0.0529194219962$, $\pm0.338378256587$
Angle rank:  $2$ (numerical)
Number field:  \(\Q(\sqrt{-386 -46 \sqrt{61}})\)
Galois group:  $D_{4}$
Jacobians:  $8$
Isomorphism classes:  8
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

$r$ $1$ $2$ $3$ $4$ $5$
$A(\F_{q^r})$ $2535$ $13656045$ $51546134835$ $191672000590005$ $713281995600954000$

Point counts of the curve

$r$ $1$ $2$ $3$ $4$ $5$ $6$ $7$ $8$ $9$ $10$
$C(\F_{q^r})$ $39$ $3671$ $227097$ $13843291$ $844524174$ $51519676223$ $3142740010449$ $191707323161011$ $11694146290811127$ $713342912420718326$

Jacobians and polarizations

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

  • $y^2=42 x^6+9 x^5+54 x^4+9 x^3+54 x^2+24 x+35$
  • $y^2=51 x^6+16 x^5+39 x^4+53 x^2+40 x+35$
  • $y^2=47 x^6+12 x^5+16 x^4+26 x^3+32 x^2+14 x+28$
  • $y^2=24 x^6+45 x^5+49 x^4+60 x^3+29 x^2+2 x+55$
  • $y^2=53 x^6+57 x^5+31 x^4+2 x^3+14 x^2+13 x+59$
  • $y^2=21 x^6+14 x^5+27 x^4+51 x^3+8 x^2+38 x+11$
  • $y^2=28 x^6+13 x^5+25 x^4+51 x^3+8 x^2+16 x+8$
  • $y^2=24 x^6+17 x^5+9 x^4+58 x^3+49 x^2+50 x+37$

Decomposition and endomorphism algebra

All geometric endomorphisms are defined over $\F_{61}$.

Endomorphism algebra over $\F_{61}$
The endomorphism algebra of this simple isogeny class is \(\Q(\sqrt{-386 -46 \sqrt{61}})\).

Base change

This is a primitive isogeny class.

Twists

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

TwistExtension degreeCommon base change
2.61.x_jf$2$(not in LMFDB)