Properties

Label 2.41.a_aby
Base field $\F_{41}$
Dimension $2$
$p$-rank $2$
Ordinary yes
Supersingular no
Simple yes
Geometrically simple no
Primitive yes
Principally polarizable yes
Contains a Jacobian yes

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Invariants

Base field:  $\F_{41}$
Dimension:  $2$
L-polynomial:  $1 - 50 x^{2} + 1681 x^{4}$
Frobenius angles:  $\pm0.145633696334$, $\pm0.854366303666$
Angle rank:  $1$ (numerical)
Number field:  \(\Q(\sqrt{-2}, \sqrt{33})\)
Galois group:  $C_2^2$
Jacobians:  $128$
Cyclic group of points:    no
Non-cyclic primes:   $2$

This isogeny class is simple but not 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

$r$ $1$ $2$ $3$ $4$ $5$
$A(\F_{q^r})$ $1632$ $2663424$ $4750231392$ $7989803237376$ $13422659341837152$

Point counts of the curve

$r$ $1$ $2$ $3$ $4$ $5$ $6$ $7$ $8$ $9$ $10$
$C(\F_{q^r})$ $42$ $1582$ $68922$ $2827486$ $115856202$ $4750358542$ $194754273882$ $7984935046078$ $327381934393962$ $13422659373521902$

Jacobians and polarizations

This isogeny class is principally polarizable and contains the Jacobians of 128 curves (of which all are hyperelliptic):

  • $y^2=7 x^6+31 x^5+x^4+33 x^3+32 x^2+2 x+35$
  • $y^2=x^6+22 x^5+6 x^4+34 x^3+28 x^2+12 x+5$
  • $y^2=36 x^6+25 x^5+36 x^4+29 x^3+16 x^2+9 x+35$
  • $y^2=x^6+16 x^5+35 x^4+36 x^3+24 x^2+26 x+21$
  • $y^2=38 x^6+19 x^5+38 x^4+22 x^3+14 x^2+27 x+21$
  • $y^2=23 x^6+32 x^5+23 x^4+9 x^3+2 x^2+39 x+3$
  • $y^2=13 x^5+35 x^4+23 x^3+28 x^2+31 x+22$
  • $y^2=37 x^5+5 x^4+15 x^3+4 x^2+22 x+9$
  • $y^2=16 x^6+6 x^5+19 x^4+x^3+38 x^2+20$
  • $y^2=14 x^6+36 x^5+32 x^4+6 x^3+23 x^2+38$
  • $y^2=23 x^6+20 x^5+9 x^4+x^3+15 x^2+37 x+4$
  • $y^2=16 x^6+7 x^5+8 x^4+4 x^3+40 x^2+35 x+12$
  • $y^2=40 x^6+2 x^5+38 x^4+30 x^3+39 x^2+8 x+17$
  • $y^2=35 x^6+12 x^5+23 x^4+16 x^3+29 x^2+7 x+20$
  • $y^2=39 x^6+26 x^5+28 x^4+5 x^3+39 x^2+29 x+13$
  • $y^2=14 x^6+38 x^5+17 x^4+2 x^3+19 x^2+7 x+22$
  • $y^2=2 x^6+23 x^5+20 x^4+12 x^3+32 x^2+x+9$
  • $y^2=39 x^6+12 x^5+x^4+30 x^3+38 x^2+26 x+13$
  • $y^2=7 x^6+37 x^5+36 x^4+3 x^3+29 x^2+8 x+12$
  • $y^2=18 x^6+21 x^5+30 x^4+8 x^3+19 x^2+13 x+32$
  • and 108 more

Decomposition and endomorphism algebra

All geometric endomorphisms are defined over $\F_{41^{2}}$.

Endomorphism algebra over $\F_{41}$
The endomorphism algebra of this simple isogeny class is \(\Q(\sqrt{-2}, \sqrt{33})\).
Endomorphism algebra over $\overline{\F}_{41}$
The base change of $A$ to $\F_{41^{2}}$ is 1.1681.aby 2 and its endomorphism algebra is $\mathrm{M}_{2}($\(\Q(\sqrt{-66}) \)$)$

Base change

This is a primitive isogeny class.

Twists

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

TwistExtension degreeCommon base change
2.41.a_by$4$(not in LMFDB)
2.41.ai_bg$8$(not in LMFDB)
2.41.i_bg$8$(not in LMFDB)