Properties

Label 2.41.a_ck
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:  $1 + 62 x^{2} + 1681 x^{4}$
Frobenius angles:  $\pm0.386448235704$, $\pm0.613551764296$
Angle rank:  $1$ (numerical)
Number field:  \(\Q(i, \sqrt{5})\)
Galois group:  $C_2^2$
Jacobians:  $227$
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

$r$ $1$ $2$ $3$ $4$ $5$
$A(\F_{q^r})$ $1744$ $3041536$ $4750029904$ $7982207078400$ $13422659099124304$

Point counts of the curve

$r$ $1$ $2$ $3$ $4$ $5$ $6$ $7$ $8$ $9$ $10$
$C(\F_{q^r})$ $42$ $1806$ $68922$ $2824798$ $115856202$ $4749955566$ $194754273882$ $7984936067518$ $327381934393962$ $13422658888096206$

Jacobians and polarizations

This isogeny class is principally polarizable and contains the Jacobians of 227 curves (of which all are hyperelliptic):

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 \(\Q(i, \sqrt{5})\).
Endomorphism algebra over $\overline{\F}_{41}$
The base change of $A$ to $\F_{41^{2}}$ is 1.1681.ck 2 and its endomorphism algebra is $\mathrm{M}_{2}($\(\Q(\sqrt{-5}) \)$)$

Base change

This is a primitive isogeny class.

Twists

Below are some of the twists of this isogeny class.

TwistExtension degreeCommon base change
2.41.ay_is$4$(not in LMFDB)
2.41.a_ack$4$(not in LMFDB)
2.41.y_is$4$(not in LMFDB)

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

TwistExtension degreeCommon base change
2.41.ay_is$4$(not in LMFDB)
2.41.a_ack$4$(not in LMFDB)
2.41.y_is$4$(not in LMFDB)
2.41.am_dz$12$(not in LMFDB)
2.41.m_dz$12$(not in LMFDB)