Properties

Label 2.71.a_ek
Base field $\F_{71}$
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:  $\F_{71}$
Dimension:  $2$
L-polynomial:  $1 + 114 x^{2} + 5041 x^{4}$
Frobenius angles:  $\pm0.398333180169$, $\pm0.601666819831$
Angle rank:  $1$ (numerical)
Number field:  \(\Q(i, \sqrt{7})\)
Galois group:  $C_2^2$
Jacobians:  $241$
Isomorphism classes:  162
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

$r$ $1$ $2$ $3$ $4$ $5$
$A(\F_{q^r})$ $5156$ $26584336$ $128100041444$ $645605491277824$ $3255243547406368676$

Point counts of the curve

$r$ $1$ $2$ $3$ $4$ $5$ $6$ $7$ $8$ $9$ $10$
$C(\F_{q^r})$ $72$ $5270$ $357912$ $25405854$ $1804229352$ $128099798966$ $9095120158392$ $645753615909694$ $45848500718449032$ $3255243543802856150$

Jacobians and polarizations

This isogeny class is principally polarizable and contains the Jacobians of 241 curves (of which all are hyperelliptic):

Decomposition and endomorphism algebra

All geometric endomorphisms are defined over $\F_{71^{2}}$.

Endomorphism algebra over $\F_{71}$
The endomorphism algebra of this simple isogeny class is \(\Q(i, \sqrt{7})\).
Endomorphism algebra over $\overline{\F}_{71}$
The base change of $A$ to $\F_{71^{2}}$ is 1.5041.ek 2 and its endomorphism algebra is $\mathrm{M}_{2}($\(\Q(\sqrt{-7}) \)$)$

Base change

This is a primitive isogeny class.

Twists

Below are some of the twists of this isogeny class.

TwistExtension degreeCommon base change
2.71.abg_pi$4$(not in LMFDB)
2.71.a_aek$4$(not in LMFDB)
2.71.bg_pi$4$(not in LMFDB)

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

TwistExtension degreeCommon base change
2.71.abg_pi$4$(not in LMFDB)
2.71.a_aek$4$(not in LMFDB)
2.71.bg_pi$4$(not in LMFDB)
2.71.aq_hd$12$(not in LMFDB)
2.71.q_hd$12$(not in LMFDB)