Properties

Label 2.71.a_as
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:  $1 - 18 x^{2} + 5041 x^{4}$
Frobenius angles:  $\pm0.229771007001$, $\pm0.770228992999$
Angle rank:  $1$ (numerical)
Number field:  \(\Q(\sqrt{10}, \sqrt{-31})\)
Galois group:  $C_2^2$
Jacobians:  $260$
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

$r$ $1$ $2$ $3$ $4$ $5$
$A(\F_{q^r})$ $5024$ $25240576$ $128100550304$ $646249611673600$ $3255243548867935904$

Point counts of the curve

$r$ $1$ $2$ $3$ $4$ $5$ $6$ $7$ $8$ $9$ $10$
$C(\F_{q^r})$ $72$ $5006$ $357912$ $25431198$ $1804229352$ $128100816686$ $9095120158392$ $645753442455358$ $45848500718449032$ $3255243546725990606$

Jacobians and polarizations

This isogeny class is principally polarizable and contains the Jacobians of 260 curves (of which all are hyperelliptic):

  • $y^2=33 x^6+7 x^5+63 x^4+65 x^3+30 x^2+23 x+27$
  • $y^2=9 x^6+44 x^5+17 x^4+49 x^3+2 x^2+34 x+52$
  • $y^2=63 x^6+24 x^5+48 x^4+59 x^3+14 x^2+25 x+9$
  • $y^2=51 x^6+65 x^5+60 x^4+2 x^3+50 x^2+49 x+21$
  • $y^2=35 x^6+43 x^5+10 x^4+65 x^3+30 x^2+51 x+6$
  • $y^2=32 x^6+17 x^5+70 x^4+29 x^3+68 x^2+2 x+42$
  • $y^2=60 x^6+48 x^5+46 x^4+15 x^3+40 x^2+50 x+34$
  • $y^2=65 x^6+52 x^5+38 x^4+34 x^3+67 x^2+66 x+25$
  • $y^2=61 x^6+13 x^5+28 x^4+28 x^3+30 x^2+13 x+14$
  • $y^2=x^6+20 x^5+54 x^4+54 x^3+68 x^2+20 x+27$
  • $y^2=29 x^6+67 x^5+39 x^4+20 x^3+65 x^2+19 x+21$
  • $y^2=61 x^6+43 x^5+60 x^4+69 x^3+29 x^2+62 x+5$
  • $y^2=50 x^6+31 x^5+23 x^4+26 x^3+27 x^2+8 x+28$
  • $y^2=66 x^6+4 x^5+19 x^4+40 x^3+47 x^2+56 x+54$
  • $y^2=18 x^6+68 x^5+57 x^4+8 x^3+39 x^2+13 x+27$
  • $y^2=55 x^6+50 x^5+44 x^4+56 x^3+60 x^2+20 x+47$
  • $y^2=50 x^6+38 x^5+47 x^4+11 x^3+23 x+68$
  • $y^2=66 x^6+53 x^5+45 x^4+6 x^3+19 x+50$
  • $y^2=62 x^6+27 x^5+9 x^4+41 x^3+8 x^2+47 x+57$
  • $y^2=8 x^6+47 x^5+63 x^4+3 x^3+56 x^2+45 x+44$
  • and 240 more

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 \(\Q(\sqrt{10}, \sqrt{-31})\).
Endomorphism algebra over $\overline{\F}_{71}$
The base change of $A$ to $\F_{71^{2}}$ is 1.5041.as 2 and its endomorphism algebra is $\mathrm{M}_{2}($\(\Q(\sqrt{-310}) \)$)$

Base change

This is a primitive isogeny class.

Twists

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

TwistExtension degreeCommon base change
2.71.a_s$4$(not in LMFDB)