Properties

Label 84.72.2-12.a.1.8
Level $84$
Index $72$
Genus $2$
Cusps $4$
$\Q$-cusps $2$

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Invariants

Level: $84$ $\SL_2$-level: $12$ Newform level: $144$
Index: $72$ $\PSL_2$-index:$36$
Genus: $2 = 1 + \frac{ 36 }{12} - \frac{ 0 }{4} - \frac{ 0 }{3} - \frac{ 4 }{2}$
Cusps: $4$ (of which $2$ are rational) Cusp widths $6^{2}\cdot12^{2}$ Cusp orbits $1^{2}\cdot2$
Elliptic points: $0$ of order $2$ and $0$ of order $3$
Analytic rank: not computed
$\Q$-gonality: $2$
$\overline{\Q}$-gonality: $2$
Rational cusps: $2$
Rational CM points: none

Other labels

Cummins and Pauli (CP) label: 12B2

Level structure

$\GL_2(\Z/84\Z)$-generators: $\begin{bmatrix}11&80\\2&57\end{bmatrix}$, $\begin{bmatrix}33&62\\8&61\end{bmatrix}$, $\begin{bmatrix}53&54\\28&73\end{bmatrix}$, $\begin{bmatrix}63&22\\76&23\end{bmatrix}$, $\begin{bmatrix}63&32\\8&55\end{bmatrix}$
Contains $-I$: no $\quad$ (see 12.36.2.a.1 for the level structure with $-I$)
Cyclic 84-isogeny field degree: $64$
Cyclic 84-torsion field degree: $1536$
Full 84-torsion field degree: $129024$

Models

Embedded model Embedded model in $\mathbb{P}^{3}$

$ 0 $ $=$ $ x^{2} w + y^{2} z + z^{2} w $
$=$ $x y w - 4 w^{3}$
$=$ $x y z - 4 z w^{2}$
$=$ $x y^{2} - 4 y w^{2}$
$=$$\cdots$
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Singular plane model Singular plane model

$ 0 $ $=$ $ 2 x^{4} y + x^{2} y^{2} z + z^{5} $
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Weierstrass model Weierstrass model

$ y^{2} $ $=$ $ x^{6} - 1 $
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Rational points

This modular curve has 2 rational cusps but no known non-cuspidal rational points. The following are the known rational points on this modular curve (one row per $j$-invariant).

Elliptic curve CM $j$-invariant $j$-heightPlane modelWeierstrass modelEmbedded model
no$\infty$ $0.000$
32.a3 $-4$$1728$ $= 2^{6} \cdot 3^{3}$$7.455$$(-1:-1:1)$, $(1:-1:1)$$(-1:0:1)$, $(1:0:1)$$(-2:-2:-2:1)$, $(2:2:-2:1)$

Maps to other modular curves

$j$-invariant map of degree 36 from the embedded model of this modular curve to the modular curve $X(1)$ :

$\displaystyle j$ $=$ $\displaystyle -\frac{256x^{2}w^{6}-256y^{4}w^{4}-z^{8}+48z^{5}w^{3}-512z^{2}w^{6}}{w^{6}z^{2}}$

Map of degree 1 from the embedded model of this modular curve to the plane model of the modular curve 12.36.2.a.1 :

$\displaystyle X$ $=$ $\displaystyle y$
$\displaystyle Y$ $=$ $\displaystyle z$
$\displaystyle Z$ $=$ $\displaystyle 2w$

Equation of the image curve:

$0$ $=$ $ 2X^{4}Y+X^{2}Y^{2}Z+Z^{5} $

Map of degree 1 from the embedded model of this modular curve to the Weierstrass model of the modular curve 12.36.2.a.1 :

$\displaystyle X$ $=$ $\displaystyle \frac{1}{2}y$
$\displaystyle Y$ $=$ $\displaystyle \frac{1}{8}y^{3}+\frac{1}{4}yzw$
$\displaystyle Z$ $=$ $\displaystyle w$

Modular covers

The following modular covers realize this modular curve as a fiber product over $X(1)$.

Factor curve Level Index Degree Genus Rank
$X_{\mathrm{ns}}^+(3)$ $3$ $24$ $12$ $0$ $0$
28.24.0-4.a.1.2 $28$ $3$ $3$ $0$ $0$

This modular curve minimally covers the modular curves listed below.

Covered curve Level Index Degree Genus Rank
28.24.0-4.a.1.2 $28$ $3$ $3$ $0$ $0$
84.36.1-6.a.1.1 $84$ $2$ $2$ $1$ $?$
84.36.1-6.a.1.5 $84$ $2$ $2$ $1$ $?$

This modular curve is minimally covered by the modular curves in the database listed below.

Covering curve Level Index Degree Genus
84.144.3-12.a.1.4 $84$ $2$ $2$ $3$
84.144.3-12.c.1.4 $84$ $2$ $2$ $3$
84.144.3-12.i.1.6 $84$ $2$ $2$ $3$
84.144.3-12.j.1.3 $84$ $2$ $2$ $3$
84.144.4-12.a.1.1 $84$ $2$ $2$ $4$
84.144.4-12.b.1.1 $84$ $2$ $2$ $4$
84.144.4-12.c.1.4 $84$ $2$ $2$ $4$
84.144.4-12.d.1.3 $84$ $2$ $2$ $4$
84.144.4-12.f.1.4 $84$ $2$ $2$ $4$
84.144.4-12.g.1.4 $84$ $2$ $2$ $4$
84.144.4-12.i.1.4 $84$ $2$ $2$ $4$
84.144.4-12.j.1.4 $84$ $2$ $2$ $4$
168.144.3-24.b.1.7 $168$ $2$ $2$ $3$
168.144.3-24.h.1.3 $168$ $2$ $2$ $3$
168.144.3-24.y.1.7 $168$ $2$ $2$ $3$
168.144.3-24.bb.1.7 $168$ $2$ $2$ $3$
168.144.4-24.a.1.11 $168$ $2$ $2$ $4$
168.144.4-24.b.1.11 $168$ $2$ $2$ $4$
168.144.4-24.d.1.11 $168$ $2$ $2$ $4$
168.144.4-24.f.1.11 $168$ $2$ $2$ $4$
168.144.4-24.k.1.12 $168$ $2$ $2$ $4$
168.144.4-24.l.1.12 $168$ $2$ $2$ $4$
168.144.4-24.o.1.12 $168$ $2$ $2$ $4$
168.144.4-24.p.1.12 $168$ $2$ $2$ $4$
168.144.4-24.ba.1.7 $168$ $2$ $2$ $4$
168.144.4-24.bc.1.7 $168$ $2$ $2$ $4$
168.144.4-24.bh.1.7 $168$ $2$ $2$ $4$
168.144.4-24.bj.1.7 $168$ $2$ $2$ $4$
168.144.4-24.ca.1.8 $168$ $2$ $2$ $4$
168.144.4-24.cb.1.8 $168$ $2$ $2$ $4$
168.144.4-24.ce.1.8 $168$ $2$ $2$ $4$
168.144.4-24.cf.1.8 $168$ $2$ $2$ $4$
168.144.5-24.a.1.8 $168$ $2$ $2$ $5$
168.144.5-24.b.1.8 $168$ $2$ $2$ $5$
168.144.5-24.e.1.8 $168$ $2$ $2$ $5$
168.144.5-24.f.1.8 $168$ $2$ $2$ $5$
168.144.5-24.i.1.12 $168$ $2$ $2$ $5$
168.144.5-24.j.1.12 $168$ $2$ $2$ $5$
168.144.5-24.m.1.12 $168$ $2$ $2$ $5$
168.144.5-24.n.1.14 $168$ $2$ $2$ $5$
252.216.8-36.a.1.8 $252$ $3$ $3$ $8$
84.144.3-84.i.1.8 $84$ $2$ $2$ $3$
84.144.3-84.j.1.4 $84$ $2$ $2$ $3$
84.144.3-84.q.1.4 $84$ $2$ $2$ $3$
84.144.3-84.r.1.4 $84$ $2$ $2$ $3$
84.144.4-84.a.1.5 $84$ $2$ $2$ $4$
84.144.4-84.b.1.1 $84$ $2$ $2$ $4$
84.144.4-84.d.1.7 $84$ $2$ $2$ $4$
84.144.4-84.e.1.5 $84$ $2$ $2$ $4$
84.144.4-84.k.1.4 $84$ $2$ $2$ $4$
84.144.4-84.l.1.8 $84$ $2$ $2$ $4$
84.144.4-84.n.1.7 $84$ $2$ $2$ $4$
84.144.4-84.o.1.7 $84$ $2$ $2$ $4$
168.144.3-168.y.1.15 $168$ $2$ $2$ $3$
168.144.3-168.bb.1.15 $168$ $2$ $2$ $3$
168.144.3-168.bw.1.15 $168$ $2$ $2$ $3$
168.144.3-168.bz.1.15 $168$ $2$ $2$ $3$
168.144.4-168.a.1.21 $168$ $2$ $2$ $4$
168.144.4-168.c.1.21 $168$ $2$ $2$ $4$
168.144.4-168.h.1.21 $168$ $2$ $2$ $4$
168.144.4-168.j.1.21 $168$ $2$ $2$ $4$
168.144.4-168.ba.1.32 $168$ $2$ $2$ $4$
168.144.4-168.bb.1.32 $168$ $2$ $2$ $4$
168.144.4-168.be.1.31 $168$ $2$ $2$ $4$
168.144.4-168.bf.1.32 $168$ $2$ $2$ $4$
168.144.4-168.bq.1.7 $168$ $2$ $2$ $4$
168.144.4-168.bs.1.7 $168$ $2$ $2$ $4$
168.144.4-168.bx.1.7 $168$ $2$ $2$ $4$
168.144.4-168.bz.1.7 $168$ $2$ $2$ $4$
168.144.4-168.em.1.24 $168$ $2$ $2$ $4$
168.144.4-168.en.1.15 $168$ $2$ $2$ $4$
168.144.4-168.eq.1.24 $168$ $2$ $2$ $4$
168.144.4-168.er.1.24 $168$ $2$ $2$ $4$
168.144.5-168.a.1.15 $168$ $2$ $2$ $5$
168.144.5-168.b.1.24 $168$ $2$ $2$ $5$
168.144.5-168.e.1.24 $168$ $2$ $2$ $5$
168.144.5-168.f.1.24 $168$ $2$ $2$ $5$
168.144.5-168.i.1.32 $168$ $2$ $2$ $5$
168.144.5-168.j.1.32 $168$ $2$ $2$ $5$
168.144.5-168.m.1.32 $168$ $2$ $2$ $5$
168.144.5-168.n.1.30 $168$ $2$ $2$ $5$