Properties

Label 991.1.b.a
Level $991$
Weight $1$
Character orbit 991.b
Self dual yes
Analytic conductor $0.495$
Analytic rank $0$
Dimension $8$
Projective image $D_{17}$
CM discriminant -991
Inner twists $2$

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Show commands: Magma / PariGP / SageMath

Newspace parameters

comment: Compute space of new eigenforms
 
[N,k,chi] = [991,1,Mod(990,991)]
 
mf = mfinit([N,k,chi],0)
 
lf = mfeigenbasis(mf)
 
from sage.modular.dirichlet import DirichletCharacter
 
H = DirichletGroup(991, base_ring=CyclotomicField(2))
 
chi = DirichletCharacter(H, H._module([1]))
 
N = Newforms(chi, 1, names="a")
 
//Please install CHIMP (https://github.com/edgarcosta/CHIMP) if you want to run this code
 
chi := DirichletCharacter("991.990");
 
S:= CuspForms(chi, 1);
 
N := Newforms(S);
 
Level: \( N \) \(=\) \( 991 \)
Weight: \( k \) \(=\) \( 1 \)
Character orbit: \([\chi]\) \(=\) 991.b (of order \(2\), degree \(1\), minimal)

Newform invariants

comment: select newform
 
sage: f = N[0] # Warning: the index may be different
 
gp: f = lf[1] \\ Warning: the index may be different
 
Self dual: yes
Analytic conductor: \(0.494573427519\)
Analytic rank: \(0\)
Dimension: \(8\)
Coefficient field: \(\Q(\zeta_{34})^+\)
comment: defining polynomial
 
gp: f.mod \\ as an extension of the character field
 
Defining polynomial: \( x^{8} - x^{7} - 7x^{6} + 6x^{5} + 15x^{4} - 10x^{3} - 10x^{2} + 4x + 1 \) Copy content Toggle raw display
Coefficient ring: \(\Z[a_1, a_2]\)
Coefficient ring index: \( 1 \)
Twist minimal: yes
Projective image: \(D_{17}\)
Projective field: Galois closure of 17.1.930227631978098127294721.1

$q$-expansion

comment: q-expansion
 
sage: f.q_expansion() # note that sage often uses an isomorphic number field
 
gp: mfcoefs(f, 20)
 

Coefficients of the \(q\)-expansion are expressed in terms of a basis \(1,\beta_1,\ldots,\beta_{7}\) for the coefficient ring described below. We also show the integral \(q\)-expansion of the trace form.

\(f(q)\) \(=\) \( q + \beta_{6} q^{2} + ( - \beta_{5} + 1) q^{4} + \beta_{2} q^{5} + (\beta_{6} - \beta_1) q^{8} + q^{9}+O(q^{10}) \) Copy content Toggle raw display \( q + \beta_{6} q^{2} + ( - \beta_{5} + 1) q^{4} + \beta_{2} q^{5} + (\beta_{6} - \beta_1) q^{8} + q^{9} + (\beta_{7} - \beta_{6} + \beta_{5} + \cdots - 1) q^{10}+ \cdots + \beta_{6} q^{98}+O(q^{100}) \) Copy content Toggle raw display
\(\operatorname{Tr}(f)(q)\) \(=\) \( 8 q - q^{2} + 7 q^{4} - q^{5} - 2 q^{8} + 8 q^{9}+O(q^{10}) \) Copy content Toggle raw display \( 8 q - q^{2} + 7 q^{4} - q^{5} - 2 q^{8} + 8 q^{9} - 2 q^{10} - q^{13} + 6 q^{16} - q^{18} - q^{19} - 3 q^{20} + 7 q^{25} - 2 q^{26} - q^{29} - q^{31} - 3 q^{32} + 7 q^{36} - 2 q^{38} - 4 q^{40} - q^{43} - q^{45} + 8 q^{49} - 3 q^{50} - 3 q^{52} - q^{53} - 2 q^{58} - q^{59} - q^{61} - 2 q^{62} + 5 q^{64} - 2 q^{65} - q^{67} - q^{71} - 2 q^{72} - 3 q^{76} - q^{79} - 5 q^{80} + 8 q^{81} - 2 q^{86} - 2 q^{90} - 2 q^{95} - q^{98}+O(q^{100}) \) Copy content Toggle raw display

Basis of coefficient ring in terms of \(\nu = \zeta_{34} + \zeta_{34}^{-1}\):

\(\beta_{1}\)\(=\) \( \nu \) Copy content Toggle raw display
\(\beta_{2}\)\(=\) \( \nu^{2} - 2 \) Copy content Toggle raw display
\(\beta_{3}\)\(=\) \( \nu^{3} - 3\nu \) Copy content Toggle raw display
\(\beta_{4}\)\(=\) \( \nu^{4} - 4\nu^{2} + 2 \) Copy content Toggle raw display
\(\beta_{5}\)\(=\) \( \nu^{5} - 5\nu^{3} + 5\nu \) Copy content Toggle raw display
\(\beta_{6}\)\(=\) \( \nu^{6} - 6\nu^{4} + 9\nu^{2} - 2 \) Copy content Toggle raw display
\(\beta_{7}\)\(=\) \( \nu^{7} - 7\nu^{5} + 14\nu^{3} - 7\nu \) Copy content Toggle raw display
\(\nu\)\(=\) \( \beta_1 \) Copy content Toggle raw display
\(\nu^{2}\)\(=\) \( \beta_{2} + 2 \) Copy content Toggle raw display
\(\nu^{3}\)\(=\) \( \beta_{3} + 3\beta_1 \) Copy content Toggle raw display
\(\nu^{4}\)\(=\) \( \beta_{4} + 4\beta_{2} + 6 \) Copy content Toggle raw display
\(\nu^{5}\)\(=\) \( \beta_{5} + 5\beta_{3} + 10\beta_1 \) Copy content Toggle raw display
\(\nu^{6}\)\(=\) \( \beta_{6} + 6\beta_{4} + 15\beta_{2} + 20 \) Copy content Toggle raw display
\(\nu^{7}\)\(=\) \( \beta_{7} + 7\beta_{5} + 21\beta_{3} + 35\beta_1 \) Copy content Toggle raw display

Character values

We give the values of \(\chi\) on generators for \(\left(\mathbb{Z}/991\mathbb{Z}\right)^\times\).

\(n\) \(6\)
\(\chi(n)\) \(-1\)

Embeddings

For each embedding \(\iota_m\) of the coefficient field, the values \(\iota_m(a_n)\) are shown below.

For more information on an embedded modular form you can click on its label.

comment: embeddings in the coefficient field
 
gp: mfembed(f)
 
Label   \(\iota_m(\nu)\) \( a_{2} \) \( a_{3} \) \( a_{4} \) \( a_{5} \) \( a_{6} \) \( a_{7} \) \( a_{8} \) \( a_{9} \) \( a_{10} \)
990.1
1.70043
−0.184537
−1.86494
−1.47802
0.547326
1.96595
1.20527
−0.891477
−1.96595 0 2.86494 0.891477 0 0 −3.66638 1.00000 −1.75260
990.2 −1.70043 0 1.89148 −1.96595 0 0 −1.51590 1.00000 3.34296
990.3 −1.20527 0 0.452674 1.47802 0 0 0.659675 1.00000 −1.78141
990.4 −0.547326 0 −0.700434 0.184537 0 0 0.930692 1.00000 −0.101002
990.5 0.184537 0 −0.965946 −1.70043 0 0 −0.362789 1.00000 −0.313793
990.6 0.891477 0 −0.205269 1.86494 0 0 −1.07447 1.00000 1.66255
990.7 1.47802 0 1.18454 −0.547326 0 0 0.272749 1.00000 −0.808958
990.8 1.86494 0 2.47802 −1.20527 0 0 2.75642 1.00000 −2.24776
\(n\): e.g. 2-40 or 990-1000
Embeddings: e.g. 1-3 or 990.8
Significant digits:
Format:

Inner twists

Char Parity Ord Mult Type
1.a even 1 1 trivial
991.b odd 2 1 CM by \(\Q(\sqrt{-991}) \)

Twists

       By twisting character orbit
Char Parity Ord Mult Type Twist Min Dim
1.a even 1 1 trivial 991.1.b.a 8
991.b odd 2 1 CM 991.1.b.a 8
    
        By twisted newform orbit
Twist Min Dim Char Parity Ord Mult Type
991.1.b.a 8 1.a even 1 1 trivial
991.1.b.a 8 991.b odd 2 1 CM

Hecke kernels

This newform subspace is the entire newspace \(S_{1}^{\mathrm{new}}(991, [\chi])\).

Hecke characteristic polynomials

$p$ $F_p(T)$
$2$ \( T^{8} + T^{7} - 7 T^{6} + \cdots + 1 \) Copy content Toggle raw display
$3$ \( T^{8} \) Copy content Toggle raw display
$5$ \( T^{8} + T^{7} - 7 T^{6} + \cdots + 1 \) Copy content Toggle raw display
$7$ \( T^{8} \) Copy content Toggle raw display
$11$ \( T^{8} \) Copy content Toggle raw display
$13$ \( T^{8} + T^{7} - 7 T^{6} + \cdots + 1 \) Copy content Toggle raw display
$17$ \( T^{8} \) Copy content Toggle raw display
$19$ \( T^{8} + T^{7} - 7 T^{6} + \cdots + 1 \) Copy content Toggle raw display
$23$ \( T^{8} \) Copy content Toggle raw display
$29$ \( T^{8} + T^{7} - 7 T^{6} + \cdots + 1 \) Copy content Toggle raw display
$31$ \( T^{8} + T^{7} - 7 T^{6} + \cdots + 1 \) Copy content Toggle raw display
$37$ \( T^{8} \) Copy content Toggle raw display
$41$ \( T^{8} \) Copy content Toggle raw display
$43$ \( T^{8} + T^{7} - 7 T^{6} + \cdots + 1 \) Copy content Toggle raw display
$47$ \( T^{8} \) Copy content Toggle raw display
$53$ \( T^{8} + T^{7} - 7 T^{6} + \cdots + 1 \) Copy content Toggle raw display
$59$ \( T^{8} + T^{7} - 7 T^{6} + \cdots + 1 \) Copy content Toggle raw display
$61$ \( T^{8} + T^{7} - 7 T^{6} + \cdots + 1 \) Copy content Toggle raw display
$67$ \( T^{8} + T^{7} - 7 T^{6} + \cdots + 1 \) Copy content Toggle raw display
$71$ \( T^{8} + T^{7} - 7 T^{6} + \cdots + 1 \) Copy content Toggle raw display
$73$ \( T^{8} \) Copy content Toggle raw display
$79$ \( T^{8} + T^{7} - 7 T^{6} + \cdots + 1 \) Copy content Toggle raw display
$83$ \( T^{8} \) Copy content Toggle raw display
$89$ \( T^{8} \) Copy content Toggle raw display
$97$ \( T^{8} \) Copy content Toggle raw display
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