Properties

Label 820.2.w.a
Level $820$
Weight $2$
Character orbit 820.w
Analytic conductor $6.548$
Analytic rank $0$
Dimension $4$
CM discriminant -4
Inner twists $4$

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Newspace parameters

Copy content comment:Compute space of new eigenforms
 
Copy content gp:[N,k,chi] = [820,2,Mod(79,820)] mf = mfinit([N,k,chi],0) lf = mfeigenbasis(mf)
 
Copy content sage:from sage.modular.dirichlet import DirichletCharacter H = DirichletGroup(820, base_ring=CyclotomicField(8)) chi = DirichletCharacter(H, H._module([4, 4, 7])) N = Newforms(chi, 2, names="a")
 
Copy content magma://Please install CHIMP (https://github.com/edgarcosta/CHIMP) if you want to run this code chi := DirichletCharacter("820.79"); S:= CuspForms(chi, 2); N := Newforms(S);
 
Level: \( N \) \(=\) \( 820 = 2^{2} \cdot 5 \cdot 41 \)
Weight: \( k \) \(=\) \( 2 \)
Character orbit: \([\chi]\) \(=\) 820.w (of order \(8\), degree \(4\), minimal)

Newform invariants

Copy content comment:select newform
 
Copy content sage:traces = [4,-4] f = next(g for g in N if [g.coefficient(i+1).trace() for i in range(2)] == traces)
 
Copy content gp:f = lf[1] \\ Warning: the index may be different
 
Self dual: no
Analytic conductor: \(6.54773296574\)
Analytic rank: \(0\)
Dimension: \(4\)
Coefficient field: \(\Q(\zeta_{8})\)
Copy content comment:defining polynomial
 
Copy content gp:f.mod \\ as an extension of the character field
 
Defining polynomial: \( x^{4} + 1 \) Copy content Toggle raw display
Coefficient ring: \(\Z[a_1, \ldots, a_{9}]\)
Coefficient ring index: \( 1 \)
Twist minimal: yes
Sato-Tate group: $\mathrm{U}(1)[D_{8}]$

$q$-expansion

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

Coefficients of the \(q\)-expansion are expressed in terms of a primitive root of unity \(\zeta_{8}\). We also show the integral \(q\)-expansion of the trace form.

\(f(q)\) \(=\) \( q + (\zeta_{8}^{2} - 1) q^{2} - 2 \zeta_{8}^{2} q^{4} + (2 \zeta_{8}^{3} + \zeta_{8}) q^{5} + (2 \zeta_{8}^{2} + 2) q^{8} + 3 \zeta_{8}^{3} q^{9} + ( - \zeta_{8}^{3} - 3 \zeta_{8}) q^{10} + (2 \zeta_{8}^{3} + 3 \zeta_{8}^{2} + \cdots + 2) q^{13} + \cdots + ( - 7 \zeta_{8}^{3} - 7 \zeta_{8}) q^{98} +O(q^{100}) \) Copy content Toggle raw display
\(\operatorname{Tr}(f)(q)\) \(=\) \( 4 q - 4 q^{2} + 8 q^{8} + 8 q^{13} - 16 q^{16} + 4 q^{17} - 16 q^{25} - 20 q^{26} - 20 q^{29} + 16 q^{32} + 12 q^{34} - 20 q^{41} - 12 q^{45} + 28 q^{50} + 24 q^{52} - 28 q^{53} + 12 q^{58} + 4 q^{61} - 32 q^{65}+ \cdots + 36 q^{97}+O(q^{100}) \) Copy content Toggle raw display

Character values

We give the values of \(\chi\) on generators for \(\left(\mathbb{Z}/820\mathbb{Z}\right)^\times\).

\(n\) \(411\) \(621\) \(657\)
\(\chi(n)\) \(-1\) \(\zeta_{8}\) \(-1\)

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.

Copy content comment:embeddings in the coefficient field
 
Copy content gp:mfembed(f)
 
Label   \(\iota_m(\nu)\) \( a_{2} \) \( a_{3} \) \( a_{4} \) \( a_{5} \) \( a_{6} \) \( a_{7} \) \( a_{8} \) \( a_{9} \) \( a_{10} \)
79.1
0.707107 0.707107i
−0.707107 0.707107i
0.707107 + 0.707107i
−0.707107 + 0.707107i
−1.00000 1.00000i 0 2.00000i −0.707107 2.12132i 0 0 2.00000 2.00000i −2.12132 2.12132i −1.41421 + 2.82843i
219.1 −1.00000 + 1.00000i 0 2.00000i 0.707107 2.12132i 0 0 2.00000 + 2.00000i 2.12132 2.12132i 1.41421 + 2.82843i
519.1 −1.00000 + 1.00000i 0 2.00000i −0.707107 + 2.12132i 0 0 2.00000 + 2.00000i −2.12132 + 2.12132i −1.41421 2.82843i
659.1 −1.00000 1.00000i 0 2.00000i 0.707107 + 2.12132i 0 0 2.00000 2.00000i 2.12132 + 2.12132i 1.41421 2.82843i
\(n\): e.g. 2-40 or 990-1000
Significant digits:
Format:

Inner twists

Char Parity Ord Mult Type
1.a even 1 1 trivial
4.b odd 2 1 CM by \(\Q(\sqrt{-1}) \)
205.m odd 8 1 inner
820.w even 8 1 inner

Twists

       By twisting character orbit
Char Parity Ord Mult Type Twist Min Dim
1.a even 1 1 trivial 820.2.w.a 4
4.b odd 2 1 CM 820.2.w.a 4
5.b even 2 1 820.2.w.b yes 4
20.d odd 2 1 820.2.w.b yes 4
41.e odd 8 1 820.2.w.b yes 4
164.i even 8 1 820.2.w.b yes 4
205.m odd 8 1 inner 820.2.w.a 4
820.w even 8 1 inner 820.2.w.a 4
    
        By twisted newform orbit
Twist Min Dim Char Parity Ord Mult Type
820.2.w.a 4 1.a even 1 1 trivial
820.2.w.a 4 4.b odd 2 1 CM
820.2.w.a 4 205.m odd 8 1 inner
820.2.w.a 4 820.w even 8 1 inner
820.2.w.b yes 4 5.b even 2 1
820.2.w.b yes 4 20.d odd 2 1
820.2.w.b yes 4 41.e odd 8 1
820.2.w.b yes 4 164.i even 8 1

Hecke kernels

This newform subspace can be constructed as the intersection of the kernels of the following linear operators acting on \(S_{2}^{\mathrm{new}}(820, [\chi])\):

\( T_{3} \) Copy content Toggle raw display
\( T_{13}^{4} - 8T_{13}^{3} + 66T_{13}^{2} - 140T_{13} + 98 \) Copy content Toggle raw display

Hecke characteristic polynomials

$p$ $F_p(T)$
$2$ \( (T^{2} + 2 T + 2)^{2} \) Copy content Toggle raw display
$3$ \( T^{4} \) Copy content Toggle raw display
$5$ \( T^{4} + 8T^{2} + 25 \) Copy content Toggle raw display
$7$ \( T^{4} \) Copy content Toggle raw display
$11$ \( T^{4} \) Copy content Toggle raw display
$13$ \( T^{4} - 8 T^{3} + \cdots + 98 \) Copy content Toggle raw display
$17$ \( T^{4} - 4 T^{3} + \cdots + 98 \) Copy content Toggle raw display
$19$ \( T^{4} \) Copy content Toggle raw display
$23$ \( T^{4} \) Copy content Toggle raw display
$29$ \( T^{4} + 20 T^{3} + \cdots + 2 \) Copy content Toggle raw display
$31$ \( T^{4} \) Copy content Toggle raw display
$37$ \( (T^{2} + 50)^{2} \) Copy content Toggle raw display
$41$ \( (T^{2} + 10 T + 41)^{2} \) Copy content Toggle raw display
$43$ \( T^{4} \) Copy content Toggle raw display
$47$ \( T^{4} \) Copy content Toggle raw display
$53$ \( T^{4} + 28 T^{3} + \cdots + 578 \) Copy content Toggle raw display
$59$ \( T^{4} \) Copy content Toggle raw display
$61$ \( (T^{2} - 2 T + 2)^{2} \) Copy content Toggle raw display
$67$ \( T^{4} \) Copy content Toggle raw display
$71$ \( T^{4} \) Copy content Toggle raw display
$73$ \( T^{4} + 1296 \) Copy content Toggle raw display
$79$ \( T^{4} \) Copy content Toggle raw display
$83$ \( T^{4} \) Copy content Toggle raw display
$89$ \( T^{4} - 32 T^{3} + \cdots + 28322 \) Copy content Toggle raw display
$97$ \( T^{4} - 36 T^{3} + \cdots + 37538 \) Copy content Toggle raw display
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