Atlas › Modular forms › Weight 8 › Level 2 › 2.8.a

Newspace 2.8.a: $S_{8}^{\mathrm{new}}(\Gamma_0(2))$

Newforms

Label	Dim	Coefficient field	Trace form	AL signs	Sign	CM	Elliptic curve
2.8.a.a	1	$\mathbb{Q}$	$q - 8q^{2} + 12q^{3} + 64q^{4} - 210q^{5} - 96q^{6} + 1016q^{7} + O(q^{8})$	+	$+1$

Hecke characteristic polynomials

The eigenvalue of $T = T_{3} + T_{5}$ generates each orbit's coefficient field; on the newspace its characteristic polynomial factors over $\mathbb{Q}$ as one irreducible factor per orbit:

Orbit	Characteristic polynomial of $T$
2.8.a.a	$x + 198$

Dimensions

Newforms $S_{8}^{\mathrm{new}}(\Gamma_0(2))$	1
Old forms	0
Cusp forms $S_{8}(\Gamma_0(2))$	1
Eisenstein series $E_{8}(\Gamma_0(2))$	2
Modular forms $M_{8}(\Gamma_0(2))$	3

Decomposition of the old subspace

The old subspace is 0.

Provenance

Stored in the atlas: computed by Sagebrush's modular symbols engine in 0.207 s (one thread) and proven: the dimensions are certified, and the characteristic polynomial of $T$ over $\mathbb{Z}$ is reconstructed by CRT past a rigorous coefficient bound.

The engine's checks

dim M^+ at levels [1, 2]: [1, 3] (certified at ell = 2147483647)
T = [(3, 1), (5, 1)]; h of degree 1 = 1 x 1 (phi(ord eps) x dim S_k^new); 1 primes, 0 rejected

Open in the notebook · JSON · stored data

Recompute it yourself

In Sage mode at sagebrush.space (or npx sagebrush --sage):

newform_orbits(2, 8)

With the Rust engine (source), in engine/:

cargo run --release -p sagebrush-web --example atlas -- 2:8 1000

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