Atlas › Modular forms › Weight 10 › Level 20 › 20.10.a

Newspace 20.10.a: $S_{10}^{\mathrm{new}}(\Gamma_0(20))$

Newforms

Label	Dim	Coefficient field	Trace form	AL signs	Sign	CM	Elliptic curve
20.10.a.a	1	$\mathbb{Q}$	$q - 48q^{3} + 625q^{5} - 532q^{7} + O(q^{8})$	−
20.10.a.b	2	$\mathbb{Q}(\sqrt{79})$	$2q - 260q^{3} - 1250q^{5} - 380q^{7} + O(q^{8})$	+

Hecke characteristic polynomials

The eigenvalue of $T = T_{3} + T_{7}$ 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 $T$
20.10.a.a	$x + 580$
20.10.a.b	$x^{2} + 640x - 98995200$

Dimensions

Newforms $S_{10}^{\mathrm{new}}(\Gamma_0(20))$	3
Old forms	21
Cusp forms $S_{10}(\Gamma_0(20))$	24
Eisenstein series $E_{10}(\Gamma_0(20))$	6
Modular forms $M_{10}(\Gamma_0(20))$	30

Decomposition of the old subspace

$S_{10}^{\mathrm{old}}(\Gamma_0(20)) =$ $S_{10}^{\mathrm{new}}(\Gamma_0(2))^{\oplus 4}$ $\oplus$ $S_{10}^{\mathrm{new}}(\Gamma_0(4))^{\oplus 2}$ $\oplus$ $S_{10}^{\mathrm{new}}(\Gamma_0(5))^{\oplus 3}$ $\oplus$ $S_{10}^{\mathrm{new}}(\Gamma_0(10))^{\oplus 2}$

Provenance

Stored in the atlas: computed by Sagebrush's modular symbols engine in 0.305 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, 4, 5, 10, 20]: [1, 3, 6, 5, 15, 30] (certified at ell = 2147483629)
T = [(3, 1), (7, 1)]; h of degree 3 = 1 x 3 (phi(ord eps) x dim S_k^new); 2 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(20, 10)

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

cargo run --release -p sagebrush-web --example atlas -- 20:10 1000

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