Effective bounds for adelic Galois representations attached to elliptic curves over the rationals

Abstract: Given an elliptic curve $E$ defined over $\mathbb{Q}$ without complex multiplication, we provide an explicit sharp bound on the index of the image of the adelic representation $\rho_E$. In particular, if $\operatorname{h}{\mathcal{F}}(E)$ is the stable Faltings height of $E$, we show that $[\operatorname{GL}_2(\widehat{\mathbb{Z}}) : \operatorname{Im}\rho_E]$ is bounded above by $10^{21} (\operatorname{h}{\mathcal{F}}(E)+40)^{4.42}$, and, for $\operatorname{h}{\mathcal{F}}(E)$ tending to infinity, by $\operatorname{h}{\mathcal{F}}(E)^{3+o(1)}$. We also classify the possible (conjecturally non-existent) images of the representations $\rho_{E,p^n}$ whenever $\operatorname{Im}\rho_{E,p}$ is contained in the normaliser of a non-split Cartan. This result improves previous work of Zywina and Lombardo.