Skip to main content
7 of 11
edited title

Lifting a real quadratic twist of an Elliptic Curve to the modular curve

Let $E$ be an elliptic curve of conductor $N\cdot p^2$ over $\mathbb{Q}$, defined by the equation $$y^2=x^3+p^2b\cdot x + p^3\cdot c$$ and parametrized by a map $$X_{0}(N\cdot {p}^{2})\rightarrow E$$ and let $E_{\sqrt(p)}$ be the curve $$y^2=x^3+b\cdot x+c$$ parametrized by a map $$X_{0}(N)\rightarrow E_{\sqrt(p)}$$ Both become isomorphic over $\mathbb{Q}[\sqrt{p}]$. Is there a lift of that isomorphism to a morphism: $$X_{0}(N\cdot {p}^{2})\rightarrow X_{0}(N)$$ and if so, can that morphism be described explicitly?