A Higher Weight Analogue of Ogg's Theorem on Weierstrass Points

Abstract

For a positive integer $N$, we say that $\infty$ is a Weierstrass point on the modular curve $X_0(N)$ if there is a non-zero cusp form of weight $2$ on ${\Gamma }_0(N)$ which vanishes at $\infty$ to order greater than the genus of $X_0(N)$. If $p$ is a prime with $p\nmid N$, Ogg proved that $\infty$ is not a Weierstrass point on $X_0(pN)$ if the genus of $X_0(N)$ is $0$. We prove a similar result for even weights $k\ge 4$. We also study the space of weight $k$ cusp forms on ${\Gamma }_0(N)$ vanishing to order greater than the dimension.

6 pages