Non-ordinary primes and congruences for weakly holomorphic modular forms of level 2

Abstract

In this paper, we investigate the arithmetic properties of the Fourier coefficients of weakly holomorphic modular forms of weight $k$ for the congruence subgroup ${\Gamma }_0(2)$, which have poles exclusively at the cusp $\infty$. Using the structure of canonical bases and the explicit duality between the coefficients of spaces of weakly holomorphic modular forms, which have a pole only at $\infty$, we prove a general family of congruences modulo primes $p\ge 5$ and derive several corollaries as examples of the theorem's application.

6 pages