Elliptic surfaces over $\mathbb{P}^1$ and large class groups of number fields

Given a non-isotrivial elliptic curve over $\mathbb{Q}(t)$ with large Mordell-Weil rank, we explain how one can build, for suitable small primes $p$, infinitely many fields of degree $p^2-1$ whose ideal class group has a large $p$-torsion subgroup. As an example, we show the existence of infinitely many cubic fields whose ideal class group contains a subgroup isomorphic to $(\mathbb{Z}/2\mathbb{Z})^{11}$.
Comment: 10 pages, LaTeX. Minor improvements following the referee's suggestions. To appear in Int. J. Number Theory