Hilbert schemes of points on canonical surfaces

Abstract

For $n\ge 1$, we investigate the Hilbert scheme of $n$-points on a surface $S$ with canonical singularities. We generalise the well-known theorem of Fogarty by showing that the underlying reduced subscheme of ${\mathrm{Hilb}}^n(S)$ is a normal variety of dimension $2n$ with canonical singularities, and for $n\le 7$, we show that ${\mathrm{Hilb}}^n(S)$ is reduced. When $S$ has symplectic singularities over $\mathbb{C}$, we show that the underlying reduced subscheme of ${\mathrm{Hilb}}^n(S)$ also has symplectic singularities, thereby generalising a result of Beauville. Our results build on work of the first author with Gyenge, Gammelgaard and Szendrői that sought to identify the underlying reduced subscheme of the Hilbert scheme of $n$-points on a Kleinian singularity with a Nakajima quiver variety.

arXiv comment33 pages. This paper contains the geometric results from v1 of our arXiv:2312.08527 preprint, though we establish reducedness only for n\leq 7