Stabilization of intersection Betti numbers for moduli spaces of one-dimensional sheaves on surfaces

Abstract

In this paper, we develop a unified approach to study the intersection Betti numbers of moduli spaces of one-dimensional semistable sheaves on smooth projective surfaces. Assuming the irreducibility of such moduli spaces, we prove that their intersection Betti numbers in a certain range of degrees coincide with the stable Betti numbers of Hilbert schemes of points. As an application, for surfaces with nef anticanonical divisor, we show that these intersection Betti numbers stabilize in each fixed degree, which fits into the broader context of stable cohomology for moduli spaces of sheaves; if in addition the moduli spaces are smooth, we also prove a refined stabilization result on perverse Hodge numbers.