Series of rational components of the moduli space of stable rank two sheaves on projective space

We describe new infinite series of irreducible components of the Gieseker-Maruyama moduli space of

stable rank 2 sheaves on the projective 3-space. A general sheaf in each moduli component either is

locally free, or has singularities of dimension 0 or 1, or of mixed dimension. We construct series of components of the moduli space having all these four types of singularities. Among them we distinguish an infinite series of components which are rational varieties. The talk is based on our joint results with M.Jardim, Ch.Almeida and D. Vassiliev.