Compactified Picard stacks over $\bar{\mathcal M}_g$

Margarida Melo

Published 2007-10-16, updated 2008-08-11Version 2

We study algebraic (Artin) stacks over $\bar{\mathcal M}_g$ giving a functorial way of compactifying the relative degree $d$ Picard variety for families of stable curves. We also describe for every $d$ the locus of genus $g$ stable curves over which we get Deligne-Mumford stacks strongly representable over $\bar{\mathcal M}_g$.