A Néron model of the universal jacobian

الأصل · EN

The jacobian of the universal curve over Mg,ₙ is an abelian scheme over Mg,ₙ. Our main result is the construction of an algebraic space β Mg,ₙ → Mg,ₙ over which this jacobian admits a Néron model, and such that β is universal with respect to this property. We prove certain basic properties, for example that β is separated, locally of finite presentation, and satisfies a certain restricted form of the valuative criterion for properness. In general, β is not quasi-compact. We relate our construction to Caporaso's balanced Picard stack Pd,g.