Asymptotics of the Néron height pairing

Abstract

The aim of this paper is twofold. First, we study the asymptotics of the Néron height pairing between degree-zero divisors on a family of degenerating compact Riemann surfaces parametrized by an algebraic curve. We show that if the monodromy is unipotent the leading term of the asymptotics is controlled by the local non-archimedean Néron height pairing on the generic fiber of the family. Second, we prove a conjecture of R. Hain to the effect that the `height jumping divisor' related to the normal function $(2g-2)x-K$ on the moduli space $\mm_{g,1}$ of 1-pointed curves of genus $g\ge 2$ is effective. Both results follow from a study of the degeneration of the canonical metric on the Poincaré bundle on a family of jacobian varieties.

Expanded sections 3 and 5. To appear in Math. Res. Lett