Copyright © The Author 2008. Published by Oxford University Press.
Some Intersections in the Poincaré Bundle and the Universal Theta Divisor on 
1 Mathematics Department, Princeton University, Fine Hall, Washington Road, Princeton, NJ 08544, USA
2 Mathematics Department, University of Michigan, 2074 East Hall, 530 Church St, Ann Arbor, USA
Correspondence: Correspondence to be sent to: sam{at}math.princeton.edu
We compute all the top intersection numbers of divisors on the total space of the Poincaré bundle restricted to B x C (where B is an abelian variety, and C
B is any test curve). We use these computations to find the class of the universal theta divisor and m-theta divisor inside the universal corank 1 semiabelian variety — the boundary of the partial toroidal compactification of the moduli space of abelian varieties. We give two computational examples: we compute the boundary coefficient of the Andreotti–Mayer divisor (computed by Mumford but in a much harder and ad hoc way), and the analog of this for the universal m-theta divisor.