Pullback formulas for arithmetic cycles on orthogonal Shimura varieties

Abstract

On an orthogonal Shimura variety, one has a collection of special cycles in the Gillet-Soule arithmetic Chow group. We describe how these cycles behave under pullback to an embedded orthogonal Shimura variety of lower dimension. The bulk of the paper is devoted to cases in which the special cycles intersect the embedded Shimura variety improperly, for which we construct logarithmic expansions of certain Green currents on the deformation to the normal bundle of the embedding.