Heights of pre-special points of Shimura varieties
Let V→A be the uniformisation of an abelian variety A over C by a complex vector space V. Identify the period lattice with Z2g and let z∈A be a torsion point. A pre-image v∈V of z belongs to Q2g and, if we choose v∈[0,1)2g, then the (multiplicative Weil) height of v is bounded by the order of z. This observation is essential in the proof of the Manin-Mumford conjecture by Pila and Zannier using o-minimality. Translating their strategy to the André-Oort conjecture for special points of Shimura varieties and, in particular, obtaining analogous bounds for special points, presents a nontrivial problem. In that setting, one considers the uniformisation X→S of a Shimura variety S by a hermitian symmetric domain X and, given a special point z∈S, one hopes to bound the height of any pre-image x of z, belonging to a fixed fundamental set, in terms of the discriminant of the centre of the endomorphism ring of the Z-Hodge structure (or CM abelian variety) associated with x. In this talk, we will explain a method for obtaining such bounds.
This is joint work with Martin Orr.