An asymptotically cusped three dimensional expanding gradient Ricci soliton

Abstract

We construct an expanding gradient Ricci soliton in dimension three over the topological manifold R x T^2 (the product of a line and a torus) that aproaches asymptotically a constant curvature cusp at one end, and a flat manifold on the other end. We prove that this is the only gradient soliton with this topology, provided the curvature is negatively pinched, -1/4 < sec < 0, at the time-zero manifold (normalizing the soliton to be born at time -1).