Adiabatic groupoid, crossed product by ${\mathbb{R}}_{+}^{\ast }$ and Pseudodifferential calculus

Abstract

We consider the crossed product $G_{ga}$ by ${\mathbb{R}}_{+}^{\ast }$ of the adiabatic groupoid associated with any Lie groupoid $G$. We construct an explicit Morita equivalence between the exact sequence of order 0 pseudodifferential operators on $G$ and (a restriction of) the natural exact sequence associated with $G_{ga}$. As an important intermediate step, we express a pseudodifferential operator on $G$ as an integral associated to a smoothing operator on the adiabatic groupoid $G_{ad}$ of $G$.