A supersymmetric and smooth compactification of M-theory to AdS5

We obtain smooth M-theory solutions whose geometry is a warped product of AdS5 and a compact internal space that can be viewed as an S4 bundle over S2. The bundle can be trivial or twisted, depending on the even or odd values of the two diagonal monopole charges. The solution preserves N=2 supersymmetry and is dual to an N=1, D=4 superconformal field theory, providing a concrete framework to study the AdS5/CFT4 correspondence in M-theory. We construct analogous embeddings of AdS4, AdS3 and AdS2 in massive type IIA, type IIB and M-theory, respectively. The internal spaces have generalized holonomy and can be viewed as Sn bundles over S2 for n=4, 5 and 7. Surprisingly, the dimensions of spaces with generalized holonomy includes D=9. We also obtain a large class of solutions of AdS×H2.