2013/05/04 by G. W. Gibbons, N. P. Warner · 2 citations
Physics and Astronomy · #hep-th
paper · pdf · doi:10.1088/0264-9381/31/2/025016
55 pages, 2 figures
arxiv created 2013/05/04 · arxiv updated 2015/06/15
We describe and study families of BPS microstate geometries, namely, smooth, horizonless asymptotically-flat solutions to supergravity. We examine these solutions from the perspective of earlier attempts to find solitonic solutions in gravity and show how the microstate geometries circumvent the earlier "No-Go" theorems. In particular, we re-analyse the Smarr formula and show how it must be modified in the presence of non-trivial second homology. This, combined with the supergravity Chern-Simons terms, allows the existence of rich classes of BPS, globally hyperbolic, asymptotically flat, microstate geometries whose spatial topology is the connected sum of N copies of S2 x S2 with a "point at infinity" removed. These solutions also exhibit "evanescent ergo-regions," that is, the non-space-like Killing vector guaranteed by supersymmetry is time-like everywhere except on time-like hypersurfaces (ergo-surfaces) where the Killing vector becomes null. As a by-product of our work, we are able to resolve the puzzle of why some regular soliton solutions violate the BPS bound: their spactimes do not admit a spin structure.