I am grateful to Emanuele Berti, John L. Friedman, Wlodek Kluźniak, Kostas D. Kokkotas, and Luciano Rezzolla for a careful reading of the manuscript and for many valuable comments. Many thanks to Dorota Gondek-Rosińska and Eric Gourgoulhon for comments and for supplying numerical results obtained with the Lorene/rotstar code, that were used in the comparison in Table 2. I am also grateful to Marcus Ansorg for discussions and to all authors of the included figures for granting permission for reproduction. This work was supported, in part, by the EU Programme “Improving the Human Research Potential and the Socio-Economic Knowledge Base” (Research Training Network Contract HPRN-CT-2000-00137), KBN-5P03D01721, and the Greek GSRT Grant EPAN-M.43/2013555.
© Max Planck Society and the author(s)