1. Institute for Gravitation and the Cosmos, Department of Physics, Pennsylvania State University, University Park, Pennsylvania 16802, USA
2. Theoretisch-Physikalisches Institut, Friedrich-Schiller-Universität Jena, 07743 Jena, Germany
3. Max Planck Institute for Gravitational Physics (Albert Einstein Institute), Am Mühlenberg 1, Potsdam 14476, Germany
4. Department of Astronomy & Astrophysics, Pennsylvania State University, University Park, Pennsylvania 16802, USA
5. School of Physics and Astronomy, Cardiff University, Cardiff CF24 3AA, United Kingdom