Observing the dynamics of super-massive black hole binaries with Pulsar   Timing Arrays
  Pulsar Timing Arrays are a prime tool to study unexplored astrophysical regimes with gravitational waves. Here we show that the detection of gravitational radiation from individually resolvable super-massive black hole binary systems can yield direct information about the masses and spins of the black holes, provided that the gravitational-wave induced timing fluctuations both at the pulsar and at the Earth are detected. This in turn provides a map of the non-linear dynamics of the gravitational field and a new avenue to tackle open problems in astrophysics connected to the formation and evolution of super-massive black holes. We discuss the potential, the challenges and the limitations of these observations. 
C. M. F. Mingarelli, K. Grover, T. Sidery, R. J. E. Smith, A. Vecchio
astro-ph.HE gr-qc