This Ph.D. thesis from the University of Birmingham UK opens new research avenues in the use of
Pulsar Timing Arrays (PTAs) to study populations of super-massive black hole binaries through
gravitational-wave observations. Chiara Mingarelli's work has shown for the first time that
PTAs can yield information about the non-linear dynamics of the gravitational field. This is
possible because PTAs capture at the same time radiation from the same source emitted at
stages of its binary evolution that are separated by thousands of years. Dr. Mingarelli who is
the recipient of a Marie Curie International Outgoing Fellowship has also been amongst the
pioneers of the technique that will allow us to probe the level of anisotropy of the diffuse
gravitational-wave background radiation from the whole population of super-massive black hole
binaries in the Universe. Indeed future observations will provide us with hints about the
distribution of galaxies harboring massive black holes and insights into end products of
hierarchical mergers of galaxies.
