The Square Kilometre Array pulsar timing array

The Square Kilometre Array (SKA) is envisioned as the meter-and centimeter-wavelength telescope of the 21st century, and gravitational wave studies via a pulsar timing array (PTA) form a key aspect of its science program. In its ultimate implementation, the SKA (phase 2) should enable the construction of a PTA consisting of as many as 100 spin-stable millisecond pulsars. The sensitivity of the SKA-PTA could approach gravitational wave strain amplitudes of 6 x 10(-16) or better at fiducial gravitational wave frequencies of order 1 yr(-1), at least an order of magnitude improvement in the gravitational wave strain amplitude that can be measured. Any nearby individual supermassive black hole binaries could be detected, and the existence of non-tensor modes can be tested. Beyond its PTA capabilities, the SKA will also enable a range of other tests of fundamental physics, such as tests of gravity in ultra-relativistic binaries and constraints on the nuclear equation of state.