Pulsar Timing Array Experiments

Abstract

Pulsar timing is a technique that uses the highly stable spin periods of neutron stars to investigate a wide range of topics in physics and astrophysics. Pulsar timing arrays (PTAs) use sets of extremely well-timed pulsars as a galaxy-scale detector with arms extending between Earth and each pulsar in the array. These challenging experiments look for correlated deviations in the pulsars’ timing that are caused by low-frequency gravitational waves (GWs) traversing our galaxy. PTAs are particularly sensitive to GWs at nanohertz frequencies, which makes them complementary to other space-and ground-based detectors. In this chapter, we will describe the methodology behind pulsar timing; provide an overview of the potential uses of PTAs; and summarize where current PTA-based detection efforts stand. Most predictions expect PTAs to successfully detect a cosmological background of GWs emitted by supermassive black hole binaries and also potentially detect continuous-wave emission from binary supermassive black holes, within the next several years.