Principles of Gravitational-Wave Detection with Pulsar Timing Arrays

TL;DR

Pulsar timing arrays are a promising method for detecting ultra-low-frequency gravitational waves, offering unique insights into supermassive black-hole binaries and cosmic strings, with recent collaborations showing promising evidence of a gravitational-wave background.

Contribution

This paper summarizes the principles of gravitational-wave detection via pulsar timing arrays and discusses recent observational results and future prospects with upcoming radio observatories.

Findings

Evidence of a common-spectrum process consistent with a stochastic gravitational-wave background

Sensitivity to ultra-low-frequency gravitational waves from supermassive black-hole binaries and cosmic strings

Potential for future detections with next-generation radio telescopes

Abstract

Pulsar timing uses the highly stable pulsar spin period to investigate many astrophysical topics. In particular, pulsar timing arrays make use of a set of extremely well-timed pulsars and their time correlations as a challenging detector of gravitational waves. It turns out that pulsar timing arrays are particularly sensitive to ultra-low-frequency gravitational waves, which makes them complementary to other gravitational-wave detectors. Here, we summarize the basics, focusing especially on supermassive black-hole binaries and cosmic strings, which have the potential to form a stochastic gravitational-wave background in the pulsar timing array detection band, and the scientific goals on this challenging topic. We also briefly outline the recent interesting results of the main pulsar timing array collaborations, which have found strong evidence of a common-spectrum process compatible with a stochastic gravitational-wave background and mention some new perspectives that are particularly interesting in view of the forthcoming radio observatories such as the Five hundred-meter Aperture Spherical Telescope, the MeerKAT telescope, and the Square Kilometer Array.