Pulsars probe the low-frequency gravitational sky: Pulsar Timing Arrays basics and recent results

TL;DR

Pulsar Timing Arrays utilize precise pulsar observations to detect low-frequency gravitational waves, with recent results setting upper limits and upcoming telescopes promising improved sensitivity.

Contribution

This paper reviews PTA basics, recent results, and discusses future prospects with new radio telescopes like SKA.

Findings

No gravitational waves detected yet.

PTA upper limits constrain galaxy formation models.

Upcoming telescopes will enhance detection sensitivity.

Abstract

Pulsar Timing Array (PTA) experiments exploit the clock-like behaviour of an array of millisecond pulsars, with the goal of detecting low-frequency gravitational waves. PTA experiments have been in operation over the last decade, led by groups in Europe, Australia, and North America. These experiments use the most sensitive radio telescopes in the world, extremely precise pulsar timing models and sophisticated detection algorithms to increase the sensitivity of PTAs. No detection of gravitational waves has been made to date with this technique, but PTA upper limits already contributed to rule out some models of galaxy formation. Moreover, a new generation of radio telescopes, such as the Five hundred metre Aperture Spherical Telescope and, in particular, the Square Kilometre Array, will offer a significant improvement to the PTA sensitivity. In this article, we review the basic concepts of PTA experiments, and discuss the latest results from the established PTA collaborations.