Gravitational-Wave Detection and Astrophysics with Pulsar Timing Arrays

TL;DR

Pulsar timing arrays are emerging as powerful tools for detecting nanohertz gravitational waves, providing insights into cosmic phenomena and constraining the universe's evolution, with ongoing advancements and challenges in the field.

Contribution

This paper offers a comprehensive review of pulsar timing arrays, detailing their use in gravitational wave detection, sources of uncertainty, and current challenges, serving as an up-to-date reference for new researchers.

Findings

PTAs are approaching expected gravitational wave signal strengths.

Current limits constrain models of cosmic string and black hole evolution.

The review highlights key challenges and future directions in PTA research.

Abstract

We have begun an exciting era for gravitational wave detection, as several world-leading experiments are breaching the threshold of anticipated signal strengths. Pulsar timing arrays (PTAs) are pan-Galactic gravitational wave detectors that are already cutting into the expected strength of gravitational waves from cosmic strings and binary supermassive black holes in the nHz-$\mu$Hz gravitational wave band. These limits are leading to constraints on the evolutionary state of the Universe. Here, we provide a broad review of this field, from how pulsars are used as tools for detection, to astrophysical sources of uncertainty in the signals PTAs aim to see, to the primary current challenge areas for PTA work. This review aims to provide an up-to-date reference point for new parties interested in the field of gravitational wave detection via pulsar timing.