Gravitational Wave Astronomy Using Pulsars: Massive Black Hole Mergers & the Early Universe

TL;DR

This paper discusses how pulsar timing can be used to detect nanohertz gravitational waves from massive black hole mergers and early Universe phenomena, opening new astrophysical insights.

Contribution

It reviews potential GW sources, current detection status, and advances needed for pulsar-based gravitational wave astronomy.

Findings

Nanohertz GWs can be detected using pulsar timing arrays.

Black hole mergers and early Universe phenomena are key GW sources.

Progress in pulsar timing is crucial for future GW detection.

Abstract

Gravitational waves (GWs) are fluctuations in the fabric of spacetime predicted by Einstein's theory of general relativity. Using a collection of millisecond pulsars as high-precision clocks, the nanohertz band of this radiation is likely to be directly detected within the next decade. Nanohertz-frequency GWs are expected to be emitted by mergers of massive black hole binary systems, and potentially also by cosmic strings or superstrings formed in the early Universe. Direct detection of GWs will open a new window to the Universe, and provide astrophysical information inaccessible via electromagnetic observations. In this paper, we describe the potential sources of low-frequency GWs and the current status and key advances needed for the detection and exploitation of GWs through pulsar timing.