Implication of Pulsar Timing Array Experiments on Cosmological Gravitational Wave Detection

TL;DR

This paper reviews how pulsar timing arrays can detect cosmological gravitational waves, discusses recent observational results from NANOGrav, and explores implications for understanding the universe.

Contribution

It introduces a framework for detecting stochastic gravitational wave backgrounds with pulsar timing arrays and interprets recent observational data.

Findings

NANOGrav's 12.5-year data provides new constraints on gravitational wave backgrounds.

Pulsar timing arrays are effective for detecting low-frequency gravitational waves.

Implications for cosmology and astrophysics are discussed based on recent results.

Abstract

Gravitational waves provide a new probe of the Universe which can reveal a number of cosmological and astrophysical phenomena that cannot be observed by electromagnetic waves. Different frequencies of gravitational waves are detected by different means. Among them, precision measurements of pulsar timing provides a natural detector for gravitational waves with light-year scale wavelengths. In this review, first a basic framework to detect a stochastic gravitational wave background using pulsar timing array is introduced, and then possible interpretations of the latest observational result of 12.5 year NANOGrav data are described.