The International Pulsar Timing Array checklist for the detection of nanohertz gravitational waves

Understand

Pulsar timing arrays (PTAs) provide a way to detect gravitational waves at nanohertz frequencies.

• In this band, the most likely signals are stochastic, with a power spectrum that rises steeply at lower frequencies.
• Indeed, the observation of a common red noise process in pulsar-timing data suggests that the first credible detection of nanohertz-frequency gravitational waves could take place within the next few years.
• The detection process is complicated by the nature of the signals and the noise: the first observational claims will be statistical inferences drawn at the threshold of detectability.