Constraining cosmological phase transitions with the Parkes Pulsar Timing Array

Understand

A cosmological first-order phase transition is expected to produce a stochastic gravitational wave background.

• If the phase transition temperature is on the MeV scale, the power spectrum of the induced stochastic gravitational waves peaks around nanohertz frequencies, and can thus be probed with high-precision pulsar timing observations.
• We search for such a stochastic gravitational wave background with the latest data set of the Parkes Pulsar Timing Array.
• We find no evidence for a Hellings-Downs spatial correlation as expected for a stochastic gravitational wave background.