Constraining Cosmological Phase Transitions with the Parkes Pulsar Timing Array

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. Therefore, we present constraints on first-order phase transition model parameters. Our analysis shows that pulsar timing is particularly sensitive to the low-temperature (T similar to 1-100 MeV) phase transition with a duration (beta/H*)(-1) similar to 10(-2) - 10(-1) and therefore can be used to constrain the dark and QCD phase transitions.

Automated summary

Researchers search for a stochastic gravitational wave background using the Parkes Pulsar Timing Array data set, but find no evidence of the expected Hellings-Downs spatial correlation, leading to constraints on first-order phase transition model parameters. The analysis indicates that pulsar timing is particularly sensitive to low-temperature phase transitions, making it a useful tool for studying dark and QCD phase transitions.