Interpretation of Nanohertz Gravitational Waves via Cosmic Strings in Post-BBN Matter and Kination Domination
The work investigates how a transient early Universe phase of matter and kination domination affects gravitational waves from cosmic strings, potentially explaining signals detected by pulsar timing arrays. The analysis shows that this expansion history modifies the string spectrum into a triangular shape, with kination favoring a blue tilt in the gravitational wave background.