Supercooled phase transitions in conformal dark sectors explain NANOGrav data

TL;DR

This paper shows that supercooled first-order phase transitions in conformal dark sectors can naturally explain the nanohertz gravitational wave background observed by NANOGrav, providing a new dark sector model for this phenomenon.

Contribution

It introduces a novel explanation for NANOGrav data using supercooled FOPTs in conformal dark U(1)' models, which was previously considered difficult to achieve.

Findings

Supercooled FOPTs in conformal dark sectors produce detectable gravitational waves.

The model naturally explains the NANOGrav signal without fine-tuning.

Dark U(1)' models can generate the observed stochastic gravitational wave background.

Abstract

According to recent lore, it is difficult to explain the evidence for a stochastic gravitational wave background obtained by pulsar timing arrays with supercooled first-order phase transitions (FOPTs). We demonstrate that supercooled FOPTs in dark U(1)' models with a conformal dark sector easily explain the nHz signal at NANOGrav.