Searching Stochastic Gravitational Wave Background Landscape Across Frequency Bands

TL;DR

This paper explores the potential of multi-band gravitational wave detectors to map the stochastic GW background, focusing on a new physics model involving hybrid topological defects from a two-step phase transition.

Contribution

It introduces a general analysis pipeline for experimental constraints and applies it to a novel model explaining pulsar timing array signals.

Findings

The model can potentially explain low-frequency pulsar timing signals.

Future detectors will be able to confirm or exclude the proposed model.

Multi-band GW observations are crucial for probing new physics scenarios.

Abstract

Gravitational wave (GW) astrophysics is entering a multi-band era with upcoming GW detectors, enabling detailed mapping of the stochastic GW background across vast frequencies. We highlight this potential via a new physics scenario: hybrid topological defects from a two-step phase transition separated by inflation. We develop a general pipeline to analyze experimental exclusions and apply it to this model. The model offers a possible explanation of the pulsar timing array signal at low frequencies, and future experiments (LISA/Cosmic Explorer/Einstein Telescope) will confirm or rule it out via the higher-frequency probes, showcasing the power of multi-band constraints.