Search for Peak Structures in the Stochastic Gravitational-Wave Background in LIGO-Virgo-KAGRA O1-O4a Datasets

TL;DR

This study searches for complex peak structures in the stochastic gravitational-wave background using LIGO-Virgo-KAGRA data, introducing a model-independent parameterization and Bayesian analysis to constrain multi-peak signals, setting the stage for future detailed searches.

Contribution

The paper develops a novel, model-independent parameterization for double-peaked gravitational-wave spectra and applies Bayesian inference to search for such signals in existing data.

Findings

No significant multi-peak signals detected.

Constraints established on inter-peak slopes and amplitudes.

Demonstrates LIGO-Virgo-KAGRA's capability to probe complex spectral shapes.

Abstract

We present a dedicated search for gravitational-wave backgrounds with nontrivial peak structures using data from the first three and the initial part of the fourth observing runs of the LIGO-Virgo-KAGRA network. The analysis is motivated by a variety of early-Universe models characterized by signals with multiple peaks. We introduce a model independent parameterization of double-peaked spectra based on the superposition of two normalized broken power laws and perform a Bayesian inference study using the LIGO-Virgo-KAGRA isotropic cross-correlation data. While no statistically significant evidence for a multi-peak background is found, the analysis provides constraints on the inter-peak slopes in correlation with the signal amplitude. These results exhibit LIGO-Virgo-KAGRA's ability to probe signals beyond a single peak structure and establish a foundation for future targeted searches for nontrivial gravitational waves background spectral shapes in future observing runs and the advanced detector era.