Searching for gravitational-wave transients with a qualitative signal model: seedless clustering strategies

TL;DR

This paper introduces seedless clustering algorithms for detecting long-lived gravitational-wave bursts, significantly improving detection sensitivity over seed-based methods and expanding the observable universe for gravitational-wave astronomy.

Contribution

The paper presents a novel seedless clustering approach that enhances detection sensitivity for long-duration gravitational-wave signals compared to traditional seed-based algorithms.

Findings

Seedless clustering detects signals at 150-200% greater distances.

Detection volume increases by 420-740%.

Potential to extend the reach of advanced gravitational-wave detectors.

Abstract

Gravitational-wave bursts are observable as bright clusters of pixels in spectrograms of strain power. Clustering algorithms can be used to identify candidate gravitational-wave events. Clusters are often identified by grouping together seed pixels in which the power exceeds some threshold. If the gravitational-wave signal is long-lived, however, the excess power may be spread out over many pixels, none of which are bright enough to become seeds. Without seeds, the problem of detection through clustering becomes more complicated. In this paper we investigate seedless clustering algorithms in searches for long-lived narrowband gravitational-wave bursts. Using four astrophysically motivated test waveforms, we compare a seedless clustering algorithm to two algorithms using seeds. We find that the seedless algorithm can detect gravitational-wave signals (at fixed false-alarm and false-dismissal rate) at distances between 150-200% greater than those achieved with the seed-based clustering algorithms, corresponding to significantly increased detection volumes: 420-740%. This improvement in sensitivity may extend the reach of second-generation detectors such as Advanced LIGO and Advanced Virgo deeper into astrophysically interesting distances.