All-sky search for short gravitational-wave bursts in the first part of the fourth LIGO-Virgo-KAGRA observing run

TL;DR

This paper reports on a comprehensive search for short-duration gravitational-wave bursts during the first eight months of the O4 observing run, finding no new signals but setting improved sensitivity limits and potential for detecting signals from supernovae and pulsar glitches.

Contribution

The study introduces four analysis methods with enhanced sensitivity, providing the most stringent upper limits to date and evaluating the detectability of specific astrophysical models.

Findings

No significant gravitational-wave transients detected beyond known mergers.

Sensitivity improvements of 2 to 10 times over previous searches.

Potential to detect signals from supernovae and pulsar glitches within the Milky Way.

Abstract

We present a search for short-duration gravitational-wave transients in data from the first eight months of Advanced LIGO-Virgo-KAGRA's fourth observing run, denoted O4a. We use four analyses which are sensitive to a wide range of potential signals lasting up to a few seconds in the 16-4096 Hz band. Excluding binary black hole merger candidates that were already identified by low-latency analyses, we find no statistically significant evidence for other gravitational-wave transients. We measure the sensitivity of the search for representative signals, including sine-Gaussians, Gaussian pulses, and white-noise bursts with different frequencies and durations, adopting a false alarm rate of 1 per 100 years as detection threshold. Depending on signal type, we find improvements over previous searches by factors of 2 to 10 in terms of sensitivity to strain amplitude and of 90% confidence upper limit on the rate density of sources. We also evaluate a variety of core-collapse supernova models and find that, for some models, the search could have detected gravitational waves from stellar core-collapse throughout the Milky Way. Finally, we consider neutron star f-modes associated with pulsar glitches and find that, assuming a source similar to the Vela Pulsar, the search could have detected a gravitational-wave signal from a glitch with fractional frequency change as small as $\sim 2$ to $6 \times 10^{-5}$ depending on the neutron star mass.