Low-latency Detection of Gravitational Wave Signals
Research Poster Physical Sciences & Mathematics 2025 Graduate ExhibitionPresentation by Shio Sakon
Exhibition Number 48
Abstract
The LIGO/Virgo/KAGRA ground-based detectors are capable of detecting gravitational waves from the merger of black holes and neutron stars. Studying gravitational wave signals tells us the properties of the source objects, confirmation of the existence of sources, and the population and merger rates. Low-latency detection pipelines like GstLAL, send alerts to the public within O(10) seconds after receiving data from the detectors. The alerts contain information that assists follow-up observations of electromagnetically bright events, thus, making multi-messenger astrophysics with gravitational waves possible. The GstLAL pipeline correlates simulated gravitational wave signals, i.e., templates, with data to detect gravitational wave event candidates and assigns significance to the event candidates based on statistics that are gathered during the observation and before the observation. For the ongoing fourth observing run (O4), templates were generated with a computationally efficient binary-tree approach. The GstLAL pipeline runs multiple analyses using different template banks, depending on the targeted search parameter space. Such analyses are IMBH (intermediate-mass black hole), AllSky (black holes and neutron star mergers), Early Warning (events with neutron stars), and sub-solar masses searches. As of 01/22/24, the LIGO/Virgo/KAGRA collaboration has detected over 270 gravitational waves since its first observing run in 2015. In O4, we have detected over 180 event candidates, including 1 neutron star-black hole merger. GstLAL contributed significantly to these detections, as a third of the O4 events were solely detected by GstLAL. The growing catalog of events will deepen our understanding of the population of gravitational wave sources.
Importance
Near real-time detection of gravitational waves enables multi-messenger astrophysics with gravitational waves, which can deepen our understanding of the sources in the Universe that emit detectable gravitational waves and electromagnetic wave signals. We present a pipeline that has been operating in the ongoing observing run, which has been successfully detecting gravitational wave signals in near real-time and sending alerts to the public with information that can assist follow-up detections. Among the over 180 gravitational wave event candidates detected in the ongoing observing run, a third of the detections were made solely by this pipeline. We also present the data products that are essential to the pipeline, which have been generated more computationally efficiently compared to previous observing runs.