LIGO-Virgo detector characterization and data quality (DetChar): from the O3 performance to the O4 preparation

TL;DR

This paper reviews the LIGO-Virgo detector characterization and data quality efforts during O3, highlighting improvements and preparations for O4, including the addition of the KAGRA detector, to enhance gravitational-wave detection and analysis.

Contribution

It provides a comprehensive overview of the detector characterization activities and upgrades from O3 to O4, emphasizing new strategies and infrastructure for improved data quality and detection confidence.

Findings

Enhanced detector characterization techniques implemented during O3.

Upcoming upgrades and the inclusion of KAGRA for O4.

Improved data quality and rapid alert capabilities.

Abstract

Detector characterization and data quality -- in short "DetChar" -- activities are key to optimize the performance of data-taking periods ("runs") and to turn gravitational-wave (GW) candidates into confirmed events. The LIGO and Virgo DetChar groups are active from the detector to the final analysis and cover various latencies: online first, to tag the data that search pipelines can analyze in real-time; then, the quick vetting (few tens of minutes at most) of the open public alerts targeting the broad astronomer community for follow-up observations; finally, offline work to define the final datasets and the final lists of GW events to be published and released publicly. These proceedings summarize the LIGO-Virgo DetChar performance during the O3 run (April 2019 - March 2020) and describe the main improvements and upgrades that are foreseen for the O4 run that should start during Summer 2022 and include a fourth detector: KAGRA.