LIGO Detector Characterization in the first half of the fourth Observing run

TL;DR

This paper discusses the recent advancements in LIGO detector characterization during the first half of the fourth observing run, highlighting improvements in sensitivity, data quality, and tools for gravitational-wave detection.

Contribution

It details the instrumental investigations and software enhancements that have increased detector sensitivity and data quality in the latest observing run.

Findings

Increased detector sensitivity and data quality.

Reduction of transient noise in the detectors.

Enhanced tools for data-quality assessment.

Abstract

Progress in gravitational-wave astronomy depends upon having sensitive detectors with good data quality. Since the end of the LIGO-Virgo-KAGRA third Observing run in March 2020, detector-characterization efforts have lead to increased sensitivity of the detectors, swifter validation of gravitational-wave candidates and improved tools used for data-quality products. In this article, we discuss these efforts in detail and their impact on our ability to detect and study gravitational-waves. These include the multiple instrumental investigations that led to reduction in transient noise, along with the work to improve software tools used to examine the detectors data-quality. We end with a brief discussion on the role and requirements of detector characterization as the sensitivity of our detectors further improves in the future Observing runs.