A guide to LIGO-Virgo detector noise and extraction of transient gravitational-wave signals (1908.11170v3)

Abstract: The LIGO Scientific Collaboration and the Virgo Collaboration have cataloged eleven confidently detected gravitational-wave events during the first two observing runs of the advanced detector era. All eleven events were consistent with being from well-modeled mergers between compact stellar-mass objects: black holes or neutron stars. The data around the time of each of these events have been made publicly available through the gravitational-wave open science center. The entirety of the gravitational-wave strain data from the first and second observing runs have also now been made publicly available. There is considerable interest among the broad scientific community in understanding the data and methods used in the analyses. In this paper, we provide an overview of the detector noise properties and the data analysis techniques used to detect gravitational-wave signals and infer the source properties. We describe some of the checks that are performed to validate the analyses and results from the observations of gravitational-wave events. We also address concerns that have been raised about various properties of LIGO-Virgo detector noise and the correctness of our analyses as applied to the resulting data.

• The paper presents a detailed analysis of LIGO-Virgo noise sources and calibration procedures essential for accurate gravitational-wave strain measurements.
• The paper employs matched-filtering techniques and veto strategies to distinguish true signals from noise artifacts effectively.
• The paper uses Bayesian inference with advanced waveform models to extract astrophysical parameters and test general relativity.

Summary of "A Guide to LIGO-Virgo Detector Noise and Extraction of Transient Gravitational-Wave Signals"

The paper entitled "A Guide to LIGO-Virgo Detector Noise and Extraction of Transient Gravitational-Wave Signals" by the LIGO and Virgo collaborations presents a comprehensive discussion on the noise characteristics of the LIGO-Virgo detectors and the methodologies employed for the detection and analysis of transient gravitational-wave signals. This summary provides an analytical overview of the paper's content, as well as insights into the broader scientific implications of gravitational-wave research.

Detector Noise and Calibration

The LIGO and Virgo detectors are Michelson interferometers designed to measure the tiny distortions in spacetime caused by passing gravitational waves. The detectors' sensitivity is impacted by various noise sources, including seismic noise, thermal noise, and quantum shot noise. The paper discusses the calibration procedures necessary to convert raw detector output into gravitational-wave strain data. This calibration is essential for accurate signal detection and involves accounting for the actuation and sensing functions of the interferometer.

Gravitational-Wave Detection

The detection of gravitational waves relies heavily on matched-filtering techniques, which are optimal for identifying signals buried in noise. The primary challenge lies in distinguishing true gravitational-wave signals from noise artifacts or glitches. The paper elaborates on several statistical tests and veto strategies used to mitigate the impact of these noise transients. The detection process involves dividing the data into short segments, applying Fourier transforms, and averaging to estimate the noise power spectral density.

Parameter Estimation and Waveform Models

To extract the physical parameters of the astrophysical sources from the detected signals, the paper employs Bayesian inference techniques. This involves using waveform templates that model the expected gravitational-wave signal from different types of compact binary coalescences, such as binary black hole mergers and binary neutron star mergers. Two primary waveform models discussed are IMRPhenomPv2 and SEOBNRv2, which account for different aspects of binary dynamics, including spin effects and precessing motion.

Implications for Astrophysics and Fundamental Physics

The paper highlights the importance of gravitational-wave astronomy as a tool for probing the universe. The detections made by the LIGO-Virgo collaborations have provided invaluable insights into astrophysical phenomena, such as the formation and properties of black holes and neutron stars. The observations have also enabled stringent tests of general relativity, as all detected signals to date are consistent with the theoretical predictions of general relativity.

Data Availability and Community Engagement

LIGO-Virgo data is made publicly available through the Gravitational-Wave Open Science Center, enabling independent researchers to perform analyses and contribute to the growing field of gravitational-wave astrophysics. The paper asserts confidence in the collaboration's data analysis methods and encourages external scrutiny to enhance the scientific robustness of gravitational-wave research.

Conclusion

This document serves as a detailed resource for understanding the complexity and precision involved in the detection and analysis of gravitational waves by the LIGO and Virgo collaborations. The paper underscores the collaborative efforts needed to advance this field and addresses challenges associated with noise characterization and signal extraction. Looking forward, further developments in detector technology and analysis techniques will continue to refine our understanding of the universe through gravitational-wave observations.