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Gravitational wave astronomy opened dramatically in September 2015 with the LIGO discovery of a distant and massive binary black hole coalescence. The more recent discovery of a binary neutron star merger, followed by a gamma ray burst (GRB) and a kilonova, reinforces the excitement of this new era, in which we may soon see other sources of gravitational waves, including continuous, nearly monochromatic signals. Potential continuous wave (CW) sources include rapidly spinning galactic neutron stars and more exotic possibilities, such as emission from axion Bose Einstein “clouds” surrounding black holes. Recent searches in Advanced LIGO data are presented, and prospects for more sensitive future searches are discussed.

The field of gravitational-wave astronomy has been opened up by gravitational-wave observations made with interferometric detectors. This review surveys the current state-of-the-art in gravitational-wave detectors and data analysis methods currently used by the Laser Interferometer Gravitational-Wave Observatory in the United States and the Virgo Observatory in Italy. These analysis methods will also be used in the recently completed KAGRA Observatory in Japan. Data analysis algorithms are developed to target one of four classes of gravitational waves. Short duration, transient sources include compact binary coalescences, and burst sources originating from poorly modeled or unanticipated sources. Long duration sources include sources which emit continuous signals of consistent frequency, and many unresolved sources forming a stochastic background. A description of potential sources and the search for gravitational waves from each of these classes are detailed.

Advanced Virgo is the French–Italian second generation laser gravitational wave detector, successor of the Initial Virgo. This new interferometer keeps only the infrastructure of its predecessor and aims to be ten times more sensitive, with its first science run planned for 2017. This article gives an overview of the Advanced Virgo design and the technical choices behind it. Finally, the up-to-date progresses and the planned upgrade for the following years are detailed.

Advanced Virgo is the French-Italian second generation laser gravitational wave detector, successor of the Initial Virgo. This new interferometer keeps only the infrastructure of its predecessor and aims to be 10 times more sensitive, with its first science run planned for 2017. This article gives an overview of the Advanced Virgo design and the technical choices behind it. Finally, the up-to-date progresses and the planned upgrade for the following years are detailed.

Over the past decade, gravitational wave detectors have undergone dramatic transitions in both sensitivity and scale — from laboratory-sized resonant bar detectors to kilometer-length-scale laser interferometers. The construction and operation of large-scale laser-interferometric gravitational wave detectors such as the Laser Interferometer Gravitational-wave Observatory (LIGO) and the Virgo interferometer as well as others have enabled searches for extra-galactic gravitational waves with unprecedented range and sensitivity. Here, we review the present state of the global laser-interferometric gravitational wave detector network, highlight the results of recent science runs, and provide a preview of the state of the network in the coming decade and beyond.

The past decade has witnessed the successful operation of the first generation of large scale ground-based gravitational-wave interferometers — LIGO, Virgo, and GEO600 — each demonstrating remarkably sensitive, robust performance over a series of observing runs beginning in 2002 and continuing through 2011. Although gravitational waves have not yet been directly detected, searches by these detectors have established noteworthy limits on the possible emission of gravitational waves from astrophysical sources. Second generation instruments currently under construction such as Advanced LIGO, Advanced Virgo, and KAGRA will begin observing in the second half of this decade with sensitivities that are predicted to lead to direct detections of binary neutron star mergers and possibly other sources of gravitational waves.