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Virgo interferometer
The Virgo interferometer is a large-scale scientific instrument near Pisa, Italy, for detecting gravitational waves. The detector is a Michelson interferometer, which can detect the minuscule length variations in its two 3 km (1.9 mi) arms induced by the passage of gravitational waves. The required precision is achieved using many systems to isolate it from the outside world, including keeping its mirrors and instrumentation in an ultra-high vacuum and suspending them using complex systems of pendula.
Between its periodic observations, the detector is upgraded to increase its sensitivity. The observation runs are performed in collaboration with other similar detectors, including the two Laser Interferometer Gravitational-Wave Observatories (LIGO) in the United States and the Japanese Kamioka Gravitational Wave Detector (KAGRA), because cooperation between several detectors is crucial for detecting gravitational waves and pinpointing their origin.
Virgo was conceived and built when gravitational waves were only a prediction of general relativity. The project, named after the Virgo galaxy cluster, was approved in 1992 and construction was completed in 2003. After several years without detection, Virgo was shut down in 2011 for the "Advanced Virgo" upgrades. In 2015, the first observation of gravitational waves was made by the two LIGO detectors, while Virgo was still being upgraded. Virgo resumed observations in early August 2017, making its first detection on 14 August (together with the LIGO detectors); this was quickly followed by the detection of the GW170817 gravitational wave, the only one also observed with classical methods (optical, gamma-ray, X-ray and radio telescopes) as of 2024.[update]
Virgo is hosted by the European Gravitational Observatory (EGO), a consortium founded by the French Centre National de la Recherche Scientifique (CNRS) and the Italian Istituto Nazionale di Fisica Nucleare (INFN). The broader Virgo Collaboration, gathering 940 members in 20 countries, operates the detector, and defines the strategy and policy for its use and upgrades. The LIGO and Virgo collaborations have shared their data since 2007, and with KAGRA since 2019, forming the LIGO-Virgo-KAGRA (LVK) collaboration.
The Virgo interferometer is managed by the European Gravitational Observatory (EGO) consortium, which was created in December 2000 by the French National Centre for Scientific Research (CNRS) and the Istituto Nazionale di Fisica Nucleare (INFN). Nikhef, the Dutch Institute for Nuclear and High-Energy Physics, later joined as an observer and eventually became a full member in 2021. Institutions from Poland, Spain and Belgium joined EGO as observers in 2023, with the Belgian FWO and FNRS joining as full members in 2025. EGO is responsible for the Virgo site and ensures the detector's commissioning, maintenance, operation and upgrades. By metonymy, the site itself is sometimes referred to as EGO, as the consortium is headquartered there. One of EGO's goals is to promote research on gravity in Europe. Between 2018 and 2024, the budget of EGO fluctuates between 9 and 11.5 million euros per year, employing around 60 people.
The Virgo Collaboration consists of all the researchers working on various aspects of the detector. About 940 members, representing 165 institutions in 20 countries, were part of the Collaboration as of December 2024.[update] This includes institutions in France, Italy, the Netherlands, Poland, Spain, Belgium, Germany, Hungary, Portugal, Greece, Czechia, Denmark, Ireland, Monaco, Switzerland, Brazil, Burkina Faso, China, Israel, Japan and South Korea.
The Virgo Collaboration is part of the larger LIGO-Virgo-KAGRA (LVK) Collaboration, which gathers scientists from the other major gravitational-waves experiments to jointly analyse the data; this is crucial for gravitational-wave detection. LVK began in 2007 as the LIGO-Virgo Collaboration, and was expanded when KAGRA joined in 2019.
Virgo is designed to look for gravitational waves emitted by astrophysical sources across the universe which can be classified into three types:
Hub AI
Virgo interferometer AI simulator
(@Virgo interferometer_simulator)
Virgo interferometer
The Virgo interferometer is a large-scale scientific instrument near Pisa, Italy, for detecting gravitational waves. The detector is a Michelson interferometer, which can detect the minuscule length variations in its two 3 km (1.9 mi) arms induced by the passage of gravitational waves. The required precision is achieved using many systems to isolate it from the outside world, including keeping its mirrors and instrumentation in an ultra-high vacuum and suspending them using complex systems of pendula.
Between its periodic observations, the detector is upgraded to increase its sensitivity. The observation runs are performed in collaboration with other similar detectors, including the two Laser Interferometer Gravitational-Wave Observatories (LIGO) in the United States and the Japanese Kamioka Gravitational Wave Detector (KAGRA), because cooperation between several detectors is crucial for detecting gravitational waves and pinpointing their origin.
Virgo was conceived and built when gravitational waves were only a prediction of general relativity. The project, named after the Virgo galaxy cluster, was approved in 1992 and construction was completed in 2003. After several years without detection, Virgo was shut down in 2011 for the "Advanced Virgo" upgrades. In 2015, the first observation of gravitational waves was made by the two LIGO detectors, while Virgo was still being upgraded. Virgo resumed observations in early August 2017, making its first detection on 14 August (together with the LIGO detectors); this was quickly followed by the detection of the GW170817 gravitational wave, the only one also observed with classical methods (optical, gamma-ray, X-ray and radio telescopes) as of 2024.[update]
Virgo is hosted by the European Gravitational Observatory (EGO), a consortium founded by the French Centre National de la Recherche Scientifique (CNRS) and the Italian Istituto Nazionale di Fisica Nucleare (INFN). The broader Virgo Collaboration, gathering 940 members in 20 countries, operates the detector, and defines the strategy and policy for its use and upgrades. The LIGO and Virgo collaborations have shared their data since 2007, and with KAGRA since 2019, forming the LIGO-Virgo-KAGRA (LVK) collaboration.
The Virgo interferometer is managed by the European Gravitational Observatory (EGO) consortium, which was created in December 2000 by the French National Centre for Scientific Research (CNRS) and the Istituto Nazionale di Fisica Nucleare (INFN). Nikhef, the Dutch Institute for Nuclear and High-Energy Physics, later joined as an observer and eventually became a full member in 2021. Institutions from Poland, Spain and Belgium joined EGO as observers in 2023, with the Belgian FWO and FNRS joining as full members in 2025. EGO is responsible for the Virgo site and ensures the detector's commissioning, maintenance, operation and upgrades. By metonymy, the site itself is sometimes referred to as EGO, as the consortium is headquartered there. One of EGO's goals is to promote research on gravity in Europe. Between 2018 and 2024, the budget of EGO fluctuates between 9 and 11.5 million euros per year, employing around 60 people.
The Virgo Collaboration consists of all the researchers working on various aspects of the detector. About 940 members, representing 165 institutions in 20 countries, were part of the Collaboration as of December 2024.[update] This includes institutions in France, Italy, the Netherlands, Poland, Spain, Belgium, Germany, Hungary, Portugal, Greece, Czechia, Denmark, Ireland, Monaco, Switzerland, Brazil, Burkina Faso, China, Israel, Japan and South Korea.
The Virgo Collaboration is part of the larger LIGO-Virgo-KAGRA (LVK) Collaboration, which gathers scientists from the other major gravitational-waves experiments to jointly analyse the data; this is crucial for gravitational-wave detection. LVK began in 2007 as the LIGO-Virgo Collaboration, and was expanded when KAGRA joined in 2019.
Virgo is designed to look for gravitational waves emitted by astrophysical sources across the universe which can be classified into three types: