Virgo Collaboration is an international team of physicists and astronomers who are studying gravitational waves using the Virgo detector. The collaboration consists of scientists from Italy, France, Belgium, the Netherlands, Germany, Poland and Spain.
The Virgo detector is a laser interferometer located in Cascina near Pisa in Italy. It consists of two arms 3 km long which are perpendicular to each other. At the intersection point of the arms there is a mirror that reflects the laser beams back to their respective origins. The light beams travel 10km before they are recombined and sent to a photodetector.
Gravitational waves are ripples in spacetime that are produced by events such as supernovae or binary black hole systems. These waves travel at the speed of light and cause a distortion in space as they pass through it. The amount of distortion is incredibly small, but by measuring it very precisely we can learn about some of the most energetic events in the Universe.
The Virgo detector is sensitive enough to detect gravitational waves from sources such as binary neutron stars or black hole-neutron star systems out to distances of hundreds of millions of light years away. By comparing data from multiple detectors we can improve our chances of seeing a signal by orders of magnitude compared to using just one detector on its own.
In 2015, the Virgo Collaboration made its first detection of gravitational waves from a binary black hole system known as GW150914 . This event was also detected by the LIGO detectors in Hanford, Washington and Livingston, Louisiana in the USA . Since then, Virgo has made several more detections together with LIGO including GW170104 , GW170608 , GW170814 , GW170817 and GW190425 . These discoveries have revolutionized our understanding of astrophysics and opened up a new era of gravitational wave astronomy .