What is the Virgo gravitational-wave antenna?

Virgo gravitational wave antenna logo

Located in the European Gravitational Observatory (EGO) in Cascina, Italy, Virgo - a gravitational-wave antenna - works to detect gravitational waves through interferometry, a technique by which two out-of-phase laser beams are superimposed to generate interference patterns.

How does Virgo work?

Virgo is composed of two arms intersecting at 90 degrees, both 3 kilometres in length, that hold within them the equipment necessary to form a laser interferometer.

The interferometer works by creating two laser beams of equal measure from a single source, with the help of a beam-splitter, and directing them into both arms of the Virgo structure.

Two sets of parallel mirrors at the extreme of each arm create Fabry-Perot resonant cavities that reflect the beams multiple times and thus elongate the optical paths of both beams from 3 kilometres to approximately 100 kilometres. Crucially, this allows for any minute distance variations caused by gravitational waves to be amplified.

The beams are recombined out of phase on their return from the two arms; the interference pattern ensures that no light reaches the ‘dark fringe’ of the detector. Any variation of the interference pattern caused by alterations in the optical paths of the beams within the Fabry-Perot resonant cavities will result in a variation of light intensity picked up by an output detector.

Virgo: A collaboration project

The Virgo gravitational-wave antenna was planned, constructed and now operates as a collaborative project, with 20 laboratories in France, Italy, the Netherlands, Poland, Spain, and Hungary, contributing to the project. This includes the following institutions:

  • Le Centre national de la recherche Scientifique (CNRS)
  • Instituto Nazionale di Fisica Nucleare (INFN)
  • Nikehef
  • European Gravitational Observatory (EGO)
  • Wigner
  • Institute of Mathematics at the Polish Academy of Sciences
  • Universitat de Valencia

Virgo partnerships

  1. Virgo-EGO Outreach

    The European Gravitational Observatory (EGO) together with Virgo organise and host regular events at the site of the observatory and various other locations.

  2. The Virgo and LIGO collaboration

    Virgo works with the LIGO (Laser Interferometer Gravitational-Wave Observatory) Scientific Community for the exchange of data and collaboration in many areas of overlapping interest.

  3. The Virgo-EGO Scientific Forum

    Virgo and the European Gravitational Observatory (EGO) have also worked together to create the Virgo-EGO Scientific Forum (VESF), a platform for astrophysicists and theorists to further scientific knowledge closely related to the Virgo project.

Are there other gravitational-wave projects?

Championing innovation in interferometry, the Einstein Telescope (ET) project - part of the Framework Programme 7 supported by the European Commission - seeks to further develop crucial research infrastrucutre for a new generation of gravitational-wave interferometers.

Experiments similar to Virgo

Meanwhile, gravitational-wave experiments similar to Virgo are also underway in the USA, Japan, Australia and Europe. These experiments are noted in the following:

  1. The Laser Interferometry in Space (LISA)
  2. The Laser Interferometer Gravitational-Wave Observatory (LIGO)
  3. The Kamioka Gravitational Wave Detector (KAGRA)
  4. The British-German GEO600 project
  5. The Australian Consortium for Interferometric Gravitational-Wave Astronomy (ACIGA)

Pulsar-timing array experiments

Other experiments that use interferometry for pulsar-timing array experiments include:

  1. Parkes Pulsar Timing Array (PPTA)
  2. The North American Nanohertz Obersvatory for Gravitational Waves (NANOGrav)
  3. The International Pulsary Timing Array (IPTA)
  4. The European Pulsar Timing Array (EPTA)

Visit Virgo at the EGO

The site of the European Gravitational Observatory (EGO), home to the Virgo gravitational-wave antenna, is located in the countryside of the province of Pisa, Italy. If you are driving or flying in, please use the following information:

Address: Via Amaldi, 56021 Santo Stefano a Macerta, Cascina (Pisa), Italy.
GPS coordinates (DD): Latitude: 43.6305 N
Longitude: 10.5021
By plane: Nearest airport - Pisa Galileo Galilei International Airport
By taxi: Call Radiotaxi Pisa on +39 050 54 16 00

Please be aware that the reception is open from Monday to Friday, 8:30am to 13:00pm, and on select weekends for scheduled site visits. Parking is available on-site. When you arrive, you must wait at the entrance gate for your EGO contact person.

If you are a new Virgo collaborator, please be sure to go through the relevant association and safety procedures before you arrive. To do so, please get in touch with the Eurpean Gravitational Observatory (EGO) Administration on +39 050 752 522/325 and the Safety and Security Office on +39 050 752 416/544.

Contact Virgo

To get in touch with the Virgo project, please use one of the many channels outlined in the table below.

Contact channel Details
By post: To Via Amaldi, 56021 Santo Stefano a Macerata, Cascina (Pisa), Italy
Phone: +39 050 752 511
Fax: +39 050 752 550
Email: info@ego-gw.it
Social media:

Get in touch with the Virgo Spokesman

If you would like to get in touch with Jo van den Brand, the Spokesman of Virgo, you can do so through the following channels:

Contact channel Details
Phone: +31 620 539 484
Email: jo@nikhef.n
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