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GW170817

LIGO and Virgo make first detection of gravitational waves produced by colliding neutron stars

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GW170817 GW170817

Discovery marks first cosmic event observed in both gravitational waves and light.

For the first time, scientists have directly detected gravitational waves — ripples in space and time — in addition to light from the spectacular collision of two neutron stars. This marks the first time that a cosmic event has been viewed in both gravitational waves and light.

The discovery was made using the U.S.-based Laser Interferometer Gravitational-Wave Observatory (LIGO); the Europe-based Virgo detector; and some 70 ground- and space-based observatories.

The image shows the localization of the gravitational-wave (from the LIGO-Virgo 3-detector global network), gamma-ray (by the Fermi and INTEGRAL satellites) and optical (the Swope discovery image) signals from the transient event detected on the 17th of August, 2017. The colored areas show the sky localization regions estimated by the gamma-ray observatories (in blue) and by the gravitational-wave detectors (in green). The insert shows the location of the apparent known galaxy NGC4993: on the top image, recorded almost 11 hours after the gravitational-wave and gamma-ray signals had been detected, a new source (marked by a reticle) is visible: it was not there on the bottom picture, taken about three weeks before the event.

Science Papers and supplementary materials

Reconstruction comparison w/o LVT

Virgo congratulates Rainer Weiss, Kip Thorne and Barry Barish for the 2017 Nobel Prize in physics

Reconstruction comparison w/o LVT Reconstruction comparison w/o LVT

Four signals...three detectors...two collaborations...one Nobel Prize!

The Virgo collaboration warmly congratulates Rainer Weiss, Kip Thorne and Barry Barish on the award of the 2017 Nobel Prize in physics 'for decisive contributions to the LIGO detector and the observation of gravitational waves'.

Press announcement

Nobel Prize website

GW170814

Straight to the source: the LIGO-Virgo global network of interferometers opens a new era for gravitational wave science

GW170814 GW170814

A fourth gravitational-wave signal coming from the merger of two stellar mass black holes located about 1.8 billion light-years away was detected on the 14th of August 2017, at 10:30:43 UTC. GW170814 is the first event observed by the global 3-detector network, including not only the two twin Advanced LIGO detectors but the Advanced Virgo detector as well.

Following a multi-year upgrade programme and several months of commissioning, the Advanced Virgo detector joined the LIGO "Observation Run 2" data-taking period on the 1st of August. The three instruments worked together until the 25th of August.

GW170814 demonstrates the potential of a 3-detector network, both in terms of localization of a source in the sky and in terms of the testing of Einstein's theory of general relativity. The best GW170814 skymaps, computed by an analysis that uses all of the available information from the three instruments, cover just 60 square degrees (to be compared with several hundreds of square degrees for the LIGO-only network) and GW170814 data have allowed the LIGO-Virgo collaboration to probe, for the first time, the polarization of gravitational waves.

Therefore, GW170814 holds great promise for the future of multimessenger astronomy. Additional results, based on data from the three-detector network, will be announced in the near future by the LIGO-Virgo Collaboration; the analysis of the data is currently being finalized.

DQ_META_ITF_Mode O2 stripchart

A very exciting LIGO-Virgo Observing run draws to a close on the 25th of August

DQ_META_ITF_Mode O2 stripchart DQ_META_ITF_Mode O2 stripchart

The Virgo and LIGO Scientific Collaborations have been observing since November 30, 2016 in the second Advanced Detector Observing Run ‘O2’, searching for gravitational-wave signals, first with the two LIGO detectors, then with both LIGO and Virgo instruments operating together since August 1, 2017. Some promising gravitational-wave candidates have been identified in data from both LIGO and Virgo during our preliminary analysis, and we have shared what we currently know with astronomical observing partners. We are working hard to assure that the candidates are valid gravitational-wave events, and it will require time to establish the level of confidence needed to bring any results to the scientific community and the greater public. We will let you know as soon we have information ready to share.

The picture shows the Virgo duty cycle during the whole data taking period: we have been taking science data more than 80% of the time over four weeks!

First detection

First detection of gravitational waves

First detection First detection

On the 14th of September 2015, a gravitational wave was detected for the first ever time. This first detection was announced to the world on the 11th of February 2016:

Status

This section displays information on the current status of Virgo. Note that the plots, which update automatically, display the status of the interferometer to within the last 15 minutes.

Click here to view the Virgo Status in stand-alone format.

BNS range

BNS range

Sensitivity

Sensitivity

Lock-Step status

Lock-Step status

ITF Mode

ITF Mode

About

Working in the tower

What is Virgo?

Virgo is an interferometric gravitational-wave antenna. It consists of two 3-kilometre-long arms, which house the various machinery required to form a laser interferometer.

A beam-splitter divides a laser beam into two equal components, which are subsequently sent into the two interferometer arms. In each arm, a two-mirror Fabry-Perot resonant cavity extends the optical length from 3 kilometres to approximately 100. This is because of multiple reflections that occur within each cavity and which consequently amplify the tiny distance variation caused by a gravitational wave.

The two beams of laser light that return from the two arms are recombined out of phase so that, in principle, no light reaches the so-called 'dark fringe' of the detector. Any variation caused by an alteration in the distance between the mirrors, produces a very small shift in phase between the beams and, thus, a variation of the intensity of the light, which is proportional to the wave's amplitude.

Click here for more information on the Virgo experiment and its science.

The Virgo Collaboration

Virgo is a gravitational-wave interformeter designed, built and operated by a collaboration made up of 20 laboratories in 6 countries and involves the following institutions:

CNRS INFN NIKHEF EGO WIGNER IMPAS VALENCIA

Virgo Outreach

Interesting events are always being prepared at EGO-Virgo. Please view our Outreach website for details on up and coming, as well as recent, events.

Virgo and LIGO

Virgo and the LIGO Scientific Community work together in many areas and have a specific agreement on the exchange of data. More information on the work of our LIGO colleagues is available here.

More information on the identification and follow up of electromagnetic counterparts of gravitational wave candidate events is available here.

The Virgo-EGO Scientific Forum

Virgo and EGO have also established a scientific forum - the VESF - for astrophysicists and theorists, dedicated specifically to the furthering of scientific knowledge related to Virgo. More information is available here.

A payload

ET - Einstein Telescope

The Einstein Telescope (ET) project is dedicated to the development of a critical research infrastructure for a third-generation gravitational-wave interferometer. More information about the project, which is supported by the European Commission as part of the Framework Programme 7, is available here.

Other gravitational-wave experiments

Have a look at some of the other gravitational wave experiments:

Interferometric experiments

Pulsar-timing-array experiments

Other gravitational-wave-related websites

Jobs & Fellowships

The following Virgo roles are currently being advertised:

Further roles at EGO are advertised on the EGO website.

Visits

Virgo viewed from the south

Events

If you are looking for information on an up-coming or recent event, please visit our Outreach website.

Opening hours

The Reception at the EGO site is open at the following times:

  • Monday to Friday, from 08:30 to 13:00 and 14:00 to 17:30
  • Closed on Saturdays and Sundays (except when site visits are scheduled)

How to get to Virgo

Virgo is at the site of the European Gravitational Observatory (EGO), the organisation responsible for the site, and is located in:

Via Amaldi
56021 Santo Stefano a Macerata – Cascina (Pisa), Italy.

As Virgo is located in the countryside, it is not particularly easy to access without a car, as there are no public transport links directly to it.

Arriving by car

The EGO-Virgo site GPS coordinates (in DD) are:

  • Latitude: 43.6305 N
  • Longitude: 10.5021

Arriving by plane/train and taxi

The nearest airport to Virgo is Pisa Galileo Galilei International Airport.

If you are travelling by aeroplane and arrive at the Pisa Galileo Galilei International Airport, or by train and arrive at Pisa Central train station, we recommend that you call a taxi (Co.Ta.Pi Radiotaxi Pisa, +39 050 54 16 00) complete your journey to EGO-Virgo.

It takes about 20-30 minutes to reach the site coming from Pisa when coming by car. The taxi fare from Pisa to the EGO-Virgo site costs about €35-40.

What do on arrival at the EGO-Virgo site

All visitors must present themselves at the site-entrance gate, where they will be met by their EGO contact person.

Visitors' vehicles may be parked at the site, in the appropriate parking areas.

New Virgo collaborators

New Virgo collaborators must complete the association and safety procedures before starting any activity on site. To this end, they should contact the EGO Administration (Building 4, first floor, +39 050 752 522/325) and the Safety and Security Office (Building 1, +39 050 752 416/544).

Badges to access the site and an account to access the Virgo documentation will only be granted by the IT department on completion of this process.

Contact

The Virgo experiment at the European Gravitational Observatory

Address: Via Amaldi, 56021 Santo Stefano a Macerata, Cascina (Pisa), Italy.

Phone: +39 050 752 511

Fax: +39 050 752 550

Email: email@ego-gw.it

Web: http://www.virgo-gw.eu

Twitter: https://twitter.com/ego_virgo

Facebook: https://it-it.facebook.com/EGOVirgoCollaboration/

Youtube: EGO & the Virgo Collaboration - LIGO-Virgo

Jo van den Brand, Spokesman of Virgo

Phone: +31 620 539 484

Email: jo@nikhef.nl

Web: https://www.nikhef.nl/~jo

Addresses: Nikhef, National Institute for Subatomic Physics, Amsterdam, The Netherlands.
VU University Amsterdam, Faculty of Sciences, Department of Physics and Astronomy.
European Gravitational Observatory - EGO, Cascina (PI), Italy.

The Virgo Collaboration

A full list of members of the Virgo Collaboration and their contact details is available here.

Please get in contact if you would like more information.