Gravitational waves: astrophysics and source modeling, data analysis, construction of the Virgo detector

LIGO and Virgo Announce Four New Gravitational-Wave Detections

03.12.18 - The LIGO and Virgo Collaborations present new results from searches for coalescing cosmic objects. The LIGO and/or Virgo interferometers have now confidently detected gravitational waves from a total of 10 stellar-mass binary black hole mergers and one merger of neutron stars, which are the dense, spherical remains of stellar explosions. Seven of these events had been reported before, while four of the black hole detections are newly announced.

From September 12, 2015, to January 19, 2016, during the first LIGO observing run since undergoing upgrades in a program called Advanced LIGO, gravitational waves from three binary black hole mergers were detected. The second observing run, which lasted from November 30, 2016, to August 25, 2017, yielded a binary neutron star merger and seven additional binary black hole mergers, including the four new gravitational wave events being reported now. The new events are known as GW170729, GW170809, GW170818 and GW170823 based on the dates on which they were detected.

The Virgo interferometer joined the two LIGO detectors on August 1, 2017, while LIGO was in its second observing run. Although the LIGO-Virgo three-detector network was operational for only three-and-a-half weeks, five events were observed in this period. Two events detected jointly by LIGO and Virgo, GW170814 and GW170817, have already been reported.

One of the new events, GW170818, detected by the global network formed by the LIGO and Virgo observatories, was precisely pinpointed in the sky. The sky position of the binary black holes, located about 2.5 billion light-years from Earth, was identified with a precision of 39 square degrees. That makes it the next best localized gravitational-wave source after the GW170817 neutron star merger Read more


Virgo-Polgraw is a Polish team of researchers analyzing the data collected by the LIGO and Virgo detectors in search for gravitational waves predicted by the general theory of relativity by Albert Einstein.

Gravitational waves astrophysics is a new and promising field of research of the Universe. In contrast to the observations of the electromagnetic waves (radio waves, visible light, X-rays and gamma), which are the main source of our current knowledge, we ''listen'' to the Universe by registering minor disturbances of the space-time curvature using the LIGO and Virgo laser interferometric detectors. Gravitational waves are emitted during the largest cosmic cataclysms: mergers of binary systems of neutron stars or black holes, explosions of supernovae, and by other sources, eg. unstable or deformed rotating neutron stars. The direct detection of gravitational waves allows the study of objects that are dark (do not shine in electromagnetic waves), testing the theory of gravity in the dynamic regime of strong gravitational field, and the direct study of the interior of neutron stars which contain the densest and most extreme matter existing currently in the Universe. These informations cannot be currently obtained using other methods.

In addition to the data analysis and the development of the statistical signal detection theory, we modeling astrophysical sources of gravitational waves, make predictions about the population of these sources, search for the electromagnetic waves emission accompanying the gravitational waves and take part in the construction of the Virgo interferometer.

The leader of the Virgo-Polgraw group is prof. Andrzej Królak from the Mathematical Institute PAS. The project is currently financed by an NCN Harmonia grant ''Gravitational-wave astronomy: participation of the Polgraw group in Advanced Virgo and Advanced LIGO projects'' no. 2017/26/M/ST9/00978; previous grant was titled ''Participation of Poland in the Advanced Virgo project'' no. UMO-2014/14/M/ST9/00707). Polish participation in the Virgo project is on the Polish Roadmap for Research Infrastructure. The group consists of

  1. Institute of Mathematics, PAS
  2. Nicolaus Copernicus Astronomical Center, PAS
  3. Warsaw University Astronomical Observatory
    • Tomasz Bulik (
    • Malgorzata Curyło
    • Bartosz Idźkowski
    • Neha Singh
    • Maria Tringali
  4. Institute of Astronomy, University of Zielona Góra
  5. Department of Physics, University of Bialystok
  6. National Centre for Nuclear Research
  7. Centre for Astronomy, Nicolaus Copernicus University in Toruń
    • Kazimierz Borkowski
  8. Institute of Theoretical Physics, University of Wrocław
    • Arkadiusz Błaut
  9. Astronomical Observatory of the Jagiellonian University
    • Andrzej Kułak
    • Michał Ostrowski

Financing sponsors and sources of computing grants.

Member of the Virgo-Polgraw group: Paweł Ciecieląg, Magdalena Sieniawska, Orest Dorosh, Izabela Kowalska-Leszczyńska, Dorota Rosińska, Adam Zadrożny, Michał Bejger, Andrzej Królak, Piotr Jaranowski, Tomasz Bulik (photo: Marek Cieślar).

Countries and institutions participating in the Advanced Virgo project (Nicolas Arnaud/Virgo Outreach team)

Members of the LIGO-Virgo Collaboration Meeting, organized in Kraków, September 2010.