The international network of the LIGO (Verenigde Staten), Virgo (Italië) and KAGRA (Japan) gravitational-wave observatories just announced the detection of their 200th candidate gravitational wave signal in this fourth observation period (O4), which is still ongoing. The signal came on March 19th 2025 and it is over 99% likely to come from a merger of two black holes. This new record of detections is impressive, considering that the total number of signals detected in all previous observation periods (O1, O2, O3) was 90, and is due to the increased sensitivity of the detectors, as a result of the upgrades made between O3 and O4.
“The scientific community is intensely engaged in the in-depth analysis of this vast amount of new data that the detectors have provided us over the past year and a half,” said, Virgo spokesperson and INFN researcher Gianluca Gemme – We will gather new information about black holes, neutron stars, and the evolution of our Universe and of course we are looking forward to the possible new discoveries on the horizon.”
The observing period O4 has been running since May 2023, with a short break at the beginning of 2024 after which the Virgo detector joined the two LIGOs, and is planned to run until the beginning of October 2025 with another break in spring for technical interventions.
Nikhef has developed several essential parts of Advanced Virgo: cryogenic vacuum links, phase cameras, seismic reduction systems and much more. Read about Nikhef’s role in Virgo: https://www.nikhef.nl/en/programs/virgo/
Read the entire press release on the website of Virgo: https://www.virgo-gw.eu/news/record-detection-of-200-gravitational-waves-in-the-current-run-of-ligo-virgo-and-kagra/
New members of the Virgo collaboration
This week, it was also announced that the Belgian research foundations FWO and FNRS joined the EGO consortium, the institution that hosts the Virgo gravitational wave detector in the countryside of Cascina, near Pisa, Italy. The membership of the two Belgian foundations brings to five the number of European research institutions funding EGO, and to four the number of member countries. Nikhef/NWO-I is one of the members of the consortium.
More information: https://www.ego-gw.it/blog/2025/03/19/belgium-is-the-fourth-european-country-to-join-the-ego-consortium/
