Virgo gravitational wave detector reaches the highest level of sensitivity

ENGINEERINGNET.BE – Virgo is an interferometer with three-kilometre-long arms near Pisa that can detect subtle oscillations of space and time. The installation measures how vibrations affect the spaces between the mirrors using lasers.

These space-time oscillations result from the collision of black holes or neutron stars in the universe. The first gravitational waves, predicted by Einstein's theory of relativity, were observed in 2015.

Virgo is part of an international collaboration between LIGO, Virgo and Kagra, with two detectors in the United States, one in Pisa and an underground installation in the testing phase in Japan.

Last year, Virgo refrained from direct participation in LIGO's fourth measurement campaign, because after a number of modifications, the detector in Italy turned out to have too many interference sources. They have been eliminated and improved step by step over the past year.

After all this work, Virgo's sensitivity is now at the highest level the detector was previously able to achieve at distances up to O3:60 Mpc, an astronomical measure of the distance at which the detector can still distinguish the signal from colliding black holes. .

Work continues to improve sensitivity during the current measurement period. Therefore, Virgo will contribute to identifying the sources of gravitational waves.

LIGO has a sensitivity of 140-160 MPa, and has detected more than eighty gravitational waves in the first half of the fourth O4a measurement period since last year. It is hoped that, in cooperation with Virgo, at least 200 wave observations will be carried out in the rest of the O4 region.

Gravitational waves provide a new window on the universe, especially if measurements are combined with astronomical observations with telescopes and radio telescopes.

The measurements can be used to test Einstein's theory of relativity, theories about black holes, neutron stars, and the evolution of the universe.

The new series of measurements also looks at so-called persistent gravitational waves that can arise when neutron stars show small irregularities.

The hope is also to observe a supernova explosion for the first time. In addition, gravitational waves originating from the Big Bang are being researched.

O4 will run until February 2025. As in previous observing runs, observations will be published immediately, so astronomers can also search for signals using their own instruments, something called multi-messenger astronomy.