The group Gravitational waves is part of the scientific collaboration LIGO / Virgo. It contributes to data collection, analysis and mirror production, in support of the IP2I’s LMA platform. The objective of LIGO / Virgo is to detect and characterize gravitational waves whose recent observation has opened the field to a new astronomy, formerly restricted to the detection of electromagnetic radiation only.

Thanks to gravitational waves, it is now possible to watch and listen to the Universe from several independent sources! Gravitational waves (link to the public gd tab) allow us to collect additional information about the Universe that is complementary to the historical messenger that is electromagnetic radiation (visible light, X-rays, radio waves, microwaves, etc.).

This was the case, in 2017, during the first observation of a gravitational wave (GW170817) coming from the coalescence of two neutron stars. This discovery marked the birth of multimessenger astronomy.

Virgo and the two LIGO detectors are Michelson’s interferometers: they superimpose two laser beams travelling along two perpendicular arms of several kilometers to obtain an interference pattern that can be analyzed. Gravitational waves are space-time vibrations: as they pass through, the relative lengths of the arms of the interferometer are very slightly affected (10-19 m) but enough to induce a measurable effect on the interference pattern.