On June 29, 2023, as part of a worldwide network dedicated to pulsar observation, a European consortium published a series of results in the journal Astronomy and Astrophysics, based on data collected over the last quarter-century by six of the world's most sensitive radio telescopes. The data from the European consortium, along with those from their American, Australian and Chinese counterparts, contain very solid evidence of the existence of gravitational waves, captured at very low frequencies, which are thought to originate from pairs of supermassive black holes located at the centers of merging galaxies. French participation in this project is significant, with contributions from researchers at Observatoire de Paris - PSL, CNRS, CEA, Université d'Orléans and Université Paris Cité.