Euclid lifts the veil on the invisible Universe: a first harvest of gravitational mirages
Thanks to the first data from the Euclid space telescope, scientists are taking a decisive step forward in their study of the Universe. Researchers from the University of Liège are taking part in this unprecedented space adventure, which is already revealing hundreds of new gravitational mirages and shedding light on the nature of dark matter.
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aunched by the European Space Agency in July 2023, the Euclid space telescope revealed today the results of its first observing campaign. With an ultra-wide field of view and exquisite resolution in the visible and infrared, Euclid began its six-year mission in February 2024. The mission’s objective is to map the Universe with unprecedented precision by studying the distribution of galaxies and their light distortion created by the gravitational pull of massive structure, such as gravitational lenses from clusters of galaxies.
Even from the very first data collected, the Euclid mission is already delivering an impressive amount of scientific results. At the heart of this quest, researchers from the University of Liège are playing a key role in identifying phenomena that are as rare as they are fascinating: gravitational mirages.
Chasing cosmic mirages
Among the major results of this initial campaign, reffered to as "Quick Release 1" (Q1), the discovery of more than 500 new gravitational lens candidates is a major breakthrough. These "cosmic mirages", produced by the deflection of light from a distant galaxy by a closer one, are unique astrophysical laboratories. They make it possible to study in detail dark matter (link https://fr.wikipedia.org/wiki/Mati%C3%A8re_noire ) and the internal properties of galaxies.
At ULiège, researchers from the MEGA and GAPHE groups (STAR Research Unit) are actively contributing to this cosmic hunt. Through collaboration with citizen scientists via the Zooniverse platform and the development of artificial intelligence algorithms, they were able to extract these rare objects from millions of galaxies captured by Euclid. "It's like looking for a needle in a haystack", explains astrophysicist Dominique Sluse.
A revolution in the study of dark matter
Until now, studies of gravitational lenses have been based on a few dozen objects. Thanks to Euclid, researchers can now study samples a hundred times larger, and this is just the beginning. "The telescope will eventually cover an area 200 times larger than that of Q1, paving the way for detailed mapping of dark matter in galaxies and clusters. At the same time, we will be able to study their brightness, shape and colour - all clues to their cosmic history," enthuses Guillaume Mahler, astrophysicist at ULiège.
Capturing galaxies in the making
In addition to the lenses, Euclid is also helping us to better understand the evolution of galaxies, from distant dwarfs to ultra-bright red quasars, not forgetting the mysterious objects known as the "little red dots", spotted for the first time by the James Webb space telescope. An exciting part of the Science Legacy programme, going beyond the core mission of the telescope,.
With these spectacular first data, the Euclid mission is poised to lead the next cosmological revolution. Far from earthly laboratories, it is in the immensity of the sky that researchers from Liège, in collaboration with more than 2,600 scientists around the world, are tracing a new map of the Universe - a map where mirages become revelations, and where the invisible begins to speak.
