For the first time, Euclid, a telescope belonging to the European Space Agency (ESA), will survey several billion galaxies. This unprecedentedly precise mapping will help us to understand how the Universe has been structured, from the Big Bang to the present day.
On the occasion of the launch at the beginning of July, Belgian scientists, notably from ULB, involved in the Euclid mission highlight their contributions and research projects.
The magical ingredient of the Universe:Discovered in 1998, the acceleration of cosmic expansion is still largely misunderstood. Its physical origin escapes us. Is it simply the cosmological constant introduced and then denied by Einstein? Is it a new physical interaction yet to be discovered? Or do we need a modified theory of gravitation to describe the infinitely large? By studying its influence on the distribution of galaxies, the Euclid mission will help us to understand the nature of the dark energy that has dominated the cosmos for five billion years and will preside over the ultimate destiny of the Universe.
Mysterious dark matter:It is invisible and its nature is still unknown, but its gravitational effects are observable. It plays a major role in the formation of the Universe’s great structures. Thanks to Euclid, Belgian researchers will be studying the properties of dark matter in dwarf galaxies and on cosmological scales. Particular attention will be paid to one candidate, primordial black holes, which may have formed from lumps in the primordial soup less than a millisecond after the Big Bang.
Back to the Big Bang:Although Euclid’s direct observations concern galaxies present in the Universe at least two billion years after the Big-Bang, their statistical distribution will enable us to constrain the primordial inhomogeneities that appeared a tiny fraction of a second after the Big-Bang. This is an invaluable mine of information for selecting viable models of cosmic inflation, probing the primordial history of the Universe, the existence of unknown particles or measuring the mass of neutrinos for the first time.
Gravitational lenses, or the Universe under the magnifying glass of dark matter:Dark matter in the Universe can deflect light rays from distant galaxies, making them appear distorted. This physical effect can become a tool for probing the properties and granularity of dark matter in galaxies. Dark matter thus becomes a tool, a microscope for observing very distant lensed galaxies, to measure the expansion rate of the Universe or probe the existence of primordial black holes... Euclid’s sharp vision will reveal details about the structure of an unprecedented sample of galaxies. The characteristics of the most massive galaxies will enable us to delve deeper into the mysteries of their formation and evolution, while dwarf galaxies will allow us to probe the properties of dark matter on a smaller scale.
The launch of Euclid by a Falcon 9 rocket is scheduled for July 1 at 5:11 pm (CEST) from Cape Canaveral.