On January 1, a new GDR devoted to physics applied to cosmology was created within the CNRS: the GDR CoPhy for "Cosmological Physics", co-run by IN2P3, INSU and INP, and directed by Sophie Henrot-Versillé. By studying the properties of the Universe as a whole, cosmologists seek to understand its origin, structure and evolution. At IJCLab you can find them in the A2C and theory poles!
The ΛCDM model, based on general relativity, describes extremely well all the observations of the numerous terrestrial and space instruments which produce increasingly vast, deep and detailed records of the Universe. Obtaining a coherent picture of all observations within the unified framework of this model required the introduction of three ingredients: first dark matter and dark energy, which we now know to be constitute respectively about two-thirds and one-third of the energy content of the Universe (dark energy being responsible for its accelerated expansion). Nevertheless, these two elements, and in particular their nature, remain enigmas. This model, known as the concordance of cosmology, is also based on the existence of primordial fluctuations that served as seeds for the formation of large structures. These fluctuations could come from a phase of inflation which requires, from a theoretical point of view, to combine general relativity and field theory. This is another enigma which we seek to prove (or not!) experimentally that it existed.
Cosmology is entering a prosperous decade with a harvest of new data, unprecedented in its precision and scope: you should regularly hear about: EUCLID, LSST-Vera Rubin, ZTF, DESI, Simons Observatory, CMB-S4 and LiteBIRD: the birth of the GDR comes at a key moment!