The Chair focuses on all aspects of structure formation in the Universe, from the initial instant of the Big Bang, when the Universe was very homogeneous. In the 21st century, cosmology has become a precision science, where the Universe's expansion rate and acceleration are known, its zero curvature and its matter and energy content have been precisely measured. Yet there is only 5 % ordinary matter, and 95 % dark matter, including 25 % dark matter and 70 % dark energy. Numerous alternative models challenge the standard cold dark matter model, which has many problems explaining galaxies.

The existence of galaxies was only established in 1926. Before then, astronomers had no good distance indicators, and confused the clouds of the Milky Way with galaxies outside our own, all of which were called " nebulae ". The expansion of the Universe, and the Hubble-Lemaître law, was only established in the 1930s. Today,the Universe up to the limits of our observable horizon has been explored, and contains at least two thousand billion galaxies. Telescopes in space (Hubble, James-Webb, Euclid), or on the ground (VLT, ELT, ALMA, SKA) enable us to pinpoint more and more details about the physics of galaxies, and to establish the theory of their formation, as well as the cosmic history of star formation.

Galaxies evolve in symbiosis with their supermassive black hole, which exists at the center of each galaxy bulge. This black hole is fed by the galaxy's gas and stars orbiting near the center. In recent years, the detection of gravitational waves has provided us with information on the rate of black hole mergers, and interferometric observations at very high angular resolution have made it possible to image the shadows of supermassive black holes.