The research themes of the Astroparticles, Astrophysics and Cosmology (A2C) pole aim to deepen our understanding of the Universe. They cover various subjects: the origin of the solar system to the creation of chemical elements, the most violent phenomena within our galaxy and in the extragalactic Universe (associated with black holes and star explosions), the nature of dark energy, dark matter, and neutrinos, the study of the primordial Universe, its formation and evolution, the nature of gravitation. This research is carried out within international collaborations, based on observations with large instruments and large infrastructures (astronomical observatories on the ground, large underground laboratories, polar bases, experiments on stratospheric balloons and space missions).

The research teams of the pole are strongly involved in detecting and understanding gravitational waves (LIGO, Virgo), detecting and studying the origin of cosmic rays of ultra-high energy (Pierre Auger Observatory), as well as observing the sky in X or gamma rays in an energy range from the keV and GeV energies (SVOM, ASTROGAM project) up to several hundred TeV (CTA). This research opens a window on energetic phenomena in the Universe:  star explosions, coalescence of compact objects (neutron stars, black holes) in binary systems, ejection of matter from active galaxy nuclei, annihilation of antimatter, etc. The teams participate fully in the current development of multi-messenger and multi-wavelength astronomy.

In cosmology, ie the study of the origin, nature, structure and evolution of the Universe, there are two major research axes of the pole. The first consists in studying the dark components of the Universe – dark energy and dark matter – through the observation of large structures, thanks to optical surveys (LSST), and in radio, at 21 cm (BAORadio). The second one aims at understanding the primordial Universe, its inflation phase and its evolution , through the search for primordial gravitational waves via measurements of the cosmic microwave background at large and small scales (Planck, LiteBIRD, and Simons Observatory). Among other activities, the teams are strongly involved in the interpretation of these data to characterize neutrinos (mass, number of families and hierarchy).

Regarding neutrinos and dark matter, studies based on observations of the sky and the Universe are complemented with activities dedicated to understanding their nature. The bolometric search for double beta decay in the CUPID experiment will provide crucial information on the nature of this particle, investigating whether the neutrino is the only fermion identical to its own antiparticle. The use of bolometers in the pole is also the basis of a future experiment for detecting coherent neutrino scattering (RICOCHET) and direct research of low-mass dark matter (EDELWEISS). The teams of the pole are also engaged in direct dark matter research projects to probe higher areas of mass, using two-phase time projection chambers (XENON) and CCDs as innovative particle detectors (DAMIC).

The activities of the pole also include research on the primitive matter of the solar system in order to specify the astrophysical context of formation of the solar system, and to understand the origin of the first mineral and organic phases, inherited from the interstellar medium or synthesized in the protoplanetary disc.

In all these aspects, the activities of the A2C pole teams cover both R&D and technical contributions to projects (gamma detectors, cryogenic bolometry and CDD, squeezing techniques on Virgo, digital electronics for 21cm, etc.), integration and calibration of instruments, up to the analysis and scientific interpretation of the data. The complementarity of these disciplinary fields allows the A2C pole of IJCLab to play a major role in understanding the physical phenomena at work in the Universe.