To measure cosmological parameters, the Euclid space telescope will use two main probes: gravitational lensing (Weak Gravitational Lensing) and galaxy distribution (Galaxy Clustering). These measurements will allow us to study dark energy and dark matter, which affect the growth of cosmic structures and the accelerated expansion of the Universe.
In addition to its implications on instrumental developments and data processing, Irfu is actively involved in the development of algorithms needed to prepare the extraction of cosmological parameters that will be derived from Euclid measurements.
Coordinated by Valeria Pettorino, physicist at Irfu's CosmoStat laboratory, in collaboration with Tom Kitching (UCL) and Ariel Sanchez (MPE), an international team from the Euclid collaboration with complementary expertise in theory and observation has just completed a 3-year study characterizing the performances expected from Euclid for these observational probes.
Publication an Arxiv: https://arxiv.org/pdf/1910.09273.pdf
Arrived safely. The focal plane of the visible imager on the Euclid satellite has just been delivered by Irfu to the laboratory responsible for the instrument (MSSL/UK) to continue its integration into the satellite, which is scheduled to take off in 2022.
The first studies of this focal plane have been carried out at Irfu since 2010 and after almost 10 years of development and testing, it was fully tested by Irfu in 2019. This Focal Plane is composed of 36 CDDs totalizing more than 600 million pixels. Each image acquired in flight by this focal plane will make it possible to characterize more than 50,000 galaxies. It is the second largest camera, observing in the visible, launched into space after that of the Gaïa satellite. In space, its observations will allow the measurement of galaxy deformations due to weak gravitational lensing effects induced by clusters of dark matter that light encounters on its way to us. These gravitational distortion effects measured at different ages of the Universe will provide measurements of the distribution of dark matter and will be a constraint on dark energy.
The international CUPID-Mo experiment conducted by French laboratories of IN2P3, CEA/IRFU and CEA/IRAMIS has been testing the use of Molybdenum-based crystals since last April to detect double beta decay without neutrino emission. The experiment is gradually gaining strength and already shows a near-zero background in the region of interest, which is very promising. The scientists of the collaboration made an update in the occasion of the official inauguration on 11 and 12 December 2019.
A few microseconds after the Big Bang the Univers may have gone through a deconfined state of quarks and gluons, the Quark–Gluon Plasma (QGP). The QGP can be recreated in high-energy heavy-ion collisions. In particular at the LHC at CERN, the QGP behaves like a fluid. All particles, light, strange, or charmed flow collectively as if being carried by the same fluid, proving the strength of the interactions between QGP constituents. The ALICE Collaboration at the LHC, with decisive contributions from the Irfu teams, has just published, in the prestigious Physical Review Letters journal, the first measurement of the elliptic flow of Υ(1S) (a particle composed of a beauty quark and its antiquark). This resonance appears as the first particle at the LHC not flowing with the fluid. This pioneering result opens up the path for deeper studies of the QGP.
The Fermi-LAT collaboration has published its fourth source catalog, named 4FGL. Based on eight years of data, it contains 5064 celestial objects emitting gamma rays at energies around 1 GeV, adding more than 2000 high-energy sources to the previous collection (published in 2015). More than one fourth of the objects are of unknown nature, calling for numerous follow-up studies. Although its volume is modest compared to the billions of sources listed in optical catalogs, the 4FGL catalog is by far the deepest in gamma-ray astronomy and serves as a reference to the entire domain. The catalog, coordinated by a researcher at the Astrophysics Department (AIM Laboratory) of CEA-Irfu at Paris-Saclay, is accessible on line at the NASA Fermi web site. In parallel, the 4LAC census of active galactic nuclei (coordinated by a researcher at CNRS/CENBG) is also made available to the community.