André Füzfa, Christophe Ringeval

Our expertise on inflation and cosmic strings is involved in the CMB data analysis of the PLANCK satellite.
Our current efforts concern the study of future CMB polarization experiments, ground based, and in space, as the CORE satellite.
We are part of the EUCLID collaboration and interested in the impact of high precision measurements of the matter power spectra of the large scale structures for cosmic inflation.
We are also involved in the LISA project, the giant space interferometer dedicated to gravitational wave astronomy, which should open a new window on cosmic string physics and other early universe phenomena.
Another direction concerns the 21cm cosmological radiation. This radiation is emitted by neutral hydrogen atoms and should shed light into the so-called "dark ages": from the recombination to the reionisation of the universe by the first stars. This new observable is expected to be sensitive to the nature of dark matter as well as to some properties of the inflationary era.

External collaborators: Sébastien Clesse (RWTH, Aachen), V. Vennin (Portsmooth, U.K.), CORE Coll., Euclid Coll., eLISA Coll.

André Füzfa, Christophe Ringeval

Although the undergoing cosmic acceleration may be explained by a non-vanishing cosmological constant in Einstein gravity, various dynamical effects could very well explain current observations, all dubbed as dark energy.

Quintessence, as a light scalar field minimally coupled to gravity, is a dark energy candidate to explain the recent acceleration of the Universe expansion. The Ratra-Peebles potential and its corrected form in supergravity are under study. Using a modified version of CAMB, including perturbations of the scalar field, we use the latest SNIa and CMB observations to select acceptable points in the parameter space. Starting with the associated matter power spectrum, in collaboration with the LUTh (Paris-Meudon Obs., France) we run N-body simulations of growth of large scale structures where the background evolution is modified by quintessence. We are involved in the Dark Energy Universe Simulation Series (DEUSS) collaboration.

Another dark energy candiate involves cosmic inflation, currently the best explanation of the origin of large scale structures and CMB anisotropies. Similarly, if dark energy is a light scalar field, the current acceleration can be the consequence of quantum fluctuations during cosmic inflation, provided this one occurs at TeV scale.

External collaborators: Jean-Michel Alimi, Yann Rasera, Pier Stefano Corasaniti (Observatoire de Paris-Meudon, France). Teruaki Suyama (The University of Tokyo, Japan), Tomo Takahashi (Saga University, Japan), Masahide Yamaguchi (Tokyo Institute of Technology, Japan), Shuichiro Yokoyama (Nagoya University, Japan).

André Füzfa, Christophe Ringeval

The statistical properties of large scale structures contain a large amount of information on cosmological observables. The abundance of halos of given mass is sensitive to various cosmological observables such as the equation of state of dark energy, to the amount of primordial non-Gaussianity as well as to the mass and cross section of the dark matter particles. Various of our activities and research are equally focused to the future EUCLID satellite mission.

External collaborators: M. Musso.