[en] We present the current status of cosmological weak lensing studies. Theoretical expectations and observational results are discussed in the framework of standard cosmology and CDM scenarios. We show that present-day surveys already provide important clues and new constraints on cosmological parameters and on the biasing. Finally, the potentials of the next generation cosmic shear surveys are discussed

[en] The Euclid mission objective is to understand why the expansion of the Universe is accelerating by mapping the geometry of the dark Universe by investigating the distance-redshift relationship and tracing the evolution of cosmic structures. The Euclid project is part of ESA's Cosmic Vision program with its launch planned for 2020. The NISP (Near Infrared Spectro-Photometer) is one of the two Euclid instruments and is operating in the near-IR spectral region (0.9-2μm) as a photometer and spectrometer. The instrument is composed of: - a cold (135 K) opto-mechanical subsystem consisting of a SiC structure, an optical assembly (corrector and camera lens), a filter wheel mechanism, a grism wheel mechanism, a calibration unit and a thermal control system - a detection subsystem based on a mosaic of 16 Teledyne HAWAII2RG cooled to 95 K with their front-end readout electronic cooled to 140 K, integrated on a mechanical focal plane structure made with Molybdenum and Aluminum. The detection subsystem is mounted on the opto-mechanical subsystem structure - a warm electronic subsystem (280 K) composed of a data processing/detector control unit and of an instrument control unit that interfaces with the spacecraft via a 1553 bus for command and control and via Spacewire links for science data This presentation describes the architecture of the instrument at the end of the phase B (Preliminary Design Review), the expected performance, the technological key challenges and preliminary test results obtained on a detection system demonstration model. (authors)

[en] The contribution of cosmological perturbations to the time drift of the cosmological redshift is derived. It is shown that the dominant correction arises from the local acceleration of both the emitter and the observer. The amplitude of this effect is estimated to be of the order of 1% of the drift signal at z=2-4, but can easily be lowered down to 0.1% by using many absorption lines and quasars

[en] For different topics (the Universe as a physical and mathematical object, black energy, black matter and Big Bang nucleosynthesis, cosmological radiation background, large structures, galaxies and galaxy clusters as cosmology tracers), this assessment report proposes presentations of the general context, of the activity of the French scientific community, of financial issues, of the relationship with the French national programmes of cosmology (PNC), and of prospective issues. It may also propose overviews of contributions or actual or virtual observations. The last chapters address new research themes and new tools, and also a presentation and an analysis of the PNC operation as well as some proposals related to actions and operating modes of the PNC. Appendices notably indicate publications on the various above-mentioned topics, some information on activities of the different work groups, and a list of operations supported by the PNC

[en] X-ray and Sunyaev-Zel'dovich data of clusters of galaxies enable to construct a test of the distance duality relation between the angular and luminosity distances. We argue that such a test on large cluster samples maybe of importance, as a consistency check, while trying to distinguish between various models accounting for the acceleration of the universe. The analysis of a data set of 18 clusters shows no significant violation of this relation for a Λ-Cold Dark Matter (CDM) model. The origin and amplitude of systematic effects and the possibility to increase the precision of this method are discussed

[en] We use the galaxy angular power spectrum at z ∼ 0.5–1.2 from the Canada-France-Hawaii-Telescope Legacy Survey Wide fields (CFHTLS-Wide) to constrain separately the total neutrino mass Σm_ν and the effective number of neutrino species N_eff. This survey has recently benefited from an accurate calibration of the redshift distribution, allowing new measurements of the (non-linear) matter power spectrum in a unique range of scales and redshifts sensitive to neutrino free streaming. Our analysis makes use of a recent model for the effect of neutrinos on the weakly non-linear matter power spectrum derived from accurate N-body simulations. We show that CFHTLS, combined with WMAP7 and a prior on the Hubble constant provides an upper limit of Σm_ν < 0.29 eV and N_eff = 4.17^+1.62_−1.26 (2 σ confidence levels). If we omit smaller scales which may be affected by non-linearities, these constraints become Σm_ν < 0.41 eV and N_eff = 3.98^+2.02_−1.20 (2 σ confidence levels). Finally we show that the addition of other large scale structures probes can further improve these constraints, demonstrating that high redshift large volumes surveys such as CFHTLS are complementary to other cosmological probes of the neutrino mass