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L'évolution et la composition de l'Univers sont deux caractéristiques apparemment indépendantes et pourtant intrinsèquement liées. La première nous apprend que l'Univers est en expansion à un rythme variable, la seconde qu'il est constitué majoritairement de composantes non lumineuses et de nature inconnue, baptisées « matière noire » et « énergie noire ». Afin d'apporter de nouvelles pierres à l'édifice cosmologique, les chercheurs s'attachent à mieux comprendre comment évolue l'expansion de notre Univers au moyen d'expériences de plus en plus ambitieuses. Tirant profit de la dualité entre géométrie et contenu de l'Univers, ils quantifient ainsi toujours plus précisément le rôle joué par les composantes sombres, espérant en dévoiler un jour la nature. [ABSTRACT FROM AUTHOR]

We have developed two independent methods for measuring the one-dimensional power spectrum of the transmitted flux in the Lyman-α forest. The first method is based on a Fourier transform and the second on a maximum-likelihood estimator. The two methods are independent and have different systematic uncertainties. Determination of the noise level in the data spectra was subject to a new treatment, because of its significant impact on the derived power spectrum. We applied the two methods to 13 821 quasar spectra from SDSS-III/BOSS DR9 selected from a larger sample of over 60 000 spectra on the basis of their high quality, high signal-to-noise ratio (S/N), and good spectral resolution. The power spectra measured using either approach are in good agreement over all twelve redshift bins from (z) = 2.2 to (z) = 4.4, and scales from 0.001 km s-1 to 0.02 km s-1. We determined the methodological and instrumental systematic uncertainties of our measurements. We provide a preliminary cosmological interpretation of our measurements using available hydrodynamical simulations. The improvement in precision over previously published results from SDSS is a factor 2-3 for constraints on relevant cosmological parameters. For a ΛCDM model and using a constraint on H0 that encompasses measurements based on the local distance ladder and on CMB anisotropies, we infer σ8 = 0.83 ± 0.03 and ns = 0.97 ± 0.02 based on Hi absorption in the range 2.1 < z < 3.7. [ABSTRACT FROM AUTHOR]

We report recent measurements of the three CKM angles of the Unitarity Triangle using about 383 millions $b\overline{b}$ pairs collected with the BABAR detector at the PEP-II asymmetric-energy B Factory at SLAC. [ABSTRACT FROM AUTHOR]

If a significant fraction of the dark matter in the Universe is made of an ultra-light scalar field, named fuzzy dark matter (FDM) with a mass ma of the order of 10-22 - 10-21 eV, then its de Broglie wavelength is large enough to impact the physics of large-scale structure formation. In particular, the associated cut-off in the linear matter power spectrum modifies the structure of the intergalactic medium (IGM) at the scales probed by the Lyman-α forest of distant quasars. We study this effect by making use of dedicated cosmological simulations which take into account the hydrodynamics of the IGM. We explore heuristically the amplitude of quantum pressure for the FDM masses considered here and conclude that quantum effects should not modify significantly the non-linear evolution of matter density at the scales relevant to the measured Lyman-α flux power, and for ma ≳ 10-22 eV. We derive a scaling law between ma and the mass of the well-studied thermal warm dark matter model that is best adapted to the Lyman-α forest data, and differs significantly from the one inferred by a simple linear extrapolation. By comparing FDM simulations with the Lyman-α flux power spectra determined from the BOSS survey, and marginalizing over relevant nuisance parameters, we exclude FDM masses in the range 10-22 ≳ ma < 2.3 × 10-21 eV at 95 per cent CL. Adding higher resolution Lyman-α spectra extends the exclusion range up to 2.9 × 10-21 eV. This provides a significant constraint on FDM models tailored to solve the 'small-scale problems' of CDM. [ABSTRACT FROM AUTHOR]

We present a measurement of the baryon acoustic oscillation (BAO) scale at redshift z = 2.35 from the three-dimensional correlation of Lyman-α (Lyα) forest absorption and quasars. The study uses 266 590 quasars in the redshift range 1.77 <  z <  3.5 from the Sloan Digital Sky Survey (SDSS) Data Release 14 (DR14). The sample includes the first two years of observations by the SDSS-IV extended Baryon Oscillation Spectroscopic Survey (eBOSS), providing new quasars and re-observations of BOSS quasars for improved statistical precision. Statistics are further improved by including Lyα absorption occurring in the Lyβ wavelength band of the spectra. From the measured BAO peak position along and across the line of sight, we determined the Hubble distance DH and the comoving angular diameter distance DM relative to the sound horizon at the drag epoch rd: DH(z = 2.35)/rd = 9.20 ± 0.36 and DM(z = 2.35)/rd = 36.3 ± 1.8. These results are consistent at 1.5σ with the prediction of the best-fit spatially-flat cosmological model with the cosmological constant reported for the Planck (2016) analysis of cosmic microwave background anisotropies. Combined with the Lyα auto-correlation measurement presented in a companion paper, the BAO measurements at z = 2.34 are within 1.7σ of the predictions of this model. [ABSTRACT FROM AUTHOR]

We measure the imprint of primordial baryon acoustic oscillations (BAOs) in the correlation function of Lyα absorption in quasar spectra from the Baryon Oscillation Spectroscopic Survey (BOSS) and the extended BOSS (eBOSS) in Data Release 14 (DR14) of the Sloan Digital Sky Survey (SDSS)-IV. In addition to 179 965 spectra with absorption in the Lyman-α (Lyα) region, we use Lyα absorption in the Lyman-β region of 56 154 spectra for the first time. We measure the Hubble distance, DH, and the comoving angular diameter distance, DM, relative to the sound horizon at the drag epoch rd at an effective redshift z = 2.34. Using a physical model of the correlation function outside the BAO peak, we find DH(2.34)/rd = 8.86 ± 0.29 and DM(2.34)/rd = 37.41 ± 1.86, within 1σ from the flat-ΛCDM model consistent with CMB anisotropy measurements. With the addition of polynomial "broadband" terms, the results remain within one standard deviation of the CMB-inspired model. Combined with the quasar-Lyα cross-correlation measurement presented in a companion paper, the BAO measurements at z = 2.35 are within 1.7σ of the predictions of this model. [ABSTRACT FROM AUTHOR]

Current and future large redshift surveys, as the Sloan Digital Sky Survey IV extended Baryon Oscillation Spectroscopic Survey (SDSS-IV/eBOSS) or the Dark Energy Spectroscopic Instrument (DESI), will use emission-line galaxies (ELGs) to probe cosmological models by mapping the large-scale structure of the Universe in the redshift range 0.6 < z < 1.7. With current data, we explore the halo-galaxy connection by measuring three clustering properties of g-selected ELGs as matter tracers in the redshift range 0.6 < z < 1: (i) the redshift-space two-point correlation function using spectroscopic redshifts from the BOSS ELG sample and VIPERS; (ii) the angular two-point correlation function on the footprint of the CFHT-LS; (iii) the galaxy-galaxy lensing signal around the ELGs using the CFHTLenS. We interpret these observations by mapping them on to the latest high-resolution MultiDark Planck N-body simulation, using a novel (Sub)Halo-Abundance Matching technique that accounts for the ELG incompleteness. ELGs at z ~ 0.8 live in haloes of (1 ± 0.5) × 1012 h-1M☉ and 22.5 ± 2.5 per cent of them are satellites belonging to a larger halo. The halo occupation distribution of ELGs indicates that we are sampling the galaxies in which stars form in the most efficient way, according to their stellar-to-halo mass ratio. [ABSTRACT FROM AUTHOR]

Emission line galaxies are one of the main tracers of the large-scale structure to be targeted by the next-generation dark energy surveys. To provide a better understanding of the properties and statistics of these galaxies, we have collected spectroscopic data from the VVDS and DEEP2 deep surveys and estimated the galaxy luminosity functions (LFs) of three distinct emission lines, [OII](λλ3726,3729) (0.5 < z < 1.3), Hβ (λ4861) (0.3 < z < 0.8) and [OIII](λ5007) (0.3 < z < 0.8). Our measurements are based on 35 639 emission line galaxies and cover a volume of ~107 Mpc³. We present the first measurement of the Hβ LF at these redshifts. We have also compiled LFs from the literature that were based on independent data or covered different redshift ranges, and we fit the entire set over the whole redshift range with analytic Schechter and Saunders models, assuming a natural redshift dependence of the parameters. We find that the characteristic luminosity (L*) and density (ϕ*) of all LFs increase with redshift. Using the Schechter model over the redshift ranges considered, we find that, for [OII] emitters, the characteristic luminosity L*(z = 0.5) = 3.2 × 1041 erg s-1 increases by a factor of 2.7 ± 0.2 from z = 0.5 to 1.3; for Hβ emitters L*(z = 0.3) = 1.3 × 1041 erg s-1 increases by a factor of 2.0 ± 0.2 from z = 0.3 to 0.8; and for [OIII] emitters L*(z = 0.3) = 7.3 × 1041 erg s-1 increases by a factor of 3.5 ± 0.4 from z = 0.3 to 0.8. [ABSTRACT FROM AUTHOR]

The signature left in quasar spectra by neutral hydrogen in the Universe allows constraining the sum of the neutrino masses with a better sensitivity than laboratory experiments and may shed new light on the neutrino mass hierarchy and the absolute mass-scale of neutrinos. Constraints on cosmological parameters and on the dark energy equation of state can also be derived from a joint parameter estimation procedure. However, this requires a detailed modeling of the line-of-sight power spectrum of the transmitted flux in the Lyman-α (Lyα) forest on scales ranging from a few to hundreds of megaparsecs, which in turn demands the inclusion and careful treatment of cosmological neutrinos. To this end, we present here a suite of state-of-the-art hydrodynamical simulations with cold dark matter (CDM), baryons and massive neutrinos, specifically targeted for modeling the low-density regions of the intergalactic medium (IGM) as probed by the Lyα forest at high-redshift. The simulations span volumes ranging from (25 h-1 Mpc)³ to (100 h-1 Mpc)³, and were made using either 3 × 192³ ≃ 21 million or 3 × 768³ ≃ 1.4 billion particles. The resolution of the various runs was further enhanced, so that we reached the equivalent of 3×3072³ ≃ 87 billion particles in a (100 h−1 Mpc)³ box size. The chosen cosmological parameters are compatible with the latest Planck 2013 results, although we also explored the effect of slight variations in the main cosmological and astrophysical parameters. We adopted a particle-type implementation of massive neutrinos, and consider three degenerate species with masses Σmν = 0.1, 0.2, 0.3, 0.4, and 0.8 eV, respectively. We improved on previous studies in several ways, in particular with updated routines for IGM radiative cooling and heating processes, and initial conditions based on second-order Lagrangian perturbation theory (2LPT) rather than the Zel'dovich approximation. This allowed us to safely start our runs at relatively low redshift (z = 30), which reduced the shot-noise contamination in the neutrino component and the CPU consumption. In addition to providing technical details on the simulations, we present the first analysis of the nonlinear three- and one-dimensional matter and flux power spectra from these models, and characterize the statistics of the transmitted flux in the Lyα forest including the effect of massive neutrinos. In synergy with recent data from the Baryon Acoustic Spectroscopic Survey (BOSS) and the Planck satellite, and with a grid of corresponding neutrino-less simulations, our realizations will allow us to constrain cosmological parameters and neutrino masses directly from the Lyα forest with improved sensitivity. In addition, our simulations can be useful for a broader variety of cosmological and astrophysical applications, ranging from the three-dimensional modeling of the Lyα forest to cross-correlations between different probes, studying the expansion history of the Universe including massive neutrinos, and particle-physics related topics. Moreover, while our simulations have been specifically designed to meet the requirements of the BOSS survey, they can also be used for upcoming or future experiments - such as eBOSS and DESI. [ABSTRACT FROM AUTHOR]

The next generation of wide-field spectroscopic redshift surveys will map the large-scale galaxy distribution in the redshift range 0.7 ⩽ z ⩽ 2 to measure baryonic acoustic oscillations (BAO). The primary optical signature used in this redshift range comes from the [OII] emission line doublet, which provides a unique redshift identification that can minimize confusion with other single emission lines. To derive the required spectrograph resolution for these redshift surveys, we simulate observations of the [OII] (λλ 3727, 3729) doublet for various instrument resolutions, and line velocities. We foresee two strategies for the choice of the resolution for future spectrographs for BAO surveys. For bright [OII] emitter surveys ([OII] flux ∼30 × 10-17erg cm-2s-1 like SDSS-IV/eBOSS), a resolution of R ∼ 3300 allows the separation of 90 percent of the doublets. The impact of the sky lines on the completeness in redshift is less than 6 percent. For faint [OII] emitter surveys ([OII] flux ∼10 × 10-17erg cm-2s-1 like DESi), the detection improves continuously with resolution, so we recommend the highest possible resolution, the limit being given by the number of pixels (4k by 4k) on the detector and the number of spectroscopic channels (2 or 3). [ABSTRACT FROM AUTHOR]

We present a new measurement of the optical quasar luminosity function (QLF), using data from the Sloan Digital Sky Survey-III: Baryon Oscillation Spectroscopic Survey (SDSS-III: BOSS). From the SDSS-IIIData ReleaseNine, a uniform sample of 22,301 i ≲ 21.8 quasars are selected over an area of 2236 deg2, with confirmed spectroscopic redshifts between 2.2 < z < 3.5, filling in a key part of the luminosity-redshift plane for optical quasar studies. The completeness of the survey is derived through simulated quasar photometry, and this completeness estimate is checked using a sample of quasars selected by their photometric variability within the BOSS footprint. We investigate the level of systematics associated with our quasar sample using the simulations, in the process generating color-redshift relations and a new quasar K-correction.We probe the faint end of the QLF toMi (z = 2.2)≈−24.5 and see a clear break in the QLF at all redshifts up to z = 3.5. A log-linear relation (in logΦ" - M") for a luminosity evolution and density evolution model is found to adequately describe our data within the range 2.2 < z < 3.5; across this interval the break luminosity increases by a factor of ∼2.6 while Φ" declines by a factor of ∼8. At z ≲ 2.2 our data are reasonably well fit by a pure luminosity evolution model, and only a weak signature of "AGN downsizing" is seen, in line with recent studies of the hard X-ray luminosity function. We compare our measured QLF to a number of theoretical models and find that modelsmaking a variety of assumptions about quasar triggering and halo occupation can fit our data over a wide range of redshifts and luminosities. [ABSTRACT FROM AUTHOR]

Abstract: 3D mapping of matter distribution in the Universe through the 21 cm radio emission of atomic hydrogen (HI) is a complementary approach to optical surveys for the study of the Large Scale Structures, in particular for measuring the BAO (Baryon Acoustic Oscillation) scale up to redshifts , and therefore constraining dark energy parameters. We propose a novel method to map the HI mass distribution in three dimensions in radio, without detecting or identifying individual compact sources. This method would require an instrument with a large instantaneous bandwidth () and high sensitivity, while a rather modest angular resolution () should be sufficient. These requirements can be met by a dense interferometric array or a phased array (FPA) in the focal plane of a large primary reflector, representing a total collecting area of a few thousand square meters with few hundred simultaneous beams covering a 20 to 100 square degrees field of view. We describe the development and qualification of an electronic and data processing system for digital radio interferometry and beam forming suitable for such instruments with several hundred receiver elements. [Copyright &y& Elsevier]

The Lyα forest transmission probability distribution function (PDF) is an established probe of the intergalactic medium (IGM) astrophysics, especially the temperature-density relationship of the IGM. We measure the transmission PDF from 3393 Baryon Oscillations Spectroscopic Survey (BOSS) quasars from Sloan Digital Sky Survey Data Release 9, and compare with mock spectra that include careful modeling of the noise, continuum, and astrophysical uncertainties. The BOSS transmission PDFs, measured at 〈 z〉 = [2.3, 2.6, 3.0], are compared with PDFs created from mock spectra drawn from a suite of hydrodynamical simulations that sample the IGM temperature-density relationship, γ, and temperature at mean density, T0, where T(Δ) = T0Δγ – 1. We find that a significant population of partial Lyman-limit systems (LLSs) with a column-density distribution slope of βpLLS ∼ – 2 are required to explain the data at the low-transmission end of transmission PDF, while uncertainties in the mean Lyα forest transmission affect the high-transmission end. After modeling the LLSs and marginalizing over mean transmission uncertainties, we find that γ = 1.6 best describes the data over our entire redshift range, although constraints on T0 are affected by systematic uncertainties. Within our model framework, isothermal or inverted temperature-density relationships (γ ⩽ 1) are disfavored at a significance of over 4σ, although this could be somewhat weakened by cosmological and astrophysical uncertainties that we did not model. [ABSTRACT FROM AUTHOR]