SPACE: the spectroscopic all-sky cosmic explorer

We describe the scientific motivations, the mission concept and the instrumentation of SPACE, a class-M mission proposed for concept study at the first call of the ESA Cosmic-Vision 2015–2025 planning cycle. SPACE aims to produce the largest three-dimensional evolutionary map of the Universe over the past 10 billion years by taking near-IR spectra and measuring redshifts for more than half a billion galaxies at 0

The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey: single-probe measurements from CMASS anisotropic galaxy clustering

Jean-Paul Richard Kneib, David Schlegel, Yuting Wang

With the largest spectroscopic galaxy survey volume drawn from the SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS), we can extract cosmological constraints from the measurements of redshift and geometric distortions at quasi-linear scales (e.g. above 50 h(-1) Mpc). We analyse the broad-range shape of the monopole and quadrupole correlation functions of the BOSS Data Release 12 (DR12) CMASS galaxy sample, at the effective redshift z = 0.59, to obtain constraints on the Hubble expansion rate H(z), the angular-diameter distance D-A(z), the normalized growth rate f(z)sigma(8)(z), and the physical matter density Omega(m)h(2). We obtain robust measurements by including a polynomial as the model for the systematic errors, and find it works very well against the systematic effects, e.g. ones induced by stars and seeing. We provide accurate measurements {D-A(0.59)r(s,fid)/r(s), H(0.59)r(s)/r(s, fid), f(0.59)sigma(8)(0.59), Omega(m)h(2)} = {1427 +/- 26 Mpc, 97.3 +/- 3.3 km s(-1) Mpc(-1), 0.488 +/- 0.060, 0.135 +/- 0.016}, where r(s) is the comoving sound horizon at the drag epoch and r(s, fid) = 147.66 Mpc is the sound scale of the fiducial cosmology used in this study. The parameters which are not well constrained by our galaxy clustering analysis are marginalized over with wide flat priors. Since no priors from other data sets, e.g. cosmic microwave background (CMB), are adopted and no dark energy models are assumed, our results from BOSS CMASS galaxy clustering alone may be combined with other data sets, i. e. CMB, SNe, lensing or other galaxy clustering data to constrain the parameters of a given cosmological model. The uncertainty on the dark energy equation of state parameter, w, from CMB+CMASS is about 8 per cent. The uncertainty on the curvature fraction, Omega(k), is 0.3 per cent. We do not find deviation from flat Lambda CDM.

Oxford Univ Press2016

Cosmological implications of baryon acoustic oscillation measurements

Johan Comparat, Timothée Guy Olivier Delubac, Jean-Paul Richard Kneib, David Schlegel

We derive constraints on cosmological parameters and tests of dark energy models from the combination of baryon acoustic oscillation (BAO) measurements with cosmic microwave background (CMB) data and a recent reanalysis of Type Ia supernova (SN) data. In particular, we take advantage of high-precision BAO measurements from galaxy clustering and the Lyman-alpha forest (LyaF) in the SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS). Treating the BAO scale as an uncalibrated standard ruler, BAO data alone yield a high confidence detection of dark energy; in combination with the CMB angular acoustic scale they further imply a nearly flat universe. Adding the CMB-calibrated physical scale of the sound horizon, the combination of BAO and SN data into an "inverse distance ladder" yields a measurement of H-0 = 67.3 +/- 1.1 km s(-1) Mpc(-1), with 1.7% precision. This measurement assumes standard prerecombination physics but is insensitive to assumptions about dark energy or space curvature, so agreement with CMB-based estimates that assume a flat Lambda CDM cosmology is an important corroboration of this minimal cosmological model. For constant dark energy (Lambda), our BAO + SN + CMB combination yields matter density Omega(m) = 0.301 +/- 0.008 and curvature Omega(k) = -0.003 +/- 0.003. When we allow more general forms of evolving dark energy, the BAO + SN + CMB parameter constraints are always consistent with flat Lambda CDM values at approximate to 1 sigma. While the overall chi(2) of model fits is satisfactory, the LyaF BAO measurements are in moderate (2-2.5 sigma) tension with model predictions. Models with early dark energy that tracks the dominant energy component at high redshift remain consistent with our expansion history constraints, and they yield a higher H-0 and lower matter clustering amplitude, improving agreement with some low redshift observations. Expansion history alone yields an upper limit on the summed mass of neutrino species, Sigma m(nu) < 0.56 eV (95% confidence), improving to Sigma m(nu) < 0.25 eV if we include the lensing signal in the Planck CMB power spectrum. In a flat Lambda CDM model that allows extra relativistic species, our data combination yields N-eff = 3.43 +/- 0.26; while the LyaF BAO data prefer higher N-eff when excluding galaxy BAO, the galaxy BAO alone favor N-eff approximate to 3. When structure growth is extrapolated forward from the CMB to low redshift, standard dark energy models constrained by our data predict a level of matter clustering that is high compared to most, but not all, observational estimates.

Amer Physical Soc2015

Cosmological implications of baryon acoustic oscillation measurements

Johan Comparat, Timothée Guy Olivier Delubac, Jean-Paul Richard Kneib, David Schlegel

Amer Physical Soc2015

The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey: single-probe measurements from CMASS anisotropic galaxy clustering

Jean-Paul Richard Kneib, David Schlegel, Yuting Wang

Oxford Univ Press2016