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The Baryon Oscillation Spectroscopic Survey (BOSS) is designed to measure the scale of baryon acoustic oscillations (BAO) in the clustering of matter over a larger volume than the combined efforts of all previous spectroscopic surveys of large-scale structure. BOSS uses 1.5 million luminous galaxies as faint as i = 19.9 over 10,000 deg 2 to measure BAO to redshifts z < 0.7. Observations of neutral hydrogen in the Lyα forest in more than 150,000 quasar spectra (g < 22) will constrain BAO over the redshift range 2.15 < z < 3.5. Early results from BOSS include the first detection of the large-scale three-dimensional clustering of the Lyα forest and a strong detection from the Data Release 9 data set of the BAO in the clustering of massive galaxies at an effective redshift z = 0.57. We project that BOSS will yield measurements of the angular diameter distance d A to an accuracy of 1.0% at redshifts z = 0.3 and z = 0.57 and measurements of H (z) to 1.8% and 1.7% at the same redshifts. Forecasts for Lyα forest constraints predict a measurement of an overall dilation factor that scales the highly degenerate D A (z) and H −1 (z) parameters to an accuracy of 1.9% at z ∼ 2.5 when the survey is complete. Here, we provide an overview of the selection of spectroscopic targets, planning of observations, and analysis of data and data quality of BOSS.

We combine the Ly-α forest power spectrum (LYA) from the Sloan Digital Sky Survey (SDSS) and high resolution spectra with cosmic microwave background (CMB) including 3-year WMAP, and supernovae (SN) and galaxy clustering constraints to derive new constraints on cosmological parameters. The existing LYA power spectrum analysis is supplemented by constraints on the mean flux decrement derived using a principle component analysis for quasar continua, which improves the LYA constraints on the linear power. We find some tension between the WMAP3 and LYA power spectrum amplitudes, at the ∼ 2σ level, which is partially alleviated by the inclusion of other observations: we find σ8 = 0.85 ± 0.02 compared to σ8 = 0.80 ± 0.03 without LYA. For the slope we find ns = 0.965 ± 0.012. We find no evidence for the running of the spectral index in the combined analysis, dn/d ln k = −(1.5 ± 1.2) × 10 −2 , in agreement with inflation. The limits on the sum of neutrino masses are significantly improved: mν < 0.17eV at 95% (< 0.32eV at 99.9%). This result, when combined with atmospheric and solar neutrino mixing constraints, requires that the neutrino masses cannot be degenerate, m3/m1 > 1.3 (95% c.l.). Assuming a thermalized fourth neutrino we find ms < 0.26eV at 95% c.l. and such neutrino cannot be an explanation for the LSND results. In the limits of massless neutrinos we obtain the effective number of neutrinos−2.5 and N eff ν = 3.04 is allowed only at 2.4 sigma. The constraint on the dark energy equation of state is w = −1.04 ± 0.06. The constraint on curvature is Ω k = −0.003 ± 0.006. Cosmic strings limits are Gµ < 2.3 × 10 −7 at 95% c.l. and correlated isocurvature models are also tightly constrained.PACS numbers: 98.80.Jk, 98.80.Cq

On very large scales, density fluctuations in the Universe are small, suggesting a perturbative model for large-scale clustering of galaxies (or other dark matter tracers), in which the galaxy density is written as a Taylor series in the local mass density, δ, with the unknown coefficients in the series treated as free "bias" parameters. We extend this model to include dependence of the galaxy density on the local values of ∇i∇j φ and ∇ivj , where φ is the potential and v is the peculiar velocity. We show that only two new free parameters are needed to model the power spectrum and bispectrum up to 4th order in the initial density perturbations, once symmetry considerations and equivalences between possible terms are accounted for. One of the new parameters is a bias multiplying sijsji, where sij =ˆ∇i∇j(There are other, observationally equivalent, ways to write the two terms, e.g., using θ − δ instead of sijsji.) We show how shortrange (non-gravitational) non-locality can be included through a controlled series of higher derivative terms, starting with R 2 ∇ 2 δ, where R is the scale of non-locality (this term will be a small correction as long as k 2 R 2 is small, where k is the observed wavenumber). We suggest that there will be much more information in future huge redshift surveys in the range of scales where beyond-linear perturbation theory is both necessary and sufficient than in the fully linear regime. * Electronic address: pmcdonal@cita.utoronto.ca † Electronic address: roy@lepus.astro.utoronto.ca

A sample of eight quasars observed at high resolution and signal-to-noise is used to determine the probability distribution function (PDF), the power spectrum, and the correlation function of the transmitted flux in the Lyα forest, in three redshift bins centered at z = 2.41, 3.00, and 3.89. All the results are presented in tabular form, with full error covariance matrices to allow for comparisons with any numerical simulations and with other data sets. The observations are compared with a numerical simulation of the Lyα forest of a ΛCDM model with Ω = 0.4, known to agree with other large-scale structure observational constraints. There is excellent agreement for the PDF, if the mean transmitted flux is adjusted to match the observations. A small difference between the observed and predicted PDF is found at high fluxes and low redshift, which may be due to the uncertain effects of fitting the spectral continuum. Using the numerical simulation, we show how the flux power spectrum can be used to recover the initial power spectrum of density fluctuations. From our sample of eight quasars, we measure the amplitude of the mass power spectrum to correspond to a linear variance per unit ln k of ∆ 2 ρ (k) = 0.72 ± 0.09 at k = 0.04( km s −1 ) −1 and z = 3, and the slope of the power spectrum near the same k to be n p = −2.55 ± 0.10 (statistical error bars). The results are statistically consistent with Croft et al. , although our value for the rms fluctuation is lower by a factor 0.75. For the ΛCDM model we use, the implied primordial slope is n = 0.93 ± 0.10, and the normalization is σ 8 = 0.68 + 1.16(0.95 − n) ± 0.04.

We use the Ly-α forest power spectrum measured by the Sloan Digital Sky Survey (SDSS) and high-resolution spectroscopy observations in combination with cosmic microwave background and galaxy clustering constraints to place limits on a sterile neutrino as a dark matter candidate in the warm dark matter (WDM) scenario. Such a neutrino would be created in the early universe through mixing with an active neutrino and would suppress structure on scales smaller than its free streaming scale. We ran a series of high-resolution hydrodynamic simulations with varying neutrino mass to describe the effect of a sterile neutrino on the Ly-α forest power spectrum. We find that the mass limit is ms > 14keV at 95% c.l. (10keV at 99.9%), which is nearly an order of magnitude tighter constraint than previously published limits and is above the upper limit allowed by X-ray constraints, excluding this candidate as dark matter in this model. The corresponding limit for a neutrino that decoupled early while in thermal equilibrium is 2.5keV (95 % c.l.). One of the major unsolved mysteries in cosmology is the nature of the dark matter in the universe. Observational evidence points towards cold dark matter (CDM), for which random velocities are negligible. Two of the leading particle physics candidates, the lightest supersymmetric partner and axions, both require extensions beyond the standard model. At the same time, neutrino experiments over the past decade have shown that neutrinos oscillate from one flavor to another, which is only possible if they have mass. Current data from atmospheric and solar neutrino experiments [1,2] are compatible with mixing between the three active neutrino families. Perhaps the simplest way to incorporate these neutrino phenomena into the standard model is to add right-handed neutrinos, just as for other fermions.Given this extension of the standard model it is natural to ask if these (almost) sterile right-handed neutrinos can also explain the dark matter [3]. At least two sterile neutrinos are required to explain the origin of neutrino mass and existence of different mass mixing scales in solar and atmospheric neutrinos, so in a model with three families of sterile neutrinos a third one can act as dark matter [4]. Such neutrinos free stream and erase all fluctuations on scales smaller than the free streaming length. This length is roughly proportional to the temperature and inversely proportional to the mass of neutrinos. Thus if the neutrino mass is sufficiently high, or the temperature sufficiently low, then it acts just like CDM and can satisfy all of the observational constraints from structure formation. Current constraints require the neutrino mass to be above 1.8keV [5,6]. This is below the 5-8keV upper limits from the absence of detection of X-ray photons from radiative decays [7,8,9,10]. A massive neutrino in the keV range has also been suggested as a possible explanation for high pulsar velocities [11] and such a model can possibly explain baryon asymmetry in the universe [12].A sterile neutri...

We present Fisher matrix projections for future cosmological parameter measurements, including neutrino masses, Dark Energy, curvature, modified gravity, the inflationary perturbation spectrum, non-Gaussianity, and dark radiation. We focus on DESI and generally redshift surveys (BOSS, HETDEX, eBOSS, Euclid, and WFIRST), but also include CMB (Planck) and weak gravitational lensing (DES and LSST) constraints. The goal is to present a consistent set of projections, for concrete experiments, which are otherwise scattered throughout many papers and proposals. We include neutrino mass as a free parameter in most projections, as it will inevitably be relevant -DESI and other experiments can measure the sum of neutrino masses to ∼ 0.02 eV or better, while the minimum possible sum is ∼ 0.06 eV. We note that constraints on Dark Energy are significantly degraded by the presence of neutrino mass uncertainty, especially when using galaxy clustering only as a probe of the BAO distance scale (because this introduces additional uncertainty in the background evolution after the CMB epoch). Using broadband galaxy power becomes relatively more powerful, and bigger gains are achieved by combining lensing survey constraints with redshift survey constraints. We do not try to be especially innovative, e.g., with complex treatments of potential systematic errors -these projections are intended as a straightforward baseline for comparison to more detailed analyses.

We measure the power spectrum, P F (k, z), of the transmitted flux in the Lyα forest using 3035 high redshift quasar spectra from the Sloan Digital Sky Survey. This sample is almost two orders of magnitude larger than any previously available data set, yielding statistical errors of ∼ 0.6% and ∼ 0.005 on, respectively, the overall amplitude and logarithmic slope of P F (k, z). This unprecedented statistical power requires a correspondingly careful analysis of the data and of possible systematic contaminations in it. For this purpose we reanalyze the raw spectra to make use of information not preserved by the standard pipeline. We investigate the details of the noise in the data, resolution of the spectrograph, sky subtraction, quasar continuum, and metal absorption. We find that background sources such as metals contribute significantly to the total power and have to be subtracted properly. We also find clear evidence for SiIII correlations with the Lyα forest and suggest a simple model to account for this contribution to the power. While it is likely that our newly developed analysis technique does not eliminate all systematic errors in the P F (k, z) measurement below the level of the statistical errors, our tests indicate that any residual systematics in the analysis are unlikely to affect the inference of cosmological parameters from P F (k, z). These results should provide an essential ingredient for all future attempts to constrain modeling of structure formation, cosmological parameters, and theories for the origin of primordial fluctuations.