We measure the luminosity and color dependence and the redshiftevolution of galaxy clustering in the Sloan Digital Sky Survey-IIIBaryon Oscillation Spectroscopic Survey Ninth Data Release. We focus onthe projected two-point correlation function (2PCF) of subsets of itsCMASS sample, which includes about 260,000 galaxies over ~3,300 sq. degin the redshift range 0.43
We explore the benefits of using a passively evolving population ofgalaxies to measure the evolution of the rate of structure growthbetween z = 0.25 and 0.65 by combining data from the Sloan Digital SkySurvey (SDSS) I/II and SDSS-III surveys. The large-scale linear bias ofa population of dynamically passive galaxies, which we select from bothsurveys, is easily modelled. Knowing the bias evolution breaksdegeneracies inherent to other methodologies, and decreases theuncertainty in measurements of the rate of structure growth and thenormalization of the galaxy power spectrum by up to a factor of 2. If wetranslate our measurements into a constraint on σ8(z =0) assuming a concordance cosmological model and general relativity(GR), we find that using a bias model improves our uncertainty by afactor of nearly 1.5. Our results are consistent with a flat Λcold dark matter model and with GR.
We analyse the density field of galaxies observed by the Sloan DigitalSky Survey (SDSS)-III Baryon Oscillation Spectroscopic Survey (BOSS)included in the SDSS Data Release Nine (DR9). DR9 includes spectroscopicredshifts for over 400 000 galaxies spread over a footprint of 3275deg2. We identify, characterize and mitigate the impact ofsources of systematic uncertainty on large-scale clusteringmeasurements, both for angular moments of the redshift-space correlationfunction, ξℓ(s), and the spherically averaged powerspectrum, P(k), in order to ensure that robust cosmological constraintswill be obtained from these data. A correlation between the projecteddensity of stars and the higher redshift (0.43 < z < 0.7) galaxysample (the approximately constant stellar mass threshold 'CMASS'sample) due to imaging systematics imparts a systematic error that islarger than the statistical error of the clustering measurements atscales s > 120 h-1 Mpc or k < 0.01 h Mpc-1.We find that these errors can be ameliorated by weighting galaxies basedon their surface brightness and the local stellar density. Theclustering of CMASS galaxies found in the Northern and Southern Galacticfootprints of the survey generally agrees to within 2σ. We usemock galaxy catalogues that simulate the CMASS selection function todetermine that randomly selecting galaxy redshifts in order to simulatethe radial selection function of a random sample imparts the leastsystematic error on ξℓ(s) measurements and that thissystematic error is negligible for the spherically averaged correlationfunction, ξ0. We find a peak in ξ0 ats˜ 200 h-1 Mpc, with a corresponding feature withperiod ˜0.03 h Mpc-1 in P(k), and find features atleast as strong in 4.8 per cent of the mock galaxy catalogues,concluding this feature is likely to be a consequence of cosmicvariance. The methods we recommend for the calculation of clusteringmeasurements using the CMASS sample are adopted in companion papers thatlocate the position of the baryon acoustic oscillation feature,constrain cosmological models using the full shape of ξ0and measure the rate of structure growth.
We analyse the anisotropic clustering of massive galaxies from the SloanDigital Sky Survey III Baryon Oscillation Spectroscopic Survey (BOSS)Data Release 9 (DR9) sample, which consists of 264 283 galaxies in theredshift range 0.43 < z < 0.7 spanning 3275 deg2. Bothpeculiar velocities and errors in the assumed redshift-distance relation('Alcock-Paczynski effect') generate correlations between clusteringamplitude and orientation with respect to the line of sight. Togetherwith the sharp baryon acoustic oscillation (BAO) standard ruler, ourmeasurements of the broad-band shape of the monopole and quadrupolecorrelation functions simultaneously constrain the comoving angulardiameter distance (2190 ± 61 Mpc) to z = 0.57, the Hubbleexpansion rate at z = 0.57 (92.4 ± 4.5 km s-1Mpc-1) and the growth rate of structure at that same redshift(dσ8/d ln a = 0.43 ± 0.069). Our analysisprovides the best current direct determination of both DA andH in galaxy clustering data using this technique. If we further assume aΛcold dark matter expansion history, our growth constrainttightens to dσ8/d ln a = 0.415 ± 0.034. Incombination with the cosmic microwave background, our measurements ofDA, H and dσ8/d ln a all separately requiredark energy at z > 0.57, and when combined implyΩΛ = 0.74 ± 0.016, independent of theUniverse's evolution at z < 0.57. All of these constraints assumescale-independent linear growth, and assume general relativity tocompute both O(10 per cent) non-linear model corrections and our errors.In our companion paper, Samushia et al., we explore further cosmologicalimplications of these observations.
We obtain constraints on cosmological parameters from the sphericallyaveraged redshift-space correlation function of the CMASS Data Release 9(DR9) sample of the Baryonic Oscillation Spectroscopic Survey (BOSS). Wecombine this information with additional data from recent cosmicmicrowave background (CMB), supernova and baryon acoustic oscillationmeasurements. Our results show no significant evidence of deviationsfrom the standard flat Λ cold dark matter model, whose basicparameters can be specified by Ωm = 0.285 ±0.009, 100 Ωb = 4.59 ± 0.09, ns =0.961 ± 0.009, H0 = 69.4 ± 0.8 kms-1 Mpc-1 and σ8 = 0.80 ±0.02. The CMB+CMASS combination sets tight constraints on the curvatureof the Universe, with Ωk = -0.0043 ± 0.0049, andthe tensor-to-scalar amplitude ratio, for which we find r < 0.16 atthe 95 per cent confidence level (CL). These data show a clear signatureof a deviation from scale invariance also in the presence of tensormodes, with ns < 1 at the 99.7 per cent CL. We deriveconstraints on the fraction of massive neutrinos of fν< 0.049 (95 per cent CL), implying a limit of ∑mν< 0.51 eV. We find no signature of a deviation from a cosmologicalconstant from the combination of all data sets, with a constraint ofwDE = -1.033 ± 0.073 when this parameter is assumedtime-independent, and no evidence of a departure from this value when itis allowed to evolve as wDE(a) = w0 +wa(1 - a). The achieved accuracy on our cosmologicalconstraints is a clear demonstration of the constraining power ofcurrent cosmological observations.
The Sloan Digital Sky Survey (SDSS) surveyed 14,555 deg2, anddelivered over a trillion pixels of imaging data. We present a study ofgalaxy clustering using 900,000 luminous galaxies with photometricredshifts, spanning between z = 0.45 and z = 0.65, constructed from theSDSS using methods described in Ross et al. This data set spans 11,000deg2 and probes a volume of 3 h -3Gpc3, making it the largest volume ever used for galaxyclustering measurements. We describe in detail the construction of thesurvey window function and various systematics affecting ourmeasurement. With such a large volume, high-precision cosmologicalconstraints can be obtained given careful control and understanding ofthe observational systematics. We present a novel treatment of theobservational systematics and its applications to the clustering signalsfrom the data set. In this paper, we measure the angular clusteringusing an optimal quadratic estimator at four redshift slices with an
Using high-resolution microwave sky maps made by the Atacama CosmologyTelescope, we for the first time present strong evidence for motions ofgalaxy clusters and groups via microwave background temperaturedistortions due to the kinematic Sunyaev-Zel’dovich effect. Galaxyclusters are identified by their constituent luminous galaxies observedby the Baryon Oscillation Spectroscopic Survey, part of the SloanDigital Sky Survey III. We measure the mean pairwise momentum ofclusters, with a probability of the signal being due to random errors of0.002, and the signal is consistent with the growth of cosmic structurein the standard model of cosmology.
We present the galaxy optical luminosity function for the redshift range0.05 < z < 0.75 from the AGN and Galaxy Evolution Survey, aspectroscopic survey of 7.6 deg2 in the Boötes field ofthe NOAO Deep Wide-Field Survey. Our statistical sample is composed of12,473 galaxies with known redshifts down to I = 20.4 (AB). Our resultsat low redshift are consistent with those from Sloan Digital Sky Survey;at higher redshift, we find strong evidence for evolution in theluminosity function, including differential evolution between blue andred galaxies. We find that the luminosity density evolves as (1 +z)(0.54 ± 0.64) for red galaxies and (1 + z)(1.64± 0.39) for blue galaxies.
We present measurements of the angular diameter distance D_A(z) and theHubble parameter H(z) at z=0.35 using the anisotropy of the baryonacoustic oscillation (BAO) signal measured in the galaxy clusteringdistribution of the Sloan Digital Sky Survey (SDSS) Data Release 7 (DR7)Luminous Red Galaxies (LRG) sample. Our work is the first to applydensity-field reconstruction to an anisotropic analysis of the acousticpeak. Reconstruction partially removes the effects of non-linearevolution and redshift-space distortions in order to sharpen theacoustic signal. We present the theoretical framework behind theanisotropic BAO signal and give a detailed account of the fitting modelwe use to extract this signal from the data. Our method focuses only onthe acoustic peak anisotropy, rather than the more model-dependentanisotropic information from the broadband power. We test the robustnessof our analysis methods on 160 LasDamas DR7 mock catalogues and find
We measure the Milky Way's rotation curve over the Galactocentric range4 kpc <~ R <~ 14 kpc from the first year of data from the ApachePoint Observatory Galactic Evolution Experiment. We model theline-of-sight velocities of 3365 stars in 14 fields with b = 0°between 30° <= l <= 210° out to distances of 10 kpc usingan axisymmetric kinematical model that includes a correction for theasymmetric drift of the warm tracer population (σ R ≈ 35 km s-1). We determine the local value of thecircular velocity to be Vc (R 0) = 218 ± 6km s-1 and find that the rotation curve isapproximately flat with a local derivative between -3.0 kms-1 kpc-1 and 0.4 kms-1 kpc-1. We also measure the Sun'sposition and velocity in the Galactocentric rest frame, finding thedistance to the Galactic center to be 8 kpc < R 0 < 9kpc, radial velocity V R, &sun; = -10 ± 1 kms-1, and rotational velocity V phi, &sun;= 242+10 - 3 km s-1, ingood agreement with local measurements of the Sun's radial velocity andwith the observed proper motion of Sgr A*. We investigate varioussystematic uncertainties and find that these are limited to offsets atthe percent level, ~2 km s-1 in Vc .Marginalizing over all the systematics that we consider, we find thatVc (R 0) < 235 km s-1 at
The Sloan Digital Sky Survey III (SDSS-III) presents the firstspectroscopic data from the Baryon Oscillation Spectroscopic Survey(BOSS). This ninth data release (DR9) of the SDSS project includes535,995 new galaxy spectra (median z ~ 0.52), 102,100 new quasar spectra(median z ~ 2.32), and 90,897 new stellar spectra, along with the datapresented in previous data releases. These spectra were obtained withthe new BOSS spectrograph and were taken between 2009 December and 2011July. In addition, the stellar parameters pipeline, which determinesradial velocities, surface temperatures, surface gravities, andmetallicities of stars, has been updated and refined with improvementsin temperature estimates for stars with T eff < 5000 K andin metallicity estimates for stars with [Fe/H] > -0.5. DR9 includesnew stellar parameters for all stars presented in DR8, including starsfrom SDSS-I and II, as well as those observed as part of the SEGUE-2.The astrometry error introduced in the DR8 imaging catalogs has beencorrected in the DR9 data products. The next data release for SDSS-IIIwill be in Summer 2013, which will present the first data from theAPOGEE along with another year of data from BOSS, followed by the finalSDSS-III data release in 2014 December.
The accelerating expansion of the universe is the most surprisingcosmological discovery in many decades, implying that the universe isdominated by some form of "dark energy" with exotic physical properties,or that Einstein's theory of gravity breaks down on cosmological scales.The profound implications of cosmic acceleration have inspired ambitiousexperimental efforts to measure the history of expansion and growth ofstructure with percent-level precision or higher. We review in detailthe four most well established methods for making such measurements:Type Ia supernovae, baryon acoustic oscillations (BAO), weakgravitational lensing, and galaxy clusters. We pay particular attentionto the systematic uncertainties in these techniques and to strategiesfor controlling them at the level needed to exploit "Stage IV" darkenergy facilities such as BigBOSS, LSST, Euclid, and WFIRST. We brieflyreview a number of other approaches including redshift-spacedistortions, the Alcock-Paczynski test, and direct measurements of H_0.We present extensive forecasts for constraints on the dark energyequation of state and parameterized deviations from GR, achievable withStage III and Stage IV experimental programs that incorporatesupernovae, BAO, weak lensing, and CMB data. We also show the level ofprecision required for other methods to provide constraints competitivewith those of these fiducial programs. We emphasize the value of abalanced program that employs several of the most powerful methods incombination, both to cross-check systematic uncertainties and to takeadvantage of complementary information. Surveys to probe cosmicacceleration produce data sets with broad applications, and theycontinue the longstanding astronomical tradition of mapping the universein ever greater detail over ever larger scales.
The Apache Point Observatory Galactic Evolution Experiment (APOGEE) usesa dedicated 300-fiber, narrow-band near-infrared (1.51-1.7 μm), highresolution (R~22,500) spectrograph to survey approximately 100,000 giantstars across the Milky Way. This three-year survey, in operation sincelate-summer 2011 as part of the Sloan Digital Sky Survey III (SDSS III),will revolutionize our understanding of the kinematical and chemicalenrichment histories of all Galactic stellar populations. We present theperformance of the instrument from its first year in operation. Theinstrument is housed in a separate building adjacent to the 2.5-m SDSStelescope and fed light via approximately 45-meter fiber runs from thetelescope. The instrument design includes numerous innovations includinga gang connector that allows simultaneous connection of all fibers witha single plug to a telescope cartridge that positions the fibers on thesky, numerous places in the fiber train in which focal ratio degradationhad to be minimized, a large mosaic-VPH (290 mm x 475 mmelliptically-shaped recorded area), an f/1.4 six-element refractivecamera featuring silicon and fused silica elements with diameters aslarge as 393 mm, three near-infrared detectors mounted in a 1 x 3 mosaicwith sub-pixel translation capability, and all of these componentshoused within a custom, LN2-cooled, stainless steel vacuum cryostat withdimensions 1.4-m x 2.3-m x 1.3-m.
We present evidence that the incidence of active galactic nuclei (AGNs)and the distribution of their accretion rates do not depend on thestellar masses of their host galaxies, contrary to previous studies. Weuse hard (2-10 keV) X-ray data from three extragalactic fields (XMM-LSS,COSMOS, and ELAIS-S1) with redshifts from the Prism Multi-object Surveyto identify 242 AGNs with L 2-10 keV = 1042-44 ergs-1 within a parent sample of ~25,000 galaxies at 0.2 < z< 1.0 over ~3.4 deg2 and to i ~ 23. We find that althoughthe fraction of galaxies hosting an AGN at fixed X-ray luminosity risesstrongly with stellar mass, the distribution of X-ray luminosities isindependent of mass. Furthermore, we show that the probability that agalaxy will host an AGN can be defined by a universal Eddington ratiodistribution that is independent of the host galaxy stellar mass and hasa power-law shape with slope -0.65. These results demonstrate that AGNsare prevalent at all stellar masses in the range 9.5 and that the samephysical processes regulate AGN activity in all galaxies in this stellarmass range. While a higher AGN fraction may be observed in massivegalaxies, this is a selection effect related to the underlying Eddingtonratio distribution. We also find that the AGN fraction drops rapidlybetween z ~ 1 and the present day and is moderately enhanced (factor ~2)in galaxies with blue or green optical colors. Consequently, while AGNactivity and star formation appear to be globally correlated, we do notfind evidence that the presence of an AGN is related to the quenching ofstar formation or the color transformation of galaxies.
The Sloan Digital Sky Survey is now in its third phase (SDSS-III;Eisenstein et al. 2011AJ....142...72E) and is carrying out a combinationof four interleaved surveys that will continue until the summer of 2014.One of those surveys, the Baryon Oscillation Spectroscopic Survey(BOSS), commenced operations in late 2009 and is using essentially allthe dark time for SDSS-III. BOSS uses the same 2.5m Sloan Foundationtelescope that was used in SDSS-I/II, but since BOSS will observefainter targets, the fiber-fed spectrographs have been significantlyupgraded. These upgrades include: new CCDs with improved blue and redresponse; 1000 2" instead of 640 3" optical diameter fibers; higherthroughput gratings over a spectral range of 3600-10000Å at aresolution of about 2000, and improved optics.Prior to the commencement of BOSS spectroscopy, we carried outspectroscopy of quasar candidates selected from co-added photometry inSDSS Stripe 82. Observations of these candidates were carried out inqueue mode between 2008 September and 2009 January using the Hectospecmulti-fiber spectrograph on the 6.5m Multiple Mirror Telescope (MMT). InTables 14 and 15, we provide positions, PSF photometry (as observed,uncorrected for Galactic extinction), and redshifts for confirmedquasars from the MMT survey. Objects that are not flagged Primary in theCAS are listed separately (table 15).(2 data files).
The Near-Infrared Camera (NIRCam) on the James Webb Space Telescope(JWST) offers revolutionary gains in sensitivity throughout the 1-5μm region. NIRCam will enable great advances in all areas ofastrophysics, from the composition of objects in our own Kuiper Belt andthe physical properties of planets orbiting nearby stars to theformation of stars and the detection of the youngest galaxies in theUniverse. NIRCam also plays an important role in initial alignment ofJWST and the long term maintenance of its image quality. NIRCam ispresently undergoing instrument Integration and Test in preparation fordelivery to the JWST project. Key near-term milestones include thecompletion of cryogenic testing of the entire instrument; demonstrationof scientific and wavefront sensing performance requirements; testing ofreplacement H2RG detectors arrays; and an analysis of coronagraphicperformance in light of measured telescope wavefront characteristics.This paper summarizes the performance of NIRCam, the scientific andeducation/outreach goals of the science team, and some results of theon-going testing program.
The SDSS-DR9 Quasar Catalog presents photometric and spectroscopicproperties of 87,822 quasars observed by the SDSS-III/BOSS survey. Weprovide the catalog in the form of a fits file but also an ascii file.We also provide a supplemental list containing 949 quasars with exactlythe same format as the main catalog.(4 data files).
The SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS), a five-yearspectroscopic survey of 10,000 deg2, achieved first light inlate 2009. One of the key goals of BOSS is to measure the signature ofbaryon acoustic oscillations (BAOs) in the distribution of Lyαabsorption from the spectra of a sample of ~150,000 z > 2.2 quasars.Along with measuring the angular diameter distance at z ≈ 2.5, BOSSwill provide the first direct measurement of the expansion rate of theuniverse at z > 2. One of the biggest challenges in achieving thisgoal is an efficient target selection algorithm for quasars in theredshift range 2.2 < z < 3.5, where their colors tend to overlapthose of the far more numerous stars. During the first year of the BOSSsurvey, quasar target selection (QTS) methods were developed and testedto meet the requirement of delivering at least 15 quasarsdeg-2 in this redshift range, with a goal of 20 out of 40targets deg-2 allocated to the quasar survey. To achievethese surface densities, the magnitude limit of the quasar targets wasset at g <= 22.0 or r <= 21.85. While detection of the BAOsignature in the distribution of Lyα absorption in quasar spectradoes not require a uniform target selection algorithm, many otherastrophysical studies do. We have therefore defined a uniformly selectedsubsample of 20 targets deg-2, for which the selection
We present the Data Release 9 Quasar (DR9Q) catalog from the BaryonOscillation Spectroscopic Survey (BOSS) of the Sloan Digital Sky SurveyIII. The catalog includes all BOSS objects that were targeted as quasarcandidates during the survey, are spectrocopically confirmed as quasarsvia visual inspection, have luminosities Mi[z = 2] < -20.5(in a ΛCDM cosmology with H0 = 70 km s-1Mpc-1, ΩM = 0.3, andΩΛ = 0.7) and either display at least oneemission line with full width at half maximum (FWHM) larger than 500 kms-1 or, if not, have interesting/complex absorption features.It includes as well, known quasars (mostly from SDSS-I and II) that werereobserved by BOSS. This catalog contains 87 822 quasars (78 086 are newdiscoveries) detected over 3275 deg2 with robustidentification and redshift measured by a combination of principalcomponent eigenspectra newly derived from a training set of 8632 spectrafrom SDSS-DR7. The number of quasars with z > 2.15 (61 931) is ~2.8times larger than the number of z > 2.15 quasars previously known.Redshifts and FWHMs are provided for the strongest emission lines (C iv,C iii], Mg ii). The catalog identifies 7533 broad absorption linequasars and gives their characteristics. For each object the catalogpresents five-band (u, g, r, i, z) CCD-based photometry with typicalaccuracy of 0.03 mag, and information on the morphology and selectionmethod. The catalog also contains X-ray, ultraviolet, near-infrared, andradio emission properties of the quasars, when available, from otherlarge-area surveys. The calibrated digital spectra cover the wavelengthregion 3600-10 500 Å at a spectral resolution in the range 1300< R < 2500; the spectra can be retrieved from the SDSS CatalogArchive Server. We also provide a supplemental list of an additional 949quasars that have been identified, among galaxy targets of the BOSS oramong quasar targets after DR9 was frozen.Catalog is only available at the CDS via anonymous ftp tocdsarc.u-strasbg.fr (18.104.22.168) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/548/A66
We describe the automated spectral classification, redshiftdetermination, and parameter measurement pipeline in use for the BaryonOscillation Spectroscopic Survey (BOSS) of the Sloan Digital Sky SurveyIII (SDSS-III) as of the survey's ninth data release (DR9), encompassing831,000 moderate-resolution optical spectra. We give a review of thealgorithms employed, and describe the changes to the pipeline that havebeen implemented for BOSS relative to previous SDSS-I/II versions,including new sets of stellar, galaxy, and quasar redshift templates.For the color-selected "CMASS" sample of massive galaxies at redshift0.4 <~ z <~ 0.8 targeted by BOSS for the purposes of large-scalecosmological measurements, the pipeline achieves an automated