Publications

2014
Guo H, Zheng Z, Zehavi I, Xu H, Eisenstein DJ, Weinberg DH, Bahcall NA, Berlind AA, Comparat J, McBride CK, et al. The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey: modeling of the luminosity and colour dependence in the Data Release 10. ArXiv e-prints [Internet]. 2014;1401:3009. WebsiteAbstract
We investigate the luminosity and colour dependence of clustering ofCMASS galaxies in the Sloan Digital Sky Survey-III Baryon OscillationSpectroscopic Survey Tenth Data Release. The halo occupationdistribution framework is adopted to model the projected two-pointcorrelation function measurements on small and intermediate scales (from$0.02$ to $60\,h^{-1}{\rm {Mpc}}$) and to interpret the observed trendsand infer the connection of galaxies to dark matter halos. We find thatluminous red galaxies reside in massive halos of mass$M{\sim}10^{13}$--$10^{14}\,h^{-1}{\rm M_\odot}$ and more luminousgalaxies are more clustered and hosted by more massive halos. The strongsmall-scale clustering requires a fraction of these galaxies to besatellites in massive halos, with the fraction at the level of 5--8 percent and decreasing with luminosity. The characteristic mass of a halohosting on average one satellite galaxy above a luminosity threshold isabout a factor $8.7$ larger than that of a halo hosting a central galaxyabove the same threshold. At a fixed luminosity, progressively reddergalaxies are more strongly clustered on small scales, which can beexplained by having a larger fraction of these galaxies in the form ofsatellites in massive halos. Our clustering measurements on scales below$0.4\,h^{-1}{\rm {Mpc}}$ allow us to study the small-scale spatialdistribution of satellites inside halos. While the clustering ofluminosity-threshold samples can be well described by aNavarro-Frenk-White (NFW) profile, that of the reddest galaxies prefersa steeper or more concentrated profile. Finally, we also use galaxysamples of constant number density at different redshifts to study theevolution of luminous galaxies, and find the clustering to be consistentwith passive evolution in the redshift range of $0.5 \lesssim z \lesssim0.6$.
Tojeiro R, Ross AJ, Burden A, Samushia L, Manera M, Percival WJ, Beutler F, Cuesta AJ, Dawson K, Eisenstein DJ, et al. The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey: galaxy clustering measurements in the low redshift sample of Data Release 11. ArXiv e-prints [Internet]. 2014;1401:1768. WebsiteAbstract
We present the distance measurement to z = 0.32 using the 11th datarelease of the Sloan Digital Sky Survey-III Baryon Acoustic OscillationSurvey (BOSS). We use 313,780 galaxies of the low-redshift (LOWZ) sampleover 7,341 square-degrees to compute $D_V = (1264 \pm
Anderson L, Aubourg E, Bailey S, Beutler F, Bolton AS, Brinkmann J, Brownstein JR, Chuang C-H, Cuesta AJ, Dawson KS, et al. The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey: measuring DA and H at z = 0.57 from the baryon acoustic peak in the Data Release 9 spectroscopic Galaxy sample. Monthly Notices of the Royal Astronomical Society [Internet]. 2014:156. WebsiteAbstract
We present measurements of the angular diameter distance to and Hubbleparameter at z = 0.57 from the measurement of the baryon acoustic peakin the correlation of galaxies from the Sloan Digital Sky Survey IIIBaryon Oscillation Spectroscopic Survey. Our analysis is based on asample from Data Release 9 of 264 283 galaxies over 3275 square degreesin the redshift range 0.43 < z < 0.70. We use two differentmethods to provide robust measurement of the acoustic peak positionacross and along the line of sight in order to measure the cosmologicaldistance scale. We find DA(0.57) = 1408 ± 45 Mpc andH(0.57) = 92.9 ± 7.8 km s-1 Mpc-1 for ourfiducial value of the sound horizon. These results from the anisotropicfitting are fully consistent with the analysis of the sphericallyaveraged acoustic peak position presented in Anderson et al. Ourdistance measurements are a close match to the predictions of thestandard cosmological model featuring a cosmological constant and zerospatial curvature.
Ross AJ, Samushia L, Burden A, Percival WJ, Tojeiro R, Manera M, Beutler F, Brinkmann J, Brownstein JR, Carnero A, et al. The clustering of galaxies in the SDSS-III DR10 Baryon Oscillation Spectroscopic Survey: no detectable colour dependence of distance scale or growth rate measurements. Monthly Notices of the Royal Astronomical Society [Internet]. 2014;437:1109-1126. WebsiteAbstract
We study the clustering of galaxies, as a function of their colour, fromData Release Ten (DR10) of the Sloan Digital Sky Survey III (SDSS-III)Baryon Oscillation Spectroscopic Survey. DR10 contains 540 505 galaxieswith 0.43 < z < 0.7; from these we select 122 967 for a `Blue'sample and 131 969 for a `Red' sample based on k + e corrected (to z =0.55) r - i colours and i-band magnitudes. The samples are chosen suchthat both contain more than 100 000 galaxies, have similar redshiftdistributions and maximize the difference in clustering amplitude. TheRed sample has a 40 per cent larger bias than the Blue(bRed/bBlue = 1.39 ± 0.04), implying thatthe Red galaxies occupy dark matter haloes with an average mass that is0.5 log10 M⊙ greater. Spherically averagedmeasurements of the correlation function, ξ0, and thepower spectrum are used to locate the position of the baryon acousticoscillation (BAO) feature of both samples. Using ξ0, weobtain distance scales, relative to the distance of our referenceΛ cold dark matter cosmology, of 1.010 ± 0.027 for the Redsample and 1.005 ± 0.031 for the Blue. After applyingreconstruction, these measurements improve to 1.013 ± 0.020 forthe Red sample and 1.008 ± 0.026 for the Blue. For each sample,measurements of ξ0 and the second multipole moment,ξ2, of the anisotropic correlation function are used todetermine the rate of structure growth, parametrized byfσ8. We find fσ8, Red = 0.511 ±0.083, fσ8, Blue = 0.509 ± 0.085 andfσ8, Cross = 0.423 ± 0.061 (from thecross-correlation between the Red and Blue samples). We use thecovariance between the bias and growth measurements obtained from eachsample and their cross-correlation to produce an optimally combinedmeasurement of fσ8, comb = 0.443 ± 0.055. Thisresult compares favourably to that of the full 0.43 < z < 0.7sample (fσ8, full = 0.422 ± 0.051) despite thefact that, in total, we use less than half of the number of galaxiesanalysed in the full sample measurement. In no instance do we detectsignificant differences in distance scale or structure growthmeasurements obtained from the Blue and Red samples. Our results areconsistent with theoretical predictions and our tests on mock samples,which predict that any colour-dependent systematic uncertainty on themeasured BAO position is less than 0.5 per cent.
Percival WJ, Ross AJ, Sánchez AG, Samushia L, Burden A, Crittenden R, Cuesta AJ, Magana MV, Manera M, Beutler F, et al. The clustering of Galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey: including covariance matrix errors. Monthly Notices of the Royal Astronomical Society [Internet]. 2014:244. WebsiteAbstract
We present improved methodology for including covariance matrices in theerror budget of Baryon Oscillation Spectroscopic Survey (BOSS) galaxyclustering measurements, revisiting Data Release 9 (DR9) analyses, anddescribing a method that is used in DR10/11 analyses presented incompanion papers. The precise analysis method adopted is becomingincreasingly important, due to the precision that BOSS can now reach:even using as many as 600 mock catalogues to estimate covariance oftwo-point clustering measurements can still lead to an increase in theerrors of ˜20 per cent, depending on how the cosmologicalparameters of interest are measured. In this paper, we extend previouswork on this contribution to the error budget, deriving formulae forerrors measured by integrating over the likelihood, and to thedistribution of recovered best-fitting parameters fitting thesimulations also used to estimate the covariance matrix. Both aresituations that previous analyses of BOSS have considered. We apply theformulae derived to baryon acoustic oscillation (BAO) and redshift-spacedistortion (RSD) measurements from BOSS in our companion papers. Tofurther aid these analyses, we consider the optimum number of bins touse for two-point measurements using the monopole power spectrum orcorrelation function for BAO, and the monopole and quadrupole moments ofthe correlation function for anisotropic-BAO and RSD measurements.
2013
Weinberg DH, Mortonson MJ, Eisenstein DJ, Hirata C, Riess AG, Rozo E. Observational probes of cosmic acceleration. Physics Reports [Internet]. 2013;530:87-255. WebsiteAbstract
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 ambitiousefforts to understand its origin, with experiments that aim to measurethe history of expansion and growth of structure with percent-levelprecision or higher. We review in detail the four most well establishedmethods for making such measurements: Type Ia supernovae, baryonacoustic oscillations (BAO), weak gravitational lensing, and theabundance of galaxy clusters. We pay particular attention to thesystematic uncertainties in these techniques and to strategies forcontrolling them at the level needed to exploit "Stage IV" dark energyfacilities such as BigBOSS, LSST, Euclid, and WFIRST. We briefly reviewa number of other approaches including redshift-space distortions, theAlcock-Paczynski effect, and direct measurements of the Hubble constantH0. We present extensive forecasts for constraints on thedark energy equation of state and parameterized deviations from GeneralRelativity, achievable with Stage III and Stage IV experimental programsthat incorporate supernovae, BAO, weak lensing, and cosmic microwavebackground data. We also show the level of precision required forclusters or other methods to provide constraints competitive with thoseof these fiducial programs. We emphasize the value of a balanced programthat employs several of the most powerful methods in combination, bothto cross-check systematic uncertainties and to take advantage ofcomplementary information. Surveys to probe cosmic acceleration producedata sets that support a wide range of scientific investigations, andthey continue the longstanding astronomical tradition of mapping theuniverse in ever greater detail over ever larger scales.
Agarwal N, Ho S, Myers AD, Seo H-J, Ross AJ, Bahcall N, Brinkmann J, Eisenstein DJ, Muna D, Palanque-Delabrouille N, et al. Characterizing unknown systematics in large scale structure surveys. ArXiv e-prints [Internet]. 2013;1309:2954. WebsiteAbstract
Photometric large scale structure (LSS) surveys probe the largestvolumes in the Universe, but are inevitably limited by systematicuncertainties. Imperfect photometric calibration leads to biases in ourmeasurements of the density fields of LSS tracers such as galaxies andquasars, and as a result in cosmological parameter estimation. Earlierstudies have proposed using cross-correlations between differentredshift slices or cross-correlations between different surveys toreduce the effects of such systematics. In this paper we develop amethod to characterize unknown systematics. We demonstrate that while wedo not have sufficient information to correct for unknown systematics inthe data, we can obtain an estimate of their magnitude. We define aparameter to estimate contamination from unknown systematics usingcross-correlations between different redshift slices and proposediscarding bins in the angular power spectrum that lie outside a certaincontamination tolerance level. We show that this method improvesestimates of the bias using simulated data and further apply it tophotometric luminous red galaxies in the Sloan Digital Sky Survey as acase study.
Kim A, Padmanabhan N, Aldering G, Allen S, Baltay C, Cahn R, D'Andrea C, Dalal N, Dawson K, Denney K, et al. Distance Probes of Dark Energy. ArXiv e-prints [Internet]. 2013;1309:5382. WebsiteAbstract
This document presents the results from the Distances subgroup of theCosmic Frontier Community Planning Study (Snowmass 2013). We summarizethe current state of the field as well as future prospects andchallenges. In addition to the established probes using Type IAsupernovae and baryon acoustic oscillations, we also considerprospective methods based on clusters, active galactic nuclei,gravitational wave sirens and strong lensing time delays.
Ahn CP, Alexandroff R, Allende Prieto C, Anders F, Anderson SF, Anderton T, Andrews BH, Aubourg É, Bailey S, Bastien FA, et al. The Tenth Data Release of the Sloan Digital Sky Survey: First Spectroscopic Data from the SDSS-III Apache Point Observatory Galactic Evolution Experiment. ArXiv e-prints [Internet]. 2013;1307:7735. WebsiteAbstract
The Sloan Digital Sky Survey (SDSS) has been in operation since 2000April. This paper presents the tenth public data release (DR10) from itscurrent incarnation, SDSS-III. This data release includes the firstspectroscopic data from the Apache Point Observatory Galaxy EvolutionExperiment (APOGEE), along with spectroscopic data from the BaryonOscillation Spectroscopic Survey (BOSS) taken through 2012 July. TheAPOGEE instrument is a near-infrared R~22,500 300-fiber spectrographcovering 1.514--1.696 microns. The APOGEE survey is studying thechemical abundances and radial velocities of roughly 100,000 red giantstar candidates in the bulge, bar, disk, and halo of the Milky Way. DR10includes 178,397 spectra of 57,454 stars, each typically observed threeor more times, from APOGEE. Derived quantities from these spectra(radial velocities, effective temperatures, surface gravities, andmetallicities) are also included.DR10 also roughly doubles the number ofBOSS spectra over those included in the ninth data release. DR10includes a total of 1,507,954 BOSS spectra, comprising 927,844 galaxyspectra; 182,009 quasar spectra; and 159,327 stellar spectra, selectedover 6373.2 square degrees.
Levi M, Bebek C, Beers T, Blum R, Cahn R, Eisenstein D, Flaugher B, Honscheid K, Kron R, Lahav O, et al. The DESI Experiment, a whitepaper for Snowmass 2013. ArXiv e-prints [Internet]. 2013;1308:847. WebsiteAbstract
The Dark Energy Spectroscopic Instrument (DESI) is a massivelymultiplexed fiber-fed spectrograph that will make the next major advancein dark energy in the timeframe 2018-2022. On the Mayall telescope, DESIwill obtain spectra and redshifts for at least 18 million emission-linegalaxies, 4 million luminous red galaxies and 3 million quasi-stellarobjects, in order to: probe the effects of dark energy on the expansionhistory using baryon acoustic oscillations (BAO), measure thegravitational growth history through redshift-space distortions, measurethe sum of neutrino masses, and investigate the signatures of primordialinflation. The resulting 3-D galaxy maps at z<2 and Lyman-alpha
Skibba RA, Smith SMM, Coil AL, Moustakas J, Aird J, Blanton MR, Bray AD, Cool RJ, Eisenstein DJ, Mendez AJ, et al. PRIMUS: Galaxy Clustering as a Function of Luminosity and Color at 0.2. ArXiv e-prints [Internet]. 2013;1310:1093. WebsiteAbstract
We present measurements of the luminosity and color-dependence of galaxyclustering at 0.2
Font-Ribera A, Kirkby D, Busca N, Miralda-Escudé J, Ross NP, Slosar A, Aubourg É, Bailey S, Bhardwaj V, Bautista J, et al. Quasar-Lyman $\alpha$ Forest Cross-Correlation from BOSS DR11 : Baryon Acoustic Oscillations. ArXiv e-prints [Internet]. 2013;1311:1767. WebsiteAbstract
We measure the large-scale cross-correlation of quasars with the Lymanalpha forest absorption, using over 164,000 quasars from Data Release 11of the SDSS-III Baryon Oscillation Spectroscopic Survey. We extend theprevious study of roughly 60,000 quasars from Data Release 9 to largerseparations, allowing a measurement of the Baryonic Acoustic Oscillation(BAO) scale along the line of sight $c/(H(z=2.36) ~ r_s) = 9.0 \pm 0.3$and across the line of sight $D_A(z=2.36)~ / ~ r_s = 10.8 \pm 0.4$,consistent with CMB and other BAO data. Using the best fit value of thesound horizon from Planck data ($r_s=147.49 Mpc$), we can translatethese results to a measurement of the Hubble parameter of $H(z=2.36) =226 \pm 8 km/s$ and of the angular diameter distance of $D_A(z=2.36) =1590 \pm 60 Mpc$. The measured cross-correlation function and an updateof the code to fit the BAO scale (baofit) are made publicly available.
Chuang C-H, Prada F, Beutler F, Eisenstein DJ, Escoffier S, Ho S, Kneib J-P, Manera M, Nuza SE, Schlegel DJ, et al. The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey: single-probe measurements from CMASS and LOWZ anisotropic galaxy clustering. ArXiv e-prints [Internet]. 2013;1312:4889. WebsiteAbstract
With the largest spectroscopic galaxy survey volume drawn from theSDSS-III Baryon Oscillation Spectroscopic Survey (BOSS), we can extractcosmological constraints from the measurements of redshift and geometricdistortions at quasi-linear scales (e.g. above 50 Mpc/h), which can bemodeled by perturbation theory. We analyze the broad-range shape of themonopole and quadrupole correlation functions of the BOSS Data Release11 (DR11) CMASS galaxy sample, at the effective redshift z=0.57, toobtain constraints on the Hubble expansion rate H(z), theangular-diameter distance D_A(z), the normalized growth ratef(z)\sigma_8(z), and the physical matter density \Omega_mh^2. We provideaccurate measurements on {H^{-1}R_{fid}^{-1.0}, D_A R_{fid}^{-0.96},f\sigma_8(\Omega_m h^2)^{0.45}}, where R_{fid}\equiv r_s/r_{s,fid}, r_sis the comoving sound horizon at the drag epoch, and r_{s,fid} is thesound scale of the fiducial cosmology used in this study. We alsoextract cosmological constraints from BOSS DR11 LOWZ sample, at theeffective redshift z=0.32, by including small scales (e.g., down to 30Mpc/h), and model small scales with Finger of God effect. The parameterswhich are not well constrained by our galaxy clustering analysis aremarginalized over with wide flat priors. Since no priors from other datasets, e.g., cosmic microwave background (CMB), are adopted and no darkenergy models are assumed, our results from BOSS CMASS and LOWZ galaxyclustering alone may be combined with other data sets, i.e., CMB, SNe,lensing or other galaxy clustering data to constrain the parameters of agiven cosmological model. We find the redshift distortion measurementsfrom most of the galaxy clustering analyses (including this study) favorWMAP9 than Planck and favor wCDM than \LambdaCDM or o\LambdaCDM. Theuncertainty on the dark energy equation of state parameter fromCMB+CMASS is about 8 per cent.
Samushia L, Reid BA, White M, Percival WJ, Cuesta AJ, Zhao G-bo, Ross AJ, Manera M, Aubourg É, Beutler F, et al. The Clustering of Galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey: Measuring growth rate and geometry with anisotropic clustering. ArXiv e-prints [Internet]. 2013;1312:4899. WebsiteAbstract
We use the observed anisotropic clustering of galaxies in the BaryonOscillation Spectroscopic Survey Data Release 11 CMASS sample to measurethe linear growth rate of structure, the Hubble expansion rate and thecomoving distance scale. Our sample covers 8498 ${\rm deg}^2$ andencloses an effective volume of 6.0 ${\rm Gpc}^3$ at an effectiveredshift of $\bar{z} = 0.57$. We find $f\sigma_8 = 0.441 \pm 0.044$, $H= 93.1 \pm 3.0\ {\mathrm{km}\ \mathrm{s}^{-1} \mathrm{Mpc}^{-1}}$ and$D_{\rm A} = 1380 \pm 23\ {\rm Mpc}$ when fitting the growth andexpansion rate simultaneously. When we fix the background expansion tothe one predicted by spatially-flat $\Lambda$CDM model in agreement withrecent Planck results, we find $f\sigma_8 = 0.447 \pm 0.028$ (6 per centaccuracy). While our measurements are generally consistent with thepredictions of $\Lambda$CDM and General Relativity, they mildly favormodels in which the strength of gravitational interactions is weakerthan what is predicted by General Relativity. Combining our measurementswith recent cosmic microwave background data results in tightconstraints on basic cosmological parameters and deviations from thestandard cosmological model. Separately varying these parameters, wefind $w = -0.983 \pm 0.075$ (8 per cent accuracy) and $\gamma = 0.69 \pm0.11$ (16 per cent accuracy) for the effective equation of state of darkenergy and the growth rate index, respectively. Both constraints are ingood agreement with the standard model values of $w=-1$ and $\gamma =0.554$.
Beutler F, Saito S, Seo H-J, Brinkmann J, Dawson KS, Eisenstein DJ, Font-Ribera A, Ho S, McBride CK, Montesano F, et al. The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey: Testing gravity with redshift-space distortions using the power spectrum multipoles. ArXiv e-prints [Internet]. 2013;1312:4611. WebsiteAbstract
We analyse the anisotropic clustering of the Baryon OscillationSpectroscopic Survey (BOSS) CMASS Data Release 11 (DR11) sample, whichconsists of $690\,827$ galaxies in the redshift range $0.43 < z <0.7$ and has a sky coverage of $8\,498\,$deg$^2$. We perform ouranalysis in Fourier space using a power spectrum estimator suggested byYamamoto et al. (2006). We measure the multipole power spectra in aself-consistent manner for the first time in the sense that we provide aproper way to treat the survey window function and the integralconstraint, without the commonly used assumption of an isotropic powerspectrum and without the need to split the survey into sub-regions. Themain cosmological signals exploited in our analysis are the BaryonAcoustic Oscillations and the signal of redshift space distortions, bothof which are distorted by the Alcock-Paczynski effect. Together, thesesignals allow us to constrain the distance ratio $D_V(z_{\rmeff})/r_s(z_d) = 13.89\pm 0.18$, the Alcock-Paczynski parameter $F_{\rmAP}(z_{\rm eff}) = 0.679\pm0.031$ and the growth rate of structure$f(z_{\rm eff})\sigma_8(z_{\rm eff}) = 0.419\pm0.044$ at the effectiveredshift $z_{\rm eff}=0.57$. Combining our dataset with Planck to testGeneral Relativity (GR) through the simple $\gamma$-parameterisation,where the growth rate is given by $f(z) = \Omega^{\gamma}_m(z)$, revealsa $\sim 2\sigma$ tension between the data and the prediction by GR. Thetension between our result and GR can be traced back to a tension in theclustering amplitude $\sigma_8$ between CMASS and Planck.
Sanchez AG, Montesano F, Kazin EA, Aubourg E, Beutler F, Brinkmann J, Brownstein JR, Cuesta AJ, Dawson KS, Eisenstein DJ, et al. The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey: cosmological implications of the full shape of the clustering wedges in the data release 10 and 11 galaxy samples. ArXiv e-prints [Internet]. 2013;1312:4854. WebsiteAbstract
We explore the cosmological implications of the angle-averagedcorrelation function, xi(s), and the clustering wedges, xi_perp(s) andxi_para(s), of the LOWZ and CMASS galaxy samples from Data Release 10and 11 of the SDSS-III Baryon Oscillation Spectroscopic Survey. Ourresults show no significant evidence for a deviation from the standardLCDM model. The combination of the information from our clusteringmeasurements with recent data from the cosmic microwave background issufficient to constrain the curvature of the Universe to Omega_k =
Anderson L, Aubourg E, Bailey S, Beutler F, Bhardwaj V, Blanton M, Bolton AS, Brinkmann J, Brownstein JR, Burden A, et al. The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey: Baryon Acoustic Oscillations in the Data Release 10 and 11 galaxy samples. ArXiv e-prints [Internet]. 2013;1312:4877. WebsiteAbstract
We present a one per cent measurement of the cosmic distance scale fromthe detections of the baryon acoustic oscillations in the clustering ofgalaxies from the Baryon Oscillation Spectroscopic Survey (BOSS), whichis part of the Sloan Digital Sky Survey III (SDSS-III). Our results comefrom the Data Release 11 (DR11) sample, containing nearly one milliongalaxies and covering approximately 8500 square degrees and the redshiftrange $0.2
Vargas Magaña M, Ho S, Xu X, Sánchez AG, O'Connell R, Eisenstein DJ, Cuesta AJ, Percival WJ, Ross AJ, Aubourg E, et al. SDSS-III Baryon Oscillation Spectroscopic Survey: Analysis of Potential Systematics in Fitting of Baryon Acoustic Feature. ArXiv e-prints [Internet]. 2013;1312:4996. WebsiteAbstract
Extraction of the Baryon Acoustic Oscillations (BAO) to percent levelaccuracy is challenging and demands an understanding of many potentialsystematic to an accuracy well below 1 per cent, in order ensure thatthey do not combine significantly when compared to statistical error ofthe BAO measurement. Sloan Digital Sky Survey (SDSS)-III BaryonOscillation Spectroscopic Survey (BOSS) SDSS Data Release Eleven (DR11)
Dawson KS, Schlegel DJ, Ahn CP, Anderson SF, Aubourg É, Bailey S, Barkhouser RH, Bautista JE, Beifiori A, Berlind AA, et al. The Baryon Oscillation Spectroscopic Survey of SDSS-III. The Astronomical Journal [Internet]. 2013;145:10. WebsiteAbstract
The Baryon Oscillation Spectroscopic Survey (BOSS) is designed tomeasure the scale of baryon acoustic oscillations (BAO) in theclustering of matter over a larger volume than the combined efforts ofall previous spectroscopic surveys of large-scale structure. BOSS uses1.5 million luminous galaxies as faint as i = 19.9 over 10,000deg2 to measure BAO to redshifts z < 0.7. Observations ofneutral hydrogen in the Lyα forest in more than 150,000 quasarspectra (g < 22) will constrain BAO over the redshift range 2.15
Kleinman SJ, Kepler SO, Koester D, Pelisoli I, Peçanha V, Nitta A, Costa JES, Krzesinski J, Dufour P, Lachapelle F-R, et al. SDSS DR7 White Dwarf Catalog. The Astrophysical Journal Supplement Series [Internet]. 2013;204:5. WebsiteAbstract
We present a new catalog of spectroscopically confirmed white dwarfstars from the Sloan Digital Sky Survey (SDSS) Data Release 7spectroscopic catalog. We find 20,407 white dwarf spectra, representing19,712 stars, and provide atmospheric model fits to 14,120 DA and 1011DB white dwarf spectra from 12,843 and 923 stars, respectively. Thesenumbers represent more than a factor of two increase in the total numberof white dwarf stars from the previous SDSS white dwarf catalogs basedon DR4 data. Our distribution of subtypes varies from previous catalogsdue to our more conservative, manual classifications of each star in ourcatalog, supplementing our automatic fits. In particular, we find alarge number of magnetic white dwarf stars whose small Zeeman splittingsmimic increased Stark broadening that would otherwise result in anoverestimated log g if fit as a non-magnetic white dwarf. We calculatemean DA and DB masses for our clean, non-magnetic sample and find the DBmean mass is statistically larger than that for the DAs.