# Publications

2013
Dawson KS, Schlegel DJ, Ahn CP, Anderson SF, Aubourg É, Bailey S, Barkhouser RH, Bautista JE, Beifiori A, Berlind AA. 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
Parejko JK, Sunayama T, Padmanabhan N, Wake DA, Berlind AA, Bizyaev D, Blanton M, Bolton AS, van den Bosch F, Brinkmann J. The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey: the low-redshift sample. Monthly Notices of the Royal Astronomical Society [Internet]. 2013;429:98-112. WebsiteAbstract
We report on the small-scale (0.5 < r < 40 h-1 Mpc)clustering of 78 895 massive (M* ˜ 1011.3M&sun;) galaxies at 0.2 < z < 0.4 from the first twoyears of data from the Baryon Oscillation Spectroscopic Survey (BOSS),to be released as part of Sloan Digital Sky Survey (SDSS) Data Release 9(DR9). We describe the sample selection, basic properties of thegalaxies and caveats for working with the data. We calculate the real-and redshift-space two-point correlation functions of these galaxies,fit these measurements using halo occupation distribution (HOD)modelling within dark matter cosmological simulations, and estimate theerrors using mock catalogues. These galaxies lie in massive haloes, witha mean halo mass of 5.2 × 1013 h-1M&sun;, a large-scale bias of ˜2.0 and a satellitefraction of 12 ± 2 per cent. Thus, these galaxies occupy haloeswith average masses in between those of the higher redshift BOSS CMASSsample and the original SDSS I/II luminous red galaxy sample.
Ross AJ, Percival WJ, Carnero A, Zhao G-bo, Manera M, Raccanelli A, Aubourg E, Bizyaev D, Brewington H, Brinkmann J. The clustering of galaxies in the SDSS-III DR9 Baryon Oscillation Spectroscopic Survey: constraints on primordial non-Gaussianity. Monthly Notices of the Royal Astronomical Society [Internet]. 2013;428:1116-1127. WebsiteAbstract
We analyse the density field of 264 283 galaxies observed by the SloanDigital Sky Survey (SDSS)-III Baryon Oscillation Spectroscopic Survey(BOSS) and included in the SDSS Data Release 9 (DR9). In total, the SDSSDR9 BOSS data include spectroscopic redshifts for over 400 000 galaxiesspread over a footprint of more than 3000 deg2. We measurethe power spectrum of these galaxies with redshifts 0.43 < z < 0.7in order to constrain the amount of local non-Gaussianity,f{_N_L^local}, in the primordial density field, paying particularattention to the impact of systematic uncertainties. The BOSS galaxydensity field is systematically affected by the local stellar densityand this influences the ability to accurately measure f{_N_L^local}. Inthe absence of any correction, we find (erroneously) that theprobability that f{_N_L^local} is greater than zero, P(f{_N_L^local}> 0), is 99.5 per cent. After quantifying and correcting for thesystematic bias and including the added uncertainty, we find - 45 0) = 91.0 per cent. A more conservative approach assumes that wehave only learnt the k dependence of the systematic bias and allows anyamplitude for the systematic correction; we find that the systematiceffect is not fully degenerate with that of f{_N_L^local}, and wedetermine that -82 < f{_N_L^local} < 178 (at 95 per centconfidence) and P(f{_N_L^local} > 0) = 68 per cent. This analysisdemonstrates the importance of accounting for the impact of Galacticforegrounds on f{_N_L^local} measurements. We outline the methods thataccount for these systematic biases and uncertainties. We expect ourmethods to yield robust constraints on f{_N_L^local} for both our ownand future large-scale structure investigations.
Aird J, Coil AL, Moustakas J, Diamond-Stanic AM, Blanton MR, Cool RJ, Eisenstein DJ, Wong KC, Zhu G. PRIMUS: An observationally motivated model to connect the evolution of the AGN and galaxy populations out to z~1. ArXiv e-prints [Internet]. 2013;1301:1689. WebsiteAbstract
We present an observationally motivated model to connect the AGN andgalaxy populations at 0.2
Moustakas J, Coil A, Aird J, Blanton MR, Cool RJ, Eisenstein DJ, Mendez AJ, Wong KC, Zhu G, Arnouts S. PRIMUS: Constraints on Star Formation Quenching and Galaxy Merging, and the Evolution of the Stellar Mass Function From z=0-1. ArXiv e-prints [Internet]. 2013;1301:1688. WebsiteAbstract
We measure the evolution of the stellar mass function (SMF) from z=0-1using multi-wavelength imaging and spectroscopic redshifts from thePRism MUlti-object Survey (PRIMUS) and the Sloan Digital Sky Survey(SDSS). From PRIMUS we construct an i<23 flux-limited sample of~40,000 galaxies at z=0.2-1.0 over five fields totaling ~5.5 deg^2, andfrom the SDSS we select ~170,000 galaxies at z=0.01-0.2 that we analyzeconsistently with respect to PRIMUS to minimize systematic errors in ourevolutionary measurements. We find that the SMF of all galaxies evolvesrelatively little since z=1, although we do find evidence for mass
Kleinman SJ, Kepler SO, Koester D, Pelisoli I, Peçanha V, Nitta A, Costa JES, Krzesinski J, Dufour P, Lachapelle F-R. 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.
Tassev S, Zaldarriaga M, Eisenstein D. Solving Large Scale Structure in Ten Easy Steps with COLA. ArXiv e-prints [Internet]. 2013;1301:322. WebsiteAbstract
We present the COmoving Lagrangian Acceleration (COLA) method: an N-bodymethod for solving for Large Scale Structure (LSS) in a frame that iscomoving with observers following trajectories calculated in LagrangianPerturbation Theory (LPT). Unlike standard N-body methods, the COLAmethod can straightforwardly trade accuracy at small-scales in order togain computational speed without sacrificing accuracy at large scales.This is especially useful for cheaply generating large ensembles ofaccurate mock halo catalogs required to study galaxy clustering and weaklensing, as those catalogs are essential for performing detailed erroranalysis for ongoing and future surveys of LSS. As an illustration, weran a COLA-based N-body code on a box of size 100Mpc/h with particles ofmass ~5*10^9Msolar/h. Running the code with only 10 timesteps wassufficient to obtain an accurate description of halo statistics down tohalo masses of at least 10^11Msolar/h. This is only at a modest speedpenalty when compared to mocks obtained with LPT. A standard detailedN-body run is orders of magnitude slower than our COLA-based code. Thespeed-up we obtain with COLA is due to the fact that we calculate thelarge-scale dynamics exactly using LPT, while letting the N-body codesolve for the small scales, without requiring it to capture exactly theinternal dynamics of halos. Achieving a similar level of accuracy inhalo statistics without the COLA method requires at least 3 times moretimesteps than when COLA is employed.
García Pérez AE, Cunha K, Shetrone M, Majewski SR, Johnson JA, Smith VV, Schiavon RP, Holtzman J, Nidever D, Zasowski G. Very Metal-poor Stars in the Outer Galactic Bulge Found by the Apogee Survey. ArXiv e-prints [Internet]. 2013;1301:1367. WebsiteAbstract
Despite its importance for understanding the nature of early stellargenerations and for constraining Galactic bulge formation models, atpresent little is known about the metal-poor stellar content of thecentral Milky Way. This is a consequence of the great distances involvedand intervening dust obscuration, which challenge optical studies.However, the Apache Point Observatory Galactic Evolution Experiment(APOGEE), a wide-area, multifiber, high-resolution spectroscopic surveywithin Sloan Digital Sky Survey III (SDSS-III), is exploring thechemistry of all Galactic stellar populations at infrared wavelengths,with particular emphasis on the disk and the bulge. An automatedspectral analysis of data on 2,403 giant stars in twelve fields in thebulge obtained during APOGEE commissioning yielded five stars with lowmetallicity([Fe/H]$\le-1.7$), including two that are very metal-poor[Fe/H]$\sim-2.1$ by bulge standards. Luminosity-based distance estimatesplace the five stars within the outer bulge, where other 1,246 of theanalyzed stars may reside. A manual reanalysis of the spectra verifiesthe low metallicities, and finds these stars to be enhanced in the$\alpha$-elements O, Mg, and Si without significant $\alpha$-patterndifferences with other local halo or metal-weak thick-disk stars ofsimilar metallicity, or even with other more metal-rich bulge stars.While neither the kinematics nor chemistry of these stars can yetdefinitively determine which, if any, are truly bulge members, ratherthan denizens of other populations co-located with the bulge, thenewly-identified stars reveal that the chemistry of metal-poor stars inthe central Galaxy resembles that of metal-weak thick-disk stars atsimilar metallicity.
2012
Padmanabhan N, Xu X, Eisenstein DJ, Scalzo R, Cuesta AJ, Mehta KT, Kazin E. A 2 per cent distance to z = 0.35 by reconstructing baryon acoustic oscillations - I. Methods and application to the Sloan Digital Sky Survey. Monthly Notices of the Royal Astronomical Society [Internet]. 2012;427:2132-2145. WebsiteAbstract
We present the first application to density field reconstruction to agalaxy survey to undo the smoothing of the baryon acoustic oscillation(BAO) feature due to non-linear gravitational evolution and therebyimprove the precision of the distance measurements possible. We applythe reconstruction technique to the clustering of galaxies from theSloan Digital Sky Survey (SDSS) Data Release 7 (DR7) luminous red galaxy(LRG) sample, sharpening the BAO feature and achieving a 1.9 per centmeasurement of the distance to z = 0.35. We update the reconstructionalgorithm of Eisenstein et al. to account for the effects of surveygeometry as well as redshift-space distortions and validate it on 160LasDamas simulations. We demonstrate that reconstruction sharpens theBAO feature in the angle averaged galaxy correlation function, reducingthe non-linear smoothing scale Σnl from 8.1 to 4.4 Mpch-1. Reconstruction also significantly reduces the effects ofredshift-space distortions at the BAO scale, isotropizing thecorrelation function. This sharpened BAO feature yields an unbiaseddistance estimate (<0.2 per cent) and reduces the scatter from 3.3 to2.1 per cent. We demonstrate the robustness of these results to thevarious reconstruction parameters, including the smoothing scale, thegalaxy bias and the linear growth rate. Applying this reconstructionalgorithm to the SDSS LRG DR7 sample improves the significance of theBAO feature in these data from 3.3σ for the unreconstructedcorrelation function to 4.2σ after reconstruction. We estimate arelative distance scale DV/rs to z = 0.35 of 8.88± 0.17, where rs is the sound horizon andDV≡(DA2H-1)1/3 is a combination of the angular diameter distanceDA and Hubble parameter H. Assuming a sound horizon of 154.25Mpc, this translates into a distance measurement DV(z = 0.35)= 1.356 ± 0.025 Gpc. We find that reconstruction reduces thedistance error in the DR7 sample from 3.5 to 1.9 per cent, equivalent toa survey with three times the volume of SDSS.
Xu X, Padmanabhan N, Eisenstein DJ, Mehta KT, Cuesta AJ. A 2 per cent distance to z = 0.35 by reconstructing baryon acoustic oscillations - II. Fitting techniques. Monthly Notices of the Royal Astronomical Society [Internet]. 2012;427:2146-2167. WebsiteAbstract
We present results from fitting the baryon acoustic oscillation (BAO)signal in the correlation function obtained from the first applicationof density-field reconstruction to a galaxy redshift survey, namely theSloan Digital Sky Survey (SDSS) Data Release 7 (DR7) luminous red galaxy(LRG) catalogue. Reconstruction works to partially remove the effects ofnon-linear structure growth on the BAO by reconstructing the linearmatter density field from the observed galaxy density field using thecontinuity equation. We also introduce more careful approaches forderiving a suitable covariance matrix and fitting model for galaxycorrelation functions. Our covariance matrix technique guarantees smoothdiagonal and off-diagonal terms by fitting a modified Gaussiancovariance matrix to that calculated from mock catalogues. Our proposedfitting model is effective at removing broad-band effects such asredshift-space distortions, scale-dependent bias and any artefactsintroduced by assuming the wrong model cosmology. These all aid inobtaining a more accurate measurement of the acoustic scale and itserror. We validate these techniques on 160 mock catalogues derived fromthe LasDamas simulations in real and redshift space. We then apply thesetechniques to the DR7 LRG sample and find that the error on the acousticscale decreases from ˜3.5 per cent before reconstruction to˜1.9 per cent after reconstruction. We also see an increase in ourBAO detection confidence from ˜3σ to ˜4σ afterreconstruction with our confidence level in measuring the correctacoustic scale increasing from ˜3σ to ˜5σ. Usingthe mean of the acoustic scale probability distributions produced fromour fits, we find Dv/rs = 8.89 ± 0.31before reconstruction and 8.88 ± 0.17 after reconstruction.
Mehta KT, Cuesta AJ, Xu X, Eisenstein DJ, Padmanabhan N. A 2 per cent distance to z = 0.35 by reconstructing baryon acoustic oscillations - III. Cosmological measurements and interpretation. Monthly Notices of the Royal Astronomical Society [Internet]. 2012;427:2168-2179. WebsiteAbstract
We use the 2 per cent distance measurement from our reconstructed baryonacoustic oscillations (BAOs) signature using the Sloan Digital SkySurvey (SDSS) Data Release 7 (DR7) luminous red galaxies fromPadmanabhan et al. and Xu et al. combined with cosmic microwavebackground data from Wilkinson Microwave Anisotropy Probe (WMAP7) tomeasure parameters for various cosmological models. We find a 1.7 percent measurement of H0 = 69.8 ± 1.2 km s-1Mpc-1 and a 5.0 per cent measurement ofΩm=0.280±0.014 for a flat universe with a cosmologicalconstant. These measurements of H0 and Ωmare robust against a range of underlying models for the expansionhistory. We measure the dark energy equation of state parameter w =-0.97 ± 0.17, which is consistent with a cosmological constant.If curvature is allowed to vary, we find that the Universe is consistentwith a flat geometry (ΩK = -0.004 ± 0.005). Wealso use a combination of the 6 Degree Field Galaxy Survey BAO data,WiggleZ Dark Energy Survey data, Type Ia supernovae data and a localmeasurement of the Hubble constant to explore cosmological models withmore parameters. Finally, we explore the effect of varying the energydensity of relativistic particles on the measurement of H0.
Seo H-J, Ho S, White M, Cuesta AJ, Ross AJ, Saito S, Reid B, Padmanabhan N, Percival WJ, de Putter R. Acoustic Scale from the Angular Power Spectra of SDSS-III DR8 Photometric Luminous Galaxies. The Astrophysical Journal [Internet]. 2012;761:13. WebsiteAbstract
We measure the acoustic scale from the angular power spectra of theSloan Digital Sky Survey III (SDSS-III) Data Release 8 imaging catalogthat includes 872, 921 galaxies over ~10,000 deg2 between0.45 < z < 0.65. The extensive spectroscopic training set of theBaryon Oscillation Spectroscopic Survey luminous galaxies allows preciseestimates of the true redshift distributions of galaxies in our imagingcatalog. Utilizing the redshift distribution information, we buildtemplates and fit to the power spectra of the data, which are measuredin our companion paper, to derive the location of Baryon acousticoscillations (BAOs) while marginalizing over many free parameters toexclude nearly all of the non-BAO signal. We derive the ratio of theangular diameter distance to the sound horizon scale DA(z)/rs = 9.212+0.416 - 0.404 at z= 0.54, and therefore DA (z) = 1411 ± 65 Mpc at z =0.54; the result is fairly independent of assumptions on the underlyingcosmology. Our measurement of angular diameter distance DA(z) is 1.4σ higher than what is expected for the concordanceΛCDM, in accordance to the trend of other spectroscopic BAOmeasurements for z >~ 0.35. We report constraints on cosmologicalparameters from our measurement in combination with the WMAP7 data andthe previous spectroscopic BAO measurements of SDSS and WiggleZ. Werefer to our companion papers (Ho et al. de Putter et al.) forinvestigations on information of the full power spectrum.
Kochanek CS, Eisenstein DJ, Cool RJ, Caldwell N, Assef RJ, Jannuzi BT, Jones C, Murray SS, Forman WR, Dey A. AGES: The AGN and Galaxy Evolution Survey. The Astrophysical Journal Supplement Series [Internet]. 2012;200:8. WebsiteAbstract
The AGN and Galaxy Evolution Survey (AGES) is a redshift surveycovering, in its standard fields, 7.7 deg2 of the Boötesfield of the NOAO Deep Wide-Field Survey. The final sample consists of23,745 redshifts. There are well-defined galaxy samples in 10 bands (theBW , R, I, J, K, IRAC 3.6, 4.5, 5.8, and 8.0 μm, and MIPS24 μm bands) to a limiting magnitude of I < 20 mag forspectroscopy. For these galaxies, we obtained 18,163 redshifts from asample of 35,200 galaxies, where random sparse sampling was used todefine statistically complete sub-samples in all 10 photometric bands.
Kochanek CS, Eisenstein DJ, Cool RJ, Caldwell N, Assef RJ, Jannuzi BT, Jones C, Murray SS, Forman WR, Dey A. AGES: the AGN and Galaxy Evolution Survey (Kochanek+, 2012). VizieR Online Data Catalog [Internet]. 2012;220:00008. WebsiteAbstract
The observations were made with Hectospec, a 300 fiber, 1 degree fieldof view, robotic spectrograph for the 6.5m MMT telescope at Mt. Hopkins,from 2004 April to 2007 July. The wavelength range is 3700-9200Åwith a pixel scale of 1.2Å and a spectral resolution of 6Å(i.e., roughly R~1000).(7 data files).
Nidever DL, Zasowski G, Majewski SR, Bird J, Robin AC, Martinez-Valpuesta I, Beaton RL, Schönrich R, Schultheis M, Wilson JC. The Apache Point Observatory Galactic Evolution Experiment: First Detection of High-velocity Milky Way Bar Stars. The Astrophysical Journal Letters [Internet]. 2012;755:L25. WebsiteAbstract
Commissioning observations with the Apache Point Observatory GalacticEvolution Experiment (APOGEE), part of the Sloan Digital Sky Survey III,have produced radial velocities (RVs) for ~4700 K/M-giant stars in theMilky Way (MW) bulge. These high-resolution (R ~ 22, 500), high-S/N(>100 per resolution element), near-infrared (NIR; 1.51-1.70 μm)spectra provide accurate RVs (epsilonV ~ 0.2 kms-1) for the sample of stars in 18 Galactic bulge fieldsspanning -1° -32°. This represents the largest NIR high-resolution spectroscopicsample of giant stars ever assembled in this region of the Galaxy. Acold (σV ~ 30 km s-1), high-velocity peak (VGSR ≈ +200 km s-1) is found to comprise a
Busca NG, Delubac T, Rich J, Bailey S, Font-Ribera A, Kirkby D, Le Goff J-M, Pieri MM, Slosar A, Aubourg É. Baryon Acoustic Oscillations in the Ly-\alpha\ forest of BOSS quasars. ArXiv e-prints [Internet]. 2012;1211:2616. WebsiteAbstract
We report a detection of the baryon acoustic oscillation (BAO) featurein the three-dimensional correlation function of the transmitted fluxfraction in the \Lya forest of high-redshift quasars. The study uses48,640 quasars in the redshift range $2.1\le z \le 3.5$ from the BaryonOscillation Spectroscopic Survey (BOSS) of the third generation of theSloan Digital Sky Survey (SDSS-III). At a mean redshift $z=2.3$, wemeasure the monopole and quadrupole components of the correlationfunction for separations in the range \$20\hMpc
Brownstein JR, Bolton AS, Schlegel DJ, Eisenstein DJ, Kochanek CS, Connolly N, Maraston C, Pandey P, Seitz S, Wake DA. The BOSS Emission-Line Lens Survey (BELLS). I. A Large Spectroscopically Selected Sample of Lens Galaxies at Redshift ~0.5. The Astrophysical Journal [Internet]. 2012;744:41. WebsiteAbstract
We present a catalog of 25 definite and 11 probable strong galaxy-galaxygravitational lens systems with lens redshifts 0.4 <~ z <~ 0.7,discovered spectroscopically by the presence of higher-redshift emissionlines within the Baryon Oscillation Spectroscopic Survey (BOSS) ofluminous galaxies, and confirmed with high-resolution Hubble SpaceTelescope (HST) images of 44 candidates. Our survey extends themethodology of the Sloan Lens Advanced Camera for Surveys survey (SLACS)to higher redshift. We describe the details of the BOSS spectroscopiccandidate detections, our HST ACS image processing and analysis methods,and our strong gravitational lens modeling procedure. We report BOSSspectroscopic parameters and ACS photometric parameters for allcandidates, and mass-distribution parameters for the best-fit singularisothermal ellipsoid models of definite lenses. Our sample to date wasselected using only the first six months of BOSS survey-qualityspectroscopic data. The full five-year BOSS database should produce asample of several hundred strong galaxy-galaxy lenses and in combinationwith SLACS lenses at lower redshift, strongly constrain the redshiftevolution of the structure of elliptical, bulge-dominated galaxies as afunction of luminosity, stellar mass, and rest-frame color, therebyproviding a powerful test for competing theories of galaxy formation andevolution.Based on observations made with the NASA/ESA Hubble Space Telescope,obtained at the Space Telescope Science Institute, which is operated bythe Association of Universities for Research in Astronomy, Inc., underNASA contract NAS 5-26555. These observations are associated withprogram 12209. Based on spectroscopic data from the Baryon OscillationSpectroscopic Survey of the Sloan Digital Sky Survey III.
Bolton AS, Brownstein JR, Kochanek CS, Shu Y, Schlegel DJ, Eisenstein DJ, Wake DA, Connolly N, Maraston C, Arneson RA. The BOSS Emission-Line Lens Survey. II. Investigating Mass-density Profile Evolution in the SLACS+BELLS Strong Gravitational Lens Sample. The Astrophysical Journal [Internet]. 2012;757:82. WebsiteAbstract
We present an analysis of the evolution of the central mass-densityprofile of massive elliptical galaxies from the SLACS and BELLS stronggravitational lens samples over the redshift interval z ≈ 0.1-0.6,based on the combination of strong-lensing aperture mass and stellarvelocity-dispersion constraints. We find a significant trend towardsteeper mass profiles (parameterized by the power-law density model withρvpropr -γ) at later cosmic times, with magnitude d< γ > /dz = -0.60 ± 0.15. We show that the combinedlens-galaxy sample is consistent with a non-evolving distribution ofstellar velocity dispersions. Considering possible additional dependenceof <γ > on lens-galaxy stellar mass, effective radius, andSérsic index, we find marginal evidence for shallower massprofiles at higher masses and larger sizes, but with a significance thatis subdominant to the redshift dependence. Using the results ofpublished Monte Carlo simulations of spectroscopic lens surveys, weverify that our mass-profile evolution result cannot be explained bylensing selection biases as a function of redshift. Interpreted as atrue evolutionary signal, our result suggests that major dry mergersinvolving off-axis trajectories play a significant role in the evolutionof the average mass-density structure of massive early-type galaxiesover the past 6 Gyr. We also consider an alternative non-evolutionaryhypothesis based on variations in the strong-lensing measurementaperture with redshift, which would imply the detection of an"inflection zone" marking the transition between the baryon-dominatedand dark-matter halo-dominated regions of the lens galaxies. Furtherobservations of the combined SLACS+BELLS sample can constrain thispicture more precisely, and enable a more detailed investigation of themultivariate dependences of galaxy mass structure across cosmic time.Based on observations made with the NASA/ESA Hubble Space Telescope,obtained at the Space Telescope Science Institute, which is operated bythe Association of Universities for Research in Astronomy, Inc., underNASA contract NAS 5-26555. These observations are associated withprograms 10174, 10494, 10587, 10798, 10886, and 12209.
Lee K-G, Bailey S, Bartsch LE, Carithers W, Dawson KS, Kirkby D, Lundgren B, Margala D, Palanque-Delabrouille N, Pieri MM. The BOSS Lyman-alpha Forest Sample from SDSS Data Release 9. ArXiv e-prints [Internet]. 2012;1211:5146. WebsiteAbstract
We present the BOSS Lyman-alpha (Lya) Forest Sample from SDSS DataRelease 9, comprising 54,468 quasar spectra with zqso > 2.15 suitablefor Lya forest analysis. This data set probes the intergalactic mediumwith absorption redshifts 2.0 < z_alpha < 5.7 over an area of 3275square degrees, and encompasses an approximate comoving volume of 20h^-3 Gpc^3. With each spectrum, we have included several productsdesigned to aid in Lya forest analysis: improved sky masks that flagpixels where data may be unreliable, corrections for known biases in thepipeline estimated noise, masks for the cores of damped Lya systems andcorrections for their wings, and estimates of the unabsorbed continua sothat the observed flux can be converted to a fractional transmission.The continua are derived using a principal component fit to the quasarspectrum redwards of restframe Lya (lambda > 1216 Ang), extrapolatedinto the forest region and normalized by a linear function to fit theexpected evolution of the Lya forest mean-flux. The estimated continuum
Anderson L, Aubourg E, Bailey S, Bizyaev D, Blanton M, Bolton AS, Brinkmann J, Brownstein JR, Burden A, Cuesta AJ. The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey: baryon acoustic oscillations in the Data Release 9 spectroscopic galaxy sample. Monthly Notices of the Royal Astronomical Society [Internet]. 2012;427:3435-3467. WebsiteAbstract
We present measurements of galaxy clustering from the Baryon OscillationSpectroscopic Survey (BOSS), which is part of the Sloan Digital SkySurvey III (SDSS-III). These use the Data Release 9 (DR9) CMASS sample,which contains 264 283 massive galaxies covering 3275 square degreeswith an effective redshift z = 0.57 and redshift range 0.43 < z <0.7. Assuming a concordance ΛCDM cosmological model, this samplecovers an effective volume of 2.2 Gpc3, and represents thelargest sample of the Universe ever surveyed at this density,n¯≈3×10-4 h-3 Mpc 3. We measure theangle-averaged galaxy correlation function and power spectrum, includingdensity-field reconstruction of the baryon acoustic oscillation (BAO)feature. The acoustic features are detected at a significance of5σ in both the correlation function and power spectrum. Combiningwith the SDSS-II luminous red galaxy sample, the detection significanceincreases to 6.7σ. Fitting for the position of the acousticfeatures measures the distance to z = 0.57 relative to the sound horizonDV/rs = 13.67 ± 0.22 at z = 0.57. Assuminga fiducial sound horizon of 153.19 Mpc, which matches cosmic microwavebackground constraints, this corresponds to a distance DV (z= 0.57) = 2094 ± 34 Mpc. At 1.7 per cent, this is the mostprecise distance constraint ever obtained from a galaxy survey. We placethis result alongside previous BAO measurements in a cosmologicaldistance ladder and find excellent agreement with the current supernovameasurements. We use these distance measurements to constrain variouscosmological models, finding continuing support for a flat Universe witha cosmological constant.