Kepler SO, Pelisoli I, Koester D, Ourique G, Romero AD, Reindl N, Kleinman SJ, Eisenstein DJ, Valois ADM, Amaral LA. New white dwarf and subdwarf stars in the Sloan Digital Sky Survey Data Release 12. Monthly Notices of the Royal Astronomical Society. 2016;455 :3413-3423. Publisher's VersionAbstract
We report the discovery of 6576 new spectroscopically confirmed whitedwarf and subdwarf stars in the Sloan Digital Sky Survey Data Release12. We obtain Teff, log g and mass for hydrogen atmospherewhite dwarf stars (DAs) and helium atmosphere white dwarf stars (DBs),estimate the calcium/helium abundances for the white dwarf stars withmetallic lines (DZs) and carbon/helium for carbon-dominated spectra(DQs). We found one central star of a planetary nebula, one ultracompacthelium binary (AM CVn), one oxygen line-dominated white dwarf, 15 hotDO/PG1159s, 12 new cataclysmic variables, 36 magnetic white dwarf stars,54 DQs, 115 helium-dominated white dwarfs, 148 white dwarf +main-sequence star binaries, 236 metal-polluted white dwarfs, 300continuum spectra DCs, 230 hot subdwarfs, 2936 new hydrogen-dominatedwhite dwarf stars, and 2675 cool hydrogen-dominated subdwarf stars. Wecalculate the mass distribution of all 5883 DAs with S/N ≥ 15 inDR12, including the ones in DR7 and DR10, with an average S/N = 26,corrected to the 3D convection scale, and also the distribution aftercorrecting for the observed volume, using 1/Vmax.
Mendez AJ, Coil AL, Aird J, Skibba RA, Diamond-Stanic AM, Moustakas J, Blanton MR, Cool RJ, Eisenstein DJ, Wong KC, et al. PRIMUS + DEEP2: Clustering of X-Ray, Radio, and IR-AGNs at z~0.7. The Astrophysical Journal. 2016;821. Publisher's VersionAbstract
We measure the clustering of X-ray, radio, and mid-IR-selected activegalactic nuclei (AGNs) at 0.2\lt z\lt 1.2 using multi-wavelength imagingand spectroscopic redshifts from the PRIMUS and DEEP2 redshift surveys,covering seven separate fields spanning ∼10 deg 2 . Using thecross-correlation of AGNs with dense galaxy samples, we measure theclustering scale length and slope, as well as the bias, of AGNs selectedat different wavelengths. Similar to previous studies, we find thatX-ray and radio AGNs are more clustered than mid-IR-selected AGNs. Wefurther compare the clustering of each AGN sample with matched galaxysamples designed to have the same stellar mass, star-formation rate(SFR), and redshift distributions as the AGN host galaxies and find nosignificant differences between their clustering properties. Theobserved differences in the clustering of AGNs selected at differentwavelengths can therefore be explained by the clustering differences oftheir host populations, which have different distributions in bothstellar mass and SFR. Selection biases inherent in AGN selectiontherefore determine the clustering of observed AGN samples. We furtherfind no significant difference between the clustering of obscured andunobscured AGNs, using IRAC or Wide-field Infrared Survey Explorercolors or X-ray hardness ratio.
Reid B, Ho S, Padmanabhan N, Percival WJ, Tinker J, Tojeiro R, White M, Eisenstein DJ, Maraston C, Ross AJ, et al. SDSS-III Baryon Oscillation Spectroscopic Survey Data Release 12: galaxy target selection and large-scale structure catalogues. Monthly Notices of the Royal Astronomical Society. 2016;455 :1553-1573. Publisher's VersionAbstract
The Baryon Oscillation Spectroscopic Survey (BOSS), part of the SloanDigital Sky Survey (SDSS) III project, has provided the largest surveyof galaxy redshifts available to date, in terms of both the number ofgalaxy redshifts measured by a single survey, and the effectivecosmological volume covered. Key to analysing the clustering of thesedata to provide cosmological measurements is understanding the detailedproperties of this sample. Potential issues include variations in thetarget catalogue caused by changes either in the targeting algorithm orproperties of the data used, the pattern of spectroscopic observations,the spatial distribution of targets for which redshifts were notobtained, and variations in the target sky density due to observationalsystematics. We document here the target selection algorithms used tocreate the galaxy samples that comprise BOSS. We also present thealgorithms used to create large-scale structure catalogues for the finalData Release (DR12) samples and the associated random catalogues thatquantify the survey mask. The algorithms are an evolution of those usedby the BOSS team to construct catalogues from earlier data, and havebeen designed to accurately quantify the galaxy sample. The code used,designated MKSAMPLE, is released with this paper.
Dawson KS, Kneib J-P, Percival WJ, Alam S, Albareti FD, Anderson SF, Armengaud E, Aubourg É, Bailey S, Bautista JE, et al. The SDSS-IV Extended Baryon Oscillation Spectroscopic Survey: Overview and Early Data. The Astronomical Journal. 2016;151. Publisher's VersionAbstract
In a six-year program started in 2014 July, the Extended BaryonOscillation Spectroscopic Survey (eBOSS) will conduct novel cosmologicalobservations using the BOSS spectrograph at Apache Point Observatory.These observations will be conducted simultaneously with the Time DomainSpectroscopic Survey (TDSS) designed for variability studies and theSpectroscopic Identification of eROSITA Sources (SPIDERS) programdesigned for studies of X-ray sources. In particular, eBOSS will measurewith percent-level precision the distance-redshift relation with baryonacoustic oscillations (BAO) in the clustering of matter. eBOSS will usefour different tracers of the underlying matter density field to vastlyexpand the volume covered by BOSS and map the large-scale-structuresover the relatively unconstrained redshift range 0.6 < z < 2.2.Using more than 250,000 new, spectroscopically confirmed luminous redgalaxies at a median redshift z = 0.72, we project that eBOSS will yieldmeasurements of the angular diameter distance dA(z) to an
Slepian Z, Eisenstein DJ. A simple analytic treatment of linear growth of structure with baryon acoustic oscillations. Monthly Notices of the Royal Astronomical Society. 2016;457 :24-37. Publisher's VersionAbstract
In linear perturbation theory, all information about the growth ofstructure is contained in the Green's function, or equivalently,transfer function. These functions are generally computed usingnumerical codes or by phenomenological fitting formula anchored inaccurate analytic results in the limits of large and small scale. Here,we present a framework for analytically solving all scales, inparticular the intermediate scales relevant for the baryon acousticoscillations (BAO). We solve for the Green's function and transferfunction using spherically averaged overdensities and the approximationthat the density of the coupled baryon-photon fluid is constant interiorto the sound horizon.
García Pérez AE, Allende Prieto C, Holtzman JA, Shetrone M, Mészáros S, Bizyaev D, Carrera R, Cunha K, García-Hernández DA, Johnson JA, et al. ASPCAP: The APOGEE Stellar Parameter and Chemical Abundances Pipeline. The Astronomical Journal. 2016;151. Publisher's VersionAbstract
The Apache Point Observatory Galactic Evolution Experiment (APOGEE) hasbuilt the largest moderately high-resolution (R ≈ 22,500)spectroscopic map of the stars across the Milky Way, and includingdust-obscured areas. The APOGEE Stellar Parameter and ChemicalAbundances Pipeline (ASPCAP) is the software developed for the automatedanalysis of these spectra. ASPCAP determines atmospheric parameters andchemical abundances from observed spectra by comparing observed spectrato libraries of theoretical spectra, using χ2minimization in a multidimensional parameter space. The package consistsof a fortran90 code that does the actual minimization and a wrapper IDLcode for book-keeping and data handling. This paper explains in detailthe ASPCAP components and functionality, and presents results from anumber of tests designed to check its performance. ASPCAP providesstellar effective temperatures, surface gravities, and metallicities
Favole G, McBride CK, Eisenstein DJ, Prada F, Swanson ME, Chuang C-H, Schneider DP. Building a better understanding of the massive high-redshift BOSS CMASS galaxies as tools for cosmology. Monthly Notices of the Royal Astronomical Society. 2016;462 :2218-2236. Publisher's VersionAbstract
We explore the massive bluer star-forming population of the SloanDigital Sky Survey (SDSS) III/BOSS CMASS DR11 galaxies at z > 0.55 toquantify their differences, in terms of redshift-space distortions andlarge-scale bias, with respect to the luminous red galaxy sample. Weperform a qualitative analysis to understand the significance of thesedifferences and whether we can model and reproduce them in mockcatalogues. Specifically, we measure galaxy clustering in CMASS on smalland intermediate scales (0.1 ≲ r ≲ 50 h-1 Mpc) bycomputing the two-point correlation function - both projected andredshift-space - of these galaxies, and a new statistic, Σ(π),able to separate the coherent and dispersed redshift-space distortioncontributions and the large-scale bias. We interpret our clusteringmeasurements by adopting a Halo Occupation Distribution (HOD) schemethat maps them on to high-resolution N-body cosmological simulations toproduce suitable mock galaxy catalogues. The traditional HODprescription can be applied to the red and the blue samples,independently, but this approach is unphysical since it allows the samemock galaxies to be either red or blue. To overcome this ambiguity, wemodify the standard formulation and infer the red and the blue models bysplitting the full mock catalogue into two complementary andnon-overlapping submocks. This separation is performed by constrainingthe HOD with the observed CMASS red and blue galaxy fractions andproduces reliable and accurate models.
Chuang C-H, Prada F, Pellejero-Ibanez M, Beutler F, Cuesta AJ, Eisenstein DJ, Escoffier S, Ho S, Kitaura F-S, Kneib J-P, et al. The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey: single-probe measurements from CMASS anisotropic galaxy clustering. Monthly Notices of the Royal Astronomical Society. 2016;461 :3781-3793. Publisher's VersionAbstract
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 h-1 Mpc).We analyse the broad-range shape of the monopole and quadrupolecorrelation functions of the BOSS Data Release 12 (DR12) CMASS galaxysample, at the effective redshift z = 0.59, to obtain constraints on theHubble expansion rate H(z), the angular- diameter distanceDA(z), the normalized growth rate f(z)σ8(z),and the physical matter density Ωm h2. Weobtain robust measurements by including a polynomial as the model forthe systematic errors, and find it works very well against thesystematic effects, e.g. ones induced by stars and seeing. We provideaccurate measurements{DA(0.59)rs,fid/rs,H(0.59)rs/rs,fid,f(0.59)σ8(0.59), Ωm h2} ={1427 ± 26 Mpc, 97.3 ± 3.3 km s-1Mpc-1, 0.488 ± 0.060, 0.135 ± 0.016}, wherers is the comoving sound horizon at the drag epoch andrs,fid = 147.66 Mpc is the sound scale of the fiducialcosmology used in this study. The parameters which are not wellconstrained by our galaxy clustering analysis are marginalized over withwide flat priors. Since no priors from other data sets, e.g. cosmicmicrowave background (CMB), are adopted and no dark energy models areassumed, our results from BOSS CMASS galaxy clustering alone may becombined with other data sets, i.e. CMB, SNe, lensing or other galaxyclustering data to constrain the parameters of a given cosmologicalmodel. The uncertainty on the dark energy equation of state parameter,w, from CMB+CMASS is about 8 per cent. The uncertainty on the curvaturefraction, Ωk, is 0.3 per cent. We do not find deviationfrom flat ΛCDM.
Favole G, Comparat J, Prada F, Yepes G, Jullo E, Niemiec A, Kneib J-P, Rodríguez-Torres SA, Klypin A, Skibba RA, et al. Clustering properties of g-selected galaxies at z ˜ 0.8. Monthly Notices of the Royal Astronomical Society. 2016;461 :3421-3431. Publisher's VersionAbstract
Current and future large redshift surveys, as the Sloan Digital SkySurvey IV extended Baryon Oscillation Spectroscopic Survey(SDSS-IV/eBOSS) or the Dark Energy Spectroscopic Instrument (DESI), willuse emission-line galaxies (ELGs) to probe cosmological models bymapping the large-scale structure of the Universe in the redshift range0.6 < z < 1.7. With current data, we explore the halo-galaxyconnection by measuring three clustering properties of g-selected ELGsas matter tracers in the redshift range 0.6 < z < 1: (i) theredshift-space two-point correlation function using spectroscopicredshifts from the BOSS ELG sample and VIPERS; (ii) the angulartwo-point correlation function on the footprint of the CFHT-LS; (iii)the galaxy-galaxy lensing signal around the ELGs using the CFHTLenS. Weinterpret these observations by mapping them on to the latesthigh-resolution MultiDark Planck N-body simulation, using a novel(Sub)Halo-Abundance Matching technique that accounts for the ELGincompleteness. ELGs at z ˜ 0.8 live in haloes of (1 ± 0.5)× 1012 h-1M and 22.5± 2.5 per cent of them are satellites belonging to a larger halo.The halo occupation distribution of ELGs indicates that we are samplingthe galaxies in which stars form in the most efficient way, according totheir stellar-to-halo mass ratio.
Speagle JS, Capak PL, Eisenstein DJ, Masters DC, Steinhardt CL. Exploring photometric redshifts as an optimization problem: an ensemble MCMC and simulated annealing-driven template-fitting approach. Monthly Notices of the Royal Astronomical Society. 2016;461 :3432-3442. Publisher's VersionAbstract
Using a 4D grid of ˜2 million model parameters (Δz = 0.005)adapted from Cosmological Origins Survey photometric redshift (photo-z)searches, we investigate the general properties of template-basedphoto-z likelihood surfaces. We find these surfaces are filled withnumerous local minima and large degeneracies that generally confoundsimplistic gradient-descent optimization schemes. We combine ensembleMarkov Chain Monte Carlo sampling with simulated annealing to robustlyand efficiently explore these surfaces in approximately constant time.Using a mock catalogue of 384 662 objects, we show our approach samples˜40 times more efficiently compared to a `brute-force' counterpartwhile maintaining similar levels of accuracy. Our results representfirst steps towards designing template-fitting photo-z approacheslimited mainly by memory constraints rather than computation time.
Montero-Dorta AD, Bolton AS, Brownstein JR, Swanson M, Dawson K, Prada F, Eisenstein D, Maraston C, Thomas D, Comparat J, et al. The high-mass end of the red sequence at z ˜ 0.55 from SDSS-III/BOSS: completeness, bimodality and luminosity function. Monthly Notices of the Royal Astronomical Society. 2016;461 :1131-1153. Publisher's VersionAbstract
We have developed an analytical method based on forward-modellingtechniques to characterize the high-mass end of the red sequence (RS)galaxy population at redshift z ˜ 0.55, from the DR10 BOSS (BaryonOscillation Spectroscopic Survey) CMASS spectroscopic sample, whichcomprises ˜600 000 galaxies. The method, which follows an unbinnedmaximum likelihood approach, allows the deconvolution of the intrinsicCMASS colour-colour-magnitude distributions from photometric errors andselection effects. This procedure requires modelling the covariancematrix for the i-band magnitude, g - r colour and r - i colour usingStripe 82 multi-epoch data. Our results indicate that theerror-deconvolved intrinsic RS distribution is consistent, within thephotometric uncertainties, with a single point (<0.05 mag) in thecolour-colour plane at fixed magnitude, for a narrow redshift slice. Wehave computed the high-mass end (0.55Mi ≲-22) of the 0.55i-band RS luminosity function (RS LF) inseveral redshift slices within the redshift range 0.52 < z < 0.63.In this narrow redshift range, the evolution of the RS LF is consistent,within the uncertainties in the modelling, with a passively evolvingmodel with Φ* = (7.248 ± 0.204) × 10-4 Mpc-3 mag-1, fading at a rate of 1.5± 0.4 mag per unit redshift. We report RS completeness as afunction of magnitude and redshift in the CMASS sample, which willfacilitate a variety of galaxy-evolution and clustering studies usingBOSS. Our forward-modelling method lays the foundations for futurestudies using other dark-energy surveys like the Extended BaryonOscillation Spectroscopic Survey or the Dark Energy SpectroscopicInstrument, which are affected by the same type of photometricblurring/selection effects.
Garrison LH, Eisenstein DJ, Ferrer D, Metchnik MV, Pinto PA. Improving initial conditions for cosmological N-body simulations. Monthly Notices of the Royal Astronomical Society. 2016;461 :4125-4145. Publisher's VersionAbstract
In cosmological N-body simulations, the representation of dark matter asdiscrete `macroparticles' suppresses the growth of structure, such thatsimulations no longer reproduce linear theory on small scales nearkNyquist. Marcos et al. demonstrate that this is due tosparse sampling of modes near kNyquist and that theoften-assumed continuum growing modes are not proper growing modes ofthe particle system. We develop initial conditions (ICs) that respectthe particle linear theory growing modes and then rescale the modeamplitudes to account for growth suppression. These ICs also allow us totake advantage of our very accurate N-body code ABACUS to implementsecond-order Lagrangian perturbation theory (2LPT) in configurationspace. The combination of 2LPT and rescaling improves the accuracy ofthe late-time power spectra, halo mass functions, and halo clustering.In particular, we achieve 1 per cent accuracy in the power spectrum downto kNyquist, versus kNyquist/4 without rescalingor kNyquist/13 without 2LPT, relative to an oversampledreference simulation. We anticipate that our 2LPT will be useful forlarge simulations where fast Fourier transforms are expensive and thatrescaling will be useful for suites of medium-resolution simulationsused in cosmic emulators and galaxy survey mock catalogues. Code togenerate ICs is available at
O'Connell R, Eisenstein D, Vargas M, Ho S, Padmanabhan N. Large covariance matrices: smooth models from the two-point correlation function. Monthly Notices of the Royal Astronomical Society. 2016;462 :2681-2694. Publisher's VersionAbstract
We introduce a new method for estimating the covariance matrix for thegalaxy correlation function in surveys of large-scale structure. Ourmethod combines simple theoretical results with a realisticcharacterization of the survey to dramatically reduce noise in thecovariance matrix. For example, with an investment of only ≈1000 CPUhours we can produce a model covariance matrix with noise levels thatwould otherwise require ˜35 000 mocks. Non-Gaussian contributionsto the model are calibrated against mock catalogues, after which themodel covariance is found to be in impressive agreement with the mockcovariance matrix. Since calibration of this method requires fewer mocksthan brute force approaches, we believe that it could dramaticallyreduce the number of mocks required to analyse future surveys.
Patej A, Eisenstein D. Quantifying the colour-dependent stochasticity of large-scale structure. Monthly Notices of the Royal Astronomical Society. 2016;460 :1310-1317. Publisher's VersionAbstract
We address the question of whether massive red and blue galaxies tracethe same large-scale structure at z ˜ 0.6 using the CMASS sampleof galaxies from Data Release 12 of the Sloan Digital Sky Survey III.After splitting the catalogue into subsamples of red and blue galaxiesusing a simple colour cut, we measure the clustering of both subsamplesand construct the correlation coefficient, r, using two statistics. Thecorrelation coefficient quantifies the stochasticity between the twosubsamples, which we examine over intermediate scales (20 ≲ R≲ 100 h-1 Mpc). We find that on these intermediatescales, the correlation coefficient is consistent with 1; in particular,we find r > 0.95 taking into account both statistics and r > 0.974using the favoured statistic.
Kitaura F-S, Chuang C-H, Liang Y, Zhao C, Tao C, Rodríguez-Torres S, Eisenstein DJ, Gil-Marín H, Kneib J-P, McBride C, et al. Signatures of the Primordial Universe from Its Emptiness: Measurement of Baryon Acoustic Oscillations from Minima of the Density Field. Physical Review Letters. 2016;116. Publisher's VersionAbstract
Sound waves from the primordial fluctuations of the Universe imprintedin the large-scale structure, called baryon acoustic oscillations(BAOs), can be used as standard rulers to measure the scale of theUniverse. These oscillations have already been detected in thedistribution of galaxies. Here we propose to measure BAOs from thetroughs (minima) of the density field. Based on two sets of accuratemock halo catalogues with and without BAOs in the seed initialconditions, we demonstrate that the BAO signal cannot be obtained fromthe clustering of classical disjoint voids, but it is clearly detectedfrom overlapping voids. The latter represent an estimate of all troughsof the density field. We compute them from the empty circumspherecenters constrained by tetrahedra of galaxies using Delaunaytriangulation. Our theoretical models based on an unprecedented largeset of detailed simulated void catalogues are remarkably well confirmedby observational data. We use the largest recently publicly availablesample of luminous red galaxies from SDSS-III BOSS DR11 to unveil forthe first time a >3 σ BAO detection from voids in observations.Since voids are nearly isotropically expanding regions, their centersrepresent the most quiet places in the Universe, keeping in mind thecosmos origin and providing a new promising window in the analysis ofthe cosmological large-scale structure from galaxy surveys.
Holtzman JA, Shetrone M, Johnson JA, Allende Prieto C, Anders F, Andrews B, Beers TC, Bizyaev D, Blanton MR, Bovy J, et al. Abundances, Stellar Parameters, and Spectra from the SDSS-III/APOGEE Survey. The Astronomical Journal. 2015;150. Publisher's VersionAbstract
The SDSS-III/Apache Point Observatory Galactic Evolution Experiment(APOGEE) survey operated from 2011-2014 using the APOGEEspectrograph, which collects high-resolution (R ˜ 22,500), near-IR(1.51-1.70 μm) spectra with a multiplexing (300 fiber-fedobjects) capability. We describe the survey data products that arepublicly available, which include catalogs with radial velocity, stellarparameters, and 15 elemental abundances for over 150,000 stars, as wellas the more than 500,000 spectra from which these quantities arederived. Calibration relations for the stellar parameters({T}{eff}, {log} g, [M/H], [α/M]) and abundances (C, N,O, Na, Mg, Al, Si, S, K, Ca, Ti, V, Mn, Fe, Ni) are presented anddiscussed. The internal scatter of the abundances within clustersindicates that abundance precision is generally between 0.05 and 0.09dex across a broad temperature range; it is smaller for some elementalabundances within more limited ranges and at high signal-to-noise ratio.We assess the accuracy of the abundances using comparison of meancluster metallicities with literature values, APOGEE observations of thesolar spectrum and of Arcturus, comparison of individual star abundanceswith other measurements, and consideration of the locus of derivedparameters and abundances of the entire sample, and find that it ischallenging to determine the absolute abundance scale; external accuracymay be good to 0.1-0.2 dex. Uncertainties may be larger at coolertemperatures ({T}{eff} \lt 4000 {{K}}). Access to thepublic data release and data products is described, and some guidancefor using the data products is provided.
Slepian Z, Eisenstein DJ. Computing the three-point correlation function of galaxies in O(N^2) time. Monthly Notices of the Royal Astronomical Society. 2015;454 :4142-4158. Publisher's VersionAbstract
We present an algorithm that computes the multipole coefficients of thegalaxy three-point correlation function (3PCF) without explicitlyconsidering triplets of galaxies. Rather, centring on each galaxy in thesurvey, it expands the radially binned density field in sphericalharmonics and combines these to form the multipoles without everrequiring the relative angle between a pair about the central. Thisapproach scales with number and number density in the same way as thetwo-point correlation function, allowing run-times that are comparable,and 500 times faster than a naive triplet count. It is exact in angleand easily handles edge correction. We demonstrate the algorithm on theLasDamas SDSS-DR7 mock catalogues, computing an edge corrected 3PCF outto 90 Mpc h-1 in under an hour on modest computing resources.We expect this algorithm will render it possible to obtain thelarge-scale 3PCF for upcoming surveys such as Euclid, Large SynopticSurvey Telescope (LSST), and Dark Energy Spectroscopic Instrument.
Skibba RA, Coil AL, Mendez AJ, Blanton MR, Bray AD, Cool RJ, Eisenstein DJ, Guo H, Miyaji T, Moustakas J, et al. Dark Matter Halo Models of Stellar Mass-dependent Galaxy Clustering in PRIMUS+DEEP2 at 0.2>z>1.2. The Astrophysical Journal. 2015;807. Publisher's VersionAbstract
We utilize ΛCDM halo occupation models of galaxy clustering toinvestigate the evolving stellar mass dependent clustering of galaxiesin the PRIsm MUlti-object Survey (PRIMUS) and DEEP2 Redshift Survey overthe past eight billion years of cosmic time, between 0.2\lt z\lt 1.2.These clustering measurements provide new constraints on the connectionsbetween dark matter halo properties and galaxy properties in the contextof the evolving large-scale structure of the universe. Using both ananalytic model and a set of mock galaxy catalogs, we find a strongcorrelation between central galaxy stellar mass and dark matter halomass over the range {M}{halo}˜{10}11-{10}13 {h}-1{M}, approximately consistent with previousobservations and theoretical predictions. However, the stellar-to-halomass relation and the mass scale where star formation efficiency reachesa maximum appear to evolve more strongly than predicted by other models,including models based primarily on abundance-matching constraints. Wefind that the fraction of satellite galaxies in halos of a given massdecreases significantly from z˜ 0.5 to z˜ 0.9, partly due to thefact that halos at fixed mass are rarer at higher redshift and havelower abundances. We also find that the{M}1/{M}{min} ratio, a model parameter thatquantifies the critical mass above which halos host at least onesatellite, decreases from ≈ 20 at z˜ 0 to ≈ 13 at z˜ 0.9.Considering the evolution of the subhalo mass function vis-à-vissatellite abundances, this trend has implications for relations betweensatellite galaxies and halo substructures and for intracluster mass,which we argue has grown due to stripped and disrupted satellitesbetween z˜ 0.9 and z˜ 0.5.
Alam S, Albareti FD, Allende Prieto C, Anders F, Anderson SF, Anderton T, Andrews BH, Armengaud E, Aubourg É, Bailey S, et al. The Eleventh and Twelfth Data Releases of the Sloan Digital Sky Survey: Final Data from SDSS-III. The Astrophysical Journal Supplement Series. 2015;219. Publisher's VersionAbstract
The third generation of the Sloan Digital Sky Survey (SDSS-III) tookdata from 2008 to 2014 using the original SDSS wide-field imager, theoriginal and an upgraded multi-object fiber-fed optical spectrograph, anew near-infrared high-resolution spectrograph, and a novel opticalinterferometer. All of the data from SDSS-III are now made public. Inparticular, this paper describes Data Release 11 (DR11) including alldata acquired through 2013 July, and Data Release 12 (DR12) adding dataacquired through 2014 July (including all data included in previous datareleases), marking the end of SDSS-III observing. Relative to ourprevious public release (DR10), DR12 adds one million new spectra ofgalaxies and quasars from the Baryon Oscillation Spectroscopic Survey(BOSS) over an additional 3000 deg2 of sky, more than triplesthe number of H-band spectra of stars as part of the Apache PointObservatory (APO) Galactic Evolution Experiment (APOGEE), and includesrepeated accurate radial velocity measurements of 5500 stars from theMulti-object APO Radial Velocity Exoplanet Large-area Survey (MARVELS).The APOGEE outputs now include the measured abundances of 15 differentelements for each star. In total, SDSS-III added 5200 deg2 ofugriz imaging; 155,520 spectra of 138,099 stars as part of the SloanExploration of Galactic Understanding and Evolution 2 (SEGUE-2) survey;2,497,484 BOSS spectra of 1,372,737 galaxies, 294,512 quasars, and247,216 stars over 9376 deg2; 618,080 APOGEE spectra of156,593 stars; and 197,040 MARVELS spectra of 5513 stars. Since itsfirst light in 1998, SDSS has imaged over 1/3 of the Celestial sphere infive bands and obtained over five million astronomical spectra.
Krolewski AG, Eisenstein DJ. Measuring the Luminosity and Virial Black Hole Mass Dependence of Quasar-Galaxy Clustering At z ˜ 0.8. The Astrophysical Journal. 2015;803. Publisher's VersionAbstract
We study the dependence of quasar clustering on quasar luminosity andblack hole mass by measuring the angular overdensity of photometricallyselected galaxies imaged by the Wide-field Infrared Survey Explorer(WISE) about z ˜ 0.8 quasars from SDSS. By measuring thequasar-galaxy cross-correlation function and using photometricallyselected galaxies, we achieve a higher density of tracer objects and amore sensitive detection of clustering than measurements of the quasarautocorrelation function. We test models of quasar formation andevolution by measuring the luminosity dependence of clusteringamplitude. We find a significant overdensity of WISE galaxies about z˜ 0.8 quasars at 0.2-6.4 h-1 Mpc in projectedcomoving separation. We find no appreciable increase in clusteringamplitude with quasar luminosity across a decade in luminosity, and apower-law fit between luminosity and clustering amplitude gives anexponent of -0.01 ± 0.06 (1 σ error). We also fail tofind a significant relationship between clustering amplitude and blackhole mass, although our dynamic range in true mass is suppressed due tothe large uncertainties in virial black hole mass estimates. Our resultsindicate that a small range in host dark matter halo mass maps to alarge range in quasar luminosity.