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Sample records for survey final redshift

  1. Redshift surveys

    NASA Technical Reports Server (NTRS)

    Geller, Margaret J.; Huchra, J. P.

    1991-01-01

    Present-day understanding of the large-scale galaxy distribution is reviewed. The statistics of the CfA redshift survey are briefly discussed. The need for deeper surveys to clarify the issues raised by recent studies of large-scale galactic distribution is addressed.

  2. Redshift Survey Strategies

    NASA Astrophysics Data System (ADS)

    Jones, A. W.; Bland-Hawthorn, J.; Kaiser, N.

    1994-12-01

    In the first half of 1995, the Anglo-Australian Observatory is due to commission a wide field (2.1(deg) ), 400-fiber, double spectrograph system (2dF) at the f/3.3 prime focus of the AAT 3.9m bi-national facility. The instrument should be able to measure ~ 4000 galaxy redshifts (assuming a magnitude limit of b_J ~\\ 20) in a single dark night and is therefore ideally suited to studies of large-scale structure. We have carried out simple 3D numerical simulations to judge the relative merits of sparse surveys and contiguous surveys. We generate a survey volume and fill it randomly with particles according to a selection function which mimics a magnitude-limited survey at b_J = 19.7. Each of the particles is perturbed by a gaussian random field according to the dimensionless power spectrum k(3) P(k) / 2pi (2) determined by Feldman, Kaiser & Peacock (1994) from the IRAS QDOT survey. We introduce some redshift-space distortion as described by Kaiser (1987), a `thermal' component measured from pairwise velocities (Davis & Peebles 1983), and `fingers of god' due to rich clusters at random density enhancements. Our particular concern is to understand how the window function W(2(k)) of the survey geometry compromises the accuracy of statistical measures [e.g., P(k), xi (r), xi (r_sigma ,r_pi )] commonly used in the study of large-scale structure. We also examine the reliability of various tools (e.g. genus) for describing the topological structure within a contiguous region of the survey.

  3. Galaxy and cluster redshift surveys

    NASA Technical Reports Server (NTRS)

    Geller, Margaret J.; Huchra, John P.

    1988-01-01

    The present evaluation of galaxy and cluster redshift surveys gives attention to the CfA redshift survey and a deep Abell cluster redshift survey. These data support a structure in which galaxies lie on thin sheets which nearly surround vast, low-density voids. Voids such as that in Bootes are a common feature of galaxy distribution, posing a serious challenge for models. The Huchra et al. (1988) deep-cluster survey exhibits a correlation function amplitude that is a factor of about 2 smaller than that of the earlier Bahcall and Soneira (1983) sample; the difference may not be significant, however, because the cluster samples are sufficiently small to be dominated by single systems.

  4. Photometric Redshifts in the IRAC Shallow Survey

    SciTech Connect

    Brodwin, M; Brown, M; Ashby, M; Bian, C; Brand, K; Dey, A; Eisenhardt, P; Eisenstein, D; Gonzalez, A; Huang, J; Kochanek, C; McKenzie, E; Pahre, M; Smith, H; Soifer, B; Stanford, S; Stern, D; Elston, R

    2006-06-13

    Accurate photometric redshifts are calculated for nearly 200,000 galaxies to a 4.5 micron flux limit of {approx} 13 {micro}Jy in the 8.5 deg{sup 2} Spitzer/IRAC Shallow survey. Using a hybrid photometric redshift algorithm incorporating both neural-net and template-fitting techniques, calibrated with over 15,000 spectroscopic redshifts, a redshift accuracy of {sigma} = 0.06 (1+z) is achieved for 95% of galaxies at 0 < z < 1.5. The accuracy is {sigma} = 0.12 (1 + z) for 95% of AGN at 0 < z < 3. Redshift probability functions, central to several ongoing studies of the galaxy population, are computed for the full sample. We demonstrate that these functions accurately represent the true redshift probability density, allowing the calculation of valid confidence intervals for all objects. These probability functions have already been used to successfully identify a population of Spitzer-selected high redshift (z > 1) galaxy clusters. We present one such spectroscopically confirmed cluster at = 1.24, ISCS J1434.2+3426. Finally, we present a measurement of the 4.5 {micro}m-selected galaxy redshift distribution.

  5. Cosmology with photometric redshift surveys

    NASA Astrophysics Data System (ADS)

    Blake, Chris; Bridle, Sarah

    2005-11-01

    We explore the utility of future photometric redshift imaging surveys for delineating the large-scale structure of the Universe, and assess the resulting constraints on the cosmological model. We perform the following two complementary types of analysis. (i) We quantify the statistical confidence and the accuracy with which such surveys will be able to detect and measure characteristic features in the clustering power spectrum such as the acoustic oscillations and the turnover, in a `model-independent' fashion. We show for example that a 10000-deg2 imaging survey with depth r= 22.5 and photometric redshift accuracy δz/(1 +z) = 0.03 will detect the acoustic oscillations with 99.9 per cent confidence, measuring the associated preferred cosmological scale with 2 per cent precision. Such a survey will also detect the turnover with 95 per cent confidence, determining the corresponding scale with 20 per cent accuracy. (ii) By assuming a Λ cold dark matter (ΛCDM) model power spectrum we calculate the confidence with which a non-zero baryon fraction can be deduced from such future galaxy surveys. We quantify `wiggle detection' by calculating the number of standard deviations by which the baryon fraction is measured, after marginalizing over the shape parameter. This is typically a factor of 4 more significant (in terms of number of standard deviations) than the above `model-independent' result. For both analyses, we quantify the variation of the results with magnitude depth and photometric redshift precision, and discuss the prospects for obtaining the required performance with realistic future surveys. We conclude that the precision with which the clustering pattern may be inferred from future photometric redshift surveys will be competitive with contemporaneous spectroscopic redshift surveys, assuming that systematic effects can be controlled. We find that for equivalent wiggle detection power, a photometric redshift survey requires an area approximately 12[δz/(1 +z

  6. Southern Sky Redshift Survey

    SciTech Connect

    Da Costa, L.N.; Pellegrini, P.S.; Sargent, W.L.W.; Tonry, J.; Davis, M.

    1988-04-01

    The general characteristics of the space distribution of galaxies in the SSRS sample, covering the southern Galactic cap, are examined, and maps of the space distribution are presented. The sample consists of 2028 galaxies in an area of 1.75 sr with declination south of -17.5 deg and galactic latitude below -30 deg. The survey provides useful information on large-scale structure to a depth of 120/h Mpc. The galaxy distribution exhibits prominent filaments, sheets, and voids. Some large-scale structures are highly subclustered; others are much more diffuse. 21 references.

  7. Bayesian redshift-space distortions correction from galaxy redshift surveys

    NASA Astrophysics Data System (ADS)

    Kitaura, Francisco-Shu; Ata, Metin; Angulo, Raul E.; Chuang, Chia-Hsun; Rodríguez-Torres, Sergio; Monteagudo, Carlos Hernández; Prada, Francisco; Yepes, Gustavo

    2016-03-01

    We present a Bayesian reconstruction method which maps a galaxy distribution from redshift- to real-space inferring the distances of the individual galaxies. The method is based on sampling density fields assuming a lognormal prior with a likelihood modelling non-linear stochastic bias. Coherent redshift-space distortions are corrected in a Gibbs-sampling procedure by moving the galaxies from redshift- to real-space according to the peculiar motions derived from the recovered density field using linear theory. The virialized distortions are corrected by sampling candidate real-space positions along the line of sight, which are compatible with the bulk flow corrected redshift-space position adding a random dispersion term in high-density collapsed regions (defined by the eigenvalues of the Hessian). This approach presents an alternative method to estimate the distances to galaxies using the three-dimensional spatial information, and assuming isotropy. Hence the number of applications is very broad. In this work, we show the potential of this method to constrain the growth rate up to k ˜ 0.3 h Mpc-1. Furthermore it could be useful to correct for photometric redshift errors, and to obtain improved baryon acoustic oscillations (BAO) reconstructions.

  8. A redshift survey of IRAS galaxies

    NASA Technical Reports Server (NTRS)

    Smith, Beverly J.; Kleinmann, S. G.; Huchra, J. P.; Low, F. J.

    1987-01-01

    Results are presented from a redshift survey of all 72 galaxies detected by IRAS in Band 3 at flux levels equal to or greater then 2 Jy. The luminosity function at the high luminosity end is proportional to L sup -2, however, a flattening was observed at the low luminosity end indicating that a single power law is not a good description of the entire luminosity function. Only three galaxies in the sample have emission line spectra indicative of AGN's, suggesting that, at least in nearby galaxies, unobscured nuclear activity is not a strong contributor to the far infrared flux. Comparisons between the selected IRAS galaxies and an optically complete sample taken from the CfA redshift survey show that they are more narrowly distributed than those optically selected, in the sence that the IRAS sample includes few galaxies of low absolute blue luminosity. It was also found that the space distributions of the two samples differ: the density enhancement or IRAS galaxies is only approx. 1/3 that of the optically selected galaxies in the core of the Coma cluster.

  9. Measuring the cosmological constant with redshift surveys

    NASA Astrophysics Data System (ADS)

    Ballinger, W. E.; Peacock, J. A.; Heavens, A. F.

    1996-10-01

    It has been proposed that the cosmological constant {LAMBDA} might be measured from geometric effects on large-scale structure. A positive vacuum density leads to correlation function contours which are squashed in the radial direction when calculated assuming a matter-dominated model. We show that this effect will be somewhat harder to detect than previous calculations have suggested: the squashing factor is likely to be < 1.3, given realistic constraints on the matter contribution to {OMEGA}. Moreover, the geometrical distortion risks being confused with the redshift-space distortions caused by the peculiar velocities associated with the growth of galaxy clustering. These depend on the density and bias parameters via the combination β = {OMEGA}^0.6/b, and we show that the main practical effect of a geometrical flattening factor F is to simulate gravitational instability with B_eff_ ~ 0.5(F - 1). Nevertheless, with datasets of sufficient size it is possible to distinguish the two effects, We discuss in detail how this should be done, and give a maximum-likelihood method for extracting {LAMBDA} and βb from anisotropic power-spectrum data. New-generation redshift surveys of galaxies and quasars are potentially capable of detecting a non-zero vacuum density, if it exists at a cosmologically interesting level.

  10. Constraining inflation with future galaxy redshift surveys

    SciTech Connect

    Huang, Zhiqi; Vernizzi, Filippo; Verde, Licia E-mail: liciaverde@icc.ub.edu

    2012-04-01

    With future galaxy surveys, a huge number of Fourier modes of the distribution of the large scale structures in the Universe will become available. These modes are complementary to those of the CMB and can be used to set constraints on models of the early universe, such as inflation. Using a MCMC analysis, we compare the power of the CMB with that of the combination of CMB and galaxy survey data, to constrain the power spectrum of primordial fluctuations generated during inflation. We base our analysis on the Planck satellite and a spectroscopic redshift survey with configuration parameters close to those of the Euclid mission as examples. We first consider models of slow-roll inflation, and show that the inclusion of large scale structure data improves the constraints by nearly halving the error bars on the scalar spectral index and its running. If we attempt to reconstruct the inflationary single-field potential, a similar conclusion can be reached on the parameters characterizing the potential. We then study models with features in the power spectrum. In particular, we consider ringing features produced by a break in the potential and oscillations such as in axion monodromy. Adding large scale structures improves the constraints on features by more than a factor of two. In axion monodromy we show that there are oscillations with small amplitude and frequency in momentum space that are undetected by CMB alone but can be measured by including galaxy surveys in the analysis.

  11. Hierarchical Bayesian inference of galaxy redshift distributions from photometric surveys

    NASA Astrophysics Data System (ADS)

    Leistedt, Boris; Mortlock, Daniel J.; Peiris, Hiranya V.

    2016-08-01

    Accurately characterizing the redshift distributions of galaxies is essential for analysing deep photometric surveys and testing cosmological models. We present a technique to simultaneously infer redshift distributions and individual redshifts from photometric galaxy catalogues. Our model constructs a piecewise constant representation (effectively a histogram) of the distribution of galaxy types and redshifts, the parameters of which are efficiently inferred from noisy photometric flux measurements. This approach can be seen as a generalization of template-fitting photometric redshift methods and relies on a library of spectral templates to relate the photometric fluxes of individual galaxies to their redshifts. We illustrate this technique on simulated galaxy survey data, and demonstrate that it delivers correct posterior distributions on the underlying type and redshift distributions, as well as on the individual types and redshifts of galaxies. We show that even with uninformative priors, large photometric errors and parameter degeneracies, the redshift and type distributions can be recovered robustly thanks to the hierarchical nature of the model, which is not possible with common photometric redshift estimation techniques. As a result, redshift uncertainties can be fully propagated in cosmological analyses for the first time, fulfilling an essential requirement for the current and future generations of surveys.

  12. A COS Survey of the Low-Redshift Intergalactic Medium

    NASA Astrophysics Data System (ADS)

    Danforth, Charles; Pieri, M.; Shull, J. M.; Keeney, B. A.; Stevans, M. L.; Stocke, J. T.; Savage, B. D.; Green, J. C.

    2013-01-01

    In three years of science operations onboard HST, the Cosmic OriginsSpectrograph has generated an archive of far-ultraviolet AGN spectra of unprecedented breadth, depth, and quality. COS was designed to be sensitive to many important diagnostic lines in the far-UV (1135-1800A) in the low-redshift, "local" universe: Lya (z<0.47), Lyb (0.1survey of extragalactic absorption systems toward ~200 low- to moderate-redshift (z<1.5), UV-bright AGN. When complete mid-2013), the COS IGM absorber catalog will provide an unbiased, statistical sampling of local intergalactic absorption along ~200 extragalactic sight lines. This significant cornerstone of the scientific legacy of COS is at least an order-of-magnitude improvement over previous low-z IGM surveys in total observed pathlength and number of absorbers as well as substantial improvements in sensitivity and uniformity. Of particular interest is the sensitivity of COS to weak and broad absorption. We discuss the scope of and methodology behind the catalog, several initial discoveries, and the overall statistical findings of the survey. Finally, we discuss the new areas of cosmology enabled by this expanded study.

  13. Mapping the Galaxy Color–Redshift Relation: Optimal Photometric Redshift Calibration Strategies for Cosmology Surveys

    NASA Astrophysics Data System (ADS)

    Masters, Daniel; Capak, Peter; Stern, Daniel; Ilbert, Olivier; Salvato, Mara; Schmidt, Samuel; Longo, Giuseppe; Rhodes, Jason; Paltani, Stephane; Mobasher, Bahram; Hoekstra, Henk; Hildebrandt, Hendrik; Coupon, Jean; Steinhardt, Charles; Speagle, Josh; Faisst, Andreas; Kalinich, Adam; Brodwin, Mark; Brescia, Massimo; Cavuoti, Stefano

    2015-11-01

    Calibrating the photometric redshifts of ≳109 galaxies for upcoming weak lensing cosmology experiments is a major challenge for the astrophysics community. The path to obtaining the required spectroscopic redshifts for training and calibration is daunting, given the anticipated depths of the surveys and the difficulty in obtaining secure redshifts for some faint galaxy populations. Here we present an analysis of the problem based on the self-organizing map, a method of mapping the distribution of data in a high-dimensional space and projecting it onto a lower-dimensional representation. We apply this method to existing photometric data from the COSMOS survey selected to approximate the anticipated Euclid weak lensing sample, enabling us to robustly map the empirical distribution of galaxies in the multidimensional color space defined by the expected Euclid filters. Mapping this multicolor distribution lets us determine where—in galaxy color space—redshifts from current spectroscopic surveys exist and where they are systematically missing. Crucially, the method lets us determine whether a spectroscopic training sample is representative of the full photometric space occupied by the galaxies in a survey. We explore optimal sampling techniques and estimate the additional spectroscopy needed to map out the color–redshift relation, finding that sampling the galaxy distribution in color space in a systematic way can efficiently meet the calibration requirements. While the analysis presented here focuses on the Euclid survey, similar analysis can be applied to other surveys facing the same calibration challenge, such as DES, LSST, and WFIRST.

  14. SHELS: Complete Redshift Surveys of Two Widely Separated Fields

    NASA Astrophysics Data System (ADS)

    Geller, Margaret J.; Hwang, Ho Seong; Dell’Antonio, Ian P.; Zahid, Harus Jabran; Kurtz, Michael J.; Fabricant, Daniel G.

    2016-05-01

    The Smithsonian Hectospec Lensing Survey (SHELS) is a complete redshift survey covering two well-separated fields (F1 and F2) of the Deep Lens Survey (DLS). Both fields are more than 94% complete to a Galactic extinction corrected R 0 = 20.2. Here, we describe the redshift survey of the F1 field centered at R.A.2000 = 00h53m25.ˢ3 and decl.2000 = 12°33‧55″ like F2, the F1 field covers ˜4 deg2. The redshift survey of the F1 field includes 9426 new galaxy redshifts measured with Hectospec on the MMT (published here). As a guide to future uses of the combined survey, we compare the mass metallicity relation and the distributions of D n 4000 as a function of stellar mass and redshift for the two fields. The mass–metallicity relations differ by an insignificant 1.6σ. For galaxies in the stellar mass range 1010–1011 M ⊙, the increase in the star-forming fraction with redshift is remarkably similar in the two fields. The seemingly surprising 31%–38% difference in the overall galaxy counts in F1 and F2 is probably consistent with the expected cosmic variance given the subtleties of the relative systematics in the two surveys. We also review the DLS cluster detections in the two fields: poorer photometric data for F1 precluded secure detection of the single massive cluster at z = 0.35 that we find in SHELS. Taken together, the two fields include 16,055 redshifts for galaxies with {R}0≤slant 20.2 and 20,754 redshifts for galaxies with R ≤ 20.6. These dense surveys in two well-separated fields provide a basis for future investigations of galaxy properties and large-scale structure.

  15. SHELS: Complete Redshift Surveys of Two Widely Separated Fields

    NASA Astrophysics Data System (ADS)

    Geller, Margaret J.; Hwang, Ho Seong; Dell’Antonio, Ian P.; Zahid, Harus Jabran; Kurtz, Michael J.; Fabricant, Daniel G.

    2016-05-01

    The Smithsonian Hectospec Lensing Survey (SHELS) is a complete redshift survey covering two well-separated fields (F1 and F2) of the Deep Lens Survey (DLS). Both fields are more than 94% complete to a Galactic extinction corrected R 0 = 20.2. Here, we describe the redshift survey of the F1 field centered at R.A.2000 = 00h53m25.ˢ3 and decl.2000 = 12°33‧55″ like F2, the F1 field covers ∼4 deg2. The redshift survey of the F1 field includes 9426 new galaxy redshifts measured with Hectospec on the MMT (published here). As a guide to future uses of the combined survey, we compare the mass metallicity relation and the distributions of D n 4000 as a function of stellar mass and redshift for the two fields. The mass–metallicity relations differ by an insignificant 1.6σ. For galaxies in the stellar mass range 1010–1011 M ⊙, the increase in the star-forming fraction with redshift is remarkably similar in the two fields. The seemingly surprising 31%–38% difference in the overall galaxy counts in F1 and F2 is probably consistent with the expected cosmic variance given the subtleties of the relative systematics in the two surveys. We also review the DLS cluster detections in the two fields: poorer photometric data for F1 precluded secure detection of the single massive cluster at z = 0.35 that we find in SHELS. Taken together, the two fields include 16,055 redshifts for galaxies with {R}0≤slant 20.2 and 20,754 redshifts for galaxies with R ≤ 20.6. These dense surveys in two well-separated fields provide a basis for future investigations of galaxy properties and large-scale structure.

  16. THE 2MASS REDSHIFT SURVEY-DESCRIPTION AND DATA RELEASE

    SciTech Connect

    Huchra, John P.; Berlind, Perry; Calkins, Michael; Falco, Emilio; Mink, Jessica D.; Tokarz, Susan; Macri, Lucas M.; Masters, Karen L.; Jarrett, Thomas H.; Crook, Aidan C.; Cutri, Roc; Erdogdu, Pirin; Lahav, Ofer; George, Teddy; Hutcheson, Conrad M.; Mader, Jeff; Martimbeau, Nathalie; Schneider, Stephen; Skrutskie, Michael; Westover, Michael E-mail: karen.masters@port.ac.uk

    2012-04-01

    We present the results of the 2MASS Redshift Survey (2MRS), a ten-year project to map the full three-dimensional distribution of galaxies in the nearby universe. The Two Micron All Sky Survey (2MASS) was completed in 2003 and its final data products, including an extended source catalog (XSC), are available online. The 2MASS XSC contains nearly a million galaxies with K{sub s} {<=} 13.5 mag and is essentially complete and mostly unaffected by interstellar extinction and stellar confusion down to a galactic latitude of |b| = 5 Degree-Sign for bright galaxies. Near-infrared wavelengths are sensitive to the old stellar populations that dominate galaxy masses, making 2MASS an excellent starting point to study the distribution of matter in the nearby universe. We selected a sample of 44,599 2MASS galaxies with K{sub s} {<=} 11.75 mag and |b| {>=} 5 Degree-Sign ({>=}8 Degree-Sign toward the Galactic bulge) as the input catalog for our survey. We obtained spectroscopic observations for 11,000 galaxies and used previously obtained velocities for the remainder of the sample to generate a redshift catalog that is 97.6% complete to well-defined limits and covers 91% of the sky. This provides an unprecedented census of galaxy (baryonic mass) concentrations within 300 Mpc. Earlier versions of our survey have been used in a number of publications that have studied the bulk motion of the Local Group, mapped the density and peculiar velocity fields out to 50 h{sup -1} Mpc, detected galaxy groups, and estimated the values of several cosmological parameters. Additionally, we present morphological types for a nearly complete sub-sample of 20,860 galaxies with K{sub s} {<=} 11.25 mag and |b| {>=} 10 Degree-Sign .

  17. On the derivation of selection functions from redshift survey data

    NASA Technical Reports Server (NTRS)

    Strauss, Michael A.; Yahil, Amos; Davis, Marc

    1991-01-01

    A previously unrecognized effect is described in the derivation of luminosity functions and selection functions from existing redshift survey data, due to binning of quoted magnitudes and diameters. Corrections are made for this effect in the Center for Astrophysics (CfA) and Southern Sky (SSRS) Redshift Surveys. The correction makes subtle but systematic changes in the derived density fields of the CfA survey, especially within 2000 km/s of the Local Group. The effect on the density field of the SSRS survey is negligible.

  18. Catastrophic photometric redshift errors: Weak-lensing survey requirements

    DOE PAGESBeta

    Bernstein, Gary; Huterer, Dragan

    2010-01-11

    We study the sensitivity of weak lensing surveys to the effects of catastrophic redshift errors - cases where the true redshift is misestimated by a significant amount. To compute the biases in cosmological parameters, we adopt an efficient linearized analysis where the redshift errors are directly related to shifts in the weak lensing convergence power spectra. We estimate the number Nspec of unbiased spectroscopic redshifts needed to determine the catastrophic error rate well enough that biases in cosmological parameters are below statistical errors of weak lensing tomography. While the straightforward estimate of Nspec is ~106 we find that using onlymore » the photometric redshifts with z ≤ 2.5 leads to a drastic reduction in Nspec to ~ 30,000 while negligibly increasing statistical errors in dark energy parameters. Therefore, the size of spectroscopic survey needed to control catastrophic errors is similar to that previously deemed necessary to constrain the core of the zs – zp distribution. We also study the efficacy of the recent proposal to measure redshift errors by cross-correlation between the photo-z and spectroscopic samples. We find that this method requires ~ 10% a priori knowledge of the bias and stochasticity of the outlier population, and is also easily confounded by lensing magnification bias. In conclusion, the cross-correlation method is therefore unlikely to supplant the need for a complete spectroscopic redshift survey of the source population.« less

  19. Galaxy clustering with photometric surveys using PDF redshift information

    DOE PAGESBeta

    Asorey, J.; Carrasco Kind, M.; Sevilla-Noarbe, I.; Brunner, R. J.; Thaler, J.

    2016-03-28

    Here, photometric surveys produce large-area maps of the galaxy distribution, but with less accurate redshift information than is obtained from spectroscopic methods. Modern photometric redshift (photo-z) algorithms use galaxy magnitudes, or colors, that are obtained through multi-band imaging to produce a probability density function (PDF) for each galaxy in the map. We used simulated data to study the effect of using different photo-z estimators to assign galaxies to redshift bins in order to compare their effects on angular clustering and galaxy bias measurements. We found that if we use the entire PDF, rather than a single-point (mean or mode) estimate, the deviations are less biased, especially when using narrow redshift bins. When the redshift bin widths aremore » $$\\Delta z=0.1$$, the use of the entire PDF reduces the typical measurement bias from 5%, when using single point estimates, to 3%.« less

  20. Galaxy clustering with photometric surveys using PDF redshift information

    NASA Astrophysics Data System (ADS)

    Asorey, J.; Carrasco Kind, M.; Sevilla-Noarbe, I.; Brunner, R. J.; Thaler, J.

    2016-06-01

    Photometric surveys produce large-area maps of the galaxy distribution, but with less accurate redshift information than is obtained from spectroscopic methods. Modern photometric redshift (photo-z) algorithms use galaxy magnitudes, or colours, that are obtained through multiband imaging to produce a probability density function (PDF) for each galaxy in the map. We used simulated data to study the effect of using different photo-z estimators to assign galaxies to redshift bins in order to compare their effects on angular clustering and galaxy bias measurements. We found that if we use the entire PDF, rather than a single-point (mean or mode) estimate, the deviations are less biased, especially when using narrow redshift bins. When the redshift bin widths are Δz = 0.1, the use of the entire PDF reduces the typical measurement bias from 5 per cent, when using single point estimates, to 3 per cent.

  1. EXTENDED PHOTOMETRY FOR THE DEEP2 GALAXY REDSHIFT SURVEY: A TESTBED FOR PHOTOMETRIC REDSHIFT EXPERIMENTS

    SciTech Connect

    Matthews, Daniel J.; Newman, Jeffrey A.; Coil, Alison L.; Cooper, Michael C.; Gwyn, Stephen D. J. E-mail: janewman@pitt.edu E-mail: m.cooper@uci.edu

    2013-02-15

    This paper describes a new catalog that supplements the existing DEEP2 Galaxy Redshift Survey photometric and spectroscopic catalogs with ugriz photometry from two other surveys: the Canada-France-Hawaii Legacy Survey (CFHTLS) and the Sloan Digital Sky Survey (SDSS). Each catalog is cross-matched by position on the sky in order to assign ugriz photometry to objects in the DEEP2 catalogs. We have recalibrated the CFHTLS photometry where it overlaps DEEP2 in order to provide a more uniform data set. We have also used this improved photometry to predict DEEP2 BRI photometry in regions where only poorer measurements were available previously. In addition, we have included improved astrometry tied to SDSS rather than USNO-A2.0 for all DEEP2 objects. In total this catalog contains {approx}27, 000 objects with full ugriz photometry as well as robust spectroscopic redshift measurements, 64% of which have r > 23. By combining the secure and accurate redshifts of the DEEP2 Galaxy Redshift Survey with ugriz photometry, we have created a catalog that can be used as an excellent testbed for future photo-z studies, including tests of algorithms for surveys such as LSST and DES.

  2. THE PRISM MULTI-OBJECT SURVEY (PRIMUS). II. DATA REDUCTION AND REDSHIFT FITTING

    SciTech Connect

    Cool, Richard J.; Moustakas, John; Blanton, Michael R.; Hogg, David W.; Burles, Scott M.; Coil, Alison L.; Aird, James; Mendez, Alexander J.; Eisenstein, Daniel J.; Wong, Kenneth C.; Zhu, Guangtun; Bernstein, Rebecca A.

    2013-04-20

    The PRIsm MUlti-object Survey (PRIMUS) is a spectroscopic galaxy redshift survey to z {approx} 1 completed with a low-dispersion prism and slitmasks allowing for simultaneous observations of {approx}2500 objects over 0.18 deg{sup 2}. The final PRIMUS catalog includes {approx}130,000 robust redshifts over 9.1 deg{sup 2}. In this paper, we summarize the PRIMUS observational strategy and present the data reduction details used to measure redshifts, redshift precision, and survey completeness. The survey motivation, observational techniques, fields, target selection, slitmask design, and observations are presented in Coil et al. Comparisons to existing higher-resolution spectroscopic measurements show a typical precision of {sigma}{sub z}/(1 + z) = 0.005. PRIMUS, both in area and number of redshifts, is the largest faint galaxy redshift survey completed to date and is allowing for precise measurements of the relationship between active galactic nuclei and their hosts, the effects of environment on galaxy evolution, and the build up of galactic systems over the latter half of cosmic history.

  3. The PRIsm MUlti-object Survey (PRIMUS). II. Data Reduction and Redshift Fitting

    NASA Astrophysics Data System (ADS)

    Cool, Richard J.; Moustakas, John; Blanton, Michael R.; Burles, Scott M.; Coil, Alison L.; Eisenstein, Daniel J.; Wong, Kenneth C.; Zhu, Guangtun; Aird, James; Bernstein, Rebecca A.; Bolton, Adam S.; Hogg, David W.; Mendez, Alexander J.

    2013-04-01

    The PRIsm MUlti-object Survey (PRIMUS) is a spectroscopic galaxy redshift survey to z ~ 1 completed with a low-dispersion prism and slitmasks allowing for simultaneous observations of ~2500 objects over 0.18 deg2. The final PRIMUS catalog includes ~130,000 robust redshifts over 9.1 deg2. In this paper, we summarize the PRIMUS observational strategy and present the data reduction details used to measure redshifts, redshift precision, and survey completeness. The survey motivation, observational techniques, fields, target selection, slitmask design, and observations are presented in Coil et al. Comparisons to existing higher-resolution spectroscopic measurements show a typical precision of σ z /(1 + z) = 0.005. PRIMUS, both in area and number of redshifts, is the largest faint galaxy redshift survey completed to date and is allowing for precise measurements of the relationship between active galactic nuclei and their hosts, the effects of environment on galaxy evolution, and the build up of galactic systems over the latter half of cosmic history.

  4. Statistical Analysis of Galaxy Redshift Surveys

    NASA Astrophysics Data System (ADS)

    Percival, Will J.

    2008-12-01

    The statistical distribution of galaxies encodes significant cosmological information. For Gaussian random fields, 2-point functions, the correlation function in real space and the power spectrum in Fourier space are complete, and offer the most direct route to this information. In this proceedings, I consider three mechanisms for extracting information from the power spectrum. The relative amplitude of small-scale and large-scale power can constrain the matter-radiation equality scale, but this is hard to disentangle from galaxy bias. Baryon Acoustic Oscillations are more robust to galaxy bias effects, and lead to constraints the evolution of the Universe by providing a standard ruler whose distance can be compared at different redshifts. Redshift-Space distortions, resulting from galaxy peculiar velocities can be used to measure the cosmological growth of structure, and are immune to density bias as the velocities are independent of galaxy properties.

  5. THE DEEP2 GALAXY REDSHIFT SURVEY: DESIGN, OBSERVATIONS, DATA REDUCTION, AND REDSHIFTS

    SciTech Connect

    Newman, Jeffrey A.; Cooper, Michael C.; Davis, Marc; Faber, S. M.; Guhathakurta, Puragra; Koo, David C.; Phillips, Andrew C.; Conroy, Charlie; Harker, Justin J.; Lai, Kamson; Dutton, Aaron A.; Finkbeiner, Douglas P.; Gerke, Brian F.; Rosario, David J.; Weiner, Benjamin J.; Willmer, C. N. A.; Yan Renbin; Kassin, Susan A.; Konidaris, N. P. E-mail: djm70@pitt.edu E-mail: mdavis@berkeley.edu E-mail: koo@ucolick.org E-mail: phillips@ucolick.org; and others

    2013-09-15

    We describe the design and data analysis of the DEEP2 Galaxy Redshift Survey, the densest and largest high-precision redshift survey of galaxies at z {approx} 1 completed to date. The survey was designed to conduct a comprehensive census of massive galaxies, their properties, environments, and large-scale structure down to absolute magnitude M{sub B} = -20 at z {approx} 1 via {approx}90 nights of observation on the Keck telescope. The survey covers an area of 2.8 deg{sup 2} divided into four separate fields observed to a limiting apparent magnitude of R{sub AB} = 24.1. Objects with z {approx}< 0.7 are readily identifiable using BRI photometry and rejected in three of the four DEEP2 fields, allowing galaxies with z > 0.7 to be targeted {approx}2.5 times more efficiently than in a purely magnitude-limited sample. Approximately 60% of eligible targets are chosen for spectroscopy, yielding nearly 53,000 spectra and more than 38,000 reliable redshift measurements. Most of the targets that fail to yield secure redshifts are blue objects that lie beyond z {approx} 1.45, where the [O II] 3727 A doublet lies in the infrared. The DEIMOS 1200 line mm{sup -1} grating used for the survey delivers high spectral resolution (R {approx} 6000), accurate and secure redshifts, and unique internal kinematic information. Extensive ancillary data are available in the DEEP2 fields, particularly in the Extended Groth Strip, which has evolved into one of the richest multiwavelength regions on the sky. This paper is intended as a handbook for users of the DEEP2 Data Release 4, which includes all DEEP2 spectra and redshifts, as well as for the DEEP2 DEIMOS data reduction pipelines. Extensive details are provided on object selection, mask design, biases in target selection and redshift measurements, the spec2d two-dimensional data-reduction pipeline, the spec1d automated redshift pipeline, and the zspec visual redshift verification process, along with examples of instrumental signatures or

  6. The DEEP2 Galaxy Redshift Survey: Design, Observations, Data Reduction, and Redshifts

    NASA Technical Reports Server (NTRS)

    Newman, Jeffrey A.; Cooper, Michael C.; Davis, Marc; Faber, S. M.; Coil, Alison L; Guhathakurta, Puraga; Koo, David C.; Phillips, Andrew C.; Conroy, Charlie; Dutton, Aaron A.; Finkbeiner, Douglas P.; Gerke, Brian F.; Rosario, David J.; Weiner, Benjamin J.; Wilmer, C. N. A.; Yan, Renbin; Harker, Justin J.; Kassin, Susan A.; Konidaris, N. P.; Lai, Kamson; Madgwick, Darren S.; Noeske, K. G.; Wirth, Gregory D.; Kirby, Evan N.; Lotz, Jennifer M.

    2013-01-01

    We describe the design and data analysis of the DEEP2 Galaxy Redshift Survey, the densest and largest high-precision redshift survey of galaxies at z approx. 1 completed to date. The survey was designed to conduct a comprehensive census of massive galaxies, their properties, environments, and large-scale structure down to absolute magnitude MB = -20 at z approx. 1 via approx.90 nights of observation on the Keck telescope. The survey covers an area of 2.8 Sq. deg divided into four separate fields observed to a limiting apparent magnitude of R(sub AB) = 24.1. Objects with z approx. < 0.7 are readily identifiable using BRI photometry and rejected in three of the four DEEP2 fields, allowing galaxies with z > 0.7 to be targeted approx. 2.5 times more efficiently than in a purely magnitude-limited sample. Approximately 60% of eligible targets are chosen for spectroscopy, yielding nearly 53,000 spectra and more than 38,000 reliable redshift measurements. Most of the targets that fail to yield secure redshifts are blue objects that lie beyond z approx. 1.45, where the [O ii] 3727 Ang. doublet lies in the infrared. The DEIMOS 1200 line mm(exp -1) grating used for the survey delivers high spectral resolution (R approx. 6000), accurate and secure redshifts, and unique internal kinematic information. Extensive ancillary data are available in the DEEP2 fields, particularly in the Extended Groth Strip, which has evolved into one of the richest multiwavelength regions on the sky. This paper is intended as a handbook for users of the DEEP2 Data Release 4, which includes all DEEP2 spectra and redshifts, as well as for the DEEP2 DEIMOS data reduction pipelines. Extensive details are provided on object selection, mask design, biases in target selection and redshift measurements, the spec2d two-dimensional data-reduction pipeline, the spec1d automated redshift pipeline, and the zspec visual redshift verification process, along with examples of instrumental signatures or other

  7. The DEEP2 Galaxy Redshift Survey: Design, Observations, Data Reduction, and Redshifts

    NASA Astrophysics Data System (ADS)

    Newman, Jeffrey A.; Cooper, Michael C.; Davis, Marc; Faber, S. M.; Coil, Alison L.; Guhathakurta, Puragra; Koo, David C.; Phillips, Andrew C.; Conroy, Charlie; Dutton, Aaron A.; Finkbeiner, Douglas P.; Gerke, Brian F.; Rosario, David J.; Weiner, Benjamin J.; Willmer, C. N. A.; Yan, Renbin; Harker, Justin J.; Kassin, Susan A.; Konidaris, N. P.; Lai, Kamson; Madgwick, Darren S.; Noeske, K. G.; Wirth, Gregory D.; Connolly, A. J.; Kaiser, N.; Kirby, Evan N.; Lemaux, Brian C.; Lin, Lihwai; Lotz, Jennifer M.; Luppino, G. A.; Marinoni, C.; Matthews, Daniel J.; Metevier, Anne; Schiavon, Ricardo P.

    2013-09-01

    We describe the design and data analysis of the DEEP2 Galaxy Redshift Survey, the densest and largest high-precision redshift survey of galaxies at z ~ 1 completed to date. The survey was designed to conduct a comprehensive census of massive galaxies, their properties, environments, and large-scale structure down to absolute magnitude MB = -20 at z ~ 1 via ~90 nights of observation on the Keck telescope. The survey covers an area of 2.8 deg2 divided into four separate fields observed to a limiting apparent magnitude of R AB = 24.1. Objects with z <~ 0.7 are readily identifiable using BRI photometry and rejected in three of the four DEEP2 fields, allowing galaxies with z > 0.7 to be targeted ~2.5 times more efficiently than in a purely magnitude-limited sample. Approximately 60% of eligible targets are chosen for spectroscopy, yielding nearly 53,000 spectra and more than 38,000 reliable redshift measurements. Most of the targets that fail to yield secure redshifts are blue objects that lie beyond z ~ 1.45, where the [O II] 3727 Å doublet lies in the infrared. The DEIMOS 1200 line mm-1 grating used for the survey delivers high spectral resolution (R ~ 6000), accurate and secure redshifts, and unique internal kinematic information. Extensive ancillary data are available in the DEEP2 fields, particularly in the Extended Groth Strip, which has evolved into one of the richest multiwavelength regions on the sky. This paper is intended as a handbook for users of the DEEP2 Data Release 4, which includes all DEEP2 spectra and redshifts, as well as for the DEEP2 DEIMOS data reduction pipelines. Extensive details are provided on object selection, mask design, biases in target selection and redshift measurements, the spec2d two-dimensional data-reduction pipeline, the spec1d automated redshift pipeline, and the zspec visual redshift verification process, along with examples of instrumental signatures or other artifacts that in some cases remain after data reduction. Redshift

  8. Spectrophotometric Redshifts in the Faint Infrared Grism Survey

    NASA Astrophysics Data System (ADS)

    Pharo, John; Malhotra, Sangeeta; Rhoads, James E.

    2016-06-01

    We have combined HST grism spectroscopy and deep broadband imaging to measure spectro-photometric redshifts (SPZs) of faint galaxies. Using a technique pioneered by Ryan et al. 2007, one can combine spectra and photometry to yield an SPZ that is more accurate than pure photometric redshifts, and can probe more deeply than ground-based spectroscopic redshifts. By taking mid-resolution spectra from the HST Faint Infrared Grism Survey (FIGS), SPZs can be found for measurements potentially down to 27th magnitude (the typical brightness of a dwarf galaxy at redshift ∼1.5). A galaxy’s redshift is vital for understanding its place in the growth and evolution of the universe. The measurement of high-accuracy SPZs for FIGS sources will improve the faint-end and high-redshift portions of the luminosity function, and make possible a robust analysis of the FIGS fields for signs of Large Scale Structure (LSS). The improved redshift and distance measurements allowed for the identification of a structure at z=0.83 in one of the FIGS fields.

  9. The La Silla-QUEST Low Redshift Supernova Survey

    NASA Astrophysics Data System (ADS)

    Baltay, Charles; Rabinowitz, David; Hadjiyska, Elena; Walker, Emma S.; Nugent, Peter; Coppi, Paolo; Ellman, Nancy; Feindt, Ulrich; McKinnon, Ryan; Horowitz, Benjamin; Effron, Aaron

    2013-06-01

    The La Silla-QUEST Low Redshift Supernova Survey is a part of the La Silla-QUEST Southern Hemisphere Variability Survey. The survey uses the 10 deg2 QUEST camera installed at the prime focus of the 1.0-m Schmidt Telescope of the European Southern Observatory at La Silla, Chile, and utilizes essentially all of the observing time of the telescope. The QUEST camera was installed on the ESO Schmidt telescope in 2009 after completing a 5 year variability survey in the northern hemisphere using the 1.2-m Oschin Schmidt telescope at Palomar. La Silla-QUEST started science operations in 2009 September. The low redshift supernova survey commenced in 2011 December and is planned to continue for the next 4 years. In this article we describe the instrumentation, software, operation, and performance characteristics of the survey.

  10. SHELS: TESTING WEAK-LENSING MAPS WITH REDSHIFT SURVEYS

    SciTech Connect

    Geller, Margaret J.; Kurtz, Michael J.; Fabricant, Daniel G.; Dell'Antonio, Ian P.; Ramella, Massimo E-mail: mkurtz@cfa.harvard.ed E-mail: ian@het.brown.ed

    2010-02-01

    Weak-lensing surveys are emerging as an important tool for the construction of 'mass-selected' clusters of galaxies. We evaluate both the efficiency and completeness of a weak-lensing selection by combining a dense, complete redshift survey, the Smithsonian Hectospec Lensing Survey (SHELS), with a weak-lensing map from the Deep Lens Survey (DLS). SHELS includes 11,692 redshifts for galaxies with R <= 20.6 in the 4 deg{sup 2} DLS field; the survey is a solid basis for identifying massive clusters of galaxies with redshift z approx< 0.55. The range of sensitivity of the redshift survey is similar to the range for the DLS convergence map. Only four of the 12 convergence peaks with signal to noise >=3.5 correspond to clusters of galaxies with M approx> 1.7 x 10{sup 14} M{sub sun}. Four of the eight massive clusters in SHELS are detected in the weak-lensing map yielding a completeness of approx50%. We examine the seven known extended cluster X-ray sources in the DLS field: three can be detected in the weak-lensing map, three should not be detected without boosting from superposed large-scale structure, and one is mysteriously undetected even though its optical properties suggest that it should produce a detectable lensing signal. Taken together, these results underscore the need for more extensive comparisons among different methods of massive cluster identification.

  11. Spectral Confusion for Cosmological Surveys of Redshifted C II Emission

    NASA Astrophysics Data System (ADS)

    Kogut, A.; Dwek, E.; Moseley, S. H.

    2015-06-01

    Far-infrared cooling lines are ubiquitous features in the spectra of star-forming galaxies. Surveys of redshifted fine-structure lines provide a promising new tool to study structure formation and galactic evolution at redshifts including the epoch of reionization as well as the peak of star formation. Unlike neutral hydrogen surveys, where the 21 cm line is the only bright line, surveys of redshifted fine-structure lines suffer from confusion generated by line broadening, spectral overlap of different lines, and the crowding of sources with redshift. We use simulations to investigate the resulting spectral confusion and derive observing parameters to minimize these effects in pencil-beam surveys of redshifted far-IR line emission. We generate simulated spectra of the 17 brightest far-IR lines in galaxies, covering the 150–1300 μm wavelength region corresponding to redshifts 0 < z < 7, and develop a simple iterative algorithm that successfully identifies the 158 μm [C ii] line and other lines. Although the [C ii] line is a principal coolant for the interstellar medium, the assumption that the brightest observed lines in a given line of sight are always [C ii] lines is a poor approximation to the simulated spectra once other lines are included. Blind line identification requires detection of fainter companion lines from the same host galaxies, driving survey sensitivity requirements. The observations require moderate spectral resolution 700 < R < 4000 with angular resolution between 20″ and 10‧, sufficiently narrow to minimize confusion yet sufficiently large to include a statistically meaningful number of sources.

  12. Catastrophic photometric redshift errors: Weak-lensing survey requirements

    SciTech Connect

    Bernstein, Gary; Huterer, Dragan

    2010-01-11

    We study the sensitivity of weak lensing surveys to the effects of catastrophic redshift errors - cases where the true redshift is misestimated by a significant amount. To compute the biases in cosmological parameters, we adopt an efficient linearized analysis where the redshift errors are directly related to shifts in the weak lensing convergence power spectra. We estimate the number Nspec of unbiased spectroscopic redshifts needed to determine the catastrophic error rate well enough that biases in cosmological parameters are below statistical errors of weak lensing tomography. While the straightforward estimate of Nspec is ~106 we find that using only the photometric redshifts with z ≤ 2.5 leads to a drastic reduction in Nspec to ~ 30,000 while negligibly increasing statistical errors in dark energy parameters. Therefore, the size of spectroscopic survey needed to control catastrophic errors is similar to that previously deemed necessary to constrain the core of the zs – zp distribution. We also study the efficacy of the recent proposal to measure redshift errors by cross-correlation between the photo-z and spectroscopic samples. We find that this method requires ~ 10% a priori knowledge of the bias and stochasticity of the outlier population, and is also easily confounded by lensing magnification bias. In conclusion, the cross-correlation method is therefore unlikely to supplant the need for a complete spectroscopic redshift survey of the source population.

  13. Galaxy redshift surveys with sparse sampling

    SciTech Connect

    Chiang, Chi-Ting; Wullstein, Philipp; Komatsu, Eiichiro; Jee, Inh; Jeong, Donghui; Blanc, Guillermo A.; Ciardullo, Robin; Gronwall, Caryl; Hagen, Alex; Schneider, Donald P.; Drory, Niv; Fabricius, Maximilian; Landriau, Martin; Finkelstein, Steven; Jogee, Shardha; Cooper, Erin Mentuch; Tuttle, Sarah; Gebhardt, Karl; Hill, Gary J.

    2013-12-01

    Survey observations of the three-dimensional locations of galaxies are a powerful approach to measure the distribution of matter in the universe, which can be used to learn about the nature of dark energy, physics of inflation, neutrino masses, etc. A competitive survey, however, requires a large volume (e.g., V{sub survey} ∼ 10Gpc{sup 3}) to be covered, and thus tends to be expensive. A ''sparse sampling'' method offers a more affordable solution to this problem: within a survey footprint covering a given survey volume, V{sub survey}, we observe only a fraction of the volume. The distribution of observed regions should be chosen such that their separation is smaller than the length scale corresponding to the wavenumber of interest. Then one can recover the power spectrum of galaxies with precision expected for a survey covering a volume of V{sub survey} (rather than the volume of the sum of observed regions) with the number density of galaxies given by the total number of observed galaxies divided by V{sub survey} (rather than the number density of galaxies within an observed region). We find that regularly-spaced sampling yields an unbiased power spectrum with no window function effect, and deviations from regularly-spaced sampling, which are unavoidable in realistic surveys, introduce calculable window function effects and increase the uncertainties of the recovered power spectrum. On the other hand, we show that the two-point correlation function (pair counting) is not affected by sparse sampling. While we discuss the sparse sampling method within the context of the forthcoming Hobby-Eberly Telescope Dark Energy Experiment, the method is general and can be applied to other galaxy surveys.

  14. Probing neutrinos from Planck and forthcoming galaxy redshift surveys

    NASA Astrophysics Data System (ADS)

    Takeuchi, Yoshitaka; Kadota, Kenji

    2014-01-01

    We investigate how much the constraints on the neutrino properties can be improved by combining the CMB, the photometric and spectroscopic galaxy redshift surveys which include the CMB lensing, galaxy lensing tomography, galaxy clustering and redshift space distortion observables. We pay a particular attention to the constraint on the neutrino mass in view of the forthcoming redshift surveys such as the Euclid satellite and the LSST survey along with the Planck CMB lensing measurements. Combining the transverse mode information from the angular power spectrum and the longitudinal mode information from the spectroscopic survey with the redshift space distortion measurements can determine the total neutrino mass with the projected error of Script O(0.02) eV. Our analysis fixes the mass splittings among the neutrino species to be consistent with the neutrino oscillation data, and we accordingly study the sensitivity of our parameter estimations on the minimal neutrino mass. The cosmological measurement of the total neutrino mass can distinguish between the normal and inverted mass hierarchy scenarios if the minimal neutrino mass lesssim0.005 eV with the predicted 1-σ uncertainties taken into account.

  15. Probing neutrinos from Planck and forthcoming galaxy redshift surveys

    SciTech Connect

    Takeuchi, Yoshitaka; Kadota, Kenji E-mail: kadota.kenji@f.nagoya-u.jp

    2014-01-01

    We investigate how much the constraints on the neutrino properties can be improved by combining the CMB, the photometric and spectroscopic galaxy redshift surveys which include the CMB lensing, galaxy lensing tomography, galaxy clustering and redshift space distortion observables. We pay a particular attention to the constraint on the neutrino mass in view of the forthcoming redshift surveys such as the Euclid satellite and the LSST survey along with the Planck CMB lensing measurements. Combining the transverse mode information from the angular power spectrum and the longitudinal mode information from the spectroscopic survey with the redshift space distortion measurements can determine the total neutrino mass with the projected error of O(0.02) eV. Our analysis fixes the mass splittings among the neutrino species to be consistent with the neutrino oscillation data, and we accordingly study the sensitivity of our parameter estimations on the minimal neutrino mass. The cosmological measurement of the total neutrino mass can distinguish between the normal and inverted mass hierarchy scenarios if the minimal neutrino mass ∼<0.005 eV with the predicted 1–σ uncertainties taken into account.

  16. On the recovery of the local group motion from galaxy redshift surveys

    SciTech Connect

    Nusser, Adi; Davis, Marc; Branchini, Enzo E-mail: mdavis@berkeley.edu

    2014-06-20

    There is an ∼150 km s{sup –1} discrepancy between the measured motion of the Local Group (LG) of galaxies with respect to the cosmic microwave background and the linear theory prediction based on the gravitational force field of the large-scale structure in full-sky redshift surveys. We perform a variety of tests which show that the LG motion cannot be recovered to better than 150-200 km s{sup –1} in amplitude and within ≈10° in direction. The tests rely on catalogs of mock galaxies identified in the Millennium simulation using semi-analytic galaxy formation models. We compare these results to the K{sub s} = 11.75 Two-Mass Galaxy Redshift Survey, which provides the deepest and most complete all-sky spatial distribution of galaxies with spectroscopic redshifts available thus far. In our analysis, we use a new concise relation for deriving the LG motion and bulk flow from the true distribution of galaxies in redshift space. Our results show that the main source of uncertainty is the small effective depth of surveys like the Two-Mass Redshift Survey (2MRS), which prevents a proper sampling of the large-scale structure beyond ∼100 h {sup –1} Mpc. Deeper redshift surveys are needed to reach the 'convergence scale' of ≈250 h {sup –1} Mpc in a ΛCDM universe. Deeper surveys would also mitigate the impact of the 'Kaiser rocket' which, in a survey like 2MRS, remains a significant source of uncertainty. Thanks to the quiet and moderate density environment of the LG, purely dynamical uncertainties of the linear predictions are subdominant at the level of ∼90 km s{sup –1}. Finally, we show that deviations from linear galaxy biasing and shot noise errors provide a minor contribution to the total error budget.

  17. Nonlinear clustering in the CfA redshift survey

    SciTech Connect

    Alimi, J.; Blanchard, A.; Schaeffer, R. Ecole Polytechnique, Palaiseau Paris VII Universite CEA, Service de Physique Theorique de Saclay, Gif-sur-Yvette )

    1990-01-01

    The probability of finding a hole in a randomly placed sphere of volume V has been considered in the Cfa survey by numerous authors. The main emphasis of these studies has been on a scaling law derived from the assumption of hierarchical clustering. Here, the counts in cell statistics P(N) in the CfA redshift survey are analyzed. The results show that the general behavior of the P(N) can be predicted on the sole assumption of the hierarchical hypothesis. Scaling forms can then be predicted which appear to be verified to a fairly good extent in the Cfa redshift survey. This implies that the hypothesis of scale-invariant many-body correlations function provides for a satisfactory description of the count-in-cell statistics. 23 refs.

  18. Data augmentation for machine learning redshifts applied to Sloan Digital Sky Survey galaxies

    NASA Astrophysics Data System (ADS)

    Hoyle, Ben; Rau, Markus Michael; Bonnett, Christopher; Seitz, Stella; Weller, Jochen

    2015-06-01

    We present analyses of data augmentation for machine learning redshift estimation. Data augmentation makes a training sample more closely resemble a test sample, if the two base samples differ, in order to improve measured statistics of the test sample. We perform two sets of analyses by selecting 800 000 (1.7 million) Sloan Digital Sky Survey Data Release 8 (Data Release 10) galaxies with spectroscopic redshifts. We construct a base training set by imposing an artificial r-band apparent magnitude cut to select only bright galaxies and then augment this base training set by using simulations and by applying the K-CORRECT package to artificially place training set galaxies at a higher redshift. We obtain redshift estimates for the remaining faint galaxy sample, which are not used during training. We find that data augmentation reduces the error on the recovered redshifts by 40 per cent in both sets of analyses, when compared to the difference in error between the ideal case and the non-augmented case. The outlier fraction is also reduced by at least 10 per cent and up to 80 per cent using data augmentation. We finally quantify how the recovered redshifts degrade as one probes to deeper magnitudes past the artificial magnitude limit of the bright training sample. We find that at all apparent magnitudes explored, the use of data augmentation with tree-based methods provide an estimate of the galaxy redshift with a low value of bias, although the error on the recovered redshifts increases as we probe to deeper magnitudes. These results have applications for surveys which have a spectroscopic training set which forms a biased sample of all photometric galaxies, for example if the spectroscopic detection magnitude limit is shallower than the photometric limit.

  19. Surveying the Origin of O VI Gas at Low Redshift

    NASA Astrophysics Data System (ADS)

    Prochaska, Jason X.; Tripp, Todd; Aracil, Bastien; Davé, Romeel; Mulchaey, John; Chen, Hsiao-Wen

    2005-08-01

    A comparison of the baryonic mass density inferred from BBN and the CMB with a census of visible baryonic components at the present epoch indicates a significant fraction of the universe's baryons are hidden in a dark component. Theoretical investigations predict that the majority of 'missing' baryons lie in a hot (T ~ 10^5-7 K), low density medium which can be efficiently detected through O VI absorption. More importantly, recent STIS+FUSE surveys for O VI are consistent with this gas comprising a significant fraction of the missing baryons. Establishing the physical nature of these O VI absorbers directly impacts our understanding of the distribution of baryons in the universe. The principal goal of our program is to determine if this O VI gas arises in galactic halos, the intragroup or intracluster medium, the low density 'cosmic web', or a different region of the universe altogether. We are pursuing an observational program to search for galaxies associated with O VI absorbers at low redshift. To accomplish this project, we require deep UBVRI images in fields surrounding quasars surveyed for O VI absorption. This dataset will provide precise photometric redshifts of z< 0.3 galaxies with L > L^*/10 and measures of color and morphology. Ultimately, we will use the photometric redshifts to efficiently pre-select galaxies for spectroscopy on multi-slit spectrometers. By correlating the galaxy redshifts against the O VI absorption lines and comparing directly with cosmological simulations, we will establish the origin of the O VI gas.

  20. Surveying the Origin of O VI Gas at Low Redshift

    NASA Astrophysics Data System (ADS)

    Prochaska, Jason X.; Tripp, Todd; Aracil, Bastien; Davé, Romeel; Mulchaey, John; Chen, Hsiao-Wen

    2006-02-01

    A comparison of the baryonic mass density inferred from BBN and the CMB with a census of visible baryonic components at the present epoch indicates a significant fraction of the universe's baryons are hidden in a dark component. Theoretical investigations predict that the majority of 'missing' baryons lie in a hot (T ~ 10^5-7 K), low density medium which can be efficiently detected through O VI absorption. More importantly, recent STIS+FUSE surveys for O VI are consistent with this gas comprising a significant fraction of the missing baryons. Establishing the physical nature of these O VI absorbers directly impacts our understanding of the distribution of baryons in the universe. The principal goal of our program is to determine if this O VI gas arises in galactic halos, the intragroup or intracluster medium, the low density 'cosmic web', or a different region of the universe altogether. We are pursuing an observational program to search for galaxies associated with O VI absorbers at low redshift. To accomplish this project, we require deep UBVRI images in fields surrounding quasars surveyed for O VI absorption. This dataset will provide precise photometric redshifts of z< 0.3 galaxies with L > L^*/10 and measures of color and morphology. Ultimately, we will use the photometric redshifts to efficiently pre-select galaxies for spectroscopy on multi-slit spectrometers. By correlating the galaxy redshifts against the O VI absorption lines and comparing directly with cosmological simulations, we will establish the origin of the O VI gas.

  1. Caltech Faint Galaxy Redshift Survey. XI. The Merger Rate to Redshift 1 from Kinematic Pairs.

    PubMed

    Carlberg; Cohen; Patton; Blandford; Hogg; Yee; Morris; Lin; Hall; Sawicki; Wirth; Cowie; Hu; Songaila

    2000-03-20

    The rate of mass accumulation due to galaxy merging depends on the mass, density, and velocity distribution of galaxies in the near neighborhood of a host galaxy. The fractional luminosity in kinematic pairs combines all of these effects in a single estimator that is relatively insensitive to population evolution. Here we use a k-corrected and evolution-compensated volume-limited sample having an R-band absolute magnitude of Mk,eRredshifts from the Caltech Faint Galaxy Redshift Survey and 3000 from the Canadian Network for Observational Cosmology field galaxy survey to measure the rate and redshift evolution of merging. The combined sample has an approximately constant comoving number and luminosity density from redshift 0.1 to 1.1 (OmegaM=0.2, OmegaLambda=0.8); hence, any merger evolution will be dominated by correlation and velocity evolution, not density evolution. We identify kinematic pairs with projected separations less than either 50 or 100 h-1 kpc and rest-frame velocity differences of less than 1000 km s-1. The fractional luminosity in pairs is modeled as fL&parl0;Deltav,rp,Mk,er&parr0;&parl0;1+z&parr0;mL, where &sqbl0;fL,mL&sqbr0; are &sqbl0;0.14+/-0.07,0+/-1.4&sqbr0; and &sqbl0;0.37+/-0.7,0.1+/-0.5&sqbr0; for rpredshift-space statistics to a merger rate, we use the data to derive a conversion factor to a physical space pair density, a merger probability, and a mean in-spiral time. The resulting mass accretion rate per galaxy (M1,M2>/=0.2M*) is 0.02+/-0.01&parl0;1+z&parr0;0.1+/-0.5M* Gyr-1. Present-day high-luminosity galaxies therefore have accreted approximately 0.15M* of their mass over the approximately 7 Gyr to redshift 1. Since merging is likely only weakly dependent on the host mass, the fractional effect, deltaM&solm0;M approximately 0.15M*&solm0;M, is dramatic for lower mass

  2. Can a galaxy redshift survey measure dark energy clustering?

    SciTech Connect

    Takada, Masahiro

    2006-08-15

    A wide-field galaxy redshift survey allows one to probe galaxy clustering at largest spatial scales, which carries invaluable information on horizon-scale physics complementarily to the cosmic microwave background (CMB). Assuming the planned survey consisting of z{approx}1 and z{approx}3 surveys with areas of 2000 and 300 deg.{sup 2}, respectively, we study the prospects for probing dark energy clustering from the measured galaxy power spectrum, assuming the dynamical properties of dark energy are specified in terms of the equation of state and the effective sound speed c{sub e} in the context of an adiabatic cold dark dominated matter model. The dark energy clustering adds a power to the galaxy power spectrum amplitude at spatial scales greater than the sound horizon, and the enhancement is sensitive to redshift evolution of the net dark energy density, i.e. the equation of state. We find that the galaxy survey, when combined with CMB expected from the Planck satellite mission, can distinguish dark energy clustering from a smooth dark energy model such as the quintessence model (c{sub e}=1), when c{sub e} < or approx. 0.04 (0.02) in the case of the constant equation of state w{sub 0}=-0.9 (-0.95). An ultimate full-sky survey of z{approx}1 galaxies allows the detection when c{sub e}(less-or-similar sign)0.08 (0.04) for w{sub 0}=0.9 (-0.95). These forecasts show a compatible power with an all-sky CMB and galaxy cross correlation that probes the integrated Sachs-Wolfe effect. We also investigate a degeneracy between the dark energy clustering and the nonrelativistic neutrinos implied from the neutrino oscillation experiments, because the two effects both induce a scale-dependent modification in the galaxy power spectrum shape at largest spatial scales accessible from the galaxy survey. It is shown that a wider redshift coverage can efficiently separate the two effects by utilizing the different redshift dependences, where dark energy clustering is apparent only at

  3. The non-linear redshift-space power spectrum: Omega from redshift surveys

    NASA Astrophysics Data System (ADS)

    Fisher, Karl B.; Nusser, Adi

    1996-03-01

    We examine the anisotropies in the power spectrum by the mapping of real space to redshift space. Using the Zel'dovich approximation, we obtain an analytic expression for the non-linear redshift-space power spectrum in the distant observer limit. For a given unbiased galaxy distribution in redshift space, the anisotropies in the power spectrum depend on the parameter f(Omega)~=Omega^0.6, where Omega is the density parameter. We quantify these anisotropies by the ratio, R, of the quadrupole and monopole angular moments of the power spectrum. In contrast to linear theory, the Zel'dovich approximation predicts a decline in R with decreasing scale. This departure from linear theory is due to non-linear dynamics and is not a result of incoherent random velocities. The rate of decline depends strongly on Omega and the initial power spectrum. However, we find a scaling relation between the quantity R/R_lin (where R_lin is the linear theory value of R) and the dimensionless variable k/k_nl, where k_nl is a wavenumber determined by the scale of non-linear structures. The scaling is weakly dependent on the initial power spectrum and is in good agreement with a large N-body simulation. This universal scaling relation greatly extends the scales over which redshift distortions can be used as a probe of Omega. The scaling relation is in agreement with the observed quadrupole-to-monopole ratio from the 1.2-Jy IRAS survey, with a best estimate of Omega^0.6/b_lin=0.6+/-0.2 where b_lin is the linear bias parameter.

  4. The Center for Astrophysics Redshift Survey - Recent results

    NASA Technical Reports Server (NTRS)

    Geller, Margaret J.; Huchra, John P.

    1989-01-01

    Six strips of the CfA redshift survey extension are now complete. The data continue to support a picture in which galaxies are on thin sheets which nearly surround vast low-density voids. The largest structures are comparable with the extent of the survey. Voids like the one in Bootes are a common feature of the large-scale distribution of galaxies. The issue of fair samples of the galaxy distribution is discussed, examining statistical measures of the galaxy distribution including the two-point correlation functions.

  5. The PC Redshift Survey and Other Adventures in Introductory Astronomy

    NASA Astrophysics Data System (ADS)

    Marschall, L. A.; Stine, P.; Snyder, G. A.; Hayden, M. B.; Luehrmann, M. K.; Good, R. F.; Cooper, P. R.

    1995-05-01

    Project CLEA's latest laboratory exercise in introductory astronomy, "The Large Scale Structure of the Universe" is a simulated red-shift survey, allowing students to investigate the large-scale structure of the universe in a restricted slice of space. Using a simulated telescope with a realistic photon-counting spectrometer, students measure the redshifts of galaxies and construct a wedge diagram showing the 3-d distribution of galaxies. A sample of just over 200 galaxies has been selected from the CfA redshift survey, chosen to outline the major features of the Coma cluster and the Great Wall. Stars down to 12th magnitude from the HST Guide Star Catalog are also included in the telescope field of view, covering a strip 5 degrees wide between 12H and 16H RA at declination +29 degrees. Students can choose from three telescopes of differing aperture to optimize their data-taking efficiency; on-line data recording and spreadsheet access are provided. The exercise can be performed collaboratively at multiple set-ups in a large laboratory, or can be performed by individuals as a long-term project. In addition to the Large Scale Structure exercise, several new and improved versions of the CLEA exercises will be shown. Project CLEA is supported by grants from the National Science Foundation and from Gettysburg College.

  6. Requirements on the Redshift Accuracy for future Supernova andNumber Count Surveys

    SciTech Connect

    Huterer, Dragan; Kim, Alex; Broderick, Tamara

    2004-08-09

    We investigate the required redshift accuracy of type Ia supernova and cluster number-count surveys in order for the redshift uncertainties not to contribute appreciably to the dark energy parameter error budget. For the SNAP supernova experiment, we find that, without the assistance of ground-based measurements, individual supernova redshifts would need to be determined to about 0.002 or better, which is a challenging but feasible requirement for a low-resolution spectrograph. However, we find that accurate redshifts for z < 0.1 supernovae, obtained with ground-based experiments, are sufficient to immunize the results against even relatively large redshift errors at high z. For the future cluster number-count surveys such as the South Pole Telescope, Planck or DUET, we find that the purely statistical error in photometric redshift is less important, and that the irreducible, systematic bias in redshift drives the requirements. The redshift bias will have to be kept below 0.001-0.005 per redshift bin (which is determined by the filter set), depending on the sky coverage and details of the definition of the minimal mass of the survey. Furthermore, we find that X-ray surveys have a more stringent required redshift accuracy than Sunyaev-Zeldovich (SZ) effect surveys since they use a shorter lever arm in redshift; conversely, SZ surveys benefit from their high redshift reach only so long as some redshift information is available for distant (zgtrsim1) clusters.

  7. Surveying the Origin of O VI Gas at Low Redshift

    NASA Astrophysics Data System (ADS)

    Prochaska, Jason X.; Tripp, Todd; Chen, Hsiao-Wen; Mulchaey, John

    2002-08-01

    A comparison of the baryonic mass density inferred from BBN with a census of visible baryonic components (i.e. galaxies, HI gas) at the present epoch indicates a significant fraction of the universe's baryons are hidden in a dark component. Theoretical investigations into these missing bayons suggest the majority lie in a hot (T ~ 10^5-7 K), low density medium which can be efficiently detected through O VI absorption. More importantly, recent STIS+FUSE surveys for O VI are consistent with this gas comprising a significant fraction of the missing baryons. Establishing the physical nature of these O VI absorbers, therefore, may have great impact on our understanding of the distribution of baryons in the universe. The principal goal of this proposal is to determine if this O VI gas arises in galactic halos, the intragroup or intracluster medium, the low density 'cosmic web' which connects collapsed objects, or a different region of the universe altogether. We are currently pursuing a program to search for galaxies associated with O VI absorbers at low redshift (z < 0.5). To accomplish this project, we will obtain deep UBVRI images of the galaxies in four fields surrounding quasars surveyed for O VI absorption. This dataset will provide accurate photometric redshifts of the z< 0.5 galaxies with L > L^*/10 and will reveal their physical characteristics. Ultimately, we will utilize the photometric redshifts to efficiently pre-select galaxies for follow-up spectroscopy on multi- slit spectrographs. By correlating the photometric and spectroscopy galaxy redshifts against the O VI absorption lines and comparing directly with detailed cosmological simulations, we will establish the origin of the O VI gas.

  8. Photometric Redshifts for Quasars in Multi-band Surveys

    NASA Astrophysics Data System (ADS)

    Brescia, M.; Cavuoti, S.; D'Abrusco, R.; Longo, G.; Mercurio, A.

    2013-08-01

    The Multi Layer Perceptron with Quasi Newton Algorithm (MLPQNA) is a machine learning method that can be used to cope with regression and classification problems on complex and massive data sets. In this paper, we give a formal description of the method and present the results of its application to the evaluation of photometric redshifts for quasars. The data set used for the experiment was obtained by merging four different surveys (Sloan Digital Sky Survey, GALEX, UKIDSS, and WISE), thus covering a wide range of wavelengths from the UV to the mid-infrared. The method is able (1) to achieve a very high accuracy, (2) to drastically reduce the number of outliers and catastrophic objects, and (3) to discriminate among parameters (or features) on the basis of their significance, so that the number of features used for training and analysis can be optimized in order to reduce both the computational demands and the effects of degeneracy. The best experiment, which makes use of a selected combination of parameters drawn from the four surveys, leads, in terms of Δz norm (i.e., (z spec - z phot)/(1 + z spec)), to an average of Δz norm = 0.004, a standard deviation of σ = 0.069, and a median absolute deviation, MAD = 0.02, over the whole redshift range (i.e., z spec <= 3.6), defined by the four-survey cross-matched spectroscopic sample. The fraction of catastrophic outliers, i.e., of objects with photo-z deviating more than 2σ from the spectroscopic value, is <3%, leading to σ = 0.035 after their removal, over the same redshift range. The method is made available to the community through the DAMEWARE Web application.

  9. PHOTOMETRIC REDSHIFTS FOR QUASARS IN MULTI-BAND SURVEYS

    SciTech Connect

    Brescia, M.; Mercurio, A.; Cavuoti, S.; Longo, G.; D'Abrusco, R.

    2013-08-01

    The Multi Layer Perceptron with Quasi Newton Algorithm (MLPQNA) is a machine learning method that can be used to cope with regression and classification problems on complex and massive data sets. In this paper, we give a formal description of the method and present the results of its application to the evaluation of photometric redshifts for quasars. The data set used for the experiment was obtained by merging four different surveys (Sloan Digital Sky Survey, GALEX, UKIDSS, and WISE), thus covering a wide range of wavelengths from the UV to the mid-infrared. The method is able (1) to achieve a very high accuracy, (2) to drastically reduce the number of outliers and catastrophic objects, and (3) to discriminate among parameters (or features) on the basis of their significance, so that the number of features used for training and analysis can be optimized in order to reduce both the computational demands and the effects of degeneracy. The best experiment, which makes use of a selected combination of parameters drawn from the four surveys, leads, in terms of {Delta}z{sub norm} (i.e., (z{sub spec} - z{sub phot})/(1 + z{sub spec})), to an average of {Delta}z{sub norm} = 0.004, a standard deviation of {sigma} = 0.069, and a median absolute deviation, MAD = 0.02, over the whole redshift range (i.e., z{sub spec} {<=} 3.6), defined by the four-survey cross-matched spectroscopic sample. The fraction of catastrophic outliers, i.e., of objects with photo-z deviating more than 2{sigma} from the spectroscopic value, is <3%, leading to {sigma} = 0.035 after their removal, over the same redshift range. The method is made available to the community through the DAMEWARE Web application.

  10. Combining weak-lensing tomography and spectroscopic redshift surveys

    DOE PAGESBeta

    Cai, Yan -Chuan; Bernstein, Gary

    2012-05-11

    Redshift space distortion (RSD) is a powerful way of measuring the growth of structure and testing General Relativity, but it is limited by cosmic variance and the degeneracy between galaxy bias b and the growth rate factor f. The cross-correlation of lensing shear with the galaxy density field can in principle measure b in a manner free from cosmic variance limits, breaking the f-b degeneracy and allowing inference of the matter power spectrum from the galaxy survey. We analyze the growth constraints from a realistic tomographic weak lensing photo-z survey combined with a spectroscopic galaxy redshift survey over the samemore » sky area. For sky coverage fsky = 0.5, analysis of the transverse modes measures b to 2-3% accuracy per Δz = 0.1 bin at z < 1 when ~10 galaxies arcmin–2 are measured in the lensing survey and all halos with M > Mmin = 1013h–1M⊙ have spectra. For the gravitational growth parameter parameter γ (f = Ωγm), combining the lensing information with RSD analysis of non-transverse modes yields accuracy σ(γ) ≈ 0.01. Adding lensing information to the RSD survey improves \\sigma(\\gamma) by an amount equivalent to a 3x (10x) increase in RSD survey area when the spectroscopic survey extends down to halo mass 1013.5 (1014) h–1 M⊙. We also find that the σ(γ) of overlapping surveys is equivalent to that of surveys 1.5-2 times larger if they are separated on the sky. This gain is greatest when the spectroscopic mass threshold is 1013 -1014 h–1 M⊙, similar to LRG surveys. The gain of overlapping surveys is reduced for very deep or very shallow spectroscopic surveys, but any practical surveys are more powerful when overlapped than when separated. As a result, the gain of overlapped surveys is larger in the case when the primordial power spectrum normalization is uncertain by > 0.5%.« less

  11. Combining weak-lensing tomography and spectroscopic redshift surveys

    SciTech Connect

    Cai, Yan -Chuan; Bernstein, Gary

    2012-05-11

    Redshift space distortion (RSD) is a powerful way of measuring the growth of structure and testing General Relativity, but it is limited by cosmic variance and the degeneracy between galaxy bias b and the growth rate factor f. The cross-correlation of lensing shear with the galaxy density field can in principle measure b in a manner free from cosmic variance limits, breaking the f-b degeneracy and allowing inference of the matter power spectrum from the galaxy survey. We analyze the growth constraints from a realistic tomographic weak lensing photo-z survey combined with a spectroscopic galaxy redshift survey over the same sky area. For sky coverage fsky = 0.5, analysis of the transverse modes measures b to 2-3% accuracy per Δz = 0.1 bin at z < 1 when ~10 galaxies arcmin–2 are measured in the lensing survey and all halos with M > Mmin = 1013h–1M have spectra. For the gravitational growth parameter parameter γ (f = Ωγm), combining the lensing information with RSD analysis of non-transverse modes yields accuracy σ(γ) ≈ 0.01. Adding lensing information to the RSD survey improves \\sigma(\\gamma) by an amount equivalent to a 3x (10x) increase in RSD survey area when the spectroscopic survey extends down to halo mass 1013.5 (1014) h–1 M. We also find that the σ(γ) of overlapping surveys is equivalent to that of surveys 1.5-2 times larger if they are separated on the sky. This gain is greatest when the spectroscopic mass threshold is 1013 -1014 h–1 M, similar to LRG surveys. The gain of overlapping surveys is reduced for very deep or very shallow spectroscopic surveys, but any practical surveys are more powerful when overlapped than when separated. As a result, the gain of overlapped surveys is larger in the case when the primordial power spectrum normalization is

  12. A Catalog of Photometry for Las Campanas Redshift Survey Galaxies on the Sloan Digital Sky Survey System

    SciTech Connect

    Sowards-Emmerd, David; Smith, J. Allyn; McKay, Timothy A.; Sheldon, Erin; Tucker, Douglas L.; Castander, Francisco J.

    2000-06-01

    We present high-quality photometry in the five Sloan Digital Sky Survey filters, u', g', r', i', and z', for 2195 galaxies with spectroscopic redshifts measured by the Las Campanas Redshift Survey. In addition, a polynomial photometric redshift estimator is derived, with an uncertainty of 0.035 out to z = 0.25. (c) 2000 The American Astronomical Society.

  13. A Catalog of Photometry for Las Campanas Redshift Survey Galaxies on the Sloan Digital Sky Survey System

    NASA Astrophysics Data System (ADS)

    Sowards-Emmerd, David; Smith, J. Allyn; McKay, Timothy A.; Sheldon, Erin; Tucker, Douglas L.; Castander, Francisco J.

    2000-06-01

    We present high-quality photometry in the five Sloan Digital Sky Survey filters, u', g', r', i', and z', for 2195 galaxies with spectroscopic redshifts measured by the Las Campanas Redshift Survey. In addition, a polynomial photometric redshift estimator is derived, with an uncertainty of 0.035 out to z=0.25.

  14. ALMA REDSHIFTS OF MILLIMETER-SELECTED GALAXIES FROM THE SPT SURVEY: THE REDSHIFT DISTRIBUTION OF DUSTY STAR-FORMING GALAXIES

    SciTech Connect

    Weiss, A.; De Breuck, C.; Aravena, M.; Biggs, A. D.; Marrone, D. P.; Bothwell, M.; Vieira, J. D.; Bock, J. J.; Aguirre, J. E.; Aird, K. A.; Ashby, M. L. N.; Bayliss, M.; Benson, B. A.; Bleem, L. E.; Carlstrom, J. E.; Chang, C. L.; Bethermin, M.; Brodwin, M.; Chapman, S. C.; and others

    2013-04-10

    Using the Atacama Large Millimeter/submillimeter Array, we have conducted a blind redshift survey in the 3 mm atmospheric transmission window for 26 strongly lensed dusty star-forming galaxies (DSFGs) selected with the South Pole Telescope. The sources were selected to have S{sub 1.4{sub mm}} > 20 mJy and a dust-like spectrum and, to remove low-z sources, not have bright radio (S{sub 843{sub MHz}} < 6 mJy) or far-infrared counterparts (S{sub 100{sub {mu}m}} < 1 Jy, S{sub 60{sub {mu}m}} < 200 mJy). We robustly detect 44 line features in our survey, which we identify as redshifted emission lines of {sup 12}CO, {sup 13}CO, C I, H{sub 2}O, and H{sub 2}O{sup +}. We find one or more spectral features in 23 sources yielding a {approx}90% detection rate for this survey; in 12 of these sources we detect multiple lines, while in 11 sources we detect only a single line. For the sources with only one detected line, we break the redshift degeneracy with additional spectroscopic observations if available, or infer the most likely line identification based on photometric data. This yields secure redshifts for {approx}70% of the sample. The three sources with no lines detected are tentatively placed in the redshift desert between 1.7 < z < 2.0. The resulting mean redshift of our sample is z-bar = 3.5. This finding is in contrast to the redshift distribution of radio-identified DSFGs, which have a significantly lower mean redshift of z-bar = 2.3 and for which only 10%-15% of the population is expected to be at z > 3. We discuss the effect of gravitational lensing on the redshift distribution and compare our measured redshift distribution to that of models in the literature.

  15. Peculiar velocity decomposition, redshift space distortion, and velocity reconstruction in redshift surveys: The methodology

    NASA Astrophysics Data System (ADS)

    Zhang, Pengjie; Pan, Jun; Zheng, Yi

    2013-03-01

    Massive spectroscopic surveys will measure the redshift space distortion (RSD) induced by galaxy peculiar velocity to unprecedented accuracy and open a new era of precision RSD cosmology. We develop a new method to improve the RSD modeling and to carry out robust reconstruction of the 3D large scale peculiar velocity through galaxy redshift surveys, in light of RSD. (1) We propose a mathematically unique and physically motivated decomposition of peculiar velocity into three eigencomponents: an irrotational component completely correlated with the underlying density field (vδ), an irrotational component uncorrelated with the density field (vS), and a rotational (curl) component (vB). The three components have different origins, different scale dependences, and different impacts on RSD. (2) This decomposition has the potential to simplify and improve the RSD modeling. (i) vB damps the redshift space clustering. (ii) vS causes both damping and enhancement to the redshift space power spectrum Ps(k,u). Nevertheless, the leading order contribution to the enhancement has a u4 directional dependence, distinctively different from the Kaiser formula. Here, u≡kz/k, k is the amplitude of the wave vector, and kz is the component along the line of sight. (iii) vδ is of the greatest importance for the RSD cosmology. We find that the induced redshift clustering shows a number of important deviations from the usual Kaiser formula. Even in the limit of vS→0 and vB→0, the leading order contribution ∝(1+fW˜(k)u2)2. It differs from the Kaiser formula by a window function W˜(k). Nonlinear evolution generically drives W˜(k)≤1. We hence identify a significant systematical error causing underestimation of the structure growth parameter f by as much as O(10%) even at a relatively large scale k=0.1h/Mpc. (iv) The velocity decomposition reveals the three origins of the “finger-of-God” (FOG) effect and suggests how to simplify and improve the modeling of FOG by treating the

  16. Measuring redshift-space distortion with future SKA surveys

    NASA Astrophysics Data System (ADS)

    Raccanelli, A.; Bull, P.; Camera, S.; Blake, C.; Ferreira, P.; Maartens, R.; Santos, M.; Bull, P.; Bacon, D.; Doré, O.; Ferreira, P.; Santos, M. G.; Viel, M.; Zhao, G. B.

    2015-04-01

    The peculiar motion of galaxies can be a particularly sensitive probe of gravitational collapse. As such, it can be used to measure the dynamics of dark matter and dark energy as well the nature of the gravitational laws at play on cosmological scales. Peculiar motions manifest themselves as an overall anisotropy in the measured clustering signal as a function of the angle to the line-of-sight, known as redshift-space distortion (RSD). Limiting factors in this measurement include our ability to model non-linear galaxy motions on small scales and the complexities of galaxy bias. The anisotropy in the measured clustering pattern in redshift-space is also driven by the unknown distance factors at the redshift in question, the Alcock-Paczynski distortion. This weakens growth rate measurements, but permits an extra geometric probe of the Hubble expansion rate. In this chapter we will briefly describe the scientific background to the RSD technique, and forecast the potential of the SKA phase 1 and the SKA2 to measure the growth rate using both galaxy catalogues and intensity mapping, assessing their competitiveness with current and future optical galaxy surveys.

  17. Redshifts for 2410 Galaxies in the Century Survey Region

    NASA Astrophysics Data System (ADS)

    Wegner, Gary; Thorstensen, John R.; Kurtz, Michael J.; Brown, Warren R.; Fabricant, Daniel G.; Geller, Margaret J.; Huchra, John P.; Marzke, Ronald O.; Sakai, Shoko

    2001-12-01

    The Century Survey strip covers 102 deg2 within the limits 8h5<=α<=16h5, 29.0d<=δ<=30.0d, equinox B1950.0. The strip passes through the Corona Borealis supercluster and the outer region of the Coma cluster. Within the Century Survey region, we have measured 2410 redshifts that constitute four overlapping complete redshift surveys: (1) 1728 galaxies with Kron-Cousins Rph<=16.13 covering the entire strip, (2) 507 galaxies with Rph<=16.4 in right ascension range 8h32m<=α<=10 h45m, equinox B1950.0, (3) 1251 galaxies with absorption- and K-corrected RCCDc<=16.2 (where ``c'' indicates ``corrected'') covering the right ascension range 8h5<=α<=13h5, equinox B1950.0, and (4) 1255 galaxies with absorption- and K-corrected VCCDc<=16.7 also covering the right ascension range 8h5<=α<=13h5, equinox B1950.0. All these redshift samples are more than 98% complete to the specified magnitude limit. We derived samples 1 and 2 from scans of the POSS1 red (E) plates calibrated with CCD photometry. We derived samples 3 and 4 from deep V and R CCD images covering the entire region. We include coarse morphological types for all the galaxies in sample 1. The distribution of (V-R)CCD for each type corresponds appropriately with the classification. Work reported here is based partly on observations obtained at the Michigan-Dartmouth-MIT Observatory.

  18. Spatial density fluctuations and selection effects in galaxy redshift surveys

    SciTech Connect

    Labini, Francesco Sylos; Tekhanovich, Daniil; Baryshev, Yurij V. E-mail: d.tekhanovich@spbu.ru

    2014-07-01

    One of the main problems of observational cosmology is to determine the range in which a reliable measurement of galaxy correlations is possible. This corresponds to determining the shape of the correlation function, its possible evolution with redshift and the size and amplitude of large scale structures. Different selection effects, inevitably entering in any observation, introduce important constraints in the measurement of correlations. In the context of galaxy redshift surveys selection effects can be caused by observational techniques and strategies and by implicit assumptions used in the data analysis. Generally all these effects are taken into account by using pair-counting algorithms to measure two-point correlations. We review these methods stressing that they are based on the a-priori assumption that galaxy distribution is spatially homogeneous inside a given sample. We show that, when this assumption is not satisfied by the data, results of the correlation analysis are affected by finite size effects. In order to quantify these effects, we introduce a new method based on the computation of the gradient of galaxy counts along tiny cylinders. We show, by using artificial homogeneous and inhomogeneous point distributions, that this method identifies redshift dependent selection effects and disentangles them from the presence of large scale density fluctuations. We then apply this new method to several redshift catalogs and we find evidence that galaxy distribution, in those samples where selection effects are small enough, is characterized by power-law correlations with exponent γ=0.9 up to 20 Mpc/h followed by a change of slope that, in the range 20–100 Mpc/h, corresponds to a power-law exponent γ=0.25. Whether a crossover to spatial uniformity occurs at ∼ 100 Mpc/h or larger scales cannot be clarified by the present data.

  19. A faint galaxy redshift survey behind massive clusters

    SciTech Connect

    Frye, Brenda

    1999-12-01

    This thesis is concerned with the gravitational lensing effect by massive galaxy clusters. We have explored a new technique for measuring galaxy masses and for detecting high-z galaxies by their optical colors. A redshift survey has been obtained at the Keck for a magnitude limited sample of objects (I<23) behind three clusters, A1689, A2390, and A2218 within a radius of 0.5M pc. For each cluster we see both a clear trend of increasing flux and redshift towards the center. This behavior is the result of image magnifications, such that at fixed redshift one sees further down the luminosity function. The gradient of this magnification is, unlike measurements of image distortion, sensitive to the mass profile, and found to depart strongly from a pure isothermal halo. We have found that V RI color selection can be used effectively as a discriminant for finding high-z galaxies behind clusters and present five 4.1 < z < 5.1 spectra which are of very high quality due to their high mean magnification of {approximately}20, showing strong, visibly-saturated interstellar metal lines in some cases. We have also investigated the radio ring lens PKS 1830-211, locating the source and multiple images and detected molecular absorption at mm wavelengths. Broad molecular absorption of width 1/40kms is found toward the southwest component only, where surprisingly it does not reach the base of the continuum, which implies incomplete coverage of the SW component by molecular gas, despite the small projected size of the source, less than 1/8h pc at the absorption redshift.

  20. Simulation of deep one- and two-dimensional redshift surveys

    NASA Technical Reports Server (NTRS)

    Park, Changbom; Gott, J. Richard, III

    1991-01-01

    It is shown that slice or pencil-beam redshift surveys of galaxies can be simulated in a box with nonequal sides. This method saves a lot of computer time and memory while providing essentially the same results as from whole-cube simulations. A 2457.6/h Mpc-long rod (out to a redshift z = 0.58 in two opposite directions) is simulated using the standard biased cold dark matter model as an example to mimic the recent deep pencil-beam surveys by Broadhurst et al. (1990). The structures (spikes) seen in these simulated samples occur when the narrow pencil-beam pierces walls, filaments, and clusters appearing randomly along the line-of-sight. A statistical test for goodness of fit to a periodic lattice has been applied to the observations and the simulations. It is found that the statistical significance level (P = 15.4 percent) is not strong enough to reject the null hypothesis that the observations and the simulations were drawn at random from the same set.

  1. The KMOS AGN Survey at High Redshift (KASHz)

    NASA Astrophysics Data System (ADS)

    Harrison, C.; Alexander, D.; Mullaney, J.; Stott, J.; Swinbank, M.; Arumugam, V.; Bauer, F.; Bower, R.; Bunker, A.; Sharples, R.

    2016-03-01

    The KMOS AGN Survey at High Redshift (KASHz) is an extensive observational programme to obtain spatially resolved spectroscopy of distant galaxies that host rapidly growing supermassive black holes (i.e., active galactic nuclei [AGN]). By exploiting the unique capabilities of KMOS we will spatially resolve the ionised gas kinematics in around 200 such galaxies. A fundamental prediction of galaxy formation models is that AGN inject considerable energy into their host galaxies and ultimately destroy or remove star-forming material via outflows. However, until now, observational constraints of this prediction have been limited to only a small number of distant galaxies. KASHz will provide the strongest constraints to date on the prevalence, properties and impact of ionised outflows in the host galaxies of distant AGN. The survey is described and our first results presented.

  2. Spectral Classification and Redshift Measurement for the SDSS-III Baryon Oscillation Spectroscopic Survey

    NASA Astrophysics Data System (ADS)

    Bolton, Adam S.; Schlegel, David J.; Aubourg, Éric; Bailey, Stephen; Bhardwaj, Vaishali; Brownstein, Joel R.; Burles, Scott; Chen, Yan-Mei; Dawson, Kyle; Eisenstein, Daniel J.; Gunn, James E.; Knapp, G. R.; Loomis, Craig P.; Lupton, Robert H.; Maraston, Claudia; Muna, Demitri; Myers, Adam D.; Olmstead, Matthew D.; Padmanabhan, Nikhil; Pâris, Isabelle; Percival, Will J.; Petitjean, Patrick; Rockosi, Constance M.; Ross, Nicholas P.; Schneider, Donald P.; Shu, Yiping; Strauss, Michael A.; Thomas, Daniel; Tremonti, Christy A.; Wake, David A.; Weaver, Benjamin A.; Wood-Vasey, W. Michael

    2012-11-01

    We describe the automated spectral classification, redshift determination, and parameter measurement pipeline in use for the Baryon Oscillation Spectroscopic Survey (BOSS) of the Sloan Digital Sky Survey III (SDSS-III) as of the survey's ninth data release (DR9), encompassing 831,000 moderate-resolution optical spectra. We give a review of the algorithms employed, and describe the changes to the pipeline that have been 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 redshift 0.4 <~ z <~ 0.8 targeted by BOSS for the purposes of large-scale cosmological measurements, the pipeline achieves an automated classification success rate of 98.7% and confirms 95.4% of unique CMASS targets as galaxies (with the balance being mostly M stars). Based on visual inspections of a subset of BOSS galaxies, we find that approximately 0.2% of confidently reported CMASS sample classifications and redshifts are incorrect, and about 0.4% of all CMASS spectra are objects unclassified by the current algorithm which are potentially recoverable. The BOSS pipeline confirms that ~51.5% of the quasar targets have quasar spectra, with the balance mainly consisting of stars and low signal-to-noise spectra. Statistical (as opposed to systematic) redshift errors propagated from photon noise are typically a few tens of km s-1 for both galaxies and quasars, with a significant tail to a few hundreds of km s-1 for quasars. We test the accuracy of these statistical redshift error estimates using repeat observations, finding them underestimated by a factor of 1.19-1.34 for galaxies and by a factor of two for quasars. We assess the impact of sky-subtraction quality, signal-to-noise ratio, and other factors on galaxy redshift success. Finally, we document known issues with the BOSS DR9 spectroscopic data set and describe directions of ongoing development.

  3. The DEEP2 Galaxy Redshift Survey: The Voronoi-Delaunay Method Catalog of Galaxy Groups

    SciTech Connect

    Gerke, Brian F.; Newman, Jeffrey A.; Davis, Marc; Marinoni, Christian; Yan, Renbin; Coil, Alison L.; Conroy, Charlie; Cooper, Michael C.; Faber, S.M.; Finkbeiner, Douglas P.; Guhathakurta, Puragra; Kaiser, Nick; Koo, David C.; Phillips, Andrew C.; Weiner, Benjamin J.; /Maryland U.

    2012-02-14

    We use the first 25% of the DEEP2 Galaxy Redshift Survey spectroscopic data to identify groups and clusters of galaxies in redshift space. The data set contains 8370 galaxies with confirmed redshifts in the range 0.7 {<=} z {<=} 1.4, over one square degree on the sky. Groups are identified using an algorithm (the Voronoi-Delaunay Method) that has been shown to accurately reproduce the statistics of groups in simulated DEEP2-like samples. We optimize this algorithm for the DEEP2 survey by applying it to realistic mock galaxy catalogs and assessing the results using a stringent set of criteria for measuring group-finding success, which we develop and describe in detail here. We find in particular that the group-finder can successfully identify {approx}78% of real groups and that {approx}79% of the galaxies that are true members of groups can be identified as such. Conversely, we estimate that {approx}55% of the groups we find can be definitively identified with real groups and that {approx}46% of the galaxies we place into groups are interloper field galaxies. Most importantly, we find that it is possible to measure the distribution of groups in redshift and velocity dispersion, n({sigma}, z), to an accuracy limited by cosmic variance, for dispersions greater than 350 km s{sup -1}. We anticipate that such measurements will allow strong constraints to be placed on the equation of state of the dark energy in the future. Finally, we present the first DEEP2 group catalog, which assigns 32% of the galaxies to 899 distinct groups with two or more members, 153 of which have velocity dispersions above 350 km s{sup -1}. We provide locations, redshifts and properties for this high-dispersion subsample. This catalog represents the largest sample to date of spectroscopically detected groups at z {approx} 1.

  4. Void statistics of the CfA redshift survey

    NASA Technical Reports Server (NTRS)

    Vogeley, Michael S.; Geller, Margaret J.; Huchra, John P.

    1991-01-01

    Clustering properties of two samples from the CfA redshift survey, each containing about 2500 galaxies, are studied. A comparison of the velocity distributions via a K-S test reveals structure on scales comparable with the extent of the survey. The void probability function (VPF) is employed for these samples to examine the structure and to test for scaling relations in the galaxy distribution. The galaxy correlation function is calculated via moments of galaxy counts. The shape and amplitude of the correlation function roughly agree with previous determinations. The VPFs for distance-limited samples of the CfA survey do not match the scaling relation predicted by the hierarchical clustering models. On scales not greater than 10/h Mpc, the VPFs for these samples roughly follow the hierarchical pattern. A variant of the VPF which uses nearly all the data in magnitude-limited samples is introduced; it accounts for the variation of the sampling density with velocity in a magnitude-limited survey.

  5. Galaxy clustering in the Two Micron All Sky Redshift Survey

    NASA Astrophysics Data System (ADS)

    Westover, Michael

    To make cosmological measurements using the galaxy distribution we must first understand galaxy biasing the way in which the galaxy distribution differs from the underlying matter distribution. Here I present studies of galaxy biasing using the Two Micron All Sky Redshift Survey, a near-infrared selected survey not subject to many of the selection effects that limit other samples. The relationship between galaxy bias and luminosity is steeper for our near- infrared selected sample than it is for optical samples, with b/b [low *] 0.73 + 0.24 L/L [low *] . I found no dependence upon luminosity in the relative bias between early and late morphologically typed galaxies once the mean dependence of bias upon luminosity was removed. I tested the relative biasing between early- and late-type galaxies using joint counts in cells. I found that a power law biasing model with b PL = 0.86-0.91 was a better fit than linear models. I did not see a significant increase in the quality of the fit when stochasticity was added to the model, in contrast with results from color- and spectral type-selected samples. I tested the hierarchical scaling hypothesis and confirmed that the scale factors S 3 , S 4 , and S 5 are independent of scale, as expected for a matter distribution evolved from Gaussian initial perturbations. There was no increase in the scale factors at large cell sizes as seen in some earlier surveys. I also measured the generalized dimensions D q using a multifractal analysis and found smaller values than have been seen in optically-selected surveys and simulations, indicating that galaxies in the near-infrared selected sample may be more likely to reside in filamentary rather than sheet-like structures.

  6. The Low Redshift survey at Calar Alto (LoRCA)

    NASA Astrophysics Data System (ADS)

    Comparat, J.; Chuang, C.-H.; Rodríguez-Torres, S.; Pellejero-Ibanez, M.; Prada, F.; Yepes, G.; Courtois, H. M.; Zhao, G.-B.; Wang, Y.; Sanchez, J.; Maraston, C.; Metcalf, R. Benton; Peiro-Perez, J.; Kitaura, F. S.; Pérez, E.; González Delgado, R. M.

    2016-05-01

    The Baryon Acoustic Oscillation (BAO) feature in the power spectrum of galaxies provides a standard ruler to measure the accelerated expansion of the Universe. To extract all available information about dark energy, it is necessary to measure a standard ruler in the local, z < 0.2, universe where dark energy dominates most the energy density of the Universe. Though the volume available in the local universe is limited, it is just big enough to measure accurately the long 100 h-1 Mpc wave-mode of the BAO. Using cosmological N-body simulations and approximate methods based on Lagrangian perturbation theory, we construct a suite of a thousand light-cones to evaluate the precision at which one can measure the BAO standard ruler in the local universe. We find that using the most massive galaxies on the full sky (34 000 deg2), i.e. a K2MASS < 14 magnitude-limited sample, one can measure the BAO scale up to a precision of 4 per cent (˜1.2 per cent using reconstruction). We also find that such a survey would help to detect the dynamics of dark energy. Therefore, we propose a 3-year long observational project, named the Low Redshift survey at Calar Alto, to observe spectroscopically about 200 000 galaxies in the northern sky to contribute to the construction of aforementioned galaxy sample. The suite of light-cones is made available to the public.

  7. A Photometric redshift galaxy catalog from the Red-Sequence Cluster Survey

    SciTech Connect

    Hsieh, Bau-Ching; Yee, H.K.C.; Lin, H.; Gladders, M.D.; /Carnegie Inst. Observ.

    2005-02-01

    The Red-Sequence Cluster Survey (RCS) provides a large and deep photometric catalog of galaxies in the z' and R{sub c} bands for 90 square degrees of sky, and supplemental V and B data have been obtained for 33.6 deg{sup 2}. They compile a photometric redshift catalog from these 4-band data by utilizing the empirical quadratic polynomial photometric redshift fitting technique in combination with CNOC2 and GOODS/HDF-N redshift data. The training set includes 4924 spectral redshifts. The resulting catalog contains more than one million galaxies with photometric redshifts < 1.5 and R{sub c} < 24, giving an rms scatter {delta}({Delta}z) < 0.06 within the redshift range 0.2 < z < 0.5 and {sigma}({Delta}z) < 0.11 for galaxies at 0.0 < z < 1.5. They describe the empirical quadratic polynomial photometric redshift fitting technique which they use to determine the relation between red-shift and photometry. A kd-tree algorithm is used to divide up the sample to improve the accuracy of the catalog. They also present a method for estimating the photometric redshift error for individual galaxies. They show that the redshift distribution of the sample is in excellent agreement with smaller and much deeper photometric and spectroscopic redshift surveys.

  8. A redshift survey of IRAS galaxies. VII - The infrared and redshift data for the 1.936 Jansky sample

    NASA Technical Reports Server (NTRS)

    Strauss, Michael A.; Huchra, John P.; Davis, Marc; Yahil, Amos; Fisher, Karl B.; Tonry, John

    1992-01-01

    We present the data for a redshift survey of galaxies selected from the database of the Infrared Astronomical Satellite (IRAS). The sample is flux limited to 1.936 Jy at 60 microns and covers 11.01 sr of the sky. It consists of 5014 objects, of which 2658 are galaxies. The remaining 2356 sources are listed in a separate table with identifications. Redshift data are also given for 212 IRAS galaxies which are not part of the complete sample, but were measured in conjunction with this project.

  9. The effects of spatial resolution on integral field spectrograph surveys at different redshifts - The CALIFA perspective

    NASA Astrophysics Data System (ADS)

    Mast, D.; Rosales-Ortega, F. F.; Sánchez, S. F.; Vílchez, J. M.; Iglesias-Paramo, J.; Walcher, C. J.; Husemann, B.; Márquez, I.; Marino, R. A.; Kennicutt, R. C.; Monreal-Ibero, A.; Galbany, L.; de Lorenzo-Cáceres, A.; Mendez-Abreu, J.; Kehrig, C.; del Olmo, A.; Relaño, M.; Wisotzki, L.; Mármol-Queraltó, E.; Bekeraitè, S.; Papaderos, P.; Wild, V.; Aguerri, J. A. L.; Falcón-Barroso, J.; Bomans, D. J.; Ziegler, B.; García-Lorenzo, B.; Bland-Hawthorn, J.; López-Sánchez, Á. R.; van de Ven, G.

    2014-01-01

    Context. Over the past decade, 3D optical spectroscopy has become the preferred tool for understanding the properties of galaxies and is now increasingly used to carry out galaxy surveys. Low redshift surveys include SAURON, DiskMass, ATLAS3D, PINGS, and VENGA. At redshifts above 0.7, surveys such as MASSIV, SINS, GLACE, and IMAGES have targeted the most luminous galaxies to study mainly their kinematic properties. The on-going CALIFA survey (z ~ 0.02) is the first of a series of upcoming integral field spectroscopy (IFS) surveys with large samples representative of the entire population of galaxies. Others include SAMI and MaNGA at lower redshift and the upcoming KMOS surveys at higher redshift. Given the importance of spatial scales in IFS surveys, the study of the effects of spatial resolution on the recovered parameters becomes important. Aims: We explore the capability of the CALIFA survey and a hypothetical higher redshift survey to reproduce the properties of a sample of objects observed with better spatial resolution at lower redshift. Methods: Using a sample of PINGS galaxies, we simulated observations at different redshifts. We then studied the behaviour of different parameters as the spatial resolution degrades with increasing redshift. Results: We show that at the CALIFA resolution, we are able to measure and map common observables in a galaxy study: the number and distribution of H ii regions (Hα flux structure), the gas metallicity (using the O3N2 method), the gas ionization properties (through the [N ii]/Hα and [O iii]/Hβ line ratios), and the age of the underlying stellar population (using the D4000 index). This supports the aim of the survey to characterise the observable properties of galaxies in the Local Universe. Our analysis of simulated IFS data cubes at higher redshifts highlights the importance of the projected spatial scale per spaxel as the most important figure of merit in the design of an integral field survey.

  10. High redshift galaxies in the ALHAMBRA survey . I. Selection method and number counts based on redshift PDFs

    NASA Astrophysics Data System (ADS)

    Viironen, K.; Marín-Franch, A.; López-Sanjuan, C.; Varela, J.; Chaves-Montero, J.; Cristóbal-Hornillos, D.; Molino, A.; Fernández-Soto, A.; Vilella-Rojo, G.; Ascaso, B.; Cenarro, A. J.; Cerviño, M.; Cepa, J.; Ederoclite, A.; Márquez, I.; Masegosa, J.; Moles, M.; Oteo, I.; Pović, M.; Aguerri, J. A. L.; Alfaro, E.; Aparicio-Villegas, T.; Benítez, N.; Broadhurst, T.; Cabrera-Caño, J.; Castander, J. F.; Del Olmo, A.; González Delgado, R. M.; Husillos, C.; Infante, L.; Martínez, V. J.; Perea, J.; Prada, F.; Quintana, J. M.

    2015-04-01

    Context. Most observational results on the high redshift restframe UV-bright galaxies are based on samples pinpointed using the so-called dropout technique or Ly-α selection. However, the availability of multifilter data now allows the dropout selections to be replaced by direct methods based on photometric redshifts. In this paper we present the methodology to select and study the population of high redshift galaxies in the ALHAMBRA survey data. Aims: Our aim is to develop a less biased methodology than the traditional dropout technique to study the high redshift galaxies in ALHAMBRA and other multifilter data. Thanks to the wide area ALHAMBRA covers, we especially aim at contributing to the study of the brightest, least frequent, high redshift galaxies. Methods: The methodology is based on redshift probability distribution functions (zPDFs). It is shown how a clean galaxy sample can be obtained by selecting the galaxies with high integrated probability of being within a given redshift interval. However, reaching both a complete and clean sample with this method is challenging. Hence, a method to derive statistical properties by summing the zPDFs of all the galaxies in the redshift bin of interest is introduced. Results: Using this methodology we derive the galaxy rest frame UV number counts in five redshift bins centred at z = 2.5,3.0,3.5,4.0, and 4.5, being complete up to the limiting magnitude at mUV(AB) = 24, where mUV refers to the first ALHAMBRA filter redwards of the Ly-α line. With the wide field ALHAMBRA data we especially contribute to the study of the brightest ends of these counts, accurately sampling the surface densities down to mUV(AB) = 21-22. Conclusions: We show that using the zPDFs it is easy to select a very clean sample of high redshift galaxies. We also show that it is better to do statistical analysis of the properties of galaxies using a probabilistic approach, which takes into account both the incompleteness and contamination issues in a

  11. Optimizing baryon acoustic oscillation surveys - II. Curvature, redshifts and external data sets

    NASA Astrophysics Data System (ADS)

    Parkinson, David; Kunz, Martin; Liddle, Andrew R.; Bassett, Bruce A.; Nichol, Robert C.; Vardanyan, Mihran

    2010-02-01

    We extend our study of the optimization of large baryon acoustic oscillation (BAO) surveys to return the best constraints on the dark energy, building on Paper I of this series by Parkinson et al. The survey galaxies are assumed to be pre-selected active, star-forming galaxies observed by their line emission with a constant number density across the redshift bin. Star-forming galaxies have a redshift desert in the region 1.6 < z < 2, and so this redshift range was excluded from the analysis. We use the Seo & Eisenstein fitting formula for the accuracies of the BAO measurements, using only the information for the oscillatory part of the power spectrum as distance and expansion rate rulers. We go beyond our earlier analysis by examining the effect of including curvature on the optimal survey configuration and updating the expected `prior' constraints from Planck and the Sloan Digital Sky Survey. We once again find that the optimal survey strategy involves minimizing the exposure time and maximizing the survey area (within the instrumental constraints), and that all time should be spent observing in the low-redshift range (z < 1.6) rather than beyond the redshift desert, z > 2. We find that, when assuming a flat universe, the optimal survey makes measurements in the redshift range 0.1 < z < 0.7, but that including curvature as a nuisance parameter requires us to push the maximum redshift to 1.35, to remove the degeneracy between curvature and evolving dark energy. The inclusion of expected other data sets (such as WiggleZ, the Baryon Oscillation Spectroscopic Survey and a stage III Type Ia supernova survey) removes the necessity of measurements below redshift 0.9, and pushes the maximum redshift up to 1.5. We discuss considerations in determining the best survey strategy in light of uncertainty in the true underlying cosmological model.

  12. Effective theory of dark energy at redshift survey scales

    NASA Astrophysics Data System (ADS)

    Gleyzes, Jérôme; Langlois, David; Mancarella, Michele; Vernizzi, Filippo

    2016-02-01

    We explore the phenomenological consequences of general late-time modifications of gravity in the quasi-static approximation, in the case where cold dark matter is non-minimally coupled to the gravitational sector. Assuming spectroscopic and photometric surveys with configuration parameters similar to those of the Euclid mission, we derive constraints on our effective description from three observables: the galaxy power spectrum in redshift space, tomographic weak-lensing shear power spectrum and the correlation spectrum between the integrated Sachs-Wolfe effect and the galaxy distribution. In particular, with ΛCDM as fiducial model and a specific choice for the time dependence of our effective functions, we perform a Fisher matrix analysis and find that the unmarginalized 68% CL errors on the parameters describing the modifications of gravity are of order σ~10-2-10-3. We also consider two other fiducial models. A nonminimal coupling of CDM enhances the effects of modified gravity and reduces the above statistical errors accordingly. In all cases, we find that the parameters are highly degenerate, which prevents the inversion of the Fisher matrices. Some of these degeneracies can be broken by combining all three observational probes.

  13. Large-scale structure in the Southern Sky Redshift Survey

    NASA Technical Reports Server (NTRS)

    Park, Changbom; Gott, J. R., III; Da Costa, L. N.

    1992-01-01

    The power spectrum from the Southern Sky Redshift Survey and the CfA samples are measured in order to explore the amplitude of fluctuation in the galaxy density. At lambda of less than or equal to 30/h Mpc the observed power spectrum is quite consistent with the standard CDM model. At larger scales the data indicate an excess of power over the standard CDM model. The observed power spectrum from these optical galaxy samples is in good agreement with that drawn from the sparsely sampled IRAS galaxies. The shape of the power spectrum is also studied by examining the relation between the genus per unit volume and the smoothing length. It is found that, over Gaussian smoothing scales from 6 to 14/h Mpc, the power spectrum has a slope of about -1. The topology of the galaxy density field is studied by measuring the shift of the genus curve from the Gaussian case. Over all smoothing scales studied, the observed genus curves are consistent with a random phase distribution of the galaxy density field, as predicted by the inflationary scenarios.

  14. THE 2dF REDSHIFT SURVEY. I. PHYSICAL ASSOCIATION AND PERIODICITY IN QUASAR FAMILIES

    SciTech Connect

    Fulton, C. C.; Arp, H. C. E-mail: arp@mpa-garching.mpg.de

    2012-08-01

    We have tested for physical association of candidate companion quasars with putative parent galaxies by virtue of Karlsson periodicity in quasar redshifts. We examined galaxies from the 2dF Galaxy Redshift Survey (2dFGRS) and quasars from the 2dF Quasar Redshift Survey (2QZ) in the two declination strips (at declinations 0 Degree-Sign and -30 Degree-Sign ) covered by the 2QZ, first filtering out galaxies and quasars using the respective survey masks and observation qualities as described, and using only quasars with z {>=} 0.5 to avoid the redshift region of mixed galaxies and quasars. Around each galaxy, quasars are detected as physically associated with a putative parent galaxy if their respective redshifts conform to empirically derived constraints based on an ejection hypothesis. We ran Monte Carlo control trials against the pure physical associations by replacing the actual redshifts of the candidate companion quasars with quasar redshifts drawn randomly from each respective right ascension hour. The constraints are grouping of quasar redshifts and Karlsson periodicity of quasar redshifts.

  15. The luminosity function for the CfA redshift survey slices

    NASA Technical Reports Server (NTRS)

    De Lapparent, Valerie; Geller, Margaret J.; Huchra, John P.

    1989-01-01

    The luminosity function for two complete slices of the extension of the CfA redshift survey is calculated. The nonparametric technique of Lynden-Bell (1971) and Turner (1979) is used to determine the shape for the luminosity function of the 12 deg slice of the redshift survey. The amplitude of the luminosity function is determined, taking large-scale inhomogeneities into account. The effects of the Malmquist bias on a magnitude-limited redshift survey are examined, showing that the random errors in the magnitudes for the 12 deg slice affect both the determination of the luminosity function and the spatial density constrast of large scale structures.

  16. An Open-Source Galaxy Redshift Survey Simulator for next-generation Large Scale Structure Surveys

    NASA Astrophysics Data System (ADS)

    Seijak, Uros

    Galaxy redshift surveys produce three-dimensional maps of the galaxy distribution. On large scales these maps trace the underlying matter fluctuations in a relatively simple manner, so that the properties of the primordial fluctuations along with the overall expansion history and growth of perturbations can be extracted. The BAO standard ruler method to measure the expansion history of the universe using galaxy redshift surveys is thought to be robust to observational artifacts and understood theoretically with high precision. These same surveys can offer a host of additional information, including a measurement of the growth rate of large scale structure through redshift space distortions, the possibility of measuring the sum of neutrino masses, tighter constraints on the expansion history through the Alcock-Paczynski effect, and constraints on the scale-dependence and non-Gaussianity of the primordial fluctuations. Extracting this broadband clustering information hinges on both our ability to minimize and subtract observational systematics to the observed galaxy power spectrum, and our ability to model the broadband behavior of the observed galaxy power spectrum with exquisite precision. Rapid development on both fronts is required to capitalize on WFIRST's data set. We propose to develop an open-source computational toolbox that will propel development in both areas by connecting large scale structure modeling and instrument and survey modeling with the statistical inference process. We will use the proposed simulator to both tailor perturbation theory and fully non-linear models of the broadband clustering of WFIRST galaxies and discover novel observables in the non-linear regime that are robust to observational systematics and able to distinguish between a wide range of spatial and dynamic biasing models for the WFIRST galaxy redshift survey sources. We have demonstrated the utility of this approach in a pilot study of the SDSS-III BOSS galaxies, in which we

  17. Spectroscopic CCD surveys for quasars at large redshift. 3: The Palomar Transit Grism Survey catalog

    NASA Technical Reports Server (NTRS)

    Schneider, Donald P.; Schmidt, Maarten; Gunn, James E.

    1994-01-01

    This paper reports the initial results of the Palomar Transit Grism Survey (PTGS). The PTGS was designed to produce a sample of z greater than 2.7 quasars that were identified by well-defined selection criteria. The survey consists of six narrow (approximately equal to 8.5 min wide) strips of sky; the total effective area is 61.47 sq deg. Low-resolution slitless spectra, covering the wavelength range from 4400 to 7500 A, were obtained for approximately 600 000 objects. The wavelength- and flux-calibrated spectra were searched for emission lines with an automatic software algorithm. A total to 1655 emission features in the grism data satisfied our signal-to-noise ratio and equivalent width selection criteria; subsequent slit spectroscopy of the candidates confirmed the existence of 1052 lines (928 different objects). Six groups of emission lines were detected in the survey: Lyman alpha + N V, C IV, C III1, Mg II, H Beta + (O III), and H alpha + (S II). More than two-thirds of the candidates are low-redshift (z less than 0.45) emission-line galaxies; ninety objects are high-redshift quasars (z greater than 2.7) detected via their Lyman alpha + N V emission lines. The survey contains three previously unknown quasars brighter than 17th magnitude; all three have redshifts of approximately equal to 1.3. In this paper we present the observational properties of the survey, the algorithms used to select the emission-line candidates, and the catalog of emission-line objects.

  18. Spectroscopic CCD surveys for quasars at large redshift. II - A Pfuei transit survey

    NASA Technical Reports Server (NTRS)

    Schmidt, Maarten; Schneider, Donald P.; Gunn, James E.

    1986-01-01

    A CCD transit survey has been carried out with the 200 in. telescope of a strip of sky 5 arcmin wide and 9 hr long. Direct images and slitless spectra of over 43,000 objects were obtained on two successive nights. An automatic search for emission lines of given minimum equivalent width and signal-to-noise ratio yielded 52 candidate sources. Slit spectra revealed that 24 were emission-line galaxies with z less than 0.4 and eight were quasars with 2 between 1.00 and 2.76. The number of quasars detect agrees with that predicted from luminosity function models for z less than 2.9. The models also indicate that between 30 and 62 quasars with z less than 2.9 should have been found in this survey, but none were detected. This result reconfirms that there is a redshift cutoff near or below redshift three. The apparent conflict of this measurement with the known existence of dozens of quasars with redshifts larger than three is discussed.

  19. The Redshift Distribution of Dusty Star-forming Galaxies from the SPT Survey

    NASA Astrophysics Data System (ADS)

    Strandet, M. L.; Weiss, A.; Vieira, J. D.; de Breuck, C.; Aguirre, J. E.; Aravena, M.; Ashby, M. L. N.; Béthermin, M.; Bradford, C. M.; Carlstrom, J. E.; Chapman, S. C.; Crawford, T. M.; Everett, W.; Fassnacht, C. D.; Furstenau, R. M.; Gonzalez, A. H.; Greve, T. R.; Gullberg, B.; Hezaveh, Y.; Kamenetzky, J. R.; Litke, K.; Ma, J.; Malkan, M.; Marrone, D. P.; Menten, K. M.; Murphy, E. J.; Nadolski, A.; Rotermund, K. M.; Spilker, J. S.; Stark, A. A.; Welikala, N.

    2016-05-01

    We use the Atacama Large Millimeter/submillimeter Array (ALMA) in Cycle 1 to determine spectroscopic redshifts of high-redshift dusty star-forming galaxies (DSFGs) selected by their 1.4 mm continuum emission in the South Pole Telescope (SPT) survey. We present ALMA 3 mm spectral scans between 84 and 114 GHz for 15 galaxies and targeted ALMA 1 mm observations for an additional eight sources. Our observations yield 30 new line detections from CO, [C i], [N ii], H2O and NH3. We further present Atacama Pathfinder Experiment [C ii] and CO mid-J observations for seven sources for which only a single line was detected in spectral-scan data from ALMA Cycle 0 or Cycle 1. We combine the new observations with previously published and new millimeter/submillimeter line and photometric data of the SPT-selected DSFGs to study their redshift distribution. The combined data yield 39 spectroscopic redshifts from molecular lines, a success rate of >85%. Our sample represents the largest data set of its kind today and has the highest spectroscopic completeness among all redshift surveys of high-z DSFGs. The median of the redshift distribution is z = 3.9 ± 0.4, and the highest-redshift source in our sample is at z = 5.8. We discuss how the selection of our sources affects the redshift distribution, focusing on source brightness, selection wavelength, and strong gravitational lensing. We correct for the effect of gravitational lensing and find the redshift distribution for 1.4 mm selected sources with a median redshift of z = 3.1 ± 0.3. Comparing to redshift distributions selected at shorter wavelengths from the literature, we show that selection wavelength affects the shape of the redshift distribution.

  20. Topological analysis of the CfA redshift survey

    NASA Technical Reports Server (NTRS)

    Vogeley, Michael S.; Park, Changbom; Geller, Margaret J.; Huchra, John P.; Gott, J. Richard, III

    1994-01-01

    We study the topology of large-scale structure in the Center for Astrophysics Redshift Survey, which now includes approximately 12,000 galaxies with limiting magnitude m(sub B) is less than or equal to 15.5. The dense sampling and large volume of this survey allow us to compute the topology on smoothing scales from 6 to 20/h Mpc; we thus examine the topology of structure in both 'nonlinear' and 'linear' regimes. On smoothing scales less than or equal to 10/h Mpc this sample has 3 times the number of resolution elements of samples examined in previous studies. Isodensity surface of the smoothed galaxy density field demonstrate that coherent high-density structures and large voids dominate the galaxy distribution. We compute the genus-threshold density relation for isodensity surfaces of the CfA survey. To quantify phase correlation in these data, we compare the CfA genus with the genus of realizations of Gaussian random fields with the power spectrum measured for the CfA survey. On scales less than or equal to 10/h Mpc the observed genus amplitude is smaller than random phase (96% confidence level). This decrement reflects the degree of phase coherence in the observed galaxy distribution. In other words the genus amplitude on these scales is not good measure of the power spectrum slope. On scales greater than 10/h Mpc, where the galaxy distribution is rougly in the 'linear' regime, the genus ampitude is consistent with the random phase amplitude. The shape of the genus curve reflects the strong coherence in the observed structure; the observed genus curve appears broader than random phase (94% confidence level for smoothing scales less than or equal to 10/h Mpc) because the topolgoy is spongelike over a very large range of density threshold. This departre from random phase consistent with a distribution like a filamentary net of 'walls with holes.' On smoothing scales approaching approximately 20/h Mpc the shape of the CfA genus curve is consistent with random phase

  1. The High-Redshift Clusters Occupied by Bent Radio AGN (COBRA) Survey

    NASA Astrophysics Data System (ADS)

    Paterno-Mahler, Rachel; Blanton, Elizabeth L.; Wing, Joshua; Ashby, M. L. N.; Brodwin, Mark; Golden-Marx, Emmet

    2015-08-01

    The number of confirmed, high-redshift galaxy clusters is very low compared to the number of well-studied clusters nearby. Bent, double-lobed radio sources are frequently found in galaxy clusters, and thus can be used as tracers for efficiently locating high-redshift clusters. Using our Spitzer Snapshot Survey, we have identified approximately 300 potential new clusters with redshifts 0.7redshift portion of the Cluster Occupied by Bent Radio AGN (COBRA) survey. We have created color-magnitude diagrams using infrared and optical data. Using the colors of the radio source host and the red sequence we can estimate redshifts for our clusters, as well as examine the evolution of the cluster galaxies over a large range of cosmic time.

  2. The final two redshifts for radio sources from the equatorial BRL sample

    NASA Astrophysics Data System (ADS)

    Best, P. N.; Peacock, J. A.; Brookes, M. H.; Dowsett, R. E.; Röttgering, H. J. A.; Dunlop, J. S.; Lehnert, M. D.

    2003-12-01

    Best, Röttgering & Lehnert (BRL) defined a new sample of powerful radio sources from the Molonglo Reference Catalogue, for which redshifts were compiled or measured for 177 of the 178 objects. For the final object, MRC1059-010 (3C 249), the host galaxy is identified here using near-infrared imaging, and the redshift is determined from Very Large Telescope (VLT) spectroscopy. For one other object in the sample, MRC0320+053 (4C05.14), the literature redshift has been questioned: new spectroscopic observations of this object are presented, deriving a corrected redshift. With these two results, the spectroscopic completeness of this sample is now 100 per cent. New redshifts are also presented for PKS0742+10 from the Wall & Peacock 2.7-GHz catalogue, and for PKS1336+003 from the Parkes Selected Regions. PKS0742+10 shows a strong neutral hydrogen absorption feature in its Lyman α emission profile.

  3. Spectral Evolution in High Redshift Quasars from the Final BOSS Sample

    NASA Astrophysics Data System (ADS)

    Jensen, Trey; Bautista, Julian; Dawson, Kyle; Harris, David; Kamble, Vikrant; Mariappan, Vivek; Suzuki, Nao

    2016-01-01

    We report on a study of the spectral variations in a sample of 102,150 quasars from the Baryon Oscillation Spectroscopic Survey (BOSS) of the Sloan Digital Sky Survey (SDSS-III). After mitigating selection effects and Malmquist bias over the redshift range 2.1 ≤ z ≤ 3.5, we create high signal-to-noise composite spectra binned by luminosity, spectral index, and redshift. We use these composite spectra to inspect the variations in quasar properties as a function of each of these three parameters. We confirm the traditional Baldwin effect (i.e. the anti-correlation of CIV equivalent width and luminosity) and identify physical trends associated with spectral index and redshift. In this poster, we will present these results with a particular focus on the clear spectroscopic signature that we find in redshift evolution.

  4. Narrow-band surveys for very high redshift Lyman-α emitters

    NASA Astrophysics Data System (ADS)

    Nilsson, K. K.; Orsi, A.; Lacey, C. G.; Baugh, C. M.; Thommes, E.

    2007-11-01

    Context: Many current and future surveys aim to detect the highest redshift (z ⪆ 7) sources through their Lyman-α (Lyα) emission, using the narrow-band imaging method. However, to date the surveys have only yielded non-detections and upper limits as no survey has reached the necessary combination of depth and area to detect these very young star forming galaxies. Aims: We aim to calculate model luminosity functions and mock surveys of Lyα emitters at z ⪆ 7 based on a variety of approaches calibrated and tested on observational data at lower redshifts. Methods: We calculate model luminosity functions at different redshifts based on three different approaches: a semi-analytical model based on CDM, a simple phenomenological model, and an extrapolation of observed Schechter functions at lower redshifts. The results of the first two models are compared with observations made at redshifts z ˜ 5.7 and z ˜ 6.5, and they are then extrapolated to higher redshift. Results: We present model luminosity functions for redshifts between z = 7{-}12.5 and give specific number predictions for future planned or possible narrow-band surveys for Lyα emitters. We also investigate what constraints future observations will be able to place on the Lyα luminosity function at very high redshift. Conclusions: It should be possible to observe z = 7{-}10 Lyα emitters with present or near-future instruments if enough observing time is allocated. In particular, large area surveys such as ELVIS (Emission Line galaxies with VISTA Survey) will be useful in collecting a large sample. However, to get a large enough sample to constrain well the z ≥ 10 Lyα luminosity function, instruments further in the future, such as an ELT, will be necessary.

  5. SHELS: A complete galaxy redshift survey with R ≤ 20.6

    SciTech Connect

    Geller, Margaret J.; Hwang, Ho Seong; Fabricant, Daniel G.; Kurtz, Michael J.; Dell'Antonio, Ian P.; Zahid, Harus Jabran E-mail: hhwang@cfa.harvard.edu E-mail: mkurtz@cfa.harvard.edu E-mail: jabran@ifa.hawaii.edu

    2014-08-01

    The SHELS (Smithsonian Hectospec Lensing Survey) is a complete redshift survey covering two well-separated fields (F1 and F2) of the Deep Lens Survey to a limiting R = 20.6. Here we describe the redshift survey of the F2 field (R.A.{sub 2000} = 09{sup h}19{sup m}32.4 and decl.{sub 2000} = +30°00'00''). The survey includes 16,294 new redshifts measured with the Hectospec on the MMT. The resulting survey of the 4 deg{sup 2} F2 field is 95% complete to R = 20.6, currently the densest survey to this magnitude limit. The median survey redshift is z = 0.3; the survey provides a view of structure in the range 0.1 ≲ z ≲ 0.6. An animation displays the large-scale structure in the survey region. We provide a redshift, spectral index D {sub n}4000, and stellar mass for each galaxy in the survey. We also provide a metallicity for each galaxy in the range 0.2 survey, we examine the behavior of the index D {sub n}4000 as a function of galaxy luminosity, stellar mass, and redshift. The known evolutionary and stellar mass dependent properties of the galaxy population are cleanly evident in the data. We also show that the mass-metallicity relation previously determined from these data is robust to the analysis approach.

  6. Investigating the Local and High Redshift Universe With Deep Survey Data and Ground-Based Spectroscopy

    NASA Astrophysics Data System (ADS)

    Masters, Daniel Charles

    Large multiwavelength surveys are now driving the frontiers of astronomical research. I describe results from my work using data from two large astronomical surveys: the Cosmic Evolution Survey (COSMOS), which has obtained deep photometric and spectroscopic data on two square degrees of the sky using many of the most powerful telescopes in the world, and the WFC3 Infrared Spectroscopic Parallels (WISP) Survey, which uses the highly sensitive slitless spectroscopic capability of the Hubble Space Telescope Wide Field Camera 3 to detect star-forming galaxies over most of the universe's history. First I describe my work on the evolution of the high-redshift quasar luminosity function, an important observational quantity constraining the growth of the supermassive black holes in the early universe. I show that the number density of faint quasars declines rapidly above z ˜ 3. This result is discussed in the context of cosmic reionization and the coevolution of galaxies and their central black holes. Next I present results of a multi-year campaign of near-infrared spectroscopy with FIRE, a world-class near-infrared spectrometer on the Magellan Baade 6.5 meter telescope in Chile, targeting emission-line galaxies at z ˜ 2 discovered with the Hubble Space Telescope. Our results showed that the typical emission-line galaxy at this redshift has low-metallicity, low dust obscuration, high ionization parameter, and little evidence for significant active galactic nucleus (AGN) contribution to the emission lines. We also find evidence that high redshift star-forming galaxies have enhanced nitrogen abundances. This result has interesting implications for the nature of the star formation in such galaxies -- in particular, it could mean that a large fraction of such galaxies harbor substantial populations of Wolf-Rayet stars, which are massive, evolved stars ejecting large amounts of enriched matter into the interstellar medium. Finally, I will discuss the discovery of three

  7. The TexOx-1000 redshift survey of radio sources I: the TOOT00 region

    NASA Astrophysics Data System (ADS)

    Vardoulaki, Eleni; Rawlings, Steve; Hill, Gary J.; Mauch, Tom; Inskip, Katherine J.; Riley, Julia; Brand, Kate; Croft, Steve; Willott, Chris J.

    2010-01-01

    We present optical spectroscopy, near-infrared (mostly K-band) and radio (151-MHz and 1.4-GHz) imaging of the first complete region (TOOT00) of the TexOx-1000 (TOOT) redshift survey of radio sources. The 0.0015-sr (~5 deg2) TOOT00 region is selected from pointed observations of the Cambridge Low-Frequency Survey Telescope at 151 MHz at a flux density limit of ~=100 mJy, approximately five times fainter than the 7C Redshift Survey (7CRS), and contains 47 radio sources. We have obtained 40 spectroscopic redshifts (~85 per cent completeness). Adding redshifts estimated for the seven other cases yields a median redshift zmed ~ 1.25. We find a significant population of objects with Fanaroff-Riley type I (FRI) like radio structures at radio luminosities above both the low-redshift FRI/II break and the break in the radio luminosity function. The redshift distribution and subpopulations of TOOT00 are broadly consistent with extrapolations from the 7CRS/6CE/3CRR data sets underlying the SKADS Simulated Skies Semi-Empirical Extragalactic Data base, S3-SEX.

  8. Comparing the 2MTF and 6dFGS Peculiar Velocity Surveys to models from redshift surveys

    NASA Astrophysics Data System (ADS)

    Springob, Christopher M.; Hong, Tao; Magoulas, Christina; Colless, Matthew; Staveley-Smith, Lister; Erdogdu, Pirin; Jones, D. Heath; Lucey, John R.; Masters, Karen; Mould, Jeremy R.; Jarrett, Tom; Koribalski, Baerbel; Macri, Lucas M.; Scrimgeour, Morag

    2015-01-01

    The 6dF Galaxy Survey (6dFGS) and 2MASS Tully-Fisher Survey (2MTF) are large galaxy peculiar velocity surveys of the local universe, providing distances and peculiar velocities for thousands of galaxies, derived via the Fundamental Plane and Tully-Fisher relations respectively. We compare these observed velocity fields to reconstructed peculiar velocity field models derived from redshift surveys such as the 2MASS Redshift Survey (2MRS) and the IRAS Point Source Redshift Survey (PSCz), addressing the question of whether the galaxy distribution traces the matter distribution, and whether the observed velocity fields include a "residual bulk flow" not predicted by the models. This research was conducted by the Australian Research Council Centre of Excellence for All-sky Astrophysics (CAASTRO), through project number CE110001020.

  9. Apples to apples A2 - I. Realistic galaxy simulated catalogues and photometric redshift predictions for next-generation surveys

    NASA Astrophysics Data System (ADS)

    Ascaso, B.; Mei, S.; Benítez, N.

    2015-11-01

    We present new mock catalogues for two of the largest Stage IV next-generation surveys in the optical and infrared: Large Synoptic Sky Telescope (LSST) and Euclid, based on an N-body simulation+semi-analytical cone with a posterior modification with PHOTREAL. This technique modifies the original photometry by using an empirical library of spectral templates to make it more realistic. The reliability of the catalogues is confirmed by comparing the obtained colour-magnitude relation, the luminosity and mass function and the angular correlation function with those of real data. Consistent comparisons between the expected photometric redshifts for different surveys are also provided. Very deep near-infrared surveys such as Euclid will provide very good performance (Δz/(1 + z) ˜ 0.025-0.053) down to H ˜ 24 AB mag and up to z ˜ 3 depending on the optical observations available from the ground, whereas extremely deep optical surveys such as LSST will obtain an overall lower photometric redshift resolution (Δz/(1 + z) ˜ 0.045) down to i ˜ 27.5 AB mag, being considerably improved (Δz/(1 + z) ˜ 0.035) if we restrict the sample down to i ˜ 24 AB mag. Those numbers can be substantially upgraded by selecting a subsample of galaxies with the best quality photometric redshifts. We finally discuss the impact that these surveys will have for the community in terms of photometric redshift legacy. This is the first of a series of papers where we set a framework for comparability between mock catalogues and observations with a particular focus on cluster surveys. The Euclid and LSST mocks are made publicly available.

  10. THE NEXT GENERATION VIRGO CLUSTER SURVEY. XV. THE PHOTOMETRIC REDSHIFT ESTIMATION FOR BACKGROUND SOURCES

    SciTech Connect

    Raichoor, A.; Mei, S.; Huertas-Company, M.; Licitra, R.; Erben, T.; Hildebrandt, H.; Ilbert, O.; Boissier, S.; Boselli, A.; Ball, N. M.; Côté, P.; Ferrarese, L.; Gwyn, S. D. J.; Kavelaars, J. J.; Chen, Y.-T.; Cuillandre, J.-C.; Duc, P. A.; Guhathakurta, P.; and others

    2014-12-20

    The Next Generation Virgo Cluster Survey (NGVS) is an optical imaging survey covering 104 deg{sup 2} centered on the Virgo cluster. Currently, the complete survey area has been observed in the u*giz bands and one third in the r band. We present the photometric redshift estimation for the NGVS background sources. After a dedicated data reduction, we perform accurate photometry, with special attention to precise color measurements through point-spread function homogenization. We then estimate the photometric redshifts with the Le Phare and BPZ codes. We add a new prior that extends to i {sub AB} = 12.5 mag. When using the u* griz bands, our photometric redshifts for 15.5 mag ≤ i ≲ 23 mag or z {sub phot} ≲ 1 galaxies have a bias |Δz| < 0.02, less than 5% outliers, a scatter σ{sub outl.rej.}, and an individual error on z {sub phot} that increases with magnitude (from 0.02 to 0.05 and from 0.03 to 0.10, respectively). When using the u*giz bands over the same magnitude and redshift range, the lack of the r band increases the uncertainties in the 0.3 ≲ z {sub phot} ≲ 0.8 range (–0.05 < Δz < –0.02, σ{sub outl.rej} ∼ 0.06, 10%-15% outliers, and z {sub phot.err.} ∼ 0.15). We also present a joint analysis of the photometric redshift accuracy as a function of redshift and magnitude. We assess the quality of our photometric redshifts by comparison to spectroscopic samples and by verifying that the angular auto- and cross-correlation function w(θ) of the entire NGVS photometric redshift sample across redshift bins is in agreement with the expectations.

  11. A Blind Green Bank Telescope Millimeter-wave Survey for Redshifted Molecular Absorption

    NASA Astrophysics Data System (ADS)

    Kanekar, N.; Gupta, A.; Carilli, C. L.; Stocke, J. T.; Willett, K. W.

    2014-02-01

    We present the methodology for "blind" millimeter-wave surveys for redshifted molecular absorption in the CO/HCO+ rotational lines. The frequency range 30-50 GHz appears optimal for such surveys, providing sensitivity to absorbers at z >~ 0.85. It is critical that the survey is "blind," i.e., based on a radio-selected sample, including sources without known redshifts. We also report results from the first large survey of this kind, using the Q-band receiver on the Green Bank Telescope (GBT) to search for molecular absorption toward 36 sources, 3 without known redshifts, over the frequency range 39.6-49.5 GHz. The GBT survey has a total redshift path of Δz ≈ 24, mostly at 0.81 < z < 1.91, and a sensitivity sufficient to detect equivalent H2 column densities >~ 3 × 1021 cm-2 in absorption at 5σ significance (using CO-to-H2 and HCO+-to-H2 conversion factors of the Milky Way). The survey yielded no confirmed detections of molecular absorption, yielding the 2σ upper limit n(z = 1.2) < 0.15 on the redshift number density of molecular gas at column densities N(H2) >~ 3 × 1021 cm-2.

  12. A blind green bank telescope millimeter-wave survey for redshifted molecular absorption

    SciTech Connect

    Kanekar, N.; Gupta, A.; Carilli, C. L.; Stocke, J. T.; Willett, K. W.

    2014-02-10

    We present the methodology for 'blind' millimeter-wave surveys for redshifted molecular absorption in the CO/HCO{sup +} rotational lines. The frequency range 30-50 GHz appears optimal for such surveys, providing sensitivity to absorbers at z ≳ 0.85. It is critical that the survey is 'blind', i.e., based on a radio-selected sample, including sources without known redshifts. We also report results from the first large survey of this kind, using the Q-band receiver on the Green Bank Telescope (GBT) to search for molecular absorption toward 36 sources, 3 without known redshifts, over the frequency range 39.6-49.5 GHz. The GBT survey has a total redshift path of Δz ≈ 24, mostly at 0.81 < z < 1.91, and a sensitivity sufficient to detect equivalent H{sub 2} column densities ≳ 3 × 10{sup 21} cm{sup –2} in absorption at 5σ significance (using CO-to-H{sub 2} and HCO{sup +}-to-H{sub 2} conversion factors of the Milky Way). The survey yielded no confirmed detections of molecular absorption, yielding the 2σ upper limit n(z = 1.2) < 0.15 on the redshift number density of molecular gas at column densities N(H{sub 2}) ≳ 3 × 10{sup 21} cm{sup –2}.

  13. The CfA redshift survey - Data for the NGP + 30 zone

    NASA Technical Reports Server (NTRS)

    Huchra, John P.; Geller, Margaret J.; De Lapparent, Valerie; Corwin, Harold G., Jr.

    1990-01-01

    Redshifts and morphological types are presented for a complete sample of 1093 galaxies with m(pg) less than or equal to 15.5 mag in a 6-deg-wide strip crossing the north Galactic pole. Also presented are redshifts for an additional 92 fainter galaxies in the same strip. Outside of the core of the Coma Cluster, both early- and late-type galaxies trace essentially the same structures in redshift space. Thinner slices illustrate the small velocity dispersion perpendicular to the surfaces in the survey.

  14. The Swift Gamma-Ray Burst Host Galaxy Legacy Survey. I. Sample Selection and Redshift Distribution

    NASA Astrophysics Data System (ADS)

    Perley, D. A.; Krühler, T.; Schulze, S.; de Ugarte Postigo, A.; Hjorth, J.; Berger, E.; Cenko, S. B.; Chary, R.; Cucchiara, A.; Ellis, R.; Fong, W.; Fynbo, J. P. U.; Gorosabel, J.; Greiner, J.; Jakobsson, P.; Kim, S.; Laskar, T.; Levan, A. J.; Michałowski, M. J.; Milvang-Jensen, B.; Tanvir, N. R.; Thöne, C. C.; Wiersema, K.

    2016-01-01

    We introduce the Swift Gamma-Ray Burst Host Galaxy Legacy Survey (“SHOALS”), a multi-observatory high-redshift galaxy survey targeting the largest unbiased sample of long-duration gamma-ray burst (GRB) hosts yet assembled (119 in total). We describe the motivations of the survey and the development of our selection criteria, including an assessment of the impact of various observability metrics on the success rate of afterglow-based redshift measurement. We briefly outline our host galaxy observational program, consisting of deep Spitzer/IRAC imaging of every field supplemented by similarly deep, multicolor optical/near-IR photometry, plus spectroscopy of events without preexisting redshifts. Our optimized selection cuts combined with host galaxy follow-up have so far enabled redshift measurements for 110 targets (92%) and placed upper limits on all but one of the remainder. About 20% of GRBs in the sample are heavily dust obscured, and at most 2% originate from z\\gt 5.5. Using this sample, we estimate the redshift-dependent GRB rate density, showing it to peak at z∼ 2.5 and fall by at least an order of magnitude toward low (z = 0) redshift, while declining more gradually toward high (z∼ 7) redshift. This behavior is consistent with a progenitor whose formation efficiency varies modestly over cosmic history. Our survey will permit the most detailed examination to date of the connection between the GRB host population and general star-forming galaxies, directly measure evolution in the host population over cosmic time and discern its causes, and provide new constraints on the fraction of cosmic star formation occurring in undetectable galaxies at all redshifts.

  15. THE REDSHIFT DISTRIBUTION OF GIANT ARCS IN THE SLOAN GIANT ARCS SURVEY

    SciTech Connect

    Bayliss, Matthew B.; Gladders, Michael D.; Koester, Benjamin P.; Oguri, Masamune; Hennawi, Joseph F.; Sharon, Keren; Dahle, Haakon

    2011-01-20

    We measure the redshift distribution of a sample of 28 giant arcs discovered as a part of the Sloan Giant Arcs Survey. Gemini/GMOS-North spectroscopy provides precise redshifts for 24 arcs, and 'redshift desert' constrains for the remaining 4 arcs. This is a direct measurement of the redshift distribution of a uniformly selected sample of bright giant arcs, which is an observable that can be used to inform efforts to predict giant arc statistics. Our primary giant arc sample has a median redshift z = 1.821 and nearly two-thirds of the arcs, 64%, are sources at z {approx}> 1.4, indicating that the population of background sources that are strongly lensed into bright giant arcs resides primarily at high redshift. We also analyze the distribution of redshifts for 19 secondary strongly lensed background sources that are not visually apparent in Sloan Digital Sky Survey imaging, but were identified in deeper follow-up imaging of the lensing cluster fields. Our redshift sample for the secondary sources is not spectroscopically complete, but combining it with our primary giant arc sample suggests that a large fraction of all background galaxies that are strongly lensed by foreground clusters reside at z {approx}> 1.4. Kolmogorov-Smirnov tests indicate that our well-selected, spectroscopically complete primary giant arc redshift sample can be reproduced with a model distribution that is constructed from a combination of results from studies of strong-lensing clusters in numerical simulations and observational constraints on the galaxy luminosity function.

  16. Redshift-Distance Survey of Early-Type Galaxies. I. The ENEARc Cluster Sample

    NASA Astrophysics Data System (ADS)

    Bernardi, M.; Alonso, M. V.; da Costa, L. N.; Willmer, C. N. A.; Wegner, G.; Pellegrini, P. S.; Rité, C.; Maia, M. A. G.

    2002-06-01

    This paper presents data on the ENEARc subsample of the larger ENEAR survey of nearby early-type galaxies. The ENEARc galaxies belong to clusters and were specifically chosen to be used for the construction of a Dn-σ template. The ENEARc sample includes new measurements of spectroscopic and photometric parameters (redshift, velocity dispersion, line index Mg2, and the angular diameter dn), as well as data from the literature. New spectroscopic data are given for 229 cluster early-type galaxies, and new photometry is presented for 348 objects. Repeat and overlap observations with external data sets are used to construct a final merged catalog consisting of 640 early-type galaxies in 28 clusters. Objective criteria, based on catalogs of groups of galaxies derived from complete redshift surveys of the nearby universe, are used to assign galaxies to clusters. In a companion paper, these data are used to construct the template Dn-σ distance relation for early-type galaxies, which has been used to estimate galaxy distances and derive peculiar velocities for the ENEAR all-sky sample. Based on observations at Complejo Astronomico El Leoncito, operated under agreement between the Consejo Nacional de Investigaciones Científicas de la República Argentina and the National Universities of La Plata, Córdoba, and San Juan; Cerro Tololo Inter-American Observatory, National Optical Astronomical Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under cooperative agreement with the National Science Foundation; the European Southern Observatory (ESO), partially under the ESO-ON agreement; the Fred Lawrence Whipple Observatory; the Observatório do Pico dos Dias, operated by the Laboratório Nacional de Astrofísica and the MDM Observatory at Kitt Peak.

  17. Using Gamma Regression for Photometric Redshifts of Survey Galaxies

    NASA Astrophysics Data System (ADS)

    Elliott, J.; de Souza, R. S.; Krone-Martins, A.; Cameron, E.; Ishida, E. E. O.; Hilbe, J.

    Machine learning techniques offer a plethora of opportunities in tackling big data within the astronomical community. We present the set of Generalized Linear Models as a fast alternative for determining photometric redshifts of galaxies, a set of tools not commonly applied within astronomy, despite being widely used in other professions. With this technique, we achieve catastrophic outlier rates of the order of ˜ 1%, that can be achieved in a matter of seconds on large datasets of size ˜ 1,000,000. To make these techniques easily accessible to the astronomical community, we developed a set of libraries and tools that are publicly available.

  18. TESTING WEAK-LENSING MAPS WITH REDSHIFT SURVEYS: A SUBARU FIELD

    SciTech Connect

    Kurtz, Michael J.; Geller, Margaret J.; Fabricant, Daniel G.; Utsumi, Yousuke; Miyazaki, Satoshi; Dell'Antonio, Ian P. E-mail: mgeller@cfa.harvard.edu E-mail: yousuke.utsumi@nao.ac.jp E-mail: ian@het.brown.edu

    2012-05-10

    We use a dense redshift survey in the foreground of the Subaru GTO2deg{sup 2} weak-lensing field (centered at {alpha}{sub 2000} = 16{sup h}04{sup m}44{sup s}; {delta}{sub 2000} = 43 Degree-Sign 11'24'') to assess the completeness and comment on the purity of massive halo identification in the weak-lensing map. The redshift survey (published here) includes 4541 galaxies; 4405 are new redshifts measured with the Hectospec on the MMT. Among the weak-lensing peaks with a signal-to-noise greater than 4.25, 2/3 correspond to individual massive systems; this result is essentially identical to the Geller et al. test of the Deep Lens Survey (DLS) field F2. The Subaru map, based on images in substantially better seeing than the DLS, enables detection of less massive halos at fixed redshift as expected. We demonstrate that the procedure adopted by Miyazaki et al. for removing some contaminated peaks from the weak-lensing map improves agreement between the lensing map and the redshift survey in the identification of candidate massive systems.

  19. THE MICRO-ARCSECOND SCINTILLATION-INDUCED VARIABILITY (MASIV) SURVEY. III. OPTICAL IDENTIFICATIONS AND NEW REDSHIFTS

    SciTech Connect

    Pursimo, Tapio; Ojha, Roopesh; Rickett, Barney J.; Dutka, Michael S.; Koay, Jun Yi; Bignall, Hayley E.; Macquart, Jean-Pierre; Lovell, James E. J.; Kedziora-Chudczer, Lucyna

    2013-04-10

    Intraday variability (IDV) of the radio emission from active galactic nuclei is now known to be predominantly due to interstellar scintillation (ISS). The MASIV (The Micro-Arcsecond Scintillation-Induced Variability) survey of 443 flat spectrum sources revealed that the IDV is related to the radio flux density and redshift. A study of the physical properties of these sources has been severely handicapped by the absence of reliable redshift measurements for many of these objects. This paper presents 79 new redshifts and a critical evaluation of 233 redshifts obtained from the literature. We classify spectroscopic identifications based on emission line properties, finding that 78% of the sources have broad emission lines and are mainly FSRQs. About 16% are weak lined objects, chiefly BL Lacs, and the remaining 6% are narrow line objects. The gross properties (redshift, spectroscopic class) of the MASIV sample are similar to those of other blazar surveys. However, the extreme compactness implied by ISS favors FSRQs and BL Lacs in the MASIV sample as these are the most compact object classes. We confirm that the level of IDV depends on the 5 GHz flux density for all optical spectral types. We find that BL Lac objects tend to be more variable than broad line quasars. The level of ISS decreases substantially above a redshift of about two. The decrease is found to be generally consistent with ISS expected for beamed emission from a jet that is limited to a fixed maximum brightness temperature in the source rest frame.

  20. The Micro-Arcsecond Scintillation-Induced Variability (MASIV) Survey III. Optical Identifications and New Redshifts

    NASA Technical Reports Server (NTRS)

    Pursimo, Tapio; Ojha, Roopesh; Jauncey, David L.; Rickett, Barney J.; Dutka, Michael S.; Koay, Jun Yi; Lovell, James E. J.; Bignall, Hayley E.; Kedziora-Chudczer, Lucyna; Macquart, Jean-Pierre

    2013-01-01

    Intraday variability (IDV) of the radio emission from active galactic nuclei is now known to be predominantly due to interstellar scintillation (ISS). The MASIV (The Microarcsecond Scintillation Induced Variability) survey of 443 at spectrum sources revealed that the IDV is related to the radio flux density and redshift. A study of the physical properties of these sources has been severely handicapped by the absence of reliable redshift measurements for many of these objects. This paper presents 79 new redshifts and a critical evaluation of 233 redshifts obtained from the literature. We classify spectroscopic identifications based on emission line properties, finding that 78% of the sources have broad emission lines and are mainly FSRQs. About 16% are weak lined objects, chiefly BL Lacs, and the remaining 6% are narrow line objects. The gross properties (redshift, spectroscopic class) of the MASIV sample are similar to those of other blazar surveys. However, the extreme compactness implied by ISS favors FSRQs and BL Lacs in the MASIV sample as these are the most compact object classes. We confirm that the level of IDV depends on the 5 GHz flux density for all optical spectral types. We find that BL Lac objects tend to be more variable than broad line quasars. The level of ISS decreases substantially above a redshift of about two. The decrease is found to be generally consistent with ISS expected for beamed emission from a jet that is limited to a fixed maximum brightness temperature in the source rest frame.

  1. Tests of redshift-space distortions models in configuration space for the analysis of the BOSS final data release

    NASA Astrophysics Data System (ADS)

    White, Martin; Reid, Beth; Chuang, Chia-Hsun; Tinker, Jeremy L.; McBride, Cameron K.; Prada, Francisco; Samushia, Lado

    2015-02-01

    Observations of redshift-space distortions in spectroscopic galaxy surveys offer an attractive method for observing the build-up of cosmological structure, which depends both on the expansion rate of the Universe and our theory of gravity. In preparation for analysis of redshift-space distortions from the Baryon Oscillation Spectroscopic Survey (BOSS) final data release, we compare a number of analytic and phenomenological models, specified in configuration space, to mock catalogues derived in different ways from several N-body simulations. The galaxies in each mock catalogue have properties similar to those of the higher redshift galaxies measured by BOSS but differ in the details of how small-scale velocities and halo occupancy are determined. We find that all of the analytic models fit the simulations over a limited range of scales while failing at small scales. We discuss which models are most robust and on which scales they return reliable estimates of the rate of growth of structure: we find that models based on some form of resummation can fit our N-body data for BOSS-like galaxies above 30 h-1 Mpc well enough to return unbiased parameter estimates.

  2. A Systematic Meta-Survey of High Redshift Quasars Probing their Environments and Evolution

    NASA Astrophysics Data System (ADS)

    Gobeille, Doug B. P.

    We have constructed a meta-survey of 298 quasars in the window from 7 to 17.5 hours in right ascension and 0 to 65 degrees in declination. These quasars span three decades of total power and redshifts from 0.158 to 5.284. All sources had a flux density of greater than 70 mJy at 1.4 GHz. At redshifts z > 2.5 our sample is complete. It is also complete for z < 1 and P Tot1:4 > 1027.55 W/Hz. Our quasar sample is built from archival Very Large Array (VLA) observations, as well as three observations in 2007 and 2008. This sample represents one of the most complete meta-surveys to date of the high redshift universe. In the 1980's, two competing groups (Ne, Gower and Hutchings, and Barthel, Miley, and Lonsdale) investigated the high redshift universe, seeking to investigate the dependence of largest linear size (LLS) and bending angles on redshift, core power, and extended power. Using our sample we test the differing results of these groups and build our own model of source evolution with redshift and power. We also seek a relationship between bending angles and core dominance, modeling this dependence on the thoughts of Orr & Browne showing that projected bending angles grow as the angle to the line of sight approaches the intrinsic bending angle of the quasar. We will also present an additional component of our high redshift quasar observations seeking arcsecond scale jets to be observed with the space based Chandra x-ray telescope. These observations will be used to investigate the nature of x-ray emission from the knots of kiloparsec jets in the high redshift universe.

  3. The VLT LBG Redshift Survey - I. Clustering and dynamics of ≈1000 galaxies at z≈ 3

    NASA Astrophysics Data System (ADS)

    Bielby, R. M.; Shanks, T.; Weilbacher, P. M.; Infante, L.; Crighton, N. H. M.; Bornancini, C.; Bouché, N.; Héraudeau, P.; Lambas, D. G.; Lowenthal, J.; Minniti, D.; Padilla, N.; Petitjean, P.; Theuns, T.

    2011-06-01

    We present the initial imaging and spectroscopic data acquired as part of the Very Large Telescope (VLT) VIMOS Lyman-break galaxy Survey. UBR (or UBVI) imaging covers five ≈36 × 36 arcmin2 fields centred on bright z > 3 quasi-stellar objects (QSOs), allowing ≈21 000 2 < z < 3.5 galaxy candidates to be selected using the Lyman-break technique. We performed spectroscopic follow-up using VLT VIMOS, measuring redshifts for 1020 z > 2 Lyman-break galaxies and 10 z > 2 QSOs from a total of 19 VIMOS pointings. From the galaxy spectra, we observe a 625 ± 510 km s-1 velocity offset between the interstellar absorption and Lyman α emission-line redshifts, consistent with previous results. Using the photometric and spectroscopic catalogues, we have analysed the galaxy clustering at z≈ 3. The angular correlation function, w(θ), is well fitted by a double power law with clustering scalelength, r0= 3.19+0.32-0.54 h-1 Mpc and slope γ= 2.45 for r < 1 h-1 Mpc and r0= 4.37+0.43-0.55 h-1 Mpc with γ= 1.61 ± 0.15 at larger scales. Using the redshift sample we estimate the semiprojected correlation function, wp(σ), and, for a γ= 1.8 power law, find r0= 3.67+0.23-0.24 h-1 Mpc for the VLT sample and r0= 3.98+0.14-0.15 h-1 Mpc for a combined VLT+Keck sample. From ξ(s) and ξ(σ, π), and assuming the above ξ(r) models, we find that the combined VLT and Keck surveys require a galaxy pairwise velocity dispersion of ≈700 km s-1, higher than ≈400 km s-1 assumed by previous authors. We also measure a value for the gravitational growth rate parameter of β(z= 3) = 0.48 ± 0.17, again higher than that previously found and implying a low value for the bias of b= 2.06+1.1-0.5. This value is consistent with the galaxy clustering amplitude which gives b= 2.22 ± 0.16, assuming the standard cosmology, implying that the evolution of the gravitational growth rate is also consistent with Einstein gravity. Finally, we have compared our Lyman-break galaxy clustering amplitudes with

  4. Photometric Redshifts for the Dark Energy Survey and VISTA and Implications for Large Scale Structure

    SciTech Connect

    Banerji, Manda; Abdalla, Filipe B.; Lahav, Ofer; Lin, Huan; /Fermilab

    2007-11-01

    We conduct a detailed analysis of the photometric redshift requirements for the proposed Dark Energy Survey (DES) using two sets of mock galaxy simulations and an artificial neural network code-ANNz. In particular, we examine how optical photometry in the DES grizY bands can be complemented with near infra-red photometry from the planned VISTA Hemisphere Survey (VHS) in the JHK{sub s} bands in order to improve the photometric redshift estimate by a factor of two at z > 1. We draw attention to the effects of galaxy formation scenarios such as reddening on the photo-z estimate and using our neural network code, calculate A{sub v} for these reddened galaxies. We also look at the impact of using different training sets when calculating photometric redshifts. In particular, we find that using the ongoing DEEP2 and VVDS-Deep spectroscopic surveys to calibrate photometric redshifts for DES, will prove effective. However we need to be aware of uncertainties in the photometric redshift bias that arise when using different training sets as these will translate into errors in the dark energy equation of state parameter, w. Furthermore, we show that the neural network error estimate on the photometric redshift may be used to remove outliers from our samples before any kind of cosmological analysis, in particular for large-scale structure experiments. By removing all galaxies with a 1{sigma} photo-z scatter greater than 0.1 from our DES+VHS sample, we can constrain the galaxy power spectrum out to a redshift of 2 and reduce the fractional error on this power spectrum by {approx}15-20% compared to using the entire catalogue.

  5. A sparse-sampling strategy for the estimation of large-scale clustering from redshift surveys

    NASA Astrophysics Data System (ADS)

    Kaiser, N.

    1986-04-01

    It is shown that a fractional faint-magnitude limited redshift survey can significantly reduce the uncertainty in the two-point function for a given telescope time investment, in the estimation of large scale clustering. The signal-to-noise ratio for a 1-in-20 bright galaxy sample is roughly twice that provided by a same-cost complete survey, and this performance is the same as for a larger complete survey of about seven times the cost. A similar performance increase is achieved with a wide-field telescope multiple redshift collection from a close to full sky coverage survey. Little performance improvement is seen for smaller multiply collected surveys ideally sampled at a 1-in-10 bright galaxy rate. The optimum sampling fraction for Abell's rich clusters is found to be close to unity, with little sparse sampling performance improvement.

  6. CLUSTER LENSING PROFILES DERIVED FROM A REDSHIFT ENHANCEMENT OF MAGNIFIED BOSS-SURVEY GALAXIES

    SciTech Connect

    Coupon, Jean; Umetsu, Keiichi; Broadhurst, Tom

    2013-07-20

    We report the first detection of a redshift-depth enhancement of background galaxies magnified by foreground clusters. Using 300,000 BOSS survey galaxies with accurate spectroscopic redshifts, we measure their mean redshift depth behind four large samples of optically selected clusters from the Sloan Digital Sky Survey (SDSS) surveys, totaling 5000-15,000 clusters. A clear trend of increasing mean redshift toward the cluster centers is found, averaged over each of the four cluster samples. In addition, we find similar but noisier behavior for an independent X-ray sample of 158 clusters lying in the foreground of the current BOSS sky area. By adopting the mass-richness relationships appropriate for each survey, we compare our results with theoretical predictions for each of the four SDSS cluster catalogs. The radial form of this redshift enhancement is well fitted by a richness-to-mass weighted composite Navarro-Frenk-White profile with an effective mass ranging between M{sub 200} {approx} 1.4-1.8 Multiplication-Sign 10{sup 14} M{sub Sun} for the optically detected cluster samples, and M{sub 200} {approx} 5.0 Multiplication-Sign 10{sup 14} M{sub Sun} for the X-ray sample. This lensing detection helps to establish the credibility of these SDSS cluster surveys, and provides a normalization for their respective mass-richness relations. In the context of the upcoming bigBOSS, Subaru Prime Focus Spectrograph, and EUCLID-NISP spectroscopic surveys, this method represents an independent means of deriving the masses of cluster samples for examining the cosmological evolution, and provides a relatively clean consistency check of weak-lensing measurements, free from the systematic limitations of shear calibration.

  7. The VIPERS Multi-Lambda Survey. I. UV and near-IR observations, multi-colour catalogues, and photometric redshifts

    NASA Astrophysics Data System (ADS)

    Moutard, T.; Arnouts, S.; Ilbert, O.; Coupon, J.; Hudelot, P.; Vibert, D.; Comte, V.; Conseil, S.; Davidzon, I.; Guzzo, L.; Llebaria, A.; Martin, C.; McCracken, H. J.; Milliard, B.; Morrison, G.; Schiminovich, D.; Treyer, M.; Van Werbaeke, L.

    2016-05-01

    We present observations collected in the CFHTLS-VIPERS region in the ultraviolet with the GALEX satellite (far- and near-ultraviolet channels) and in the near-infrared with the CFHT/WIRCam camera (Ks band) over an area of 22 and 27 deg2, respectively. The depth of the photometry was optimised to measure the physical properties (e.g., star formation rate, stellar masses) of all the galaxies in the VIPERS spectroscopic survey. The large volume explored by VIPERS will enable a unique investigation of the relationship between the galaxy properties and their environment (density field and cosmic web) at high redshift (0.5 ≤ z ≤ 1.2). In this paper, we present the observations, the data reductions, and the build-up of the multi-colour catalogues. The CFHTLS-T0007 (gri-χ2) images are used as reference to detect and measure the Ks-band photometry, while the T0007 u∗-selected sources are used as priors to perform the GALEX photometry based on a dedicated software (EMphot). Our final sample reaches NUVAB ~ 25 (at 5σ) and KAB ~ 22 (at 3σ). The large spectroscopic sample (~51 000 spectroscopic redshifts) allows us to highlight the robustness of our star/galaxy separation and the reliability of our photometric redshifts with a typical accuracy of σz ≤ 0.04 and a fraction of catastrophic failures η ≤ 2% down to i ~ 23. We present various tests on the Ks-band completeness and photometric redshift accuracy by comparing our results with existing overlapping deep photometric catalogues. Finally, we discuss the BzK sample of passive and active galaxies at high redshift and the evolution of galaxy morphology in the (NUV-r) vs. (r-Ks) diagram at low redshift (z ≤ 0.25) based on the high image quality of the CFHTLS. The catalogue is available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/590/A102The images, catalogues, and photometric redshifts for 1.5 million sources (down to NUV

  8. The DEEP Groth Strip Survey. VIII. The Evolution of Luminous Field Bulges at Redshift z ~ 1

    NASA Astrophysics Data System (ADS)

    Koo, David C.; Simard, Luc; Willmer, Christopher N. A.; Gebhardt, Karl; Bouwens, Rychard J.; Kauffmann, Guinevere; Crosby, Timothy; Faber, S. M.; Harker, Justin; Sarajedini, Vicki L.; Vogt, Nicole P.; Weiner, Benjamin J.; Phillips, Andrew J.; Im, Myungshin; Wu, K. L.

    2005-04-01

    We present a candidate sample of luminous bulges (including ellipticals) found within the Groth Strip Survey (GSS), with spectroscopic redshifts of 0.73redshift z~0.8 are nearly as red (U-B~0.50) as local E/S0s. Almost all (90%) of these very red bulges reside in galaxies with the morphologies of normal early-type or spiral galaxies. Moreover, the slope of the color-luminosity relation is shallow (-0.04+/-0.04) and the intrinsic U-B color dispersion is small (σ<~0.03 mag), suggesting roughly coeval formation. All three results are similar to that seen among early-type cluster galaxies at the same epoch. Yet we also measured ~1 mag increase in surface brightness. Since simple passive evolution of a single-burst stellar population results in redder colors as the galaxy fades, the observed constancy of very red colors at high redshift suggests more complex histories. One alternative starts with a metal-rich (twice solar), early-formation (z~1.5-2.0) population that is later polluted with small amounts (~4% by total mass) of star formation over an extended period of several Gyr. This ``drizzling'' history is supported by our finding spectroscopic evidence for continued star formation ([O II] emission lines) among 80% of luminous high-redshift

  9. Redshifts for a sample of fainter galaxies in the first CfA survey slice

    SciTech Connect

    Thorstensen, J.R.; Wegner, G.A.; Hamwey, R.; Boley, F.; Geller, M.J. Harvard-Smithsonian Center for Astrophysics, Cambridge, MA )

    1989-10-01

    Redshifts were measured for 93 of the 94 galaxies in the Zwicky-Nilson merged catalog with the value of m(B/01) between 15.5 and 15.7 and with right ascension alpha between 8(h) and 17(h) and declination delta between 29 and 30 deg. This region is within the one covered by the first slice of the CfA (Center for Astrophysics) survey. The galaxies reinforce features already visible in the earlier survey. 19 refs.

  10. Redshifts for a sample of fainter galaxies in the first CfA survey slice

    NASA Technical Reports Server (NTRS)

    Thorstensen, J. R.; Wegner, G. A.; Hamwey, R.; Boley, F.; Geller, M. J.

    1989-01-01

    Redshifts were measured for 93 of the 94 galaxies in the Zwicky-Nilson merged catalog with the value of m(B/01) between 15.5 and 15.7 and with right ascension alpha between 8(h) and 17(h) and declination delta between 29 and 30 deg. This region is within the one covered by the first slice of the CfA (Center for Astrophysics) survey. The galaxies reinforce features already visible in the earlier survey.

  11. Spectroscopic CCD surveys for quasars at large redshift. I - A deep PFUEI survey. [Prime Focus Universal Extragalactic Instrument

    NASA Technical Reports Server (NTRS)

    Schmidt, M.; Schneider, D. P.; Gunn, J. E.

    1986-01-01

    A survey for faint quasars has been conducted using slitless spectroscopy with the PFUEI at the 200 inch (5 m) telescope. The survey covers a total of 0.91 sq deg in 113 fields at galactic latitudes above 30 deg. Calibrated spectra in the range 4500-7200 A were obtained for more than 9000 objects. Emission-line candidates were selected on the basis of two criteria: the equivalent width must exceed 50 A, and the signal-to-noise ratio of the detection of the line versus the sky background should be larger than 7. Among 45 candidates so selected, subsequent slit spectroscopy confirmed 27 emission-line objects. Among these, 17 are emission-line galaxies with redshifts in the range 0.04-0.31, and 10 are quasars with redshifts between 0.91 and 2.66. The well-defined selection criteria for these objects, together with the distribution of rest frame equivalent widths of the emission lines, allow derivation of the area of sky covered as a function of the continuum limiting magnitude. The observed number of quasars in the redshift range 0.7-2.7 agrees well with that predicted by the luminosity function models published by Schmidt and Green in 1983. It is concluded that quasars with an absolute magnitude of M(B) = -25 suffer a redshift cutoff near or below a redshift of 3.

  12. The Herschel Multi-Tiered Extragalactic Survey: SPIRE-mm Photometric Redshifts

    NASA Technical Reports Server (NTRS)

    Roseboom, I. G.; Ivison, R. J.; Greve, T. R.; Amblard, A.; Arumugam, V.; Auld, R.; Aussel, H.; Bethermin, M.; Blain, A.; Block, J.; Boselli, A.; Brisbin, D.; Buat, V.; Burgarella, D.; Castro-Rodriquez, N.; Cava, A.; Chanial, P.; Chapin, E.; Chapman, S.; Clements, D. L.; Conley, A.; Conversi, L.; Dowell, C. D.; Dunlop, J. S.; Dwek, E.

    2012-01-01

    We investigate the potential of submm-mm and submm-mm-radio photometric redshifts using a sample of mm-selected sources as seen at 250, 350 and 500 micron by the SPIRE instrument on Herschel. From a sample of 63 previously identified mm sources with reliable radio identifications in the Great Observatories Origins Deep Survey North and Lockman Hole North fields, 46 (73 per cent) are found to have detections in at least one SPIRE band. We explore the observed submm/mm color evolution with redshift, finding that the colors of mm sources are adequately described by a modified blackbody with constant optical depth Tau = (Nu/nu(sub 0))(exp Beta), where Beta = +1.8 and nu(sub 0) = c/100 micron. We find a tight correlation between dust temperature and IR luminosity. Using a single model of the dust temperature and IR luminosity relation, we derive photometric redshift estimates for the 46 SPIRE-detected mm sources. Testing against the 22 sources with known spectroscopic or good quality optical/near-IR photometric redshifts, we find submm/mm photometric redshifts offer a redshift accuracy of (absolute value of Delta sub (z))/(1 + z) = 0.16 (absolute value of Delta sub (z)) = 0.51). Including constraints from the radio-far-IR correlation, the accuracy is improved to (absolute value of Delta sub (z))/(1 + z) = 0.14 (((absolute value of Delta sub (z))) = 0.45). We estimate the redshift distribution of mm-selected sources finding a significant excess at Z > 3 when compared to approx 8S0 micron selected samples.

  13. Tests of smoothing methods for topological study of galaxy redshift surveys

    NASA Technical Reports Server (NTRS)

    Melott, Adrian L.; Dominik, Kurt G.

    1993-01-01

    Studying the topology of large-scale structure as a way to better understand initial conditions has become more widespread in recent years. Studying topology of simulations (which have periodic boundary conditions) in redshift space produces results compatible with the real topological characteristics of the simulation. Thus we expect we can extract useful information from redshift surveys. However, with nonperiodic boundary conditions, the use of smoothing must result in the loss of information at survey boundaries. In this paper, we test different methods of smoothing samples with nonperiodic boundary conditions to see which most efficiently preserves the topological features of the real distribution. We find that a smoothing method which (unlike most previous published analysis) sums only over cells inside the survey volume produces the best results among the schemes tested.

  14. The luminosity function for different morphological types in the CfA Redshift Survey

    NASA Technical Reports Server (NTRS)

    Marzke, Ronald O.; Geller, Margaret J.; Huchra, John P.; Corwin, Harold G., Jr.

    1994-01-01

    We derive the luminosity function for different morphological types in the original CfA Redshift Survey (CfA1) and in the first two slices of the CfA Redshift Survey Extension (CfA2). CfA1 is a complete sample containing 2397 galaxies distributed over 2.7 steradians with m(sub z) less than or equal 14.5. The first two complete slices of CfA2 contain 1862 galaxies distributed over 0.42 steradians with m(sub z)=15.5. The shapes of the E-S0 and spiral luminosity functions (LF) are indistinguishable. We do not confirm the steeply decreasing faint end in the E-S0 luminosity function found by Loveday et al. for an independent sample in the southern hemisphere. We demonstrate that incomplete classification in deep redshift surveys can lead to underestimates of the faint end of the elliptical luminosity function and could be partially responsible for the difference between the CfA survey and other local field surveys. The faint end of the LF for the Magellanic spirals and irregulars is very steep. The Sm-Im luminosity function is well fit by a Schechter function with M*=-18.79, alpha=-1.87, and phi*=0.6x10(exp -3) for M(sub z) less than or equal to -13. These galaxies are largely responsible for the excess at the faint end of the general CfA luminosity function. The abundance of intrinsically faint, blue galaxies nearby affects the interpretation of deep number counts. The dwarf population increases the expected counts at B=25 in a no-evolution, q(sub 0)=0.05 model by a factor of two over standard no-evolution estimates. These dwarfs change the expected median redshift in deep redshift surveys by less than 10 percent . Thus the steep Sm-Im LF may contribute to the reconciliation of deep number counts with deep redshift surveys.

  15. Five New High-Redshift Quasar Lenses from the Sloan Digital Sky Survey

    SciTech Connect

    Inada, Naohisa; Oguri, Masamune; Shin, Min-Su; Kayo, Issha; Strauss, Michael A.; Morokuma, Tomoki; Schneider, Donald P.; Becker, Robert H.; Bahcall, Neta A.; York, Donald G.

    2008-09-08

    We report the discovery of five gravitationally lensed quasars from the Sloan Digital Sky Survey (SDSS). All five systems are selected as two-image lensed quasar candidates from a sample of high-redshift (z > 2.2) SDSS quasars. We confirmed their lensing nature with additional imaging and spectroscopic observations. The new systems are SDSS J0819+5356 (source redshift z{sub s} = 2.237, lens redshift z{sub l} = 0.294, and image separation {theta} = 4.04 inch), SDSS J1254+2235 (z{sub s} = 3.626, {theta} = 1.56 inch), SDSS J1258+1657 (z{sub s} = 2.702, {theta} = 1.28 inch), SDSS J1339+1310 (z{sub s} = 2.243, {theta} = 1.69 cin), and SDSS J1400+3134 (z{sub s} = 3.317, {theta} = 1.74 inch). We estimate the lens redshifts of the latter four systems to be z{sub l} = 0.4-0.6 from the colors and magnitudes of the lensing galaxies. We find that the image configurations of all systems are well reproduced by standard mass models. Although these lenses will not be included in our statistical sample of z{sub s} < 2.2 lenses, they expand the number of lensed quasars which can be used for high-redshift galaxy and quasar studies.

  16. Deep 2mm Surveys with GISMO : Searching for submillimeter galaxies at the highest redshifts

    NASA Astrophysics Data System (ADS)

    Staguhn, Johannes Gunter; Kovacs, Attila; Karim, Alexander; Arendt, Richard; Benford, Dominic J.; Decarli, Roberto; Dwek, Eli; Fixsen, Dale; Gene, Hilton; Irwin, Kent; Moseley, S. Harvey; Sharp, Elmer; Walter, Fabian; Edward, Wollack

    2015-08-01

    The GISMO 2 mm camera at the IRAM 30m telescope has been available to the astronomical community for years through the semi-annual IRAM call for proposals. The 2 mm band is in particular well suited to trace the first dusty galaxies in the universe, since their redshifted SEDs peak close to GISMO's observing frequency, whereas the medium redshift galaxy foreground is almost invisible in this band. This effect makes GISMO's deep field observations a valuable complement, rather than a redundancy, to the HERSCHEL far-infrared and sub-mm surveys. Two survey projects aiming at obtaining 2mm galaxy number counts are at the core of GISMO’s science. Simple models predict an appreciable number of galaxies detected in these surveys to be be at very high redshifts (z~5-6 and above) with intrinsic luminosities of a few 10^12 L_sol.The first of these projects is the GISMO Deep Field (GDF) survey, which is centered on the Hubble Deep Field North. This survey by now has reached the confusion limit (we measure a confusion noise of 60 microJy). Our detailed statistical analysis of the GDF data provides a solid estimate of the expected rate of false detections among those source identifications. Furthermore, numerical simulations were used, to estimate the "completeness" of our set of extracted sources. A comparison of our observations with model predictions shows that our results are in good agreement with galaxy count models.The second survey covers a ~ 1/4 square degree region in the COSMOS field, in which by now we have obtained sufficient sensitivity to extract statistically relevant galaxy number counts, and by using auxiliary data, redshift distributions. We will present first results that complement those obtained in the deeper GDF.

  17. CFHTLenS and RCSLenS: Testing Photometric Redshift Distributions Using Angular Cross-Correlations with Spectroscopic Galaxy Surveys

    NASA Astrophysics Data System (ADS)

    Choi, A.; Heymans, C.; Blake, C.; Hildebrandt, H.; Duncan, C. A. J.; Erben, T.; Nakajima, R.; Van Waerbeke, L.; Viola, M.

    2016-09-01

    We determine the accuracy of galaxy redshift distributions as estimated from photometric redshift probability distributions p(z). Our method utilises measurements of the angular cross-correlation between photometric galaxies and an overlapping sample of galaxies with spectroscopic redshifts. We describe the redshift leakage from a galaxy photometric redshift bin j into a spectroscopic redshift bin i using the sum of the p(z) for the galaxies residing in bin j. We can then predict the angular cross-correlation between photometric and spectroscopic galaxies due to intrinsic galaxy clustering when i ≠ j as a function of the measured angular cross-correlation when i = j. We also account for enhanced clustering arising from lensing magnification using a halo model. The comparison of this prediction with the measured signal provides a consistency check on the validity of using the summed p(z) to determine galaxy redshift distributions in cosmological analyses, as advocated by the Canada-France-Hawaii Telescope Lensing Survey (CFHTLenS). We present an analysis of the photometric redshifts measured by CFHTLenS, which overlaps the Baryon Oscillation Spectroscopic Survey (BOSS). We also analyse the Red-sequence Cluster Lensing Survey (RCSLenS), which overlaps both BOSS and the WiggleZ Dark Energy Survey. We find that the summed p(z) from both surveys are generally biased with respect to the true underlying distributions. If unaccounted for, this bias would lead to errors in cosmological parameter estimation from CFHTLenS by less than ˜4%. For photometric redshift bins which spatially overlap in 3-D with our spectroscopic sample, we determine redshift bias corrections which can be used in future cosmological analyses that rely on accurate galaxy redshift distributions.

  18. The luminosity function of the CfA Redshift Survey

    NASA Technical Reports Server (NTRS)

    Marzke, R. O.; Huchra, J. P.; Geller, M. J.

    1994-01-01

    We use the CfA Reshift Survey of galaxies with m(sub z) less than or equal to 15.5 to calculate the galaxy luminosity function over the range -13 less than or equal to M(sub z) less than or equal to -22. The sample includes 9063 galaxies distributed over 2.1 sr. For galaxies with velocities cz greater or equal to 2500 km per sec, where the effects of peculiar velocities are small, the luminosity function is well represented by a Schechter function with parameters phi(sub star) = 0.04 +/- 0.01 per cu Mpc, M(sub star) = -18.8 +/- 0.3, and alpha = -1.0 +/- 0.2. When we include all galaxies with cz greater or equal to 500 km per sec, the number of galaxies in the range -16 less than or equal to M(sub z) less than or equal to -13 exceeds the extrapolation of the Schechter function by a factor of 3.1 +/- 0.5. This faint-end excess is not caused by the local peculiar velocity field but may be partially explained by small scale errors in the Zwicky magnitudes. Even with a scale error as large as 0.2 mag per mag, which is unlikely, the excess is still a factor of 1.8 +/- 0.3. If real, this excess affects the interpretation of deep counts of field galaxies.

  19. High-Redshift Clusters form NVSS: The TexOx Cluster (TOC) Survey

    SciTech Connect

    Croft, S; Rawlings, S; Hill, G J

    2003-02-11

    The TexOx Cluster (TOC) Survey uses overdensities of radiosources in the NVSS to trace clusters of galaxies. The links between radiosources and rich environments make this a powerful way to find clusters which may potentially be overlooked by other selection techniques. By including constraints from optical surveys, TOC is an extremely efficient way to find clusters at high redshift. One such field, TOC J0233.3+3021, contains at least one galaxy cluster (at z {approx} 1.4) and has been detected using the Sunyaev-Zel'dovich (SZ) effect. Even in targeted deep optical observations, however, distinguishing the cluster galaxies from the background is difficult, especially given the tendency of TOC to select fields containing multiple structures at different redshifts.

  20. Probabilistic Selection of High-redshift Quasars with Subaru/Hyper Suprime-Cam Survey

    NASA Astrophysics Data System (ADS)

    Onoue, Masafusa

    High-redshift quasars are an important probe of the distant Universe. They enable observational studies of the early growth of supermassive blackholes, cosmic reionization, chemical enrichment of host galaxies, and so on. Through pioneering optical and near-infrared wide-area surveys such as the SDSS and the VIKING Survey, about one hundred quasars have been found at z > 6 (e.g., Fan et al. (2006b), Venemans et al. (2013)). However, its current small sample size and the fact that most of them are the most luminous (M 1450 <~ -24) population in this epoch prevents one from constraining statistics on high-redshift quasars, namely quasar luminosity function (QLF), and redshift evolution of IGM neutral fraction. Thus, discovery of large number of z > 6 quasars, especially low-luminous or z > 7 quasars, is highly desired for further understanding of the early universe. We are now starting a new ground-breaking survey of high-redshift (z > 6) quasars using the exquisite imaging data provided by the Hyper Suprime-Cam (HSC) Subaru Strategic Program (SSP) Survey. Thanks to its extremely wide coverage and its high sensitivity thorough five optical bands (1,400 deg2 to the depth of r ~ 26 in HSC-Wide layer), it is one of the most powerful contemporary surveys that makes it possible for us to increase the number of z > 6 quasars by almost an order of magnitude, i.e., 300 at z ~ 6 and 50 at z ~ 7, based on the current estimate of the QLF at z > 6 by Willott et al. (2010b). One of the biggest challenges in z > 6 quasar candidate selection is contamination of Galactic brown dwarfs, which have the same point-like appearance as and similarly red colors to the quasars. To overcome this issue and maximize the selection efficiency, we apply a double-layered approach to the HSC survey products, namely combination of two probabilistic selections: SED-fitting and Bayesian selection. In particular, we have developed a template SED fitting method optimized to high-redshift quasars

  1. Large-scale clustering of galaxies in the CfA Redshift Survey

    NASA Technical Reports Server (NTRS)

    Vogeley, Michael S.; Park, Changbom; Geller, Margaret J.; Huchra, John P.

    1992-01-01

    The power spectrum of the galaxy distribution in the Center for Astrophysics Redshift Survey (de Lapparent et al., 1986; Geller and Huchra, 1989; and Huchra et al., 1992) is measured up to wavelengths of 200/h Mpc. Results are compared with several cosmological simulations with Gaussian initial conditions. It is shown that the power spectrum of the standard CDM model is inconsistent with the observed power spectrum at the 99 percent confidence level.

  2. THE POPULATION OF HIGH-REDSHIFT ACTIVE GALACTIC NUCLEI IN THE CHANDRA-COSMOS SURVEY

    SciTech Connect

    Civano, F.; Elvis, M.; Hao, H.; Brusa, M.; Comastri, A.; Zamorani, G.; Gilli, R.; Mignoli, M.; Salvato, M.; Capak, P.; Kakazu, Y.; Masters, D.; Fiore, F.; Ikeda, H.; Kartaltepe, J. S.; Miyaji, T.; Puccetti, S.; Shankar, F.; Silverman, J.; Vignali, C.

    2011-11-10

    We present the high-redshift (3 Survey. The sample comprises 81 X-ray-detected sources with available spectroscopic (31) and photometric (50) redshifts plus 20 sources with a formal z{sub phot} < 3 but with a broad photometric redshift probability distribution, such that z{sub phot} + 1{sigma} > 3. Eighty-one sources are selected in the 0.5-2 keV band, fourteen are selected in the 2-10 keV and six in the 0.5-10 keV bands. We sample the high-luminosity (log L{sub (2-10keV)} > 44.15 erg s{sup -1}) space density up to z {approx} 5 and a fainter luminosity range (43.5 erg s{sup -1} < log L{sub (2-10keV)} < 44.15 erg s{sup -1}) than previous studies, up to z = 3.5. We weighted the contribution to the number counts and the space density of the sources with photometric redshift by using their probability of being at z > 3. We find that the space density of high-luminosity AGNs declines exponentially at all the redshifts, confirming the trend observed for optically selected quasars. At lower luminosity, the measured space density is not conclusive, and a larger sample of faint sources is needed. Comparisons with optical luminosity functions and black hole formation models are presented together with prospects for future surveys.

  3. GALAXY ZOO MORPHOLOGY AND PHOTOMETRIC REDSHIFTS IN THE SLOAN DIGITAL SKY SURVEY

    SciTech Connect

    Way, M. J.

    2011-06-10

    It has recently been demonstrated that one can accurately derive galaxy morphology from particular primary and secondary isophotal shape estimates in the Sloan Digital Sky Survey (SDSS) imaging catalog. This was accomplished by applying Machine Learning techniques to the Galaxy Zoo morphology catalog. Using the broad bandpass photometry of the SDSS in combination with precise knowledge of galaxy morphology should help in estimating more accurate photometric redshifts for galaxies. Using the Galaxy Zoo separation for spirals and ellipticals in combination with SDSS photometry we attempt to calculate photometric redshifts. In the best case we find that the root-mean-square error for luminous red galaxies classified as ellipticals is as low as 0.0118. Given these promising results we believe better photometric redshift estimates for all galaxies in the SDSS ({approx}350 million) will be feasible if researchers can also leverage their derived morphologies via Machine Learning. These initial results look to be promising for those interested in estimating weak lensing, baryonic acoustic oscillation, and other fields dependent upon accurate photometric redshifts.

  4. Precise photometric redshifts with a narrow-band filter set: the PAU survey at the William Herschel Telescope

    NASA Astrophysics Data System (ADS)

    Martí, P.; Miquel, R.; Castander, F. J.; Gaztañaga, E.; Eriksen, M.; Sánchez, C.

    2014-07-01

    The Physics of the Accelerating Universe (PAU) survey at the William Herschel Telescope will use a new optical camera (PAUCam) with a large set of narrow-band filters to perform a photometric galaxy survey with a quasi-spectroscopic redshift precision of σ(z)/(1 + z) ˜ 0.0035 and map the large-scale structure of the universe in three dimensions up to iAB < 22.5-23.0. In this paper, we present a detailed photo-z performance study using photometric simulations for 40 equally spaced 12.5-nm-wide (full width at half-maximum) filters with an ˜25 per cent overlap and spanning the wavelength range from 450 to 850 nm, together with a ugrizY broad-band filter system. We then present the migration matrix rij, containing the probability that a galaxy in a true redshift bin j is measured in a photo-z bin i, and study its effect on the determination of galaxy auto- and cross-correlations. Finally, we also study the impact on the photo-z performance of small variations of the filter set in terms of width, wavelength coverage, etc., and find a broad region where slightly modified filter sets provide similar results, with the original set being close to optimal.

  5. The VIMOS Public Extragalactic Redshift Survey (VIPERS). On the recovery of the count-in-cell probability distribution function

    NASA Astrophysics Data System (ADS)

    Bel, J.; Branchini, E.; Di Porto, C.; Cucciati, O.; Granett, B. R.; Iovino, A.; de la Torre, S.; Marinoni, C.; Guzzo, L.; Moscardini, L.; Cappi, A.; Abbas, U.; Adami, C.; Arnouts, S.; Bolzonella, M.; Bottini, D.; Coupon, J.; Davidzon, I.; De Lucia, G.; Fritz, A.; Franzetti, P.; Fumana, M.; Garilli, B.; Ilbert, O.; Krywult, J.; Le Brun, V.; Le Fèvre, O.; Maccagni, D.; Małek, K.; Marulli, F.; McCracken, H. J.; Paioro, L.; Polletta, M.; Pollo, A.; Schlagenhaufer, H.; Scodeggio, M.; Tasca, L. A. M.; Tojeiro, R.; Vergani, D.; Zanichelli, A.; Burden, A.; Marchetti, A.; Mellier, Y.; Nichol, R. C.; Peacock, J. A.; Percival, W. J.; Phleps, S.; Wolk, M.

    2016-04-01

    We compare three methods to measure the count-in-cell probability density function of galaxies in a spectroscopic redshift survey. From this comparison we found that, when the sampling is low (the average number of object per cell is around unity), it is necessary to use a parametric method to model the galaxy distribution. We used a set of mock catalogues of VIPERS to verify if we were able to reconstruct the cell-count probability distribution once the observational strategy is applied. We find that, in the simulated catalogues, the probability distribution of galaxies is better represented by a Gamma expansion than a skewed log-normal distribution. Finally, we correct the cell-count probability distribution function from the angular selection effect of the VIMOS instrument and study the redshift and absolute magnitude dependency of the underlying galaxy density function in VIPERS from redshift 0.5 to 1.1. We found a very weak evolution of the probability density distribution function and that it is well approximated by a Gamma distribution, independently of the chosen tracers. Based on observations collected at the European Southern Observatory, Cerro Paranal, Chile, using the Very Large Telescope under programmes 182.A-0886 and partly 070.A-9007. Also based on observations obtained with MegaPrime/MegaCam, a joint project of CFHT and CEA/DAPNIA, at the Canada-France-Hawaii Telescope (CFHT), which is operated by the National Research Council (NRC) of Canada, the Institut National des Sciences de l'Univers of the Centre National de la Recherche Scientifique (CNRS) of France, and the University of Hawaii. This work is based in part on data products produced at TERAPIX and the Canadian Astronomy Data Centre as part of the Canada-France-Hawaii Telescope Legacy Survey, a collaborative project of NRC and CNRS. The VIPERS web site is http://www.vipers.inaf.it/

  6. RED-SEQUENCE GALAXIES AT HIGH REDSHIFT BY THE COMBO-17+4 SURVEY

    SciTech Connect

    Nicol, Marie-Helene; Meisenheimer, Klaus; Wolf, Christian; Tapken, Christian E-mail: meise@mpia.de E-mail: ctapken@aip.de

    2011-01-20

    We investigate the evolution of the galaxy population since redshift 2 with a focus on the color bimodality and mass density of the red sequence. We obtain precise and reliable photometric redshifts up to z = 2 by supplementing the optical survey COMBO-17 with observations in four near-infrared bands on 0.2 deg{sup 2} of the COMBO-17 A901-field. Our results are based on an H-band-selected catalog of 10,692 galaxies complete to H = 21fm7. We measure the rest-frame color (U{sub 280}-V) of each galaxy, which across the redshift range of our interest requires no extrapolation and is robust against moderate redshift errors by staying clear of the 4000 A break. We measure the color-magnitude relation of the red sequence as a function of look-back time from the peak in a color-error-weighted histogram, and thus trace the galaxy bimodality out to z {approx_equal} 1.65. The (U{sub 280}-V) of the red sequence is found to evolve almost linearly with look-back time. At high redshift, we find massive galaxies in both the red and the blue population. Red-sequence galaxies with log M{sub *}/M{sub sun}>11 increase in mass density by a factor of {approx}4 from z {approx} 2 to 1 and remain nearly constant at z < 1. However, some galaxies as massive as log M{sub *}/M{sub sun} = 11.5 are already in place at z {approx} 2.

  7. Photometric Redshift Survey Forecast for Luminous Red Galaxies at z 1.0

    NASA Astrophysics Data System (ADS)

    Huang, Xiaosheng; Schlegel, D. J.

    2006-12-01

    We analyzed the data from the DEEP2 Redshift Survey to obtain the number densities for luminous red galaxies between z=0.4 and 1.2. Based on the DEEP photometric data in B, R and I bands and the spectroscopic redshift we synthesized spectrophotometry for the 4000 DEEP galaxies in the extended groth strip (EGS) field, using templates from the Kinney-Calzetti catalog and Coleman, Wu and Weedman. We determined the number densities in the redshift ranges of 0.4survey, the sound horizon scale can be measured to an accuracy of 1.2-2% and w to 6-10%. This work has been supported by the Office of Science, U.S. Department of Energy, through contract DE-AC02-05CH11231.

  8. Redshifts for fainter galaxies in the first CfA survey slice. II

    NASA Technical Reports Server (NTRS)

    Wegner, Gary; Thorstensen, John R.; Kurtz, Michael J.; Geller, Margaret J.; Huchra, John P.

    1990-01-01

    Redshifts were measured for 96 galaxies in right ascension alpha between 8h and 17h declination delta between 30 and 31 deg, and with m(Zwicky) in the range 15.6-15.7. These correspond to 94 of the 96 entries in the Zwicky-Nilson merged catalog. The declination range delta between 29 deg and 31 deg is now complete to m(Zwicky) = 15.7. The structures in the first 6-deg-wide slice of the Center for Astrophysics redshift survey slice (delta between 26.5 and 32.5 deg are clearly defined in the 2-deg-wide slightly deeper sample; the fainter galaxies trace the structures defined by the brighter ones.

  9. Superclusters of galaxies from the 2df redshift survey. 1. the catalogue

    SciTech Connect

    Einasto, Jaan; Einasto, M.; Tago, E.; Saar, E.; Huetsi, G.; Joeveer, M.; Liivamagi, L.J.; Suhhonenko, I.; Jaaniste, J.; Heinamaki, P.; Mueller, V.; Knebe, A.; Tucker, D. /Tartu Observ. /Estonian U. /Tuorla Observ. /Potsdam, Astrophys. Inst. /Fermilab

    2006-03-01

    We use the 2dF Galaxy Redshift Survey data to compile catalogues of superclusters for the Northern and Southern regions of the 2dFGRS, altogether 543 superclusters at redshifts 0.009 {le} z {le} 0.2. We analyze methods of compiling supercluster catalogues and use results of the Millennium Simulation to investigate possible selection effects and errors. We find that the most effective method is the density field method using smoothing with an Epanechnikov kernel of radius 8 h{sup -1} Mpc. We derive positions of the highest luminosity density peaks and find the most luminous cluster in the vicinity of the peak, this cluster is considered as the main cluster and its brightest galaxy the main galaxy of the supercluster. In catalogues we give equatorial coordinates and distances of superclusters as determined by positions of their main clusters. We also calculate the expected total luminosities of the superclusters.

  10. The VIMOS Public Extragalactic Redshift Survey (VIPERS). Hierarchical scaling and biasing

    NASA Astrophysics Data System (ADS)

    Cappi, A.; Marulli, F.; Bel, J.; Cucciati, O.; Branchini, E.; de la Torre, S.; Moscardini, L.; Bolzonella, M.; Guzzo, L.; Abbas, U.; Adami, C.; Arnouts, S.; Bottini, D.; Coupon, J.; Davidzon, I.; De Lucia, G.; Fritz, A.; Franzetti, P.; Fumana, M.; Garilli, B.; Granett, B. R.; Ilbert, O.; Iovino, A.; Krywult, J.; Le Brun, V.; Le Fèvre, O.; Maccagni, D.; Małek, K.; McCracken, H. J.; Paioro, L.; Polletta, M.; Pollo, A.; Scodeggio, M.; Tasca, L. A. M.; Tojeiro, R.; Vergani, D.; Zanichelli, A.; Burden, A.; Di Porto, C.; Marchetti, A.; Marinoni, C.; Mellier, Y.; Nichol, R. C.; Peacock, J. A.; Percival, W. J.; Phleps, S.; Schimd, C.; Schlagenhaufer, H.; Wolk, M.; Zamorani, G.

    2015-07-01

    Aims: Building on the two-point correlation function analyses of the VIMOS Public Extragalactic Redshift Survey (VIPERS), we investigate the higher-order correlation properties of the same galaxy samples to test the hierarchical scaling hypothesis at z ~ 1 and the dependence on galaxy luminosity, stellar mass, and redshift. With this work we also aim to assess possible deviations from the linearity of galaxy bias independently from a previously performed analysis of our survey. Methods: We have measured the count probability distribution function in spherical cells of varying radii (3 ≤ R ≤ 10 h-1 Mpc), deriving σ8g (the galaxy rms at 8 h-1 Mpc), the volume-averaged two-, three-, and four-point correlation functions and the normalized skewness S3g and kurtosis S4g for different volume-limited subsamples, covering the following ranges: -19.5 ≤ MB(z = 1.1) - 5log (h) ≤ -21.0 in absolute magnitude, 9.0 ≤ log (M∗/M⊙h-2) ≤ 11.0 in stellar mass, and 0.5 ≤ z< 1.1 in redshift. Results: We have performed the first measurement of high-order correlation functions at z ~ 1 in a spectroscopic redshift survey. Our main results are the following. 1) The hierarchical scaling between the volume-averaged two- and three-point and two- and four-point correlation functions holds throughout the whole range of scale and redshift we could test. 2) We do not find a significant dependence of S3g on luminosity (below z = 0.9 the value of S3g decreases with luminosity, but only at 1σ-level). 3) We do not detect a significant dependence of S3g and S4g on scale, except beyond z ~ 0.9, where S3g and S4g have higher values on large scales (R ≥ 10 h-1 Mpc): this increase is mainly due to one of the two CFHTLS Wide Fields observed by VIPERS and can be explained as a consequence of sample variance, consistently with our analysis of mock catalogs. 4) We do not detect a significant evolution of S3g and S4g with redshift (apart from the increase of their values with scale in the

  11. COMPARING DENSE GALAXY CLUSTER REDSHIFT SURVEYS WITH WEAK-LENSING MAPS

    SciTech Connect

    Hwang, Ho Seong; Geller, Margaret J.; Zahid, H. Jabran; Diaferio, Antonaldo; Rines, Kenneth J. E-mail: mgeller@cfa.harvard.edu E-mail: diaferio@ph.unito.it

    2014-12-20

    We use dense redshift surveys of nine galaxy clusters at z ∼ 0.2 to compare the galaxy distribution in each system with the projected matter distribution from weak lensing. By combining 2087 new MMT/Hectospec redshifts and the data in the literature, we construct spectroscopic samples within the region of weak-lensing maps of high (70%-89%) and uniform completeness. With these dense redshift surveys, we construct galaxy number density maps using several galaxy subsamples. The shape of the main cluster concentration in the weak-lensing maps is similar to the global morphology of the number density maps based on cluster members alone, mainly dominated by red members. We cross-correlate the galaxy number density maps with the weak-lensing maps. The cross-correlation signal when we include foreground and background galaxies at 0.5z {sub cl} < z < 2z {sub cl} is 10%-23% larger than for cluster members alone at the cluster virial radius. The excess can be as high as 30% depending on the cluster. Cross-correlating the galaxy number density and weak-lensing maps suggests that superimposed structures close to the cluster in redshift space contribute more significantly to the excess cross-correlation signal than unrelated large-scale structure along the line of sight. Interestingly, the weak-lensing mass profiles are not well constrained for the clusters with the largest cross-correlation signal excesses (>20% for A383, A689, and A750). The fractional excess in the cross-correlation signal including foreground and background structures could be a useful proxy for assessing the reliability of weak-lensing cluster mass estimates.

  12. Probing primordial non-Gaussianity with SKA galaxy redshift surveys: a fully relativistic analysis

    NASA Astrophysics Data System (ADS)

    Camera, Stefano; Santos, Mário G.; Maartens, Roy

    2015-04-01

    The Square Kilometre Array (SKA) will produce spectroscopic surveys of tens to hundreds of millions of neutral hydrogen (H I) galaxies, eventually covering 30 000 deg2 and reaching out to redshift z ≳ 2. The huge volumes probed by the SKA will allow for some of the best constraints on primordial non-Gaussianity, based on measurements of the large-scale power spectrum. We investigate various observational set-ups for H I galaxy redshift surveys, compatible with the SKA Phase 1 and Phase 2 (full SKA) configurations. We use the corresponding number counts and bias for each survey from realistic simulations and derive the magnification bias and the evolution of source counts directly from these. For the first time, we produce forecasts that fully include the general relativistic effects on the galaxy number counts. These corrections to the standard analysis become important on very large scales, where the signal of primordial non-Gaussianity grows strongest. Our results show that, for the full survey, the non-Gaussianity parameter fNL can be constrained down to σ(fNL) = 1.54. This improves the current limit set by the Planck satellite by a factor of 5, using a completely different approach.

  13. THE SLOAN DIGITAL SKY SURVEY CO-ADD: A GALAXY PHOTOMETRIC REDSHIFT CATALOG

    SciTech Connect

    Reis, Ribamar R. R.; Soares-Santos, Marcelle; Annis, James; Dodelson, Scott; Hao Jiangang; Johnston, David; Kubo, Jeffrey; Lin Huan; Seo, Hee-Jong; Simet, Melanie

    2012-03-01

    We present and describe a catalog of galaxy photometric redshifts (photo-z) for the Sloan Digital Sky Survey (SDSS) Co-add Data. We use the artificial neural network (ANN) technique to calculate the photo-z and the nearest neighbor error method to estimate photo-z errors for {approx}13 million objects classified as galaxies in the co-add with r < 24.5. The photo-z and photo-z error estimators are trained and validated on a sample of {approx}83,000 galaxies that have SDSS photometry and spectroscopic redshifts measured by the SDSS Data Release 7 (DR7), the Canadian Network for Observational Cosmology Field Galaxy Survey, the Deep Extragalactic Evolutionary Probe Data Release 3, the VIsible imaging Multi-Object Spectrograph-Very Large Telescope Deep Survey, and the WiggleZ Dark Energy Survey. For the best ANN methods we have tried, we find that 68% of the galaxies in the validation set have a photo-z error smaller than {sigma}{sub 68} = 0.031. After presenting our results and quality tests, we provide a short guide for users accessing the public data.

  14. Gravitational redshift of galaxies in clusters from the sloan digital sky survey and the Baryon Oscillation spectroscopic survey.

    PubMed

    Sadeh, Iftach; Feng, Low Lerh; Lahav, Ofer

    2015-02-20

    The gravitational redshift effect allows one to directly probe the gravitational potential in clusters of galaxies. Following up on Wojtak et al. [Nature (London) 477, 567 (2011)], we present a new measurement. We take advantage of new data from the tenth data release of the Sloan Digital Sky Survey and the Baryon Oscillation Spectroscopic Survey. We compare the spectroscopic redshift of the brightest cluster galaxies (BCGs) with that of galaxies at the outskirts of clusters, using a sample with an average cluster mass of 1014M⊙. We find that these galaxies have an average relative redshift of -11  km/s compared with that of BCGs, with a standard deviation of +7 and -5  km/s. Our measurement is consistent with that of Wojtak et al. [Nature (London) 477, 567 (2011)]. However, our derived standard deviation is larger, as we take into account various systematic effects, beyond the size of the data set. The result is in good agreement with the predictions from general relativity. PMID:25763947

  15. The Subaru FMOS galaxy redshift survey (FastSound). IV. New constraint on gravity theory from redshift space distortions at z ˜ 1.4

    NASA Astrophysics Data System (ADS)

    Okumura, Teppei; Hikage, Chiaki; Totani, Tomonori; Tonegawa, Motonari; Okada, Hiroyuki; Glazebrook, Karl; Blake, Chris; Ferreira, Pedro G.; More, Surhud; Taruya, Atsushi; Tsujikawa, Shinji; Akiyama, Masayuki; Dalton, Gavin; Goto, Tomotsugu; Ishikawa, Takashi; Iwamuro, Fumihide; Matsubara, Takahiko; Nishimichi, Takahiro; Ohta, Kouji; Shimizu, Ikkoh; Takahashi, Ryuichi; Takato, Naruhisa; Tamura, Naoyuki; Yabe, Kiyoto; Yoshida, Naoki

    2016-04-01

    We measure the redshift-space correlation function from a spectroscopic sample of 2783 emission line galaxies from the FastSound survey. The survey, which uses the Subaru Telescope and covers a redshift range of 1.19 < z < 1.55, is the first cosmological study at such high redshifts. We detect clear anisotropy due to redshift-space distortions (RSD) both in the correlation function as a function of separations parallel and perpendicular to the line of sight and its quadrupole moment. RSD has been extensively used to test general relativity on cosmological scales at z < 1. Adopting a ΛCDM cosmology with the fixed expansion history and no velocity dispersion (σv = 0), and using the RSD measurements on scales above 8 h-1 Mpc, we obtain the first constraint on the growth rate at the redshift, f (z)σ8(z) = 0.482 ± 0.116 at z ˜ 1.4 after marginalizing over the galaxy bias parameter b(z)σ8(z). This corresponds to 4.2 σ detection of RSD. Our constraint is consistent with the prediction of general relativity fσ8 ˜ 0.392 within the 1 σ confidence level. When we allow σv to vary and marginalize over it, the growth rate constraint becomes fσ _8=0.494^{+0.126}_{-0.120}. We also demonstrate that by combining with the low-z constraints on fσ8, high-z galaxy surveys like the FastSound can be useful to distinguish modified gravity models without relying on CMB anisotropy experiments.

  16. The Subaru FMOS galaxy redshift survey (FastSound). IV. New constraint on gravity theory from redshift space distortions at z ˜ 1.4

    NASA Astrophysics Data System (ADS)

    Okumura, Teppei; Hikage, Chiaki; Totani, Tomonori; Tonegawa, Motonari; Okada, Hiroyuki; Glazebrook, Karl; Blake, Chris; Ferreira, Pedro G.; More, Surhud; Taruya, Atsushi; Tsujikawa, Shinji; Akiyama, Masayuki; Dalton, Gavin; Goto, Tomotsugu; Ishikawa, Takashi; Iwamuro, Fumihide; Matsubara, Takahiko; Nishimichi, Takahiro; Ohta, Kouji; Shimizu, Ikkoh; Takahashi, Ryuichi; Takato, Naruhisa; Tamura, Naoyuki; Yabe, Kiyoto; Yoshida, Naoki

    2016-06-01

    We measure the redshift-space correlation function from a spectroscopic sample of 2783 emission line galaxies from the FastSound survey. The survey, which uses the Subaru Telescope and covers a redshift range of 1.19 < z < 1.55, is the first cosmological study at such high redshifts. We detect clear anisotropy due to redshift-space distortions (RSD) both in the correlation function as a function of separations parallel and perpendicular to the line of sight and its quadrupole moment. RSD has been extensively used to test general relativity on cosmological scales at z < 1. Adopting a ΛCDM cosmology with the fixed expansion history and no velocity dispersion (σv = 0), and using the RSD measurements on scales above 8 h-1 Mpc, we obtain the first constraint on the growth rate at the redshift, f (z)σ8(z) = 0.482 ± 0.116 at z ˜ 1.4 after marginalizing over the galaxy bias parameter b(z)σ8(z). This corresponds to 4.2 σ detection of RSD. Our constraint is consistent with the prediction of general relativity fσ8 ˜ 0.392 within the 1 σ confidence level. When we allow σv to vary and marginalize over it, the growth rate constraint becomes fσ _8=0.494^{+0.126}_{-0.120}. We also demonstrate that by combining with the low-z constraints on fσ8, high-z galaxy surveys like the FastSound can be useful to distinguish modified gravity models without relying on CMB anisotropy experiments.

  17. Photometric Redshifts in the Sloan Colors

    NASA Astrophysics Data System (ADS)

    Sowards-Emmerd, D.; McKay, T. A.; Sheldon, E.; Smith, J. A.

    1999-05-01

    In the past few years, photometric redshifts have proven themselves to be a robust means of estimating redshifts. In the near future, the Sloan Digital Sky Survey will compile high-quality photometric data for 108 galaxies. Photometric redshifts will provide approximate distances to this enormous set of objects. In this poster, we describe results from a preliminary study of photometric redshift calibration on data in the SDSS colors. We present 5 color photometry for 2195 galaxies drawn from the Las Campanas Redshift Survey. Data was obtained on the Curtis Schmidt telescope at CTIO during Aug 97 and Feb/Mar 98 using filters nearly identical to the SDSS system. We also present photometric redshift predictions expressed as polynomial functions of galaxy colors and magnitudes derived from this training set. Finally, applications of photometric redshifts will be considered, including lensing studies, cosmology, and determination of fundamental astrophysical quantities. Support was provided by NSF grant #9703282.

  18. Photometric Redshifts for the Large-Area Stripe 82X Multiwavelength Survey

    NASA Astrophysics Data System (ADS)

    Tasnim Ananna, Tonima; Salvato, Mara; Urry, C. Megan; LaMassa, Stephanie M.; STRIPE 82X

    2016-06-01

    The Stripe 82X survey currently includes 6000 X-ray sources in 31.3 square degrees of XMM-Newton and Chandra X-ray coverage, most of which are AGN. Using a maximum-likelihood approach, we identified optical and infrared counterparts in the SDSS, VHS K-band and WISE W1-band catalogs. 1200 objects which had different best associations in different catalogs were checked by eye. Our most recent paper provided the multiwavelength catalogs for this sample. More than 1000 counterparts have spectroscopic redshifts, either from SDSS spectroscopy or our own follow-up program. Using the extensive multiwavelength data in this field, we provide photometric redshift estimates for most of the remaining sources, which are 80-90% accurate according to the training set. Our sample has a large number of candidates that are very faint in optical and bright in IR. We expect a large fraction of these objects to be the obscured AGN sample we need to complete the census on black hole growth at a range of redshifts.

  19. A DATA-DRIVEN MODEL FOR SPECTRA: FINDING DOUBLE REDSHIFTS IN THE SLOAN DIGITAL SKY SURVEY

    SciTech Connect

    Tsalmantza, P.; Hogg, David W.

    2012-07-10

    We present a data-driven method-heteroscedastic matrix factorization, a kind of probabilistic factor analysis-for modeling or performing dimensionality reduction on observed spectra or other high-dimensional data with known but non-uniform observational uncertainties. The method uses an iterative inverse-variance-weighted least-squares minimization procedure to generate a best set of basis functions. The method is similar to principal components analysis (PCA), but with the substantial advantage that it uses measurement uncertainties in a responsible way and accounts naturally for poorly measured and missing data; it models the variance in the noise-deconvolved data space. A regularization can be applied, in the form of a smoothness prior (inspired by Gaussian processes) or a non-negative constraint, without making the method prohibitively slow. Because the method optimizes a justified scalar (related to the likelihood), the basis provides a better fit to the data in a probabilistic sense than any PCA basis. We test the method on Sloan Digital Sky Survey (SDSS) spectra, concentrating on spectra known to contain two redshift components: these are spectra of gravitational lens candidates and massive black hole binaries. We apply a hypothesis test to compare one-redshift and two-redshift models for these spectra, utilizing the data-driven model trained on a random subset of all SDSS spectra. This test confirms 129 of the 131 lens candidates in our sample and all of the known binary candidates, and turns up very few false positives.

  20. THE AzTEC/SMA INTERFEROMETRIC IMAGING SURVEY OF SUBMILLIMETER-SELECTED HIGH-REDSHIFT GALAXIES

    SciTech Connect

    Younger, Joshua D.; Fazio, Giovanni G.; Huang Jiasheng; Ashby, Matthew L. N.; Gurwell, Mark A.; Petitpas, Glen R.; Wilner, David J.; Yun, Min S.; Wilson, Grant W.; Scott, Kimberly S.; Austermann, Jason; Perera, Thushara; Peck, Alison B.; Hughes, David H.; Aretxaga, Itziar; Kim, Sungeun; Lowenthal, James D.

    2009-10-10

    We present results from a continuing interferometric survey of high-redshift submillimeter galaxies (SMGs) with the Submillimeter Array, including high-resolution (beam size approx2 arcsec) imaging of eight additional AzTEC 1.1 mm selected sources in the COSMOS field, for which we obtain six reliable (peak signal-to-noise ratio (S/N) >5 or peak S/N >4 with multiwavelength counterparts within the beam) and two moderate significance (peak S/N >4) detections. When combined with previous detections, this yields an unbiased sample of millimeter-selected SMGs with complete interferometric follow up. With this sample in hand, we (1) empirically confirm the radio-submillimeter association, (2) examine the submillimeter morphology-including the nature of SMGs with multiple radio counterparts and constraints on the physical scale of the far infrared-of the sample, and (3) find additional evidence for a population of extremely luminous, radio-dim SMGs that peaks at higher redshift than previous, radio-selected samples. In particular, the presence of such a population of high-redshift sources has important consequences for models of galaxy formation-which struggle to account for such objects even under liberal assumptions-and dust production models given the limited time since the big bang.

  1. Clustering of High Redshift (z>2.9) Quasars from the Sloan Digital Sky Survey

    SciTech Connect

    Shen, Yue; Strauss, Michael A.; Oguri, Masamune; Hennawi, Joseph F.; Fan, Xiaohui; Richards, Gordon T.; Hall, Patrick B.; Schneider, Donald P.; Szalay, Alexander S.; Thakar, Anirudda R.; Berk, Daniel E.Vanden; Anderson, Scott F.; Bahcall, Neta A.; /KIPAC, Menlo Park

    2006-11-30

    We study the two-point correlation function of a uniformly selected sample of 4,428 optically selected luminous quasars with redshift 2.9 {le} z {le} 5.4 selected over 4041 deg{sup 2} from the Fifth Data Release of the Sloan Digital Sky Survey. We fit a power-law to the projected correlation function w{sub p}(r{sub p}) to marginalize over redshift space distortions and redshift errors. For a real-space correlation function of the form {zeta}(r) = (r/r{sub 0}){sup -{gamma}}, the fitted parameters in comoving coordinates are r{sub 0} = 15.2 {+-} 2.7 h{sup -1} Mpc and {gamma} = 2.0 {+-} 0.3, over a scale range 4 {le} r{sub p} {le} 150 h{sup -1} Mpc. Thus high-redshift quasars are appreciably more strongly clustered than their z {approx} 1.5 counterparts, which have a comoving clustering length r{sub 0} {approx} 6.5 h{sup -1} Mpc. Dividing our sample into two redshift bins: 2.9 {le} z {le} 3.5 and z {ge} 3.5, and assuming a power-law index {gamma} = 2.0, we find a correlation length of r{sub 0} = 16.9 {+-} 1.7 h{sup -1} Mpc for the former, and r{sub 0} = 24.3 {+-} 2.4 h{sup -1} Mpc for the latter. Strong clustering at high redshift indicates that quasars are found in very massive, and therefore highly biased, halos. Following Martini & Weinberg, we relate the clustering strength and quasar number density to the quasar lifetimes and duty cycle. Using the Sheth & Tormen halo mass function, the quasar lifetime is estimated to lie in the range 4 {approx} 50 Myr for quasars with 2.9 {le} z {le} 3.5; and 30 {approx} 600 Myr for quasars with z {ge} 3.5. The corresponding duty cycles are 0.004 {approx} 0.05 for the lower redshift bin and 0.03 {approx} 0.6 for the higher redshift bin. The minimum mass of halos in which these quasars reside is 2-3 x 10{sup 12} h{sup -1} M{sub {circle_dot}} for quasars with 2.9 {le} z {le} 3.5 and 4-6 x 10{sup 12} h{sup -1} M{sub {circle_dot}} for quasars with z {ge} 3.5; the effective bias factor b{sub eff} increases with redshift, e.g., b

  2. Measures of large-scale structure in the CfA redshift survey slices

    NASA Technical Reports Server (NTRS)

    De Lapparent, Valerie; Geller, Margaret J.; Huchra, John P.

    1991-01-01

    Variations of the counts-in-cells with cell size are used here to define two statistical measures of large-scale clustering in three 6 deg slices of the CfA redshift survey. A percolation criterion is used to estimate the filling factor which measures the fraction of the total volume in the survey occupied by the large-scale structures. For the full 18 deg slice of the CfA redshift survey, f is about 0.25 + or - 0.05. After removing groups with more than five members from two of the slices, variations of the counts in occupied cells with cell size have a power-law behavior with a slope beta about 2.2 on scales from 1-10/h Mpc. Application of both this statistic and the percolation analysis to simulations suggests that a network of two-dimensional structures is a better description of the geometry of the clustering in the CfA slices than a network of one-dimensional structures. Counts-in-cells are also used to estimate at 0.3 galaxy h-squared/Mpc the average galaxy surface density in sheets like the Great Wall.

  3. Measures of large-scale structure in the CfA redshift survey slices

    SciTech Connect

    De Lapparent, V.; Geller, M.J.; Huchra, J.P. Harvard-Smithsonian Center for Astrophysics, Cambridge, MA )

    1991-03-01

    Variations of the counts-in-cells with cell size are used here to define two statistical measures of large-scale clustering in three 6 deg slices of the CfA redshift survey. A percolation criterion is used to estimate the filling factor which measures the fraction of the total volume in the survey occupied by the large-scale structures. For the full 18 deg slice of the CfA redshift survey, f is about 0.25 + or - 0.05. After removing groups with more than five members from two of the slices, variations of the counts in occupied cells with cell size have a power-law behavior with a slope beta about 2.2 on scales from 1-10/h Mpc. Application of both this statistic and the percolation analysis to simulations suggests that a network of two-dimensional structures is a better description of the geometry of the clustering in the CfA slices than a network of one-dimensional structures. Counts-in-cells are also used to estimate at 0.3 galaxy h-squared/Mpc the average galaxy surface density in sheets like the Great Wall. 46 refs.

  4. VLP - High-Redshift AGNs and the X-SERVS Survey

    NASA Astrophysics Data System (ADS)

    Brandt, W.

    2016-06-01

    In the first part of this talk, I will review how X-ray observations of high-redshift AGNs at z = 4-7 have played a critical role in understanding their basic demographics as well as their physical processes; e.g., accretion rates, jet emission, X-ray absorption by nuclear material and winds. Since 2000, XMM-Newton and Chandra have provided new X-ray detections for more than 120 such objects, and well-defined samples of z > 4 AGNs now allow reliable basic X-ray population studies. I will point out key remaining areas of uncertainty, highlighting where further XMM-Newton and Chandra observations can advance understanding. I will then describe the X-SERVS project which aims to go ``beyond COSMOS'' via a 12 deg^2 survey of three prime sky regions: W-CDF-S, XMM-LSS, and ELAIS-S1. The X-SERVS survey will allow outstanding studies of the detected AGNs and groups/clusters by powerfully leveraging multiple intensive radio-to-UV surveys: ATLAS/HerMES/SERVS/VIDEO/DES/HSC/PS1MD/VOICE/CSI/PRIMUS. We aim to dramatically advance studies of SMBH growth across the full range of cosmic environments, links between SMBH accretion and star formation, exceptional AGNs at high redshifts, protoclusters, etc. The targeted X-SERVS fields will have extraordinary legacy value as MOONS massive spectroscopy fields, prime ALMA fields, and DES/LSST deep-drilling fields.

  5. VLP - High-Redshift AGNs and the X-SERVS Survey

    NASA Astrophysics Data System (ADS)

    Brandt, W.

    2016-06-01

    In the first part of this talk, I will review how X-ray observations of high-redshift AGNs at z = 4-7 have played a critical role in understanding their basic demographics as well as their physical processes; e.g., accretion rates, jet emission, X-ray absorption by nuclear material and winds. Since 2000, XMM-Newton and Chandra have provided new X-ray detections for more than 120 such objects, and well-defined samples of z > 4 AGNs now allow reliable basic X-ray population studies. I will point out key remaining areas of uncertainty, highlighting where further XMM-Newton and Chandra observations can advance understanding. I will then describe the X-SERVS project which aims to go ``beyond COSMOS'' via a 12 deg^2 survey of three prime sky regions: W-CDF-S, XMM-LSS, and ELAIS-S1. The X-SERVS survey will allow outstanding studies of the detected AGNs and groups/clusters by powerfully leveraging multiple intensive radio-to-UV surveys: ATLAS/HerMES/SERVS/VIDEO/DES/HSC/PS1MD/VOICE/ CSI/PRIMUS. We aim to dramatically advance studies of SMBH growth across the full range of cosmic environments, links between SMBH accretion and star formation, exceptional AGNs at high redshifts, protoclusters, etc. The targeted X-SERVS fields will have extraordinary legacy value as MOONS massive spectroscopy fields, prime ALMA fields, and DES/LSST deep-drilling fields.

  6. A redshift survey of IRAS galaxies. V - The acceleration on the Local Group

    NASA Technical Reports Server (NTRS)

    Strauss, Michael A.; Yahil, Amos; Davis, Marc; Huchra, John P.; Fisher, Karl

    1992-01-01

    The acceleration on the Local Group is calculated based on a full-sky redshift survey of 5288 galaxies detected by IRAS. A formalism is developed to compute the distribution function of the IRAS acceleration for a given power spectrum of initial perturbations. The computed acceleration on the Local Group points 18-28 deg from the direction of the Local Group peculiar velocity vector. The data suggest that the CMB dipole is indeed due to the motion of the Local Group, that this motion is gravitationally induced, and that the distribution of IRAS galaxies on large scales is related to that of dark matter by a simple linear biasing model.

  7. A simple test of independence for truncated data with applications to redshift surveys

    NASA Technical Reports Server (NTRS)

    Efron, Bradley; Petrosian, Vahe

    1992-01-01

    This paper presents an easily applied permutation test for H0, closely related to Lyden-Bell's (1971) estimate of the marginal distribution of truncated data. The test is applied to two redshift-magnitude surveys, one of galaxies and one of quasars. Assuming statistical independence, testing H0 amounts to testing validity of the cosmological model. Segal's (1986) chronomatic cosmological model is rejected under H0. On the other hand, for the quasar sample H0 is rejected strongly in a conventional cosmological model (and in a chronomatic model as well) indicating either incorrectness of the models or, as is more commonly assumed, indicating strong luminosity evolution.

  8. A REDSHIFT SURVEY OF HERSCHEL FAR-INFRARED SELECTED STARBURSTS AND IMPLICATIONS FOR OBSCURED STAR FORMATION

    SciTech Connect

    Casey, C. M.; Budynkiewicz, J.; Berta, S.; Lutz, D.; Magnelli, B.; Bethermin, M.; Le Floc'h, E.; Magdis, G.; Burgarella, D.; Chapin, E.; Chapman, S. C.; Clements, D. L.; Conley, A.; Conselice, C. J.; Cooray, A.; Farrah, D.; Hatziminaoglou, E.; Ivison, R. J.; and others

    2012-12-20

    We present Keck spectroscopic observations and redshifts for a sample of 767 Herschel-SPIRE selected galaxies (HSGs) at 250, 350, and 500 {mu}m, taken with the Keck I Low Resolution Imaging Spectrometer and the Keck II DEep Imaging Multi-Object Spectrograph. The redshift distribution of these SPIRE sources from the Herschel Multitiered Extragalactic Survey peaks at z = 0.85, with 731 sources at z < 2 and a tail of sources out to z {approx} 5. We measure more significant disagreement between photometric and spectroscopic redshifts (({Delta}z/(1 + z{sub spec})) = 0.29) than is seen in non-infrared selected samples, likely due to enhanced star formation rates and dust obscuration in infrared-selected galaxies. The infrared data are used to directly measure integrated infrared luminosities and dust temperatures independent of radio or 24 {mu}m flux densities. By probing the dust spectral energy distribution (SED) at its peak, we estimate that the vast majority (72%-83%) of z < 2 Herschel-selected galaxies would drop out of traditional submillimeter surveys at 0.85-1 mm. We find that dust temperature traces infrared luminosity, due in part to the SPIRE wavelength selection biases, and partially from physical effects. As a result, we measure no significant trend in SPIRE color with redshift; if dust temperature were independent of luminosity or redshift, a trend in SPIRE color would be expected. Composite infrared SEDs are constructed as a function of infrared luminosity, showing the increase in dust temperature with luminosity, and subtle change in near-infrared and mid-infrared spectral properties. Moderate evolution in the far-infrared (FIR)/radio correlation is measured for this partially radio-selected sample, with q{sub IR}{proportional_to}(1 + z){sup -0.30{+-}0.02} at z < 2. We estimate the luminosity function and implied star formation rate density contribution of HSGs at z < 1.6 and find overall agreement with work based on 24 {mu}m extrapolations of the LIRG

  9. THE CANADA-FRANCE HIGH-z QUASAR SURVEY: NINE NEW QUASARS AND THE LUMINOSITY FUNCTION AT REDSHIFT 6

    SciTech Connect

    Willott, Chris J.; Crampton, David; Hutchings, John B.; Schade, David; Delorme, Philippe; Reyle, Celine; Albert, Loic; Bergeron, Jacqueline; Omont, Alain; Delfosse, Xavier; Forveille, Thierry; McLure, Ross J.

    2010-03-15

    We present discovery imaging and spectroscopy for nine new z {approx} 6 quasars found in the Canada-France High-z Quasar Survey (CFHQS) bringing the total number of CFHQS quasars to 19. By combining the CFHQS with the more luminous Sloan Digital Sky Survey sample, we are able to derive the quasar luminosity function from a sample of 40 quasars at redshifts 5.74 < z < 6.42. Our binned luminosity function shows a slightly lower normalization and flatter slope than found in previous work. The binned data also suggest a break in the luminosity function at M {sub 1450} {approx} -25. A double power-law maximum likelihood fit to the data is consistent with the binned results. The luminosity function is strongly constrained (1{sigma} uncertainty <0.1 dex) over the range -27.5 < M {sub 1450} < -24.7. The best-fit parameters are {phi}(M*{sub 1450}) = 1.14 x 10{sup -8} Mpc{sup -3} mag{sup -1}, break magnitude M*{sub 1450} = -25.13, and bright end slope {beta} = -2.81. However, the covariance between {beta} and M*{sub 1450} prevents strong constraints being placed on either parameter. For a break magnitude in the range -26 < M*{sub 1450} < -24, we find -3.8 < {beta} < -2.3 at 95% confidence. We calculate the z = 6 quasar intergalactic ionizing flux and show it is between 20 and 100 times lower than that necessary for reionization. Finally, we use the luminosity function to predict how many higher redshift quasars may be discovered in future near-IR imaging surveys.

  10. A deep redshift survey of field galaxies. Comments on the reality of the Butcher-Oemler effect

    NASA Technical Reports Server (NTRS)

    Koo, David C.; Kron, Richard G.

    1987-01-01

    A spectroscopic survey of over 400 field galaxies has been completed in three fields for which we have deep UBVI photographic photometry. The galaxies typically range from B=20 to 22 and possess redshifts z from 0.1 to 0.5 that are often quite spiky in distribution. Little, if any, luminosity evolution is observed up to redshifts z approx 0.5. By such redshifts, however, an unexpectedly large fraction of luminous galaxies has very blue intrinsic colors that suggest extensive star formation; in contrast, the reddest galaxies still have colors that match those of present-day ellipticals.

  11. The Observations of Redshift Evolution in Large Scale Environments (ORELSE) Survey

    NASA Astrophysics Data System (ADS)

    Squires, Gordon K.; Lubin, L. M.; Gal, R. R.

    2007-05-01

    We present the motivation, design, and latest results from the Observations of Redshift Evolution in Large Scale Environments (ORELSE) Survey, a systematic search for structure on scales greater than 10 Mpc around 20 known galaxy clusters at z > 0.6. When complete, the survey will cover nearly 5 square degrees, all targeted at high-density regions, making it complementary and comparable to field surveys such as DEEP2, GOODS, and COSMOS. For the survey, we are using the Large Format Camera on the Palomar 5-m and SuPRIME-Cam on the Subaru 8-m to obtain optical/near-infrared imaging of an approximately 30 arcmin region around previously studied high-redshift clusters. Colors are used to identify likely member galaxies which are targeted for follow-up spectroscopy with the DEep Imaging Multi-Object Spectrograph on the Keck 10-m. This technique has been used to identify successfully the Cl 1604 supercluster at z = 0.9, a large scale structure containing at least eight clusters (Gal & Lubin 2004; Gal, Lubin & Squires 2005). We present the most recent structures to be photometrically and spectroscopically confirmed through this program, discuss the properties of the member galaxies as a function of environment, and describe our planned multi-wavelength (radio, mid-IR, and X-ray) observations of these systems. The goal of this survey is to identify and examine a statistical sample of large scale structures during an active period in the assembly history of the most massive clusters. With such a sample, we can begin to constrain large scale cluster dynamics and determine the effect of the larger environment on galaxy evolution.

  12. Clustering at High Redshift: Precise Constraints from a Deep, Wide-Area Survey

    NASA Astrophysics Data System (ADS)

    Postman, Marc; Lauer, Tod R.; Szapudi, István; Oegerle, William

    1998-10-01

    We present constraints on the evolution of large-scale structure from a catalog of 710,000 galaxies with IAB <= 24 derived from a KPNO 4 m CCD imaging survey of a contiguous 4° × 4° region. The advantage of using large contiguous surveys for measuring clustering properties on even modest angular scales is substantial: the effects of cosmic scatter are strongly suppressed. We provide highly accurate measurements of the two-point angular correlation function, ω(θ), as a function of magnitude on scales up to 1.5d. The amplitude of ω(θ) declines by a factor of ~10 over the range 16 <= I <= 20 but only by a factor of 2-3 over the range 20 < I <= 23. For a redshift dependence of the spatial correlation function, ξ(r), parameterized as ξ(r, z) = (r/r0)-γ(1 + z)-(3+ε), we find r0 = 5.2 +/- 0.4 h-1 Mpc, and ε >~ 0 for I <= 20. This is in good agreement with the results from local redshift surveys. At I > 20, our best-fit values shift toward lower r0 and more negative ε. A strong covariance between r0 and ε prevents us from rejecting ε > 0 even at faint magnitudes, but if ε > 1, we strongly reject r0 <~ 4 h-1 Mpc (comoving). The above expression for ξ(r, z) and our data give a correlation length of r0(z = 0.5) ~ 3.0 +/- 0.4 h-1 Mpc, about a factor of 2 larger than the correlation length at z = 0.5 derived from the Canada-France Redshift Survey (CFRS). The small volume sampled by the CFRS and other deep redshift probes, however, makes these spatial surveys strongly susceptible to cosmic scatter and will tend to bias their derived correlation lengths toward the low end. Our results are consistent with redshift distributions in which ~30%-50% of the galaxies at I = 23 lie at z > 1. The best-fit power-law slope of the correlation function remains independent of I magnitude for I <= 22. At fainter limits, there is a suggestive trend toward flatter slopes that occurs at fluxes consistent with similar trends seen by Neuschaffer & Windhorst and Campos and coworkers

  13. The Team Keck Redshift Survey 2: MOSFIRE Spectroscopy of the GOODS-North Field

    NASA Astrophysics Data System (ADS)

    Wirth, Gregory D.; Trump, Jonathan R.; Barro, Guillermo; Guo, Yicheng; Koo, David C.; Liu, Fengshan; Kassis, Marc; Lyke, Jim; Rizzi, Luca; Campbell, Randy; Goodrich, Robert W.; Faber, S. M.

    2015-11-01

    We present the Team Keck Redshift Survey 2 (TKRS2), a near-infrared spectral observing program targeting selected galaxies within the CANDELS subsection of the GOODS-North Field. The TKRS2 program exploits the unique capabilities of the Multi-Object Spectrometer For Infra-Red Exploration (MOSFIRE), which entered service on the Keck I telescope in 2012 and contributes substantially to the study of galaxy spectral features at redshifts inaccessible to optical spectrographs. The TKRS2 project targets 97 galaxies drawn from samples that include z ≈ 2 emission-line galaxies with features observable in the JHK bands as well as lower-redshift targets with features in the Y band. We present a detailed measurement of MOSFIRE’s sensitivity as a function of wavelength, including the effects of telluric features across the YJHK filters. The largest utility of our survey is in providing rest-frame-optical emission lines for z > 1 galaxies, and we demonstrate that the ratios of strong, optical emission lines of z ≈ 2 galaxies suggest the presence of either higher N/O abundances than are found in z ≈ 0 galaxies or low-metallicity gas ionized by an active galactic nucleus. We have released all TKRS2 data products into the public domain to allow researchers access to representative raw and reduced MOSFIRE spectra. Based in part on data obtained at the W. M. Keck Observatory, which operates as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The generous financial support of the W. M. Keck Foundation made the Observatory possible.

  14. EARLY-TYPE GALAXIES IN THE PEARS SURVEY: PROBING THE STELLAR POPULATIONS AT MODERATE REDSHIFT

    SciTech Connect

    Ferreras, Ignacio; Pasquali, Anna; Malhotra, Sangeeta; Rhoads, James; Cohen, Seth; Windhorst, Rogier; Pirzkal, Nor; Grogin, Norman; Koekemoer, Anton M.; Panagia, Nino; Lisker, Thorsten; Daddi, Emanuele; Hathi, Nimish P.

    2009-11-20

    Using Hubble Space Telescope (HST)/Advanced Camera for Surveys (ACS) slitless grism spectra from the PEARS program, we study the stellar populations of morphologically selected early-type galaxies in the GOODS North and South fields. The sample-extracted from a visual classification of the (v2.0) HST/ACS images and restricted to redshifts z > 0.4-comprises 228 galaxies (i {sub F775W} < 24 mag, AB) out to z approx< 1.3 over 320 arcmin{sup 2}, with a median redshift z {sub M} = 0.75. This work significantly increases our previous sample from the GRAPES survey in the HUDF (18 galaxies over approx11 arcmin{sup 2}). The grism data allow us to separate the sample into 'red' and 'blue' spectra, with the latter comprising 15% of the total. Three different grids of models parameterizing the star formation history are used to fit the low-resolution spectra. Over the redshift range of the sample-corresponding to a cosmic age between 5 and 10 Gyr-we find a strong correlation between stellar mass and average age, whereas the spread of ages (defined by the root mean square of the distribution) is roughly approx1 Gyr and independent of stellar mass. The best-fit parameters suggest that it is the formation epoch and not the formation timescale that best correlates with mass in early-type galaxies. This result-along with the recently observed lack of evolution of the number density of massive galaxies-motivates the need for a channel of (massive) galaxy formation bypassing any phase in the blue cloud, as suggested by the simulations of Dekel et al.

  15. Two Micron All Sky Survey Photometric Redshift Catalog: A Comprehensive Three-dimensional Census of the Whole Sky

    NASA Astrophysics Data System (ADS)

    Bilicki, Maciej; Jarrett, Thomas H.; Peacock, John A.; Cluver, Michelle E.; Steward, Louise

    2014-01-01

    Key cosmological applications require the three-dimensional (3D) galaxy distribution on the entire celestial sphere. These include measuring the gravitational pull on the Local Group, estimating the large-scale bulk flow, and testing the Copernican principle. However, the largest all-sky redshift surveys—the 2MASS Redshift Survey and IRAS Point Source Catalog Redshift Survey—have median redshifts of only z = 0.03 and sample the very local universe. All-sky galaxy catalogs exist that reach much deeper—SuperCOSMOS in the optical, the Two Micron All Sky Survey (2MASS) in the near-IR, and WISE in the mid-IR—but these lack complete redshift information. At present, the only rapid way toward larger 3D catalogs covering the whole sky is through photometric redshift techniques. In this paper we present the 2MASS Photometric Redshift catalog (2MPZ) containing one million galaxies, constructed by cross-matching Two Micron All Sky Survey Extended Source Catalog (2MASS XSC), WISE, and SuperCOSMOS all-sky samples and employing the artificial neural network approach (the ANNz algorithm), trained on such redshift surveys as the Sloan Digital Sky Survey, 6dFGS, and 2dFGRS. The derived photometric redshifts have errors nearly independent of distance, with an all-sky accuracy of σ z = 0.015 and a very small percentage of outliers. In this way, we obtain redshift estimates with a typical precision of 12% for all the 2MASS XSC galaxies that lack spectroscopy. In addition, we have made an early effort toward probing the entire 3D sky beyond 2MASS, by pairing up WISE with SuperCOSMOS and training the ANNz on GAMA redshift data currently reaching to z med ~ 0.2. This has yielded photo-z accuracies comparable to those in the 2MPZ. These all-sky photo-z catalogs, with a median z ~ 0.1 for the 2MPZ, and significantly deeper for future WISE-based samples, will be the largest and most complete of their kind for the foreseeable future.

  16. An ANN Approach to Classification of Galaxy Spectra for the 2DF Galaxy Redshift Survey

    NASA Astrophysics Data System (ADS)

    Folkes, S. R.; Lahav, O.; Maddox, S. J.

    We present a method for automated classification of galaxies with low signal-to-noise (S/N) spectra typical of redshift surveys. We develop spectral simulations based on the parameters for the 2dF Galaxy Redshift Survey, and with these simulations we investigate the technique of Principal Component Analysis when applied specifically to spectra of low S/N. We relate the objective principal components to features in the spectra and use a small number of components to successfully reconstruct the underlying signal from the low quality spectra. Using the principal components as input, we train an Artificial Neural Network (ANN) to classify the noisy simulated spectra into morphological classes, revealing the success of the classification against the observed bJ magnitude of the source, which we compare with alternative methods of classification. We find that more than 90% of our sample of normal galaxies are correctly classified into one of five broad morphological classes for simulations at bJ = 19.7. We also show the application of these methods to spectra from other sources.

  17. High efficiency SNAP survey for Lyman alpha emitters at low redshift

    NASA Astrophysics Data System (ADS)

    McCandliss, Stephan

    2014-10-01

    The goal of this proposal is to provide the first statistically significant survey of star-forming galaxies with Lyman alpha emission at redshifts 0.02 < z < 0.24. It will provide an overall assessment of the evolution in Lyman alpha luminosity at the lowest redshifts and allowed detailed studies of the physical processes that shape the Lyman alpha profile and govern escape in multi-phase, kinematic media. It will also provide a serendipitous search for star-forming galaxies with high LyC escape fractions that are analogous to those commonly invoked as being responsible for initiating and sustaining the epoch of reionization. The SNAP survey proposed here employing the G140L mode of COS offers a highly efficient means to examine the Lyman alpha emission properties of our candidate emitters and to inform our choice of objects that could warrant deeper integrations in future observations. These data have high UV legacy value and will be of broad interest to the star-forming galaxy community, so we have elected to waive the proprietary period.

  18. The Brightest of Reionizing Galaxies Survey: A Protocluster Candidate at redshift z 8

    NASA Astrophysics Data System (ADS)

    Trenti, Michele; Collective, BoRG

    2012-01-01

    Theoretical and numerical modeling of dark-matter halo assembly predicts that the most luminous galaxies at high redshift are surrounded by overdensities of fainter companions. We test this prediction with HST observations acquired by our Brightest of Reionizing Galaxies (BoRG) survey, finding a correlation between counts of bright and faint candidate galaxies at z 8 which is significant at >99.8% confidence. Furthermore, the best z 8 bright candidate of the survey is associated to the most significant overdensity of faint galaxies (4 additional sources within a region of diameter 70arcsec, where only 0.2 where expected), indicating that we identified a candidate protocluster at confidence >99.99%. We modeled the overdensity by means of cosmological simulations and estimate that the principal dark matter halo has mass Mh (4-7)x1011Msun ( 5sigma density peak) and is surrounded by several Mh 1011Msun halos which could host the fainter dropouts. In this scenario, we predict that all halos will eventually merge into a Mh>2x1014Msun galaxy cluster by z=0. Follow-up observations with ground and space based telescopes are required to secure the z 8 nature of the overdensity, discover new members, and measure their precise redshift.

  19. H-alpha Imaging Survey of Low-Redshift Cluster Dwarf Galaxies

    NASA Astrophysics Data System (ADS)

    Barkhouse, Wayne; Kalawila, Sandanuwan; Rude, Cody; Sultanova, Madina; Archer, Haylee Nichole; Foote, Gregory

    2016-01-01

    We describe our on-going H-alpha imaging survey to measure the star formation activity of dwarf galaxies selected from a sample of low-redshift (0.02 < z< 0.15) galaxy clusters using the KPNO 4-meter telescope+Mosaic camera. H-alpha observations are obtained using the narrow-band BATC filters centered on the redshifted H-alpha emission line. The continuum-subtracted H-alpha images allow us to constrain star formation rates via the correlation between star formation and H-alpha luminosity and equivalent width. The impact of the cluster environment can be quantified using radial-dependent measures of the star formation rate within individual clusters, and by comparing clusters within our sample on a cluster-to-cluster basis. Comparison of our H-alpha measurements to CFHT u-band imaging data of our cluster sample, permits us to explore the correlation between the UV continuum and H-alpha emission of the dwarf galaxy population. The goal of our survey is to further understand the mechanism that is responsible for the enhancement/quenching of star formation as dwarf galaxies fall into the galaxy cluster environment.

  20. Redshift Survey of Galaxies around a Selected Sample of Compact Groups

    NASA Astrophysics Data System (ADS)

    de Carvalho, Reinaldo R.; Ribeiro, André L. B.; Capelato, Hugo V.; Zepf, Stephen E.

    We report the results of a spectroscopic survey of faint galaxies in the regions surrounding Hickson compact groups. Our sample is composed of 17 groups within 9000 km s-1. The spectra were taken at the prime focus of the Tololo 4 m telescope, using the ARGUS fiber-fed spectrograph. From these observations, redshifts were determined for the faint galaxies previously identified by de Carvalho, Ribeiro, & Zepf in the surroundings of the groups. Statistical methods were applied to the resultant catalog in order to determine the kinematical structure of each group. This analysis confirms the idea that the Hickson sample of compact groups contains a wide variety of projection and dynamical configurations. Our results demonstrate the necessity of new spectroscopic surveys around compact groups in order to assess their complete velocity distribution.

  1. The DEEP2 Galaxy Redshift Survey: Clustering of Galaxies in Early Data

    NASA Astrophysics Data System (ADS)

    Coil, Alison L.; Davis, Marc; Madgwick, Darren S.; Newman, Jeffrey A.; Conselice, Christopher J.; Cooper, Michael; Ellis, Richard S.; Faber, S. M.; Finkbeiner, Douglas P.; Guhathakurta, Puragra; Kaiser, Nick; Koo, David C.; Phillips, Andrew C.; Steidel, Charles C.; Weiner, Benjamin J.; Willmer, Christopher N. A.; Yan, Renbin

    2004-07-01

    We measure the two-point correlation function ξ(rp,π) in a sample of 2219 galaxies between z=0.7 and 1.35 to a magnitude limit of RAB=24.1 from the first season of the DEEP2 Galaxy Redshift Survey. From ξ(rp,π) we recover the real-space correlation function, ξ(r), which we find can be approximated within the errors by a power law, ξ(r)=(r/r0)-γ, on scales ~0.1-10 h-1 Mpc. In a sample with an effective redshift of zeff=0.82, for a ΛCDM cosmology we find r0=3.53+/-0.81 h-1 Mpc (comoving) and γ=1.66+/-0.12, while in a higher redshift sample with zeff=1.14 we find r0=3.12+/-0.72 h-1 Mpc and γ=1.66+/-0.12. These errors are estimated from mock galaxy catalogs and are dominated by the cosmic variance present in the current data sample. We find that red, absorption-dominated, passively evolving galaxies have a larger clustering scale length, r0, than blue, emission-line, actively star-forming galaxies. Intrinsically brighter galaxies also cluster more strongly than fainter galaxies at z~=1. Our results imply that the DEEP2 galaxies have an effective bias b=0.96+/-0.13 if σ8DM=1 today or b=1.19+/-0.16 if σ8DM=0.8 today. This bias is lower than that predicted by semianalytic simulations at z~=1, which may be the result of our R-band target selection. We discuss possible evolutionary effects within our survey volume, and we compare our results with galaxy-clustering studies at other redshifts, noting that our star-forming sample at z~=1 has selection criteria very similar to the Lyman break galaxies at z~=3 and that our red, absorption-line sample displays a clustering strength comparable to the expected clustering of the Lyman break galaxy descendants at z~=1. Our results demonstrate that galaxy-clustering properties as a function of color, spectral type, and luminosity seen in the local universe were largely in place by z~=1.

  2. An HST/COS Survey of the Low-redshift Intergalactic Medium. I. Survey, Methodology, and Overall Results

    NASA Astrophysics Data System (ADS)

    Danforth, Charles W.; Keeney, Brian A.; Tilton, Evan M.; Shull, J. Michael; Stocke, John T.; Stevans, Matthew; Pieri, Matthew M.; Savage, Blair D.; France, Kevin; Syphers, David; Smith, Britton D.; Green, James C.; Froning, Cynthia; Penton, Steven V.; Osterman, Steven N.

    2016-02-01

    We use high-quality, medium-resolution Hubble Space Telescope/Cosmic Origins Spectrograph (HST/COS) observations of 82 UV-bright active galactic nuclei (AGNs) at redshifts zAGN < 0.85 to construct the largest survey of the low-redshift intergalactic medium (IGM) to date: 5138 individual extragalactic absorption lines in H i and 25 different metal-ion species grouped into 2611 distinct redshift systems at zabs < 0.75 covering total redshift pathlengths ΔzH i = 21.7 and ΔzO vi = 14.5. Our semi-automated line-finding and measurement technique renders the catalog as objectively defined as possible. The cumulative column density distribution of H i systems can be parametrized d{ N }(\\gt N)/{dz} = {C}14{(N/{10}14{{cm}}-2)}-(β -1), with C14 = 25 ± 1 and β = 1.65 ± 0.02. This distribution is seen to evolve both in amplitude, {C}14\\propto {(1+z)}2.3+/- 0.1, and slope β(z) = 1.75-0.31 z for z ≤ 0.47. We observe metal lines in 418 systems, and find that the fraction of IGM absorbers detected in metals is strongly dependent on {N}{{H}{{I}}}. The distribution of O vi absorbers appears to evolve in the same sense as the Lyα forest. We calculate contributions to Ωb from different components of the low-z IGM and determine the Lyα decrement as a function of redshift. IGM absorbers are analyzed via a two-point correlation function in velocity space. We find substantial clustering of H i absorbers on scales of Δv = 50-300 km s-1 with no significant clustering at Δv ≳ 1000 km s-1. Splitting the sample into strong and weak absorbers, we see that most of the clustering occurs in strong, NH i ≳ 1013.5 cm-2, metal-bearing IGM systems. The full catalog of absorption lines and fully reduced spectra is available via the Mikulski Archive for Space Telescopes (MAST) as a high-level science product at http://archive.stsci.edu/prepds/igm/. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained from the data archive at the Space Telescope Science

  3. Special Needs Survey. Final Report.

    ERIC Educational Resources Information Center

    Adult Education Linkage Services, Troy, PA.

    Adult Education Linkage Services undertook a project for the Bureau of Adult Basic and Literacy Education (ABLE) to identify characteristics of programs and services available to adult learners who attend ABLE-funded programs in Pennsylvania. Results of a survey of 249 ABLE-funded programs identified 33 programs serving one or more of 6 special…

  4. Spectroscopic identification of a redshift 1.55 supernova host galaxy from the Subaru Deep Field Supernova Survey

    NASA Astrophysics Data System (ADS)

    Frederiksen, Teddy F.; Graur, Or; Hjorth, Jens; Maoz, Dan; Poznanski, Dovi

    2014-03-01

    Context. The Subaru Deep Field (SDF) Supernova Survey discovered ten Type Ia supernovae (SNe Ia) in the redshift range 1.5 < z < 2.0, determined solely from photometric redshifts of the host galaxies. However, photometric redshifts might be biased, and the SN sample could be contaminated by active galactic nuclei (AGNs). Aims: We aim to obtain the first robust redshift measurement and classification of a z > 1.5 SDF SN Ia host galaxy candidate. Methods: We use the X-shooter (U-to-K-band) spectrograph on the Very Large Telescope to allow the detection of different emission lines in a wide spectral range. Results: We measure a spectroscopic redshift of 1.54563 ± 0.00027 of hSDF0705.25, consistent with its photometric redshift of 1.552 ± 0.018. From the strong emission-line spectrum we rule out AGN activity, thereby confirming the optical transient as a SN. The host galaxy follows the fundamental metallicity relation showing that the properties of this high-redshift SN Ia host galaxy is similar to other field galaxies. Conclusions: Spectroscopic confirmation of additional SDF SN hosts would be required to confirm the cosmic SN rate evolution measured in the SDF. Based on observations made with ESO telescopes at the La Silla Paranal Observatory under program ID 089.A-0739.

  5. The ESO Slice Project (ESP) galaxy redshift survey. II. The luminosity function and mean galaxy density.

    NASA Astrophysics Data System (ADS)

    Zucca, E.; Zamorani, G.; Vettolani, G.; Cappi, A.; Merighi, R.; Mignoli, M.; Stirpe, G. M.; MacGillivray, H.; Collins, C.; Balkowski, C.; Cayatte, V.; Maurogordato, S.; Proust, D.; Chincarini, G.; Guzzo, L.; Maccagni, D.; Scaramella, R.; Blanchard, A.; Ramella, M.

    1997-10-01

    The ESO Slice Project (ESP) is a galaxy redshift survey we have recently completed as an ESO Key-Project over about 23 square degrees, in a region near the South Galactic Pole. The survey is nearly complete to the limiting magnitude b_J_=19.4 and consists of 3342 galaxies with reliable redshift determination. The ESP survey is intermediate between shallow, wide angle samples and very deep, one-dimensional pencil beams: spanning a volume of ~5x10^4^h^-3^Mpc^3^ at the sensitivity peak (z~0.1), it provides an accurate determination of the "local" luminosity function and the mean galaxy density. We find that, although a Schechter function (with α=-1.22, M^*^_bJ_=-19.61+5logh and φ^*^=0.020h^3^/Mpc^3^) is an acceptable representation of the luminosity function over the entire range of magnitudes (M_bJ_<=-12.4+5logh), our data suggest the presence of a steepening of the luminosity function for M_bJ_>=-17+5logh. Such a steepening at the faint end of the luminosity function, well fitted by a power law with slope β~-1.6, is almost completely due to galaxies with emission lines: in fact, dividing our galaxies into two samples, i.e. galaxies with and without emission lines, we find significant differences in their luminosity functions. In particular, galaxies with emission lines show a significantly steeper slope and a fainter M^*^. The amplitude and the α and M^*^ parameters of our luminosity function are in good agreement with those of the AUTOFIB redshift survey (Ellis et al. 1996). Vice-versa, our amplitude is significantly higher, by a factor ~1.6 at M~M^*^, than that found for both the Stromlo-APM (Loveday et al. 1992) and the Las Campanas (Lin et al. 1996) redshift surveys. Also the faint end slope of our luminosity function is significantly steeper than that found in these two surveys. The galaxy number density for M_bJ_<=-16+5logh is well determined (n{bar}=0.08+/-0.015h^3^/Mpc^3^). Its estimate for M_bJ_<=-12.4+5logh is more uncertain, ranging from n{bar}=0.28h

  6. New Approaches to Photometric Redshift Prediction Via Gaussian Process Regression in the Sloan Digital Sky Survey

    NASA Astrophysics Data System (ADS)

    Way, M. J.; Foster, L. V.; Gazis, P. R.; Srivastava, A. N.

    2009-11-01

    Expanding upon the work of Way & Srivastava we demonstrate how the use of training sets of comparable size continue to make Gaussian process regression (GPR) a competitive approach to that of neural networks and other least-squares fitting methods. This is possible via new large-size matrix inversion techniques developed for Gaussian processes (GPs) that do not require that the kernel matrix be sparse. This development, combined with a neural-network kernel function appears to give superior results for this problem. Our best-fit results for the Sloan Digital Sky Survey (SDSS) Main Galaxy Sample using u, g, r, i, z filters gives an rms error of 0.0201 while our results for the same filters in the luminous red galaxy sample yield 0.0220. We also demonstrate that there appears to be a minimum number of training-set galaxies needed to obtain the optimal fit when using our GPR rank-reduction methods. We find that morphological information included with many photometric surveys appears, for the most part, to make the photometric redshift evaluation slightly worse rather than better. This would indicate that most morphological information simply adds noise from the GP point of view in the data used herein. In addition, we show that cross-match catalog results involving combinations of the Two Micron All Sky Survey, SDSS, and Galaxy Evolution Explorer have to be evaluated in the context of the resulting cross-match magnitude and redshift distribution. Otherwise one may be misled into overly optimistic conclusions.

  7. THE HUBBLE SPACE TELESCOPE CLUSTER SUPERNOVA SURVEY. II. THE TYPE Ia SUPERNOVA RATE IN HIGH-REDSHIFT GALAXY CLUSTERS

    SciTech Connect

    Barbary, K.; Amanullah, R.; Fakhouri, H. K.; Goldhaber, G.; Huang, X.; Aldering, G.; Dawson, K. S.; Faccioli, L.; Hsiao, E.; Brodwin, M.; Connolly, N.; Doi, M.; Ihara, Y.; Eisenhardt, P.; Fadeyev, V.; Fruchter, A. S.; Gilbank, D. G.; Gladders, M. D.; Goobar, A.; Hattori, T.; Collaboration: Supernova Cosmology Project; and others

    2012-01-20

    We report a measurement of the Type Ia supernova (SN Ia) rate in galaxy clusters at 0.9 < z < 1.46 from the Hubble Space Telescope Cluster Supernova Survey. This is the first cluster SN Ia rate measurement with detected z > 0.9 SNe. Finding 8 {+-} 1 cluster SNe Ia, we determine an SN Ia rate of 0.50{sup +0.23}{sub -0.19} (stat){sup +0.10}{sub -0.09} (sys) h{sup 2}{sub 70} SNuB (SNuB {identical_to} 10{sup -12} SNe L{sup -1}{sub Sun ,B} yr{sup -1}). In units of stellar mass, this translates to 0.36{sup +0.16}{sub -0.13} (stat){sup +0.07}{sub -0.06} (sys) h{sup 2}{sub 70} SNuM (SNuM {identical_to} 10{sup -12} SNe M{sup -1}{sub Sun} yr{sup -1}). This represents a factor of Almost-Equal-To 5 {+-} 2 increase over measurements of the cluster rate at z < 0.2. We parameterize the late-time SN Ia delay time distribution (DTD) with a power law: {Psi}(t){proportional_to}t{sup s} . Under the approximation of a single-burst cluster formation redshift of z{sub f} = 3, our rate measurement in combination with lower-redshift cluster SN Ia rates constrains s = -1.41{sup +0.47}{sub -0.40}, consistent with measurements of the DTD in the field. This measurement is generally consistent with expectations for the 'double degenerate' scenario and inconsistent with some models for the 'single degenerate' scenario predicting a steeper DTD at large delay times. We check for environmental dependence and the influence of younger stellar populations by calculating the rate specifically in cluster red-sequence galaxies and in morphologically early-type galaxies, finding results similar to the full cluster rate. Finally, the upper limit of one hostless cluster SN Ia detected in the survey implies that the fraction of stars in the intra-cluster medium is less than 0.47 (95% confidence), consistent with measurements at lower redshifts.

  8. DISCOVERY OF NINE INTERMEDIATE-REDSHIFT COMPACT QUIESCENT GALAXIES IN THE SLOAN DIGITAL SKY SURVEY

    SciTech Connect

    Damjanov, Ivana; Chilingarian, Igor; Hwang, Ho Seong; Geller, Margaret J.

    2013-10-01

    We identify nine galaxies with dynamical masses of M {sub dyn} ∼> 10{sup 10} M {sub ☉} as photometric point sources, but with redshifts between z = 0.2 and z = 0.6, in the Sloan Digital Sky Survey (SDSS) spectro-photometric database. All nine galaxies have archival Hubble Space Telescope images. Surface brightness profile fitting confirms that all nine galaxies are extremely compact (0.4 < R {sub e,c} < 6.6 kpc with the median R {sub e,c} = 0.74 kpc) for their velocity dispersion (110 < σ < 340 km s{sup –1}; median σ = 178 km s{sup –1}). From the SDSS spectra, three systems are dominated by very young stars; the other six are older than ∼1 Gyr (two are E+A galaxies). The three young galaxies have disturbed morphologies and the older systems have smooth profiles consistent with a single-Sérsic function. All nine lie below the z ∼ 0 velocity dispersion-half-light radius relation. The most massive system—SDSSJ123657.44+631115.4—lies right within the locus for massive compact z > 1 galaxies and the other eight objects follow the high-redshift dynamical size-mass relation.

  9. Detecting the integrated Sachs-Wolfe effect with high-redshift 21-cm surveys

    NASA Astrophysics Data System (ADS)

    Raccanelli, Alvise; Kovetz, Ely; Dai, Liang; Kamionkowski, Marc

    2016-04-01

    We investigate the possibility of detecting the integrated Sachs-Wolfe (ISW) effect by cross-correlating 21-cm surveys at high redshifts with galaxies in a way similar to the usual CMB-galaxy cross-correlation. The high-redshift 21-cm signal is dominated by CMB photons that travel freely without interacting with the intervening matter, and hence its late-time ISW signature should correlate extremely well with that of the CMB at its peak frequencies. Using the 21-cm temperature brightness instead of the CMB would thus be a further check of the detection of the ISW effect, measured by different instruments at different frequencies and suffering from different systematics. We also study the ISW effect on the photons that are scattered by HI clouds. We show that a detection of the unscattered photons is achievable with planned radio arrays, while one using scattered photons will require advanced radio interferometers, either an extended version of the planned Square Kilometre Array or futuristic experiments such as a lunar radio array.

  10. Spectroscopic Determination of the Low Redshift Type Ia Supernova Rate from the Sloan Digital Sky Survey

    SciTech Connect

    Krughoff, K. S.; Connolly, Andrew J.; Frieman, Joshua; SubbaRao, Mark; Kilper, Gary; Schneider, Donald P.

    2011-04-10

    Supernova rates are directly coupled to high mass stellar birth and evolution. As such, they are one of the few direct measures of the history of cosmic stellar evolution. In this paper we describe an probabilistic technique for identifying supernovae within spectroscopic samples of galaxies. We present a study of 52 type Ia supernovae ranging in age from -14 days to +40 days extracted from a parent sample of \\simeq 50,000 spectra from the SDSS DR5. We find a Supernova Rate (SNR) of 0.472^{+0.048}_{-0.039}(Systematic)^{+0.081}_{-0.071}(Statistical)SNu at a redshift of = 0.1. This value is higher than other values at low redshift at the 1{\\sigma}, but is consistent at the 3{\\sigma} level. The 52 supernova candidates used in this study comprise the third largest sample of supernovae used in a type Ia rate determination to date. In this paper we demonstrate the potential for the described approach for detecting supernovae in future spectroscopic surveys.

  11. Mapping the Galaxy Color-Redshift Relation: Optimal Photo-z Calibration Strategies for Cosmology Surveys

    NASA Astrophysics Data System (ADS)

    Masters, Daniel C.; Capak, Peter L.; Stern, Daniel; Rhodes, Jason; Mobasher, Bahram; Schmidt, Samuel; Steinhardt, Charles L.; Faisst, Andreas; Speagle, Josh S.

    2016-01-01

    A primary objective of the upcoming dark energy surveys LSST, Euclid, and WFIRST is to map the 3D distribution of matter over a significant fraction of the universe via the weak lensing cosmic shear field. Doing so will require accurate distance estimates to billions of faint galaxies, meaning that photo-z's will be essential for the ultimate scientific success of these missions. Because galaxy colors drive photo-z estimates, spectroscopic calibration samples must at least be representative in color. Here we present a technique, based on the self-organizing map (Kohonen 1990), to map the empirical distribution of galaxies in the high-dimensional color space of a given survey. We apply the technique to Euclid-like data for ~131k galaxies from the COSMOS survey, allowing us to determine where - in galaxy color space - spectroscopic coverage exists and where it is systematically missing. We show that the mapping technique lets us develop efficient spectroscopic sampling strategies to measure the color-redshift relation by focusing effort on poorly constrained regions of multicolor space. We discuss the nature of the galaxies in un-sampled regions of galaxy color space, and show that a fiducial survey with Keck (making use of LRIS, DEIMOS, and MOSFIRE) could meet the Euclid calibration requirements in ~40 nights of observing.

  12. Superclusters of galaxies from the 2dF redshift survey. 2. Comparison with simulations

    SciTech Connect

    Einasto, Jaan; Einasto, M.; Saar, E.; Tago, E.; Liivamagi, L.J.; Joeveer, M.J; Suhhonenko, I.; Hutsi, G.; Jaaniste, J.; Heinamaki, P.; Muller, V.; Knebe, A.; Tucker, D.; /Fermilab

    2006-04-01

    We investigate properties of superclusters of galaxies found on the basis of the 2dF Galaxy Redshift Survey, and compare them with properties of superclusters from the Millennium Simulation.We study the dependence of various characteristics of superclusters on their distance from the observer, on their total luminosity, and on their multiplicity. The multiplicity is defined by the number of Density Field (DF) clusters in superclusters. Using the multiplicity we divide superclusters into four richness classes: poor, medium, rich and extremely rich.We show that superclusters are asymmetrical and have multi-branching filamentary structure, with the degree of asymmetry and filamentarity being higher for the more luminous and richer superclusters. The comparison of real superclusters with Millennium superclusters shows that most properties of simulated superclusters agree very well with real data, the main differences being in the luminosity and multiplicity distributions.

  13. New upper limit on the total neutrino mass from the 2 degree field galaxy redshift survey.

    PubMed

    Elgarøy, Ø; Lahav, O; Percival, W J; Peacock, J A; Madgwick, D S; Bridle, S L; Baugh, C M; Baldry, I K; Bland-Hawthorn, J; Bridges, T; Cannon, R; Cole, S; Colless, M; Collins, C; Couch, W; Dalton, G; De Propris, R; Driver, S P; Efstathiou, G P; Ellis, R S; Frenk, C S; Glazebrook, K; Jackson, C; Lewis, I; Lumsden, S; Maddox, S; Norberg, P; Peterson, B A; Sutherland, W; Taylor, K

    2002-08-01

    We constrain f(nu) identical with Omega(nu)/Omega(m), the fractional contribution of neutrinos to the total mass density in the Universe, by comparing the power spectrum of fluctuations derived from the 2 Degree Field Galaxy Redshift Survey with power spectra for models with four components: baryons, cold dark matter, massive neutrinos, and a cosmological constant. Adding constraints from independent cosmological probes we find f(nu)<0.13 (at 95% confidence) for a prior of 0.1

  14. VizieR Online Data Catalog: Team Keck Redshift Survey 2 (TKRS2) (Wirth+, 2015)

    NASA Astrophysics Data System (ADS)

    Wirth, G. D.; Trump, J. R.; Barro, G.; Guo, Y.; Koo, D. C.; Liu, F.; Kassis, M.; Lyke, J.; Rizzi, L.; Campbell, R.; Goodrich, R. W.; Faber, S. M.

    2016-04-01

    We present the Team Keck Redshift Survey 2 (TKRS2), a spectroscopic survey of 97 distant galaxies exploiting the capabilities of the Multi-Object Spectrometer For Infra-Red Exploration (MOSFIRE) on the Keck I telescope at the W. M. Keck Observatory. MOSFIRE features a 2048*2048 pixel HAWAII-2RG HgCdTe detector array from Teledyne Imaging Sensors that couples high quantum efficiency with low noise and low dark current. The operating range of 0.97-2.41μm covers the YJHK infrared passbands, with wavelength coverage of 0.97-1.12μm in Y, 1.15-1.35μm in J, 1.47-1.80μm in H, and 1.95-2.40μm in K. The resolving power for the default slit width of 0.7" is R=3380 in Y, 3310 in J, 3660 in H, and 3620 in K, corresponding to full-width-half-maximum (FWHM) spectral resolutions of 3.1Å in Y, 3.7Å in J, 4.4Å in H, and 6.0Å in K. Our survey targets the south-central region of the GOODS-North survey field (Giavalisco et al. 2004, cat. II/261). We employed MOSFIRE to acquire spectra in the GOODS-North field over a series of partial nights spanning the period from 2012 November to 2013 May. We present the results of our survey in Table3 and on the website (http://arcoiris.ucsc.edu/TKRS2/) devoted to the survey. (1 data file).

  15. BULK FLOWS FROM GALAXY LUMINOSITIES: APPLICATION TO 2MASS REDSHIFT SURVEY AND FORECAST FOR NEXT-GENERATION DATA SETS

    SciTech Connect

    Nusser, Adi; Branchini, Enzo; Davis, Marc E-mail: branchin@fis.uniroma3.it

    2011-07-10

    We present a simple method for measuring cosmological bulk flows from large redshift surveys, based on the apparent dimming or brightening of galaxies due to their peculiar motion. It is aimed at estimating bulk flows of cosmological volumes containing large numbers of galaxies. Constraints on the bulk flow are obtained by minimizing systematic variations in galaxy luminosities with respect to a reference luminosity function measured from the whole survey. This method offers two advantages over more popular bulk flow estimators: it is independent of error-prone distance indicators and of the poorly known galaxy bias. We apply the method to the Two Micron All Sky Survey redshift survey to measure the local bulk flows of spherical shells centered on the Milky Way (MW). The result is consistent with that obtained by Nusser and Davis using the SFI++ catalogue of Tully-Fisher distance indicators. We also make an assessment of the ability of the method to constrain bulk flows at larger redshifts (z = 0.1-0.5) from next-generation data sets. As a case study we consider the planned EUCLID survey. Using this method we will be able to measure a bulk motion of {approx}200 km s{sup -1} of 10{sup 6} galaxies with photometric redshifts, at the 3{sigma} level for both z {approx} 0.15 and z {approx} 0.5. Thus, the method will allow us to put strong constraints on dark energy models as well as alternative theories for structure formation.

  16. The bispectrum of galaxies from high-redshift galaxy surveys: Primordial non-Gaussianity and non-linear galaxy bias

    SciTech Connect

    Sefusatti, Emiliano; Komatsu, Eiichiro; /Texas U., Astron. Dept.

    2007-05-01

    The greatest challenge in the interpretation of galaxy clustering data from any surveys is galaxy bias. Using a simple Fisher matrix analysis, we show that the bispectrum provides an excellent determination of linear and non-linear bias parameters of intermediate and high-z galaxies, when all measurable triangle configurations down to mildly non-linear scales, where perturbation theory is still valid, are included. The bispectrum is also a powerful probe of primordial non-Gaussianity. The planned galaxy surveys at z {approx}> 2 should yield constraints on non-Gaussian parameters, f{sub NL}{sup loc.} and f{sub NL}{sup eq.}, that are comparable to, or even better than, those from CMB experiments. We study how these constraints improve with volume, redshift range, as well as the number density of galaxies. Finally we show that a halo occupation distribution may be used to improve these constraints further by lifting degeneracies between gravity, bias, and primordial non-Gaussianity.

  17. The Galaxy Mass Function at High-Redshift from the Largest Available Spitzer-Based Survey (SERVS)

    NASA Astrophysics Data System (ADS)

    Morice-Atkinson, Xan; Maraston, Claudia; Lacy, Mark; Capozzi, Diego

    2015-08-01

    We exploit the largest (18 deg2) and deepest (AB = 23.1) galaxy and QSO survey available up to date of five highly observed astronomical fields (SERVS) to derive the galaxy stellar mass function and detailed galaxy properties as a function of cosmic time. SERVS obtained Spitzer 3.6µm and 4.5µm magnitudes for ~1 million galaxies up to redshift ~6, which we complement with multi-wavelength data from other on-going surveys, including VIDEO, GALEX, CFHTLS, UKIDSS, etc. in order to perform full SED fitting to models. The power of Spitzer data is its sensitivity to evolved stars at high-redshift, which allows us to better constrain the galaxy star formation histories. The wide area and depth of SERVS was designed precisely to capture the light from the most massive galaxies up to high-redshift. Results and comparison with the literature will be presented.

  18. The VLT LBG redshift survey - V. Characterizing the z = 3.1 Lyman α emitter population

    NASA Astrophysics Data System (ADS)

    Bielby, R. M.; Tummuangpak, P.; Shanks, T.; Francke, H.; Crighton, N. H. M.; Bañados, E.; González-López, Jorge; Infante, L.; Orsi, A.

    2016-03-01

    We present a survey of z ˜ 3 Lyα emitters (LAEs) within the fields of the VLT Lyman break galaxies (LBG) redshift survey. The data encompass five independent survey fields co-spatial with spectroscopic LBG data and covering a larger total area than previously analysed for LAE number counts and clustering. This affords an improved analysis over previous work by minimizing the effects of cosmic variance and allowing the cross-clustering analysis of LAEs and LBGs. Our photometric sample consists of ≈600 LAE candidates, over an area of 1.07 deg2, with equivalent widths of ≳65 Å and a flux limit of ≈2 × 10-17 erg cm-2 s-1. From spectroscopic follow-up, we measured a success rate of 78 ± 18 per cent. We find the R-band continuum luminosity function to be ˜10 times lower than the luminosity function of LBGs at this redshift, consistent with previous studies. Exploiting the large area of the survey, we estimate the LAE auto-correlation function and find a clustering length of r0 = 2.86 ± 0.33 h-1 Mpc, low compared to the z ˜ 3 LBG population, but somewhat higher than previous LAE measurements. This corresponds to a median halo mass of MDM = 1011.0±0.3 h-1 M⊙. We present an analysis of clustering length versus continuum magnitude and find that the measurements for LAEs and LBGs are consistent at faint magnitudes. Our combined data set of LAEs and LBGs allows us to measure, for the first time, the LBG-LAE cross-correlation, finding a clustering length of r0 = 3.29 ± 0.57 h-1 Mpc and a LAE halo mass of 1011.1±0.4 h-1 M⊙. Overall, we conclude that LAEs inhabit primarily low-mass haloes, but form a relatively small proportion of the galaxy population found in such haloes.

  19. VLA observations of unidentified Leiden-Berkeley Deep-Survey sources - Luminosity and redshift dependence of spectral properties

    NASA Technical Reports Server (NTRS)

    Kapahi, Vijay K.; Kulkarni, Vasant K.

    1990-01-01

    VLA observations of a complete subset of the Leiden-Berkeley Deep Survey sources that have S(1.4 GHz) greater than 10 mJy and are not optically identified down to F=22 mag are reported. By comparing the spectral and structural properties of the sources with samples from the literature, an attempt was made to disentangle the luminosity and redshift dependence of the spectral indices of extended emission in radio galaxies and of the incidence of compact steep-spectrum sources. It is found that the fraction of compact sources among those with a steep spectrum is related primarily to redshift, being much larger at high redshifts for sources of similar radio luminosity. Only a weak and marginally significant dependence of spectral indices of the extended sources on luminosity and redshift is found in samples selected at 1.4 and 2.7 GHz. It is pointed out that the much stronger correlation of spectral indices with luminosity may be arising partly from spectral curvature, and partly due to the preferential inclusion of very steep-spectrum sources from high redshift in low-frequency surveys.

  20. The Radio luminosity Function of Radio-Loud Quasars from the 7C Redshift Survey

    NASA Technical Reports Server (NTRS)

    Willott, Chris J.; Rawlings, Steve; Blundell, Katherine M.; Lacy, Mark

    1998-01-01

    We present a complete sample of 24 radio-loud quasars (RLQs) from the new 7C Redshift Survey. Every quasar with a low-frequency (151 MHz) radio flux-density S(sub 151) > 0.5 Jy in two regions of the sky covering 0.013 sr is included; 23 of these have sufficient extended flux to meet the selection criteria, 18 of these have steep radio spectra (hereafter denoted as SSQs). The key advantage of this sample over most samples of RLQs is the lack of an optical magnitude limit. By combining the 7C and 3CRR samples, we have investigated the properties of RLQs as a function of redshift z and radio luminosity L(sub 151). We derive the radio luminosity function (RLF) of RLQs and find that the data are well fitted by a single power-law with slope alpha(sub 1) = 1.9 +/- 0.1 (for H(sub 0) = 50 km/s.Mpc, OMEGA(sub M) = 1, OMEGA(sub DELTA) = 0). We find that there must be a break in the RLQ RLF at log(sub 10)(L(sub 151)/W Hz.sr) approximately < or = 27, in order for the models to be consistent with the 7C and 6C source counts. The z-dependence of the RLF follows a one-tailed gaussian which peaks at z = 1.7 +/- 0.2. We find no evidence for a decline in the co-moving space density of RLQs at higher redshifts. A positive correlation between the radio and optical luminosities of SSQs is observed, confirming a result of Serjeant. We are able to rule out this correlation being due to selection effects or biases in our combined sample. The radio-optical correlation and best-fit model RLF enable us to estimate the distribution of optical magnitudes of quasars in samples selected at low radio frequencies, We con- clude that for samples with S(sub 151) approximately < or = 1 Jy one must use optical data significantly deeper than the POSS-I limit (R approximately equal 20), in order to avoid severe incompleteness.

  1. High-Redshift QSOs in the SWIRE Survey and the z~3 QSO Luminosity Function

    NASA Astrophysics Data System (ADS)

    Siana, Brian; Polletta, Maria del Carmen; Smith, Harding E.; Lonsdale, Carol J.; Gonzalez-Solares, Eduardo; Farrah, Duncan; Babbedge, Tom S. R.; Rowan-Robinson, Michael; Surace, Jason; Shupe, David; Fang, Fan; Franceschini, Alberto; Oliver, Seb

    2008-03-01

    We use a simple optical/infrared (IR) photometric selection of high-redshift QSOs that identifies a Lyman break in the optical photometry and requires a red IR color to distinguish QSOs from common interlopers. The search yields 100 z ~ 3 (U-dropout) QSO candidates with 19 < r' < 22 over 11.7 deg2 in the ELAIS-N1 (EN1) and ELAIS-N2 (EN2) fields of the Spitzer Wide-area Infrared Extragalactic (SWIRE) Legacy Survey. The z ~ 3 selection is reliable, with spectroscopic follow-up of 10 candidates confirming that they are all QSOs at 2.83 < z < 3.44. We find that our z ~ 4 (g'-dropout) sample suffers from both unreliability and incompleteness but present seven previously unidentified QSOs at 3.50 < z < 3.89. Detailed simulations show our z ~ 3 completeness to be ~80%-90% from 3.0 < z < 3.5, significantly better than the ~30%-80% completeness of the SDSS at these redshifts. The resulting luminosity function extends 2 mag fainter than SDSS and has a faint-end slope of β = - 1.42 +/- 0.15, consistent with values measured at lower redshift. Therefore, we see no evidence for evolution of the faint-end slope of the QSO luminosity function. Including the SDSS QSO sample, we have now directly measured the space density of QSOs responsible for ~70% of the QSO UV luminosity density at z ~ 3. We derive a maximum rate of H I photoionization from QSOs at z ~ 3.2, Γ = 4.8 × 10-13 s-1, about half of the total rate inferred through studies of the Lyα forest. Therefore, star-forming galaxies and QSOs must contribute comparably to the photoionization of H I in the intergalactic medium at z ~ 3. Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation.

  2. The zCOSMOS redshift survey: how group environment alters global downsizing trends

    NASA Astrophysics Data System (ADS)

    Iovino, A.; Cucciati, O.; Scodeggio, M.; Knobel, C.; Kovač, K.; Lilly, S.; Bolzonella, M.; Tasca, L. A. M.; Zamorani, G.; Zucca, E.; Caputi, K.; Pozzetti, L.; Oesch, P.; Lamareille, F.; Halliday, C.; Bardelli, S.; Finoguenov, A.; Guzzo, L.; Kampczyk, P.; Maier, C.; Tanaka, M.; Vergani, D.; Carollo, C. M.; Contini, T.; Kneib, J.-P.; Le Fèvre, O.; Mainieri, V.; Renzini, A.; Bongiorno, A.; Coppa, G.; de la Torre, S.; de Ravel, L.; Franzetti, P.; Garilli, B.; Le Borgne, J.-F.; Le Brun, V.; Mignoli, M.; Pellò, R.; Peng, Y.; Perez-Montero, E.; Ricciardelli, E.; Silverman, J. D.; Tresse, L.; Abbas, U.; Bottini, D.; Cappi, A.; Cassata, P.; Cimatti, A.; Koekemoer, A. M.; Leauthaud, A.; Maccagni, D.; Marinoni, C.; McCracken, H. J.; Memeo, P.; Meneux, B.; Porciani, C.; Scaramella, R.; Schiminovich, D.; Scoville, N.

    2010-01-01

    Context. Groups of galaxies are a common environment, bridging the gap between starforming field galaxies and quiescent cluster galaxies. Within groups secular processes could be at play, contributing to the observed strong decrease of star formation with cosmic time in the global galaxy population. Aims: We took advantage of the wealth of information provided by the first 10 000 galaxies of the zCOSMOS-bright survey and its group catalogue to study in detail the complex interplay between group environment and galaxy properties. Methods: The classical indicator Fblue, i.e., the fraction of blue galaxies, proved to be a simple but powerful diagnostic tool. We studied its variation for different luminosity and mass selected galaxy samples, divided as to define groups/field/isolated galaxy subsamples. Results: Using rest-frame evolving B-band volume-limited samples, the groups galaxy population exhibits significant blueing as redshift increases, but maintains a systematic difference (a lower Fblue) with respect to the global galaxy population, and an even larger difference with respect to the isolated galaxy population. However moving to mass selected samples it becomes apparent that such differences are largely due to the biased view imposed by the B-band luminosity selection, being driven by the population of lower mass, bright blue galaxies for which we miss the redder, equally low mass, counterparts. By carefully focusing the analysis on narrow mass bins such that mass segregation becomes negligible we find that only for the lowest mass bin explored, i.e., log ({\\cal M}*/{\\cal M}⊙) ≤ 10.6 , does a significant residual difference in color remain as a function of environment, while this difference becomes negligible toward higher masses. Conclusions: Our results indicate that red galaxies of mass log ({\\cal M}*/{\\cal M}⊙) ≥ 10.8 are already in place at z 1 and do not exhibit any strong environmental dependence, possibly originating from so-called nature

  3. ESTIMATING PHOTOMETRIC REDSHIFTS OF QUASARS VIA THE k-NEAREST NEIGHBOR APPROACH BASED ON LARGE SURVEY DATABASES

    SciTech Connect

    Zhang Yanxia; Ma He; Peng Nanbo; Zhao Yongheng; Wu Xuebing

    2013-08-01

    We apply one of the lazy learning methods, the k-nearest neighbor (kNN) algorithm, to estimate the photometric redshifts of quasars based on various data sets from the Sloan Digital Sky Survey (SDSS), the UKIRT Infrared Deep Sky Survey (UKIDSS), and the Wide-field Infrared Survey Explorer (WISE; the SDSS sample, the SDSS-UKIDSS sample, the SDSS-WISE sample, and the SDSS-UKIDSS-WISE sample). The influence of the k value and different input patterns on the performance of kNN is discussed. kNN performs best when k is different with a special input pattern for a special data set. The best result belongs to the SDSS-UKIDSS-WISE sample. The experimental results generally show that the more information from more bands, the better performance of photometric redshift estimation with kNN. The results also demonstrate that kNN using multiband data can effectively solve the catastrophic failure of photometric redshift estimation, which is met by many machine learning methods. Compared with the performance of various other methods of estimating the photometric redshifts of quasars, kNN based on KD-Tree shows superiority, exhibiting the best accuracy.

  4. The VIMOS Public Extragalactic Redshift Survey (VIPERS). Never mind the gaps: comparing techniques to restore homogeneous sky coverage

    NASA Astrophysics Data System (ADS)

    Cucciati, O.; Granett, B. R.; Branchini, E.; Marulli, F.; Iovino, A.; Moscardini, L.; Bel, J.; Cappi, A.; Peacock, J. A.; de la Torre, S.; Bolzonella, M.; Guzzo, L.; Polletta, M.; Fritz, A.; Adami, C.; Bottini, D.; Coupon, J.; Davidzon, I.; Franzetti, P.; Fumana, M.; Garilli, B.; Krywult, J.; Małek, K.; Paioro, L.; Pollo, A.; Scodeggio, M.; Tasca, L. A. M.; Vergani, D.; Zanichelli, A.; Di Porto, C.; Zamorani, G.

    2014-05-01

    Aims: Non-uniform sampling and gaps in sky coverage are common in galaxy redshift surveys, but these effects can degrade galaxy counts-in-cells measurements and density estimates. We carry out a comparative study of methods that aim to fill the gaps to correct for the systematic effects. Our study is motivated by the analysis of the VIMOS Public Extragalactic Redshift Survey (VIPERS), a flux-limited survey at iAB < 22.5 consisting of single-pass observations with the VLT Visible Multi-Object Spectrograph (VIMOS) with gaps representing 25% of the surveyed area and an averagesampling rate of 35%. However, our findings are generally applicable to other redshift surveys with similar observing strategies. Methods: We applied two algorithms that use photometric redshift information and assign redshifts to galaxies based upon the spectroscopic redshifts of the nearest neighbours. We compared these methods with two Bayesian methods, the Wiener filter and the Poisson-Lognormal filter. Using galaxy mock catalogues we quantified the accuracy and precision of the counts-in-cells measurements on scales of R = 5 h-1 Mpc and 8 h-1 Mpc after applying each of these methods. We further investigated how these methods perform to account for other sources of uncertainty typical of spectroscopic surveys, such as the spectroscopic redshift error and the sparse, inhomogeneous sampling rate. We analysed each of these sources separately, then all together in a mock catalogue that mimicks the full observational strategy of a VIPERS-like survey. Results: In a survey such as VIPERS, the errors in counts-in-cells measurements on R < 10 h-1 Mpc scales are dominated by the sparseness of the sample due to the single-pass observing strategy. All methods under-predict the counts in high-density regions by 20-35%, depending on the cell size, method, and underlying overdensity. This systematic bias is similar to random errors. No method outperforms the others: differences are not large, and methods

  5. Self-calibration of photometric redshift scatter in weak-lensing surveys

    SciTech Connect

    Zhang, Pengjie; Pen, Ue -Li; Bernstein, Gary

    2010-06-11

    Photo-z errors, especially catastrophic errors, are a major uncertainty for precision weak lensing cosmology. We find that the shear-(galaxy number) density and density-density cross correlation measurements between photo-z bins, available from the same lensing surveys, contain valuable information for self-calibration of the scattering probabilities between the true-z and photo-z bins. The self-calibration technique we propose does not rely on cosmological priors nor parameterization of the photo-z probability distribution function, and preserves all of the cosmological information available from shear-shear measurement. We estimate the calibration accuracy through the Fisher matrix formalism. We find that, for advanced lensing surveys such as the planned stage IV surveys, the rate of photo-z outliers can be determined with statistical uncertainties of 0.01-1% for z < 2 galaxies. Among the several sources of calibration error that we identify and investigate, the galaxy distribution bias is likely the most dominant systematic error, whereby photo-z outliers have different redshift distributions and/or bias than non-outliers from the same bin. This bias affects all photo-z calibration techniques based on correlation measurements. As a result, galaxy bias variations of O(0.1) produce biases in photo-z outlier rates similar to the statistical errors of our method, so this galaxy distribution bias may bias the reconstructed scatters at several-σ level, but is unlikely to completely invalidate the self-calibration technique.

  6. Self-calibration of photometric redshift scatter in weak-lensing surveys

    DOE PAGESBeta

    Zhang, Pengjie; Pen, Ue -Li; Bernstein, Gary

    2010-06-11

    Photo-z errors, especially catastrophic errors, are a major uncertainty for precision weak lensing cosmology. We find that the shear-(galaxy number) density and density-density cross correlation measurements between photo-z bins, available from the same lensing surveys, contain valuable information for self-calibration of the scattering probabilities between the true-z and photo-z bins. The self-calibration technique we propose does not rely on cosmological priors nor parameterization of the photo-z probability distribution function, and preserves all of the cosmological information available from shear-shear measurement. We estimate the calibration accuracy through the Fisher matrix formalism. We find that, for advanced lensing surveys such as themore » planned stage IV surveys, the rate of photo-z outliers can be determined with statistical uncertainties of 0.01-1% for z < 2 galaxies. Among the several sources of calibration error that we identify and investigate, the galaxy distribution bias is likely the most dominant systematic error, whereby photo-z outliers have different redshift distributions and/or bias than non-outliers from the same bin. This bias affects all photo-z calibration techniques based on correlation measurements. As a result, galaxy bias variations of O(0.1) produce biases in photo-z outlier rates similar to the statistical errors of our method, so this galaxy distribution bias may bias the reconstructed scatters at several-σ level, but is unlikely to completely invalidate the self-calibration technique.« less

  7. Power spectrum, correlation function, and tests for luminosity bias in the CfA redshift survey

    NASA Technical Reports Server (NTRS)

    Park, Changbom; Vogeley, Michael S.; Geller, Margaret J.; Huchra, John P.

    1994-01-01

    We describe and apply a method for directly computing the power spectrum for the galaxy distribution in the extension of the Center for Astrophysics Redshift Survey. Tests show that our technique accurately reproduces the true power spectrum for k greater than 0.03 h Mpc(exp -1). The dense sampling and large spatial coverage of this survey allow accurate measurement of the redshift-space power spectrum on scales from 5 to approximately 200 h(exp -1) Mpc. The power spectrum has slope n approximately equal -2.1 on small scales (lambda less than or equal 25 h(exp -1) Mpc) and n approximately -1.1 on scales 30 less than lambda less than 120 h(exp -1) Mpc. On larger scales the power spectrum flattens somewhat, but we do not detect a turnover. Comparison with N-body simulations of cosmological models shows that an unbiased, open universe CDM model (OMEGA h = 0.2) and a nonzero cosmological constant (CDM) model (OMEGA h = 0.24, lambda(sub zero) = 0.6, b = 1.3) match the CfA power spectrum over the wavelength range we explore. The standard biased CDM model (OMEGA h = 0.5, b = 1.5) fails (99% significance level) because it has insufficient power on scales lambda greater than 30 h(exp -1) Mpc. Biased CDM with a normalization that matches the Cosmic Microwave Background (CMB) anisotropy (OMEGA h = 0.5, b = 1.4, sigma(sub 8) (mass) = 1) has too much power on small scales to match the observed galaxy power spectrum. This model with b = 1 matches both Cosmic Background Explorer Satellite (COBE) and the small-scale power spect rum but has insufficient power on scales lambda approximately 100 h(exp -1) Mpc. We derive a formula for the effect of small-scale peculiar velocities on the power spectrum and combine this formula with the linear-regime amplification described by Kaiser to compute an estimate of the real-space power spectrum. Two tests reveal luminosity bias in the galaxy distribution: First, the amplitude of the pwer spectrum is approximately 40% larger for the brightest

  8. SIX MORE QUASARS AT REDSHIFT 6 DISCOVERED BY THE CANADA-FRANCE HIGH-z QUASAR SURVEY

    SciTech Connect

    Willott, Chris J.; Crampton, David; Hutchings, John B.; Schade, David; Delorme, Philippe; Delfosse, Xavier; Forveille, Thierry; Reyle, Celine; Albert, Loic; Bergeron, Jacqueline; Omont, Alain; McLure, Ross J.

    2009-03-15

    We present imaging and spectroscopic observations for six quasars at z {>=} 5.9 discovered by the Canada-France High-z Quasar Survey (CFHQS). The CFHQS contains subsurveys with a range of flux and area combinations to sample a wide range of quasar luminosities at z {approx} 6. The new quasars have luminosities 10-75 times lower than the most luminous Sloan Digital Sky Survey quasars at this redshift. The least luminous quasar, CFHQS J0216-0455 at z = 6.01, has absolute magnitude M {sub 1450} = -22.21, well below the likely break in the luminosity function. This quasar is not detected in a deep XMM-Newton survey showing that optical selection is still a very efficient tool for finding high-redshift quasars.

  9. The middle-aged universe: Results from high-z supernovae and the DEEP2 Galaxy Redshift Survey

    NASA Astrophysics Data System (ADS)

    Coil, Alison Laurel

    2004-12-01

    This thesis presents observational results detailing the state of the Universe ~5-9 billion years ago, focusing primarily on the spatial distribution and clustering of galaxies. We first present optical spectra, obtained with the Keck 10-m telescope, of two high-redshift type Ia supernovae (SNe Ia) at maximum light, discovered by the High-z Supernova Search Team: SN 1999ff at z = 0.455 and SN 1999fv at z ~= 1.2. We compare our high- z spectra with low- z normal and peculiar SNe Ia as well as with SNe Ic, Ib, and II and find that are no significant differences between SN 1999ff and SN1999fv and normal SNe la at low redshift. This solidifies the use of type Ia SNe as standard candles at cosmological distances. We then develop and test mock galaxy catalogs to be used for the DEEP2 Galaxy Redshift Survey, which will obtain redshifts for ~50,000 galaxies between 0.7 < z < 1.5, mapping the galaxy distribution in a comoving volume of roughly 7 x 10 6 Mpc 3 h -3 . Using data from the first observing season of the DEEP2 Redshift Survey, we measure the amplitude of galaxy clustering using the two-point correlation function, x( r ), for a sample of 2219 galaxies between 0.7 < z < 1.35. We find that galaxies are significantly less clustered at z ~ 1 relative to z ~ 0; r 0 ~ 3.0-3.5 h -1 Mpc (comoving). We find that red, absorption-dominated, passively-evolving galaxies have a larger clustering scale length than blue, emission-line, actively star-forming galaxies. Intrinsically brighter galaxies also cluster more strongly than fainter galaxies at z ~= 1. Our results imply that the DEEP2 galaxies have an effective bias b ~ 1.0-1.2, lower than what is predicted by semi-analytic simulations at z ~= 1, which may be the result of our R -band target selection. Our results demonstrate that galaxy clustering properties as a function of color, spectral type and luminosity seen in the local Universe were largely in place by z ~= 1. We also present measurements of the projected angular

  10. The WiggleZ Dark Energy Survey: Final Results

    NASA Astrophysics Data System (ADS)

    Davis, Tamara; Blake, C.; Parkinson, D.; Riemer-Sørensen, S.; Poole, G. B.; Scrimgeour, M.; Kazin, E.; Beutler, F.; Glazebrook, K.; Drinkwater, M.; Couch, W.; WiggleZ Dark Energy Survey Team

    2013-01-01

    Observations are now complete for the WiggleZ dark energy survey and we have mapped the positions of ~220,000 bright blue galaxies out to a redshift of 1, over a cubic giga-parsec of space. I will present the full complement of cosmological results coming out of this data set. With the addition of WiggleZ data, baryon acoustic oscillations are now able to confirm the acceleration of the expansion of the universe, independent of any supernova data, and this has since been further strengthened by the addition of Baryon Oscillation Spectroscopic Survey data. Arguably the most exciting results are our measurements of the growth of structure out to 0.8, and measurements of the Alcock-Paczynski effect (sphericity of spheres) that allow us to measure the rate of expansion at different redshifts H(z) without needing a cosmological model. These allow us to distinguish between non-standard models of gravity that are indistinguishable using only measurements of expansion rate. I will also cover our constraints on the mass of the neutrino and the effective number of neutrinos, which are amongst the tightest constraints available from any experiment. Finally, I will show how the large volume we have sampled has allowed us to detect the scale at which the universe transitions from clustered to homogeneous, confirming one of the cornerstones of modern cosmology. The WiggleZ data have now been made public, and include data, random catalogues, and lognormal realizations. With it we have also released our CosmoMC module so our data can easily be included in your own cosmological analyses.

  11. High-Redshift Quasars Found in Sloan Digital Sky Survey Commissioning Data. II. The Spring Equatorial Stripe

    SciTech Connect

    Fan, Xiaohui; Strauss, Michael A.; Schneider, Donald P.; Gunn, James E.; Lupton, Robert H.; Anderson, Scott F.; Voges, Wolfgang; Margon, Bruce; Annis, James; Bahcall, Neta A.

    2000-01-01

    This is the second paper in a series aimed at finding high-redshift quasars from five-color (u{sup '} g{sup '} r{sup '} i{sup '} z{sup '}) imaging data taken along the Celestial Equator by the Sloan Digital Sky Survey (SDSS) during its commissioning phase. In this paper, we present 22 high-redshift quasars (z>3.6) discovered from {approx}250 deg2 of data in the spring Equatorial Stripe, plus photometry for two previously known high-redshift quasars in the same region of the sky. Our success rate in identifying high-redshift quasars is 68%. Five of the newly discovered quasars have redshifts higher than 4.6 (z=4.62, 4.69, 4.70, 4.92, and 5.03). All the quasars have i{sup *} <20.2 with absolute magnitude - 28.8

  12. QSO Clustering - Part One - Optical Surveys in the Redshift Range 0.3

    NASA Astrophysics Data System (ADS)

    Shanks, T.; Boyle, B. J.

    1994-12-01

    We present QSO clustering results from ~700 QSOs detected in three surveys, including the Durham/AAT UVX Survey. We have made a 4σ detection of QSO clustering at scales of < 10 h^-1^ Mpc (q_0_ = 0.5), stronger than expected on the basis of models of the evolution of the galaxy correlation function where the clustering is assumed to be stable in proper coordinates. A model in which QSOs randomly sample a galaxy distribution with present-day clustering coherence length, r_0_ ~ 6 h^-1^ Mpc, and which is fixed in comoving coordinates, is strongly suggested by the data; a stable-clustering, high-amplitude (r_0_ ~ 11 h^-1^ Mpc) model can be excluded when the low-redshift Seyfert clustering results of Georgantopoulos & Shanks (Paper II) are considered. The conclusion that ultraviolet-excess (UVX) QSOs randomly sample the underlying galaxy distribution is also given strong support from the observation by Ellingson, Yee & Green that the clustering environment of z ~ 0.6 radio- quiet QSOs is no different from that of average galaxies. Our results therefore suggest that a comoving model may also describe the evolution of galaxy clustering out to z = 2.2; such a model is consistent with biased models of galaxy clustering with either q_0_ = 0.01 or q_0_ = 0.5. We have also tentatively detected, at a lower level of significance (~2σ), anticorrelation at the ξ ~ -0.1 level in the range 40 < r < 100 h^-1^ Mpc in the q_0_ = 0.5 QSO correlation function. Anticorrelation is expected in models where the power-law spectral index, n, of the primordial mass spectrum has a value >= 1. No other features are detectable at the +/- 0.05 level in ξ at any scale in the range 10 < r < 1000 h^-1^ Mpc. Finally, we show that the spatial position of features in the QSO correlation function is very sensitive to the cosmological model. In particular, we find that, in a model with zero spatial curvature, {LAMBDA} not equal to 0 and {OMEGA}_0_ < 0.03, the QSO clustering extends up to a comoving

  13. Michigan Early Adolescent Survey: Final Report.

    ERIC Educational Resources Information Center

    Keith, Joanne; And Others

    This document contains the final report from the Michigan Early Adolescent Survey, a study undertaken to: (1) develop a profile of Michigan early adolescents that focused on out-of-school time and included biological, psychological, and sociological information; (2) develop a profile of families which included early adolescents; (3) assess the…

  14. GALAXY CLUSTERING IN THE COMPLETED SDSS REDSHIFT SURVEY: THE DEPENDENCE ON COLOR AND LUMINOSITY

    SciTech Connect

    Zehavi, Idit; Zheng Zheng; Weinberg, David H.; Blanton, Michael R.; Bahcall, Neta A.; Gunn, James E.; Lupton, Robert H.; Strauss, Michael A.; Berlind, Andreas A.; Brinkmann, Jon; Frieman, Joshua A.; Nichol, Robert C.; Percival, Will J.; Schneider, Donald P.; Skibba, Ramin A.; Tegmark, Max; York, Donald G.

    2011-07-20

    We measure the luminosity and color dependence of galaxy clustering in the largest-ever galaxy redshift survey, the main galaxy sample of the Sloan Digital Sky Survey Seventh Data Release. We focus on the projected correlation function w{sub p} (r{sub p}) of volume-limited samples, extracted from the parent sample of {approx}700,000 galaxies over 8000 deg{sup 2}, extending up to redshift of 0.25. We interpret our measurements using halo occupation distribution (HOD) modeling assuming a {Lambda}CDM cosmology (inflationary cold dark matter with a cosmological constant). The amplitude of w{sub p} (r{sub p}) grows slowly with luminosity for L < L{sub *} and increases sharply at higher luminosities, with a large-scale bias factor b(> L) x ({sigma}{sub 8}/0.8) = 1.06 + 0.21(L/L{sub *}){sup 1.12}, where L is the sample luminosity threshold. At fixed luminosity, redder galaxies exhibit a higher amplitude and steeper correlation function, a steady trend that runs through the 'blue cloud' and 'green valley' and continues across the 'red sequence'. The cross-correlation of red and blue galaxies is close to the geometric mean of their autocorrelations, dropping slightly below at r{sub p} < 1 h{sup -1} Mpc. The luminosity trends for the red and blue galaxy populations separately are strikingly different. Blue galaxies show a slow but steady increase of clustering strength with luminosity, with nearly constant shape of w{sub p} (r{sub p}). The large-scale clustering of red galaxies shows little luminosity dependence until a sharp increase at L > 4 L{sub *}, but the lowest luminosity red galaxies (0.04-0.25 L{sub *}) show very strong clustering on small scales (r{sub p} < 2 h{sup -1} Mpc). Most of the observed trends can be naturally understood within the {Lambda}CDM+HOD framework. The growth of w{sub p} (r{sub p}) for higher luminosity galaxies reflects an overall shift in the mass scale of their host dark matter halos, in particular an increase in the minimum host halo mass M

  15. The Carnegie-Spitzer-IMACS redshift survey of galaxy evolution since z = 1.5. I. Description and methodology

    SciTech Connect

    Kelson, Daniel D.; Williams, Rik J.; Dressler, Alan; McCarthy, Patrick J.; Shectman, Stephen A.; Mulchaey, John S.; Villanueva, Edward V.; Crane, Jeffrey D.; Quadri, Ryan F.

    2014-03-10

    We describe the Carnegie-Spitzer-IMACS (CSI) Survey, a wide-field, near-IR selected spectrophotometric redshift survey with the Inamori Magellan Areal Camera and Spectrograph (IMACS) on Magellan-Baade. By defining a flux-limited sample of galaxies in Spitzer Infrared Array Camera 3.6 μm imaging of SWIRE fields, the CSI Survey efficiently traces the stellar mass of average galaxies to z ∼ 1.5. This first paper provides an overview of the survey selection, observations, processing of the photometry and spectrophotometry. We also describe the processing of the data: new methods of fitting synthetic templates of spectral energy distributions are used to derive redshifts, stellar masses, emission line luminosities, and coarse information on recent star formation. Our unique methodology for analyzing low-dispersion spectra taken with multilayer prisms in IMACS, combined with panchromatic photometry from the ultraviolet to the IR, has yielded high-quality redshifts for 43,347 galaxies in our first 5.3 deg{sup 2} of the SWIRE XMM-LSS field. We use three different approaches to estimate our redshift errors and find robust agreement. Over the full range of 3.6 μm fluxes of our selection, we find typical redshift uncertainties of σ {sub z}/(1 + z) ≲ 0.015. In comparisons with previously published spectroscopic redshifts we find scatters of σ {sub z}/(1 + z) = 0.011 for galaxies at 0.7 ≤ z ≤ 0.9, and σ {sub z}/(1 + z) = 0.014 for galaxies at 0.9 ≤ z ≤ 1.2. For galaxies brighter and fainter than i = 23 mag, we find σ {sub z}/(1 + z) = 0.008 and σ {sub z}/(1 + z) = 0.022, respectively. Notably, our low-dispersion spectroscopy and analysis yields comparable redshift uncertainties and success rates for both red and blue galaxies, largely eliminating color-based systematics that can seriously bias observed dependencies of galaxy evolution on environment.

  16. The Carnegie-Spitzer-IMACS Redshift Survey of Galaxy Evolution since z = 1.5. I. Description and Methodology

    NASA Astrophysics Data System (ADS)

    Kelson, Daniel D.; Williams, Rik J.; Dressler, Alan; McCarthy, Patrick J.; Shectman, Stephen A.; Mulchaey, John S.; Villanueva, Edward V.; Crane, Jeffrey D.; Quadri, Ryan F.

    2014-03-01

    We describe the Carnegie-Spitzer-IMACS (CSI) Survey, a wide-field, near-IR selected spectrophotometric redshift survey with the Inamori Magellan Areal Camera and Spectrograph (IMACS) on Magellan-Baade. By defining a flux-limited sample of galaxies in Spitzer Infrared Array Camera 3.6 μm imaging of SWIRE fields, the CSI Survey efficiently traces the stellar mass of average galaxies to z ~ 1.5. This first paper provides an overview of the survey selection, observations, processing of the photometry and spectrophotometry. We also describe the processing of the data: new methods of fitting synthetic templates of spectral energy distributions are used to derive redshifts, stellar masses, emission line luminosities, and coarse information on recent star formation. Our unique methodology for analyzing low-dispersion spectra taken with multilayer prisms in IMACS, combined with panchromatic photometry from the ultraviolet to the IR, has yielded high-quality redshifts for 43,347 galaxies in our first 5.3 deg2 of the SWIRE XMM-LSS field. We use three different approaches to estimate our redshift errors and find robust agreement. Over the full range of 3.6 μm fluxes of our selection, we find typical redshift uncertainties of σ z /(1 + z) <~ 0.015. In comparisons with previously published spectroscopic redshifts we find scatters of σ z /(1 + z) = 0.011 for galaxies at 0.7 <= z <= 0.9, and σ z /(1 + z) = 0.014 for galaxies at 0.9 <= z <= 1.2. For galaxies brighter and fainter than i = 23 mag, we find σ z /(1 + z) = 0.008 and σ z /(1 + z) = 0.022, respectively. Notably, our low-dispersion spectroscopy and analysis yields comparable redshift uncertainties and success rates for both red and blue galaxies, largely eliminating color-based systematics that can seriously bias observed dependencies of galaxy evolution on environment. This paper includes data gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile.

  17. SIS Mixer Design for a Broadband Millimeter Spectrometer Suitable for Rapid Line Surveys and Redshift Determinations

    NASA Technical Reports Server (NTRS)

    Rice, F.; Sumner, M.; Zmuidzinas, J.; Hu, R.; LeDuc, H.; Harris, A.; Miller, D.

    2004-01-01

    We present some detail of the waveguide probe and SIS mixer chip designs for a low-noise 180-300 GHz double- sideband receiver with an instantaneous RF bandwidth of 24 GHz. The receiver's single SIS junction is excited by a broadband, fixed-tuned waveguide probe on a silicon substrate. The IF output is coupled to a 6-18 GHz MMIC low- noise preamplifier. Following further amplification, the output is processed by an array of 4 GHz, 128-channel analog autocorrelation spectrometers (WASP 11). The single-sideband receiver noise temperature goal of 70 Kelvin will provide a prototype instrument capable of rapid line surveys and of relatively efficient carbon monoxide (CO) emission line searches of distant, dusty galaxies. The latter application's goal is to determine redshifts by measuring the frequencies of CO line emissions from the star-forming regions dominating the submillimeter brightness of these galaxies. Construction of the receiver has begun; lab testing should begin in the fall. Demonstration of the receiver on the Caltech Submillimeter Observatory (CSO) telescope should begin in spring 2003.

  18. The 2dF Galaxy Redshift Survey: voids and hierarchical scaling models

    NASA Astrophysics Data System (ADS)

    Croton, Darren J.; Colless, Matthew; Gaztañaga, Enrique; Baugh, Carlton M.; Norberg, Peder; Baldry, I. K.; Bland-Hawthorn, J.; Bridges, T.; Cannon, R.; Cole, S.; Collins, C.; Couch, W.; Dalton, G.; de Propris, R.; Driver, S. P.; Efstathiou, G.; Ellis, R. S.; Frenk, C. S.; Glazebrook, K.; Jackson, C.; Lahav, O.; Lewis, I.; Lumsden, S.; Maddox, S.; Madgwick, D.; Peacock, J. A.; Peterson, B. A.; Sutherland, W.; Taylor, K.

    2004-08-01

    We measure the redshift-space reduced void probability function (VPF) for 2dFGRS volume-limited galaxy samples covering the absolute magnitude range MbJ-5log10h=-18 to -22. Theoretically, the VPF connects the distribution of voids to the moments of galaxy clustering of all orders, and can be used to discriminate clustering models in the weakly non-linear regime. The reduced VPF measured from the 2dFGRS is in excellent agreement with the paradigm of hierarchical scaling of the galaxy clustering moments. The accuracy of our measurement is such that we can rule out, at a very high significance, popular models for galaxy clustering, including the lognormal distribution. We demonstrate that the negative binomial model gives a very good approximation to the 2dFGRS data over a wide range of scales, out to at least 20 h-1 Mpc. Conversely, the reduced VPF for dark matter in a Λ cold dark matter (ΛCDM) universe does appear to be lognormal on small scales but deviates significantly beyond ~4 h-1 Mpc. We find little dependence of the 2dFGRS reduced VPF on galaxy luminosity. Our results hold independently in both the North and South Galactic Pole survey regions.

  19. A PUBLIC VOID CATALOG FROM THE SDSS DR7 GALAXY REDSHIFT SURVEYS BASED ON THE WATERSHED TRANSFORM

    SciTech Connect

    Sutter, P. M.; Wandelt, Benjamin D.; Lavaux, Guilhem; Weinberg, David H.

    2012-12-10

    We produce the most comprehensive public void catalog to date using the Sloan Digital Sky Survey Data Release 7 main sample out to redshift z = 0.2 and the luminous red galaxy sample out to z = 0.44. Using a modified version of the parameter-free void finder ZOBOV, we fully take into account the presence of the survey boundary and masks. Our strategy for finding voids is thus appropriate for any survey configuration. We produce two distinct catalogs: a complete catalog including voids near any masks, which would be appropriate for void galaxy surveys, and a bias-free catalog of voids away from any masks, which is necessary for analyses that require a fair sampling of void shapes and alignments. Our discovered voids have effective radii from 5 to 135 h {sup -1} Mpc. We discuss basic catalog statistics such as number counts and redshift distributions and describe some additional data products derived from our catalog, such as radial density profiles and projected density maps. We find that radial profiles of stacked voids show a qualitatively similar behavior across nearly two decades of void radii and throughout the full redshift range.

  20. Machine-learning-based photometric redshifts for galaxies of the ESO Kilo-Degree Survey data release 2

    NASA Astrophysics Data System (ADS)

    Cavuoti, S.; Brescia, M.; Tortora, C.; Longo, G.; Napolitano, N. R.; Radovich, M.; Barbera, F. La; Capaccioli, M.; de Jong, J. T. A.; Getman, F.; Grado, A.; Paolillo, M.

    2015-09-01

    We have estimated photometric redshifts (zphot) for more than 1.1 million galaxies of the public European Southern Observatory (ESO) Kilo-Degree Survey (KiDS) data release 2. KiDS is an optical wide-field imaging survey carried out with the Very Large Telescope (VLT) Survey Telescope (VST) and the OmegaCAM camera, which aims to tackle open questions in cosmology and galaxy evolution, such as the origin of dark energy and the channel of galaxy mass growth. We present a catalogue of photometric redshifts obtained using the Multi-Layer Perceptron with Quasi-Newton Algorithm (MLPQNA) model, provided within the framework of the DAta Mining and Exploration Web Application REsource (DAMEWARE). These photometric redshifts are based on a spectroscopic knowledge base that was obtained by merging spectroscopic data sets from the Galaxy and Mass Assembly (GAMA) data release 2 and the Sloan Digital Sky Survey III (SDSS-III) data release 9. The overall 1σ uncertainty on Δz = (zspec - zphot)/(1 + zspec) is ˜0.03, with a very small average bias of ˜0.001, a normalized median absolute deviation of ˜0.02 and a fraction of catastrophic outliers (|Δz| > 0.15) of ˜0.4 per cent.

  1. Bright Galaxies at Hubble’s Redshift Detection Frontier: Preliminary Results and Design from the Redshift z ~ 9-10 BoRG Pure-Parallel HST Survey

    NASA Astrophysics Data System (ADS)

    Calvi, V.; Trenti, M.; Stiavelli, M.; Oesch, P.; Bradley, L. D.; Schmidt, K. B.; Coe, D.; Brammer, G.; Bernard, S.; Bouwens, R. J.; Carrasco, D.; Carollo, C. M.; Holwerda, B. W.; MacKenty, J. W.; Mason, C. A.; Shull, J. M.; Treu, T.

    2016-02-01

    We present the first results and design from the redshift z ˜ 9-10 Brightest of the Reionizing Galaxies Hubble Space Telescope survey BoRG[z9-10], aimed at searching for intrinsically luminous unlensed galaxies during the first 700 Myr after the Big Bang. BoRG[z9-10] is the continuation of a multi-year pure-parallel near-IR and optical imaging campaign with the Wide Field Camera 3. The ongoing survey uses five filters, optimized for detecting the most distant objects and offering continuous wavelength coverage from λ = 0.35 μm to λ = 1.7 μm. We analyze the initial ˜130 arcmin2 of area over 28 independent lines of sight (˜25% of the total planned) to search for z\\gt 7 galaxies using a combination of Lyman-break and photometric redshift selections. From an effective comoving volume of (5-25) × 105 Mpc3 for magnitudes brighter than {m}{AB}=26.5{{{--}}}24.0 in the {H}{{160}}-band respectively, we find five galaxy candidates at z\\quad ˜ 8.3-10 detected at high confidence ({{S}}/{{N}}\\gt 8), including a source at z\\quad ˜ 8.4 with {m}{AB}=24.5 ({{S}}/{{N}} ˜ 22), which, if confirmed, would be the brightest galaxy identified at such early times (z\\gt 8). In addition, BoRG[z9-10] data yield four galaxies with 7.3≲ z≲ 8. These new Lyman-break galaxies with m≲ 26.5 are ideal targets for follow-up observations from ground and space-based observatories to help investigate the complex interplay between dark matter growth, galaxy assembly, and reionization.

  2. Analytic photometric redshift estimator for Type Ia supernovae from the Large Synoptic Survey Telescope

    NASA Astrophysics Data System (ADS)

    Wang, Yun; Gjergo, E.; Kuhlmann, S.

    2015-08-01

    Accurate and precise photometric redshifts (photo-zs) of Type Ia supernovae (SNe Ia) can enable the use of SNe Ia, measured only with photometry, to probe cosmology. This dramatically increases the science return of supernova surveys planned for the Large Synoptic Survey Telescope (LSST). In this paper we describe a significantly improved version of the simple analytic photo-z estimator proposed by Wang and further developed by Wang, Narayan & Wood-Vasey. We apply it to 55 422 simulated SNe Ia generated using the SNANA package with the LSST filters. We find that the estimated errors on the photo-zs, σ _{z_phot}/(1+z_phot), can be used as filters to produce a set of photo-zs that have high precision, accuracy, and purity. Using SN Ia colours as well as SN Ia peak magnitude in the i band, we obtain a set of photo-zs with 2 per cent accuracy (with σ(zphot - zspec)/(1 + zspec) = 0.02), a bias in zphot (the mean of zphot - zspec) of -9 × 10-5, and an outlier fraction (with |(zphot - zspec)/(1 + zspec)| > 0.1) of 0.23 per cent, with the requirement that σ _{z_phot}/(1+z_phot)<0.01. Using the SN Ia colours only, we obtain a set of photo-zs with similar quality by requiring that σ _{z_phot}/(1+z_phot)<0.007; this leads to a set of photo-zs with 2 per cent accuracy, a bias in zphot of 5.9 × 10-4, and an outlier fraction of 0.32 per cent.

  3. THE DEEP2 GALAXY REDSHIFT SURVEY: THE VORONOI-DELAUNAY METHOD CATALOG OF GALAXY GROUPS

    SciTech Connect

    Gerke, Brian F.; Newman, Jeffrey A.; Davis, Marc; Coil, Alison L.; Cooper, Michael C.; Dutton, Aaron A.; Faber, S. M.; Guhathakurta, Puragra; Koo, David C.; Phillips, Andrew C.; Noeske, Kai; Rosario, David J.; Weiner, Benjamin J.; Willmer, Christopher N. A.; Yan, Renbin

    2012-05-20

    We present a public catalog of galaxy groups constructed from the spectroscopic sample of galaxies in the fourth data release from the Deep Extragalactic Evolutionary Probe 2 (DEEP2) Galaxy Redshift Survey, including the Extended Groth Strip (EGS). The catalog contains 1165 groups with two or more members in the EGS over the redshift range 0 < z < 1.5 and 1295 groups at z > 0.6 in the rest of DEEP2. Twenty-five percent of EGS galaxies and fourteen percent of high-z DEEP2 galaxies are assigned to galaxy groups. The groups were detected using the Voronoi-Delaunay method (VDM) after it has been optimized on mock DEEP2 catalogs following similar methods to those employed in Gerke et al. In the optimization effort, we have taken particular care to ensure that the mock catalogs resemble the data as closely as possible, and we have fine-tuned our methods separately on mocks constructed for the EGS and the rest of DEEP2. We have also probed the effect of the assumed cosmology on our inferred group-finding efficiency by performing our optimization on three different mock catalogs with different background cosmologies, finding large differences in the group-finding success we can achieve for these different mocks. Using the mock catalog whose background cosmology is most consistent with current data, we estimate that the DEEP2 group catalog is 72% complete and 61% pure (74% and 67% for the EGS) and that the group finder correctly classifies 70% of galaxies that truly belong to groups, with an additional 46% of interloper galaxies contaminating the catalog (66% and 43% for the EGS). We also confirm that the VDM catalog reconstructs the abundance of galaxy groups with velocity dispersions above {approx}300 km s{sup -1} to an accuracy better than the sample variance, and this successful reconstruction is not strongly dependent on cosmology. This makes the DEEP2 group catalog a promising probe of the growth of cosmic structure that can potentially be used for cosmological tests.

  4. The VIMOS Public Extragalactic Redshift Survey (VIPERS). Environmental effects shaping the galaxy stellar mass function

    NASA Astrophysics Data System (ADS)

    Davidzon, I.; Cucciati, O.; Bolzonella, M.; De Lucia, G.; Zamorani, G.; Arnouts, S.; Moutard, T.; Ilbert, O.; Garilli, B.; Scodeggio, M.; Guzzo, L.; Abbas, U.; Adami, C.; Bel, J.; Bottini, D.; Branchini, E.; Cappi, A.; Coupon, J.; de la Torre, S.; Di Porto, C.; Fritz, A.; Franzetti, P.; Fumana, M.; Granett, B. R.; Guennou, L.; Iovino, A.; Krywult, J.; Le Brun, V.; Le Fèvre, O.; Maccagni, D.; Małek, K.; Marulli, F.; McCracken, H. J.; Mellier, Y.; Moscardini, L.; Polletta, M.; Pollo, A.; Tasca, L. A. M.; Tojeiro, R.; Vergani, D.; Zanichelli, A.

    2016-02-01

    We exploit the first public data release of VIPERS to investigate environmental effects in the evolution of galaxies between z ~ 0.5 and 0.9. The large number of spectroscopic redshifts (more than 50 000) over an area of about 10 deg2 provides a galaxy sample with high statistical power. The accurate redshift measurements (σz = 0.00047(1 + zspec)) allow us to robustly isolate galaxies living in the lowest and highest density environments (δ< 0.7 and δ> 4, respectively) as defined in terms of spatial 3D density contrast δ. We estimate the stellar mass function of galaxies residing in these two environments and constrain the high-mass end (ℳ ≳ 1011 ℳ⊙) with unprecedented precision. We find that the galaxy stellar mass function in the densest regions has a different shape than was measured at low densities, with an enhancement of massive galaxies and a hint of a flatter (less negative) slope at z< 0.8. We normalise each mass function to the comoving volume occupied by the corresponding environment and relate estimates from different redshift bins. We observe an evolution of the stellar mass function of VIPERS galaxies in high densities, while the low-density one is nearly constant. We compare these results to semi-analytical models and find consistent environmental signatures in the simulated stellar mass functions. We discuss how the halo mass function and fraction of central/satellite galaxies depend on the environments considered, making intrinsic and environmental properties of galaxies physically coupled, hence difficult to disentangle. The evolution of our low-density regions is described well by the formalism introduced by Peng et al. (2010, ApJ, 721, 193), and is consistent with the idea that galaxies become progressively passive because of internal physical processes. The same formalism could also describe the evolution of the mass function in the high density regions, but only if a significant contribution from dry mergers is considered. Based on

  5. The mean density and two-point correlation function for the CfA redshift survey slices

    NASA Technical Reports Server (NTRS)

    De Lapparent, Valerie; Geller, Margaret J.; Huchra, John P.

    1988-01-01

    The effect of large-scale inhomogeneities on the determination of the mean number density and the two-point spatial correlation function were investigated for two complete slices of the extension of the Center for Astrophysics (CfA) redshift survey (de Lapparent et al., 1986). It was found that the mean galaxy number density for the two strips is uncertain by 25 percent, more so than previously estimated. The large uncertainty in the mean density introduces substantial uncertainty in the determination of the two-point correlation function, particularly at large scale; thus, for the 12-deg slice of the CfA redshift survey, the amplitude of the correlation function at intermediate scales is uncertain by a factor of 2. The large uncertainties in the correlation functions might reflect the lack of a fair sample.

  6. Using cross correlations to calibrate lensing source redshift distributions: Improving cosmological constraints from upcoming weak lensing surveys

    SciTech Connect

    De Putter, Roland; Doré, Olivier; Das, Sudeep

    2014-01-10

    Cross correlations between the galaxy number density in a lensing source sample and that in an overlapping spectroscopic sample can in principle be used to calibrate the lensing source redshift distribution. In this paper, we study in detail to what extent this cross-correlation method can mitigate the loss of cosmological information in upcoming weak lensing surveys (combined with a cosmic microwave background prior) due to lack of knowledge of the source distribution. We consider a scenario where photometric redshifts are available and find that, unless the photometric redshift distribution p(z {sub ph}|z) is calibrated very accurately a priori (bias and scatter known to ∼0.002 for, e.g., EUCLID), the additional constraint on p(z {sub ph}|z) from the cross-correlation technique to a large extent restores the cosmological information originally lost due to the uncertainty in dn/dz(z). Considering only the gain in photo-z accuracy and not the additional cosmological information, enhancements of the dark energy figure of merit of up to a factor of four (40) can be achieved for a SuMIRe-like (EUCLID-like) combination of lensing and redshift surveys, where SuMIRe stands for Subaru Measurement of Images and Redshifts). However, the success of the method is strongly sensitive to our knowledge of the galaxy bias evolution in the source sample and we find that a percent level bias prior is needed to optimize the gains from the cross-correlation method (i.e., to approach the cosmology constraints attainable if the bias was known exactly).

  7. The KMOS Redshift One Spectroscopic Survey (KROSS): The Tully-Fisher Relation at z ˜ 1

    NASA Astrophysics Data System (ADS)

    Tiley, Alfred L.; Stott, John P.; Swinbank, A. M.; Bureau, Martin; Harrison, Chris M.; Bower, Richard; Johnson, Helen L.; Bunker, Andrew J.; Jarvis, Matt J.; Magdis, Georgios; Sharples, Ray; Smail, Ian; Sobral, David; Best, Philip

    2016-04-01

    We present the stellar mass (M★), and K-corrected K-band absolute magnitude (MK) Tully-Fisher relations (TFRs) for sub-samples of the 584 galaxies spatially resolved in Hα emission by the KMOS Redshift One Spectroscopic Survey (KROSS). We model the velocity field of each of the KROSS galaxies and extract a rotation velocity, V80 at a radius equal to the major axis of an ellipse containing 80% of the total integrated Hα flux. The large sample size of KROSS allowed us to select 210 galaxies with well measured rotation speeds. We extract from this sample a further 56 galaxies that are rotationally supported, using the stringent criterion V80/σ > 3, where σ is the flux weighted average velocity dispersion. We find the MK and M★ TFRs for this sub-sample to be MK / {mag}= (-7.3 ± 0.9) × [(log (V_{80}/{km s^{-1}})-2.25]- 23.4 ± 0.2 , and log (M_{*} / M_{⊙})= (4.7 ± 0.4) × [(log (V_{80}/{km s^{-1}}) - 2.25] + 10.0 ± 0.3, respectively. We find an evolution of the M★ TFR zero-point of -0.41 ± 0.08 dex over the last ˜8 billion years. However, we measure no evolution in the MK TFR zero-point over the same period. We conclude that rotationally supported galaxies of a given dynamical mass had less stellar mass at z ˜ 1 than the present day, yet emitted the same amounts of K-band light. The ability of KROSS to differentiate, using integral field spectroscopy with KMOS, between those galaxies that are rotationally supported and those that are not explains why our findings are at odds with previous studies without the same capabilities.

  8. The KMOS Redshift One Spectroscopic Survey (KROSS): the Tully-Fisher relation at z ˜ 1

    NASA Astrophysics Data System (ADS)

    Tiley, Alfred L.; Stott, John P.; Swinbank, A. M.; Bureau, Martin; Harrison, Chris M.; Bower, Richard; Johnson, Helen L.; Bunker, Andrew J.; Jarvis, Matt J.; Magdis, Georgios; Sharples, Ray; Smail, Ian; Sobral, David; Best, Philip

    2016-07-01

    We present the stellar mass (M*), and K-corrected K-band absolute magnitude (MK) Tully-Fisher relations (TFRs) for subsamples of the 584 galaxies spatially resolved in H α emission by the KMOS Redshift One Spectroscopic Survey (KROSS). We model the velocity field of each of the KROSS galaxies and extract a rotation velocity, V80 at a radius equal to the major axis of an ellipse containing 80 per cent of the total integrated H α flux. The large sample size of KROSS allowed us to select 210 galaxies with well-measured rotation speeds. We extract from this sample a further 56 galaxies that are rotationally supported, using the stringent criterion V80/σ > 3, where σ is the flux weighted average velocity dispersion. We find the MK and M* TFRs for this subsample to be MK / {mag}= (-7.3 ± 0.9) × [(log (V_{80}/{km s^{-1}})-2.25]- 23.4 ± 0.2, and log (M_{{ast }} / M_{{⊙}})= (4.7 ± 0.4) × [(log (V_{80}/{km s^{-1}}) - 2.25] + 10.0 ± 0.3, respectively. We find an evolution of the M* TFR zero-point of -0.41 ± 0.08 dex over the last ˜8 billion years. However, we measure no evolution in the MK TFR zero-point over the same period. We conclude that rotationally supported galaxies of a given dynamical mass had less stellar mass at z ˜ 1 than the present day, yet emitted the same amounts of K-band light. The ability of KROSS to differentiate, using integral field spectroscopy with KMOS, between those galaxies that are rotationally supported and those that are not explains why our findings are at odds with previous studies without the same capabilities.

  9. The Herschel Multi-Tiered Extragalactic Survey: SPIRE-mm Photometric Redshifts

    NASA Technical Reports Server (NTRS)

    Roseboom, I. G.; Ivison, R. J.; Greve, T. R.; Amblard, A.; Arumugam, V.; Auld, R.; Aussel, H.; Bethermin, M.; Blain, A.; Bock, J.; Boselli, A.; Brisbin, D.; Buat, V.; Burgarella, D.; Castro-Rodriguez, N.; Cava, A.; Chanial, P.; Chapin, E.; Chapman, S.; Clements, D. L.; Conley, A.; Conversi, L.; Cooray, A.; Dowell, C. D.; Dwek, E.

    2011-01-01

    We investigate the potential of submm-mm and submm-mm-radio photometric red-shifts using a sample of mm-selected sources as seen at 250, 350 and 500 micrometers by the SPIRE instrument on Herschel. From a sample of 63 previously identified mm-sources with reliable radio identifications in the GOODS-N and Lockman Hole North fields 46 (73 per cent) are found to have detections in at least one SPIRE band. We explore the observed submm/mm colour evolution with redshift, finding that the colours of mm-sources are adequately described by a modified blackbody with constant optical depth Tau = (nu/nu(0))beta where beta = +1.8 and nu(0) = c/100 micrometers. We find a tight correlation between dust temperature and IR luminosity. Using a single model of the dust temperature and IR luminosity relation we derive photometric redshift estimates for the 46 SPIRE detected mm-sources. Testing against the 22 sources with known spectroscopic, or good quality optical/near-IR photometric, redshifts we find submm/mm photometric redshifts offer a redshift accuracy of |delta z|/(1+z) = 0.16 (less than |delta z| greater than = 0.51). Including constraints from the radio-far IR correlation the accuracy is improved to |delta z|/(1 + z) = 0.15 (less than |delta z| greater than = 0.45). We estimate the redshift distribution of mm-selected sources finding a significant excess at z greater than 3 when compared to 850 micrometer selected samples.

  10. Gemini Spectroscopy of Supernovae from the Supernova Legacy Survey: Improving High-Redshift Supernova Selection and Classification

    NASA Astrophysics Data System (ADS)

    Howell, D. A.; Sullivan, M.; Perrett, K.; Bronder, T. J.; Hook, I. M.; Astier, P.; Aubourg, E.; Balam, D.; Basa, S.; Carlberg, R. G.; Fabbro, S.; Fouchez, D.; Guy, J.; Lafoux, H.; Neill, J. D.; Pain, R.; Palanque-Delabrouille, N.; Pritchet, C. J.; Regnault, N.; Rich, J.; Taillet, R.; Knop, R.; McMahon, R. G.; Perlmutter, S.; Walton, N. A.

    2005-12-01

    We present new techniques for improving the efficiency of supernova (SN) classification at high redshift using 64 candidates observed at Gemini North and South during the first year of the Supernova Legacy Survey (SNLS). The SNLS is an ongoing 5 year project with the goal of measuring the equation of state of dark energy by discovering and following over 700 high-redshift SNe Ia using data from the Canada-France-Hawaii Telescope Legacy Survey. We achieve an improvement in the SN Ia spectroscopic confirmation rate: at Gemini 71% of candidates are now confirmed as SNe Ia, compared to 54% using the methods of previous surveys. This is despite the comparatively high redshift of this sample, in which the median SN Ia redshift is z=0.81 (0.155<=z<=1.01). These improvements were realized because we use the unprecedented color coverage and light curve sampling of the SNLS to predict whether a candidate is a SN Ia and to estimate its redshift, before obtaining a spectrum, using a new technique called the ``SN photo-z.'' In addition, we have improved techniques for galaxy subtraction and SN template χ2 fitting, allowing us to identify candidates even when they are only 15% as bright as the host galaxy. The largest impediment to SN identification is found to be host galaxy contamination of the spectrum-when the SN was at least as bright as the underlying host galaxy the target was identified more than 90% of the time. However, even SNe in bright host galaxies can be easily identified in good seeing conditions. When the image quality was better than 0.55", the candidate was identified 88% of the time. Over the 5 year course of the survey, using the selection techniques presented here, we will be able to add ~170 more confirmed SNe Ia than would be possible using previous methods. APC, 11 Place Marcelin Berthelot, 75231 Paris Cedex 05, France. DSM/DAPNIA, CEA/Saclay, 91191 Gif-sur-Yvette Cedex, France.

  11. Galaxy evolution at high-redshift: Millimeter-wavelength surveys with the AzTEC camera

    NASA Astrophysics Data System (ADS)

    Scott, Kimberly S.

    Galaxies detected by their thermal dust emission at submillimeter (submm) and millimeter (mm) wavelengths comprise a population of massive, intensely star-forming systems in the early Universe. These "submm/mm- galaxies", or SMGs, likely represent an important phase in the assembly and/or evolution of massive galaxies and are thought to be the progenitors of massive elliptical galaxies. While their projected number density as a function of source brightness provides key constraints on models of galaxy evolution, SMG surveys carried out over the past twelve years with the first generation of submm/mm-wavelength cameras have not imaged a large enough area to sufficient depths to provide the statistical power needed to discriminate between competing galaxy evolution scenarios. In this dissertation, we present the results from SMG surveys carried out over the past four years using the new sensitive mm-wavelength camera AzTEC. With the improved mapping speed of the AzTEC camera combined with dedicated telescope time devoted to deep, large-area extragalactic surveys, we have tripled both the area surveyed towards blank- fields (that is, regions with no known galaxy over-densities) at submm/mm wavelengths and the total number of detected SMGs. Here, we describe the properties and performance of the AzTEC instrument while operating on the James Clerk Maxwell Telescope (JCMT) and the Atacama Submillimeter Telescope Experiment (ASTE). We then present the results from two of the blank-field regions imaged with AzTEC: the JCMT/COSMOS field, which we discovered is over- dense in the number of very bright SMGs, and the ASTE survey of the Great Observatories Origins Deep-South field, which represents one of the deepest surveys ever carried out at submm/mm wavelengths. Finally, we combine the results from all of the blank-fields imaged with AzTEC while operating on the JCMT and the ASTE to calculate the most accurate measurements to date of the SMG number counts.

  12. Searches for High Redshift Galaxies

    NASA Astrophysics Data System (ADS)

    Stevens, R.

    In recent years, the technique of Lyman break imaging has proven very effective at identifying large numbers of galaxies at high redshifts through deep multicolour imaging (Steidel et al 1996b; Steidel et al 1999). The combination of an intrinsic break in the spectra of star-forming galaxies below the rest-frame wavelength of Lyman-alpha and attenuation by intervening HI systems on the line of sight to high redshifts makes for a pronounced drop in the flux of high redshift galaxies between 912 Å and 1216 Å in the rest-frame. At redshifts z> 3, the break is shifted sufficiently far into the optical window accessible to ground-based telescopes for galaxies at such redshift to be distinguished from the foreground galaxy population through photometry alone. Through modelling of the expected colours of a wide range of galaxy types, ages and redshifts, taking into account the effects of reddening (Calzetti, Kinney and Storchi-Bergmann 1994) and intergalactic attenuation (Madau 1995), we assess the likely colours of high redshift galaxies and determine the redshift ranges most effectively probed by the imaging filters. We obtain multicolour imaging of the fields of four high redshift radio galaxies, covering around 40 arcmin2 in each, allowing us to attempt to find ordinary galaxies at similar redshifts to the central radio galaxies through photometric colour selection techniques. Some idea as to the effectiveness comes through additional colour and morphological information obtained from high-resolution Hubble Space Telescope images and from data taken in the near infra-red. While we do not have spectroscopic evidence for the redshifts of our candidates, given the available evidence we conclude that the number densities of Lyman break galaxies in the radio galaxy fields are in broad agreement with the data of Steidel et al (1999). Finally, we assess the prospects for future studies of the high redshift Universe, in particular the potential of the Oxford Deep Wide Field

  13. VizieR Online Data Catalog: SHELS: redshift survey of the F1 DLS field (Geller+, 2016)

    NASA Astrophysics Data System (ADS)

    Geller, M. J.; Hwang, H. S.; Dell'Antonio, I. P.; Zahid, H. J.; Kurtz, M. J.; Fabricant, D. G.

    2016-07-01

    The Smithsonian Hectospec Lensing Survey (SHELS) redshift survey covers two 4deg2 fields originally selected as part of the Deep Lens Survey (DLS; Wittman et al. 2006ApJ...643..128W). We used the 300-fiber Hectospec instrument on the MMT to acquire spectroscopy for galaxy candidates typically brighter than R=20.6. We observed the F1 field (centered at RA=00:53:25.3 and DEC=12:33:55 (J2000)) in queue mode during dark runs in four periods: 2005 October 24-28; 2006 October 17-November 22; 2012 October 10-December 10; 2014 September 26-November 28. The wavelength range covered by Hectospec in the observer's frame is 3700-9100Å with a resolution of ~5Å. See section 2.2 for further explanations. (4 data files).

  14. Quasi-stellar objects in the ALHAMBRA survey. I. Photometric redshift accuracy based on 23 optical-NIR filter photometry

    NASA Astrophysics Data System (ADS)

    Matute, I.; Márquez, I.; Masegosa, J.; Husillos, C.; del Olmo, A.; Perea, J.; Alfaro, E. J.; Fernández-Soto, A.; Moles, M.; Aguerri, J. A. L.; Aparicio-Villegas, T.; Benítez, N.; Broadhurst, T.; Cabrera-Cano, J.; Castander, F. J.; Cepa, J.; Cerviño, M.; Cristóbal-Hornillos, D.; Infante, L.; González Delgado, R. M.; Martínez, V. J.; Molino, A.; Prada, F.; Quintana, J. M.

    2012-06-01

    Context. Even the spectroscopic capabilities of today's ground and space-based observatories can not keep up with the enormous flow of detections (>105 deg-2) unveiled in modern cosmological surveys as: i) would be required enormous telescope time to perform the spectroscopic follow-ups and ii) spectra remain unattainable for the fainter detected population. In the past decade, the typical accuracy of photometric redshift (photo-z) determination has drastically improved. Nowdays, it has become a perfect complement to spectroscopy, closing the gap between photometric surveys and their spectroscopic follow-ups. The photo-z precision for active galactic nuclei (AGN) has always lagged behind that for the galaxy population owing to the lack of proper templates and their intrinsic variability. Aims: Our goal is to characterize the ability of the Advanced Large, Homogeneous Area Medium-Band Redshift Astronomical (ALHAMBRA) survey in assigning accurate photo-z's to broad-line AGN (BLAGN) and quasi-stellar objects (QSOs) based on their ALHAMBRA very-low-resolution optical-near-infrared (NIR) spectroscopy. This will serve as a benchmark for any future compilation of ALHAMBRA selected QSOs and the basis for the statistical analysis required to derive luminosity functions up to z ~ 5. Methods: We selected a sample of spectroscopically identified BLAGN and QSOs and used a library of templates (including the SEDs of AGN and both normal and starburst galaxies, as well as stars) to fit the 23 photometric data points provided by ALHAMBRA in the optical and NIR (20 medium-band optical filters plus the standard JHKs). Results: We find that the ALHAMBRA photometry is able to provide an accurate photo-z and spectral classification for ~88% of the 170 spectroscopically identified BLAGN/QSOs over 2.5 deg2 in different areas of the survey and brighter than m678 = 23.5 (equivalent to rSLOAN ~ 24.0). The derived photo-z accuracy is below 1% and is comparable to the most recent results in

  15. MEASUREMENTS OF CO REDSHIFTS WITH Z-SPEC FOR LENSED SUBMILLIMETER GALAXIES DISCOVERED IN THE H-ATLAS SURVEY

    SciTech Connect

    Lupu, R. E.; Scott, K. S.; Aguirre, J. E.; Aretxaga, I.; Auld, R.; Dariush, A.; Barton, E.; Cooke, J.; Cooray, A.; Beelen, A.; Bertoldi, F.; Bock, J. J.; Bradford, C. M.; Bonfield, D.; Buttiglione, S.; De Zotti, G.; Cava, A.; Dannerbauer, H.; and others

    2012-10-01

    We present new observations from Z-Spec, a broadband 185-305 GHz spectrometer, of five submillimeter bright lensed sources selected from the Herschel-Astrophysical Terahertz Large Area Survey science demonstration phase catalog. We construct a redshift-finding algorithm using combinations of the signal to noise of all the lines falling in the Z-Spec bandpass to determine redshifts with high confidence, even in cases where the signal to noise in individual lines is low. We measure the dust continuum in all sources and secure CO redshifts for four out of five (z {approx} 1.5-3). In one source, SDP.17, we tentatively identify two independent redshifts and a water line, confirmed at z = 2.308. Our sources have properties characteristic of dusty starburst galaxies, with magnification-corrected star formation rates of 10{sup 2-3} M{sub Sun} yr{sup -1}. Lower limits for the dust masses ({approx} a few 10{sup 8} M{sub Sun }) and spatial extents ({approx}1 kpc equivalent radius) are derived from the continuum spectral energy distributions, corresponding to dust temperatures between 54 and 69 K. In the local thermodynamic equilibrium (LTE) approximation, we derive relatively low CO excitation temperatures ({approx}< 100 K) and optical depths ({tau} {approx}< 1). Performing a non-LTE excitation analysis using RADEX, we find that the CO lines measured by Z-Spec (from J = 4 {yields} 3 to 10 {yields} 9, depending on the galaxy) localize the best solutions to either a high-temperature/low-density region or a low/temperature/high-density region near the LTE solution, with the optical depth varying accordingly. Observations of additional CO lines, CO(1-0) in particular, are needed to constrain the non-LTE models.

  16. The KMOS Redshift One Spectroscopic Survey (KROSS): dynamical properties, gas and dark matter fractions of typical z ˜ 1 star-forming galaxies

    NASA Astrophysics Data System (ADS)

    Stott, John P.; Swinbank, A. M.; Johnson, Helen L.; Tiley, Alfie; Magdis, Georgios; Bower, Richard; Bunker, Andrew J.; Bureau, Martin; Harrison, Chris M.; Jarvis, Matt J.; Sharples, Ray; Smail, Ian; Sobral, David; Best, Philip; Cirasuolo, Michele

    2016-04-01

    The KMOS Redshift One Spectroscopic Survey (KROSS) is an ESO-guaranteed time survey of 795 typical star-forming galaxies in the redshift range z = 0.8-1.0 with the KMOS instrument on the Very Large Telescope. In this paper, we present resolved kinematics and star formation rates for 584 z ˜ 1 galaxies. This constitutes the largest near-infrared Integral Field Unit survey of galaxies at z ˜ 1 to date. We demonstrate the success of our selection criteria with 90 per cent of our targets found to be H α emitters, of which 81 per cent are spatially resolved. The fraction of the resolved KROSS sample with dynamics dominated by ordered rotation is found to be 83 ± 5 per cent. However, when compared with local samples these are turbulent discs with high gas to baryonic mass fractions, ˜35 per cent, and the majority are consistent with being marginally unstable (Toomre Q ˜ 1). There is no strong correlation between galaxy averaged velocity dispersion and the total star formation rate, suggesting that feedback from star formation is not the origin of the elevated turbulence. We postulate that it is the ubiquity of high (likely molecular) gas fractions and the associated gravitational instabilities that drive the elevated star formation rates in these typical z ˜ 1 galaxies, leading to the 10-fold enhanced star formation rate density. Finally, by comparing the gas masses obtained from inverting the star formation law with the dynamical and stellar masses, we infer an average dark matter to total mass fraction within 2.2re (9.5 kpc) of 65 ± 12 per cent, in agreement with the results from hydrodynamic simulations of galaxy formation.

  17. The Role of Environment in Shaping Galaxy Evolution at High Redshift: Insights from the SpARCS Cluster Survey

    NASA Astrophysics Data System (ADS)

    Wilson, Gillian

    2015-08-01

    Between z = 2 and z = 1, the main progenitors of present-day massive clusters undergo rapid collapse, and cluster members transform from active star-forming to quiescent galaxies. The SpARCS survey is one of the largest surveys designed to detect clusters of galaxies at z> 1, and has discovered hundreds of Spitzer IR-selected clusters.I will present results from GCLASS, a 25-night Gemini/GMOS spectroscopic follow-up survey of ten of the most massive SpARCS clusters at z~1, and explain what we are learning about quenching and stellar mass assembly of galaxies in these, the densest of environments, relative to the field population. I will explain how predictions and observations of the stellar mass growth of Brightest Cluster Galaxies, previously controversially divergent, are now coming into agreement, and discuss the evidence for the relative importance of mergers versus in-situ star formation in driving this stellar mass growth as a function of redshift.I will also present a sample of newly-confirmed clusters at z~2 for which we have HST spectroscopy and imaging, and have been targeting with Keck/MOSFIRE. I will conclude by discussing GOGREEN and DEEPDRILL, two new large surveys approved by Gemini & Spitzer, designed to study the effects of environment at lower stellar mass and at higher redshift, respectively. Collectively, these powerful new surveys are beginning to allow us to place constraints on the location and timescale of quenching and, in concert with both hydro-simulations and semi-analytic models, identify the complex role of environment in shaping galaxy evolution over cosmic time.

  18. The zCOSMOS redshift survey: the role of environment and stellar mass in shaping the rise of the morphology-density relation from z ~ 1

    NASA Astrophysics Data System (ADS)

    Tasca, L. A. M.; Kneib, J.-P.; Iovino, A.; Le Fèvre, O.; Kovač, K.; Bolzonella, M.; Lilly, S. J.; Abraham, R. G.; Cassata, P.; Cucciati, O.; Guzzo, L.; Tresse, L.; Zamorani, G.; Capak, P.; Garilli, B.; Scodeggio, M.; Sheth, K.; Zucca, E.; Carollo, C. M.; Contini, T.; Mainieri, V.; Renzini, A.; Bardelli, S.; Bongiorno, A.; Caputi, K.; Coppa, G.; de La Torre, S.; de Ravel, L.; Franzetti, P.; Kampczyk, P.; Knobel, C.; Koekemoer, A. M.; Lamareille, F.; Le Borgne, J.-F.; Le Brun, V.; Maier, C.; Mignoli, M.; Pello, R.; Peng, Y.; Perez Montero, E.; Ricciardelli, E.; Silverman, J. D.; Vergani, D.; Tanaka, M.; Abbas, U.; Bottini, D.; Cappi, A.; Cimatti, A.; Ilbert, O.; Leauthaud, A.; Maccagni, D.; Marinoni, C.; McCracken, H. J.; Memeo, P.; Meneux, B.; Oesch, P.; Porciani, C.; Pozzetti, L.; Scaramella, R.; Scarlata, C.

    2009-08-01

    up to z ~ 1 for luminosity-selected, volume-limited samples. The behaviour of the morphology-density relation gets flatter at fixed masses expecially above 1010.6 M⊙. We suggest the existence of a critical mass above which the physical processes governing galaxy stellar mass also determine the shaping of the galaxy more than its environment. We finally show that at a fixed morphology there is still a residual variation in galaxy colours with density. Conclusions: The observed evolution with redshift of the morphology-density relation offers an opportunity to trace the effect of nature and nurture as a function of environment. Even though it is based mainly on a biased view, the environmental dependence of the morphological evolution for luminosity-selected, volume-limited samples seems to indicate that nurture is in play. On the other hand, the lack of evolution observed for early-type and spiral galaxies that are more massive than 1010.8 M⊙ independents of the environment indicates that nature has imprinted these properties early in the life of these galaxies. We conclude that the relative contribution of nature and nurture in different environments strongly depends on the mass of galaxies, consistent with a downsizing scenario. Based on observations obtained at the European Southern Observatory (ESO) Very Large Telescope (VLT), Paranal, Chile, as part of the Large Program 175.A-0839 (the zCOSMOS Spectroscopic Redshift Survey).

  19. The VIMOS Ultra-Deep Survey: ~10 000 galaxies with spectroscopic redshifts to study galaxy assembly at early epochs 2 < z ≃ 6

    NASA Astrophysics Data System (ADS)

    Le Fèvre, O.; Tasca, L. A. M.; Cassata, P.; Garilli, B.; Le Brun, V.; Maccagni, D.; Pentericci, L.; Thomas, R.; Vanzella, E.; Zamorani, G.; Zucca, E.; Amorin, R.; Bardelli, S.; Capak, P.; Cassarà, L.; Castellano, M.; Cimatti, A.; Cuby, J. G.; Cucciati, O.; de la Torre, S.; Durkalec, A.; Fontana, A.; Giavalisco, M.; Grazian, A.; Hathi, N. P.; Ilbert, O.; Lemaux, B. C.; Moreau, C.; Paltani, S.; Ribeiro, B.; Salvato, M.; Schaerer, D.; Scodeggio, M.; Sommariva, V.; Talia, M.; Taniguchi, Y.; Tresse, L.; Vergani, D.; Wang, P. W.; Charlot, S.; Contini, T.; Fotopoulou, S.; López-Sanjuan, C.; Mellier, Y.; Scoville, N.

    2015-04-01

    We present the VIMOS Ultra Deep Survey (VUDS), a spectroscopic redshift survey of ~10 000 very faint galaxies to study the main phase of galaxy assembly in 2 < z ≃ 6. The survey covers 1 deg2 in three separate fields: COSMOS, ECDFS, and VVDS-02h, with the selection of targets based on an inclusive combination of photometric redshifts and colour properties. Spectra covering 3650 < λ < 9350 Å are obtained with VIMOS on the ESO-VLT with integration times of 14h. Here we present the survey strategy, target selection, data processing, and the redshift measurement process with an emphasis on the specific methods used to adapt to this high-redshift range. We discuss the spectra quality and redshift reliability and derive a success rate in redshift measurement of 91%, or 74% by limiting the dataset to the most reliable measurements, down to a limiting magnitude iAB = 25. Measurements are performed all the way down to iAB = 27. The mean redshift of the main sample is z ~ 3 and extends over a broad redshift range mainly in 2 < z < 6. At 3 < z < 5, the galaxies cover a wide range of luminosities -23 < MNUV < -20.5, stellar mass 109M⊙ < M∗ < 1011M⊙, and star formation rates 1M⊙/yr < SFR < 103M⊙/yr. We discuss the spectral properties of galaxies using individual as well asstacked spectra. The comparison between spectroscopic and photometric redshifts as well as colour selection demonstrate the effectiveness of our selection scheme. From about ~ 90% of the data analysed so far, we expect to assemble >6000 galaxies with reliable spectroscopic redshifts in 2 < z < 6 when complete. This makes the VUDS the largest survey at these redshifts and offers the opportunity for unprecedented studies of the star-forming galaxy population and its distribution in large-scale structures during the main phase of galaxy assembly. Based on data obtained with the European Southern Observatory Very Large Telescope, Paranal, Chile, under Large Program 185.A-0791.Staged releases of the

  20. The VIMOS Public Extragalactic Redshift Survey (VIPERS) . Luminosity and stellar mass dependence of galaxy clustering at 0.5 < z < 1.1

    NASA Astrophysics Data System (ADS)

    Marulli, F.; Bolzonella, M.; Branchini, E.; Davidzon, I.; de la Torre, S.; Granett, B. R.; Guzzo, L.; Iovino, A.; Moscardini, L.; Pollo, A.; Abbas, U.; Adami, C.; Arnouts, S.; Bel, J.; Bottini, D.; Cappi, A.; Coupon, J.; Cucciati, O.; De Lucia, G.; Fritz, A.; Franzetti, P.; Fumana, M.; Garilli, B.; Ilbert, O.; Krywult, J.; Le Brun, V.; Le Fèvre, O.; Maccagni, D.; Małek, K.; McCracken, H. J.; Paioro, L.; Polletta, M.; Schlagenhaufer, H.; Scodeggio, M.; Tasca, L. A. M.; Tojeiro, R.; Vergani, D.; Zanichelli, A.; Burden, A.; Di Porto, C.; Marchetti, A.; Marinoni, C.; Mellier, Y.; Nichol, R. C.; Peacock, J. A.; Percival, W. J.; Phleps, S.; Wolk, M.; Zamorani, G.

    2013-09-01

    Aims: We investigate the dependence of galaxy clustering on luminosity and stellar mass in the redshift range 0.5 < z < 1.1, using the first ~ 55 000 redshifts from the VIMOS Public Extragalactic Redshift Survey (VIPERS). Methods: We measured the redshift-space two-point correlation functions (2PCF), ξ(s) and ξ(rp,π) , and the projected correlation function, wp(rp), in samples covering different ranges of B-band absolute magnitudes and stellar masses. We considered both threshold and binned galaxy samples, with median B-band absolute magnitudes - 21.6 ≲ MB - 5log (h) ≲ - 19.5 and median stellar masses 9.8 ≲ log (M⋆ [h-2 M⊙]) ≲ 10.7. We assessed the real-space clustering in the data from the projected correlation function, which we model as a power law in the range 0.2 < rp [h-1 Mpc ] < 20. Finally, we estimated the galaxy bias as a function of luminosity, stellar mass, and redshift, assuming a flat Λ cold dark matter model to derive the dark matter 2PCF. Results: We provide the best-fit parameters of the power-law model assumed for the real-space 2PCF - the correlation length, r0, and the slope, γ - as well as the linear bias parameter, as a function of the B-band absolute magnitude, stellar mass, and redshift. We confirm and provide the tightest constraints on the dependence of clustering on luminosity at 0.5 < z < 1.1. We prove the complexity of comparing the clustering dependence on stellar mass from samples that are originally flux-limited and discuss the possible origin of the observed discrepancies. Overall, our measurements provide stronger constraints on galaxy formation models, which are now required to match, in addition to local observations, the clustering evolution measured by VIPERS galaxies between z = 0.5 and z = 1.1 for a broad range of luminosities and stellar masses. Based on observations collected at the European Southern Observatory, Paranal, Chile, under programmes 182.A-0886 (LP) at the Very Large Telescope, and also based on

  1. Leveraging 3D-HST Grism Redshifts to Quantify Photometric Redshift Performance

    NASA Astrophysics Data System (ADS)

    Bezanson, Rachel; Wake, David A.; Brammer, Gabriel B.; van Dokkum, Pieter G.; Franx, Marijn; Labbé, Ivo; Leja, Joel; Momcheva, Ivelina G.; Nelson, Erica J.; Quadri, Ryan F.; Skelton, Rosalind E.; Weiner, Benjamin J.; Whitaker, Katherine E.

    2016-05-01

    We present a study of photometric redshift accuracy in the 3D-HST photometric catalogs, using 3D-HST grism redshifts to quantify and dissect trends in redshift accuracy for galaxies brighter than JH IR > 24 with an unprecedented and representative high-redshift galaxy sample. We find an average scatter of 0.0197 ± 0.0003(1 + z) in the Skelton et al. photometric redshifts. Photometric redshift accuracy decreases with magnitude and redshift, but does not vary monotonically with color or stellar mass. The 1σ scatter lies between 0.01 and 0.03 (1 + z) for galaxies of all masses and colors below z < 2.5 (for JH IR < 24), with the exception of a population of very red (U ‑ V > 2), dusty star-forming galaxies for which the scatter increases to ∼0.1 (1 + z). We find that photometric redshifts depend significantly on galaxy size; the largest galaxies at fixed magnitude have photo-zs with up to ∼30% more scatter and ∼5 times the outlier rate. Although the overall photometric redshift accuracy for quiescent galaxies is better than that for star-forming galaxies, scatter depends more strongly on magnitude and redshift than on galaxy type. We verify these trends using the redshift distributions of close pairs and extend the analysis to fainter objects, where photometric redshift errors further increase to ∼0.046 (1 + z) at {H}F160W=26. We demonstrate that photometric redshift accuracy is strongly filter dependent and quantify the contribution of multiple filter combinations. We evaluate the widths of redshift probability distribution functions and find that error estimates are underestimated by a factor of ∼1.1–1.6, but that uniformly broadening the distribution does not adequately account for fitting outliers. Finally, we suggest possible applications of these data in planning for current and future surveys and simulate photometric redshift performance in the Large Synoptic Survey Telescope, Dark Energy Survey (DES), and combined DES and Vista Hemisphere

  2. A far-infrared spectroscopic survey of intermediate redshift (ultra) luminous infrared galaxies

    SciTech Connect

    Magdis, Georgios E.; Rigopoulou, D.; Hopwood, R.; Clements, D.; Huang, J.-S.; Farrah, D.; Pearson, C.; Alonso-Herrero, Almudena; Bock, J. J.; Cooray, A.; Griffin, M. J.; Oliver, S.; Perez Fournon, I.; Riechers, D.; Swinyard, B. M.; Thatte, N.; Scott, D.; Valtchanov, I.; Vaccari, M.

    2014-11-20

    We present Herschel far-IR photometry and spectroscopy as well as ground-based CO observations of an intermediate redshift (0.21 ≤ z ≤ 0.88) sample of Herschel-selected (ultra)-luminous infrared galaxies (L {sub IR} > 10{sup 11.5} L {sub ☉}). With these measurements, we trace the dust continuum, far-IR atomic line emission, in particular [C II] 157.7 μm, as well as the molecular gas of z ∼ 0.3 luminous and ultraluminous infrared galaxies (LIRGs and ULIRGs) and perform a detailed investigation of the interstellar medium of the population. We find that the majority of Herschel-selected intermediate redshift (U)LIRGs have L {sub C} {sub II}/L {sub FIR} ratios that are a factor of about 10 higher than that of local ULIRGs and comparable to that of local normal and high-z star-forming galaxies. Using our sample to bridge local and high-z [C II] observations, we find that the majority of galaxies at all redshifts and all luminosities follow an L {sub C} {sub II}–L {sub FIR} relation with a slope of unity, from which local ULIRGs and high- z active-galactic-nucleus-dominated sources are clear outliers. We also confirm that the strong anti-correlation between the L {sub C} {sub II}/L {sub FIR} ratio and the far-IR color L {sub 60}/L {sub 100} observed in the local universe holds over a broad range of redshifts and luminosities, in the sense that warmer sources exhibit lower L {sub C} {sub II}/L {sub FIR} at any epoch. Intermediate redshift ULIRGs are also characterized by large molecular gas reservoirs and by lower star formation efficiencies compared to that of local ULIRGs. The high L {sub C} {sub II}/L {sub FIR} ratios, the moderate star formation efficiencies (L {sub IR}/L{sub CO}{sup ′} or L {sub IR}/M{sub H{sub 2}}), and the relatively low dust temperatures of our sample (which are also common characteristics of high-z star-forming galaxies with ULIRG-like luminosities) indicate that the evolution of the physical properties of (U)LIRGs between the

  3. Unsupervised self-organized mapping: a versatile empirical tool for object selection, classification and redshift estimation in large surveys

    NASA Astrophysics Data System (ADS)

    Geach, James E.

    2012-01-01

    We present an application of unsupervised machine learning - the self-organized map (SOM) - as a tool for visualizing, exploring and mining the catalogues of large astronomical surveys. Self-organization culminates in a low-resolution representation of the 'topology' of a parameter volume, and this can be exploited in various ways pertinent to astronomy. Using data from the Cosmological Evolution Survey (COSMOS), we demonstrate two key astronomical applications of the SOM: (i) object classification and selection, using galaxies with active galactic nuclei as an example, and (ii) photometric redshift estimation, illustrating how SOMs can be used as totally empirical predictive tools. With a training set of ˜3800 galaxies with zspec≤ 1, we achieve photometric redshift accuracies competitive with other (mainly template fitting) techniques that use a similar number of photometric bands [σ(Δz) = 0.03 with a ˜2 per cent outlier rate when using u* band to 8 ?m photometry]. We also test the SOM as a photo-z tool using the PHoto-z Accuracy Testing (PHAT) synthetic catalogue of Hildebrandt et al., which compares several different photo-z codes using a common input/training set. We find that the SOM can deliver accuracies that are competitive with many of the established template fitting and empirical methods. This technique is not without clear limitations, which are discussed, but we suggest it could be a powerful tool in the era of extremely large -'petabyte'- data bases where efficient data mining is a paramount concern.

  4. Luminosity and redshift dependence of the covering factor of active galactic nuclei viewed with WISE and Sloan digital sky survey

    SciTech Connect

    Toba, Y.; Matsuhara, H.; Oyabu, S.; Malkan, M. A.; Gandhi, P.; Nakagawa, T.; Isobe, N.; Shirahata, M.; Oi, N.; Takita, S.; Yano, K.; Ohyama, Y.; Yamauchi, C.

    2014-06-10

    In this work, we investigate the dependence of the covering factor (CF) of active galactic nuclei (AGNs) on the mid-infrared (MIR) luminosity and the redshift. We constructed 12 and 22 μm luminosity functions (LFs) at 0.006 ≤z ≤ 0.3 using Wide-field Infrared Survey Explorer (WISE) data. Combining the WISE catalog with Sloan Digital Sky Survey (SDSS) spectroscopic data, we selected 223,982 galaxies at 12 μm and 25,721 galaxies at 22 μm for spectroscopic classification. We then identified 16,355 AGNs at 12 μm and 4683 AGNs at 22 μm by their optical emission lines and cataloged classifications in the SDSS. Following that, we estimated the CF as the fraction of Type 2 AGN in all AGNs whose MIR emissions are dominated by the active nucleus (not their host galaxies) based on their MIR colors. We found that the CF decreased with increasing MIR luminosity, regardless of the choice of Type 2 AGN classification criteria, and the CF did not change significantly with redshift for z ≤ 0.2. Furthermore, we carried out various tests to determine the influence of selection bias and confirmed that similar dependences exist, even when taking these uncertainties into account. The luminosity dependence of the CF can be explained by the receding torus model, but the 'modified' receding torus model gives a slightly better fit, as suggested by Simpson.

  5. THE BOSS EMISSION-LINE LENS SURVEY (BELLS). I. A LARGE SPECTROSCOPICALLY SELECTED SAMPLE OF LENS GALAXIES AT REDSHIFT {approx}0.5

    SciTech Connect

    Brownstein, Joel R.; Bolton, Adam S.; Pandey, Parul; Schlegel, David J.; Eisenstein, Daniel J.; Kochanek, Christopher S.; Connolly, Natalia; Maraston, Claudia; Seitz, Stella; Wake, David A.; Wood-Vasey, W. Michael; Brinkmann, Jon; Schneider, Donald P.; Weaver, Benjamin A.

    2012-01-01

    We present a catalog of 25 definite and 11 probable strong galaxy-galaxy gravitational lens systems with lens redshifts 0.4 {approx}< z {approx}< 0.7, discovered spectroscopically by the presence of higher-redshift emission lines within the Baryon Oscillation Spectroscopic Survey (BOSS) of luminous galaxies, and confirmed with high-resolution Hubble Space Telescope (HST) images of 44 candidates. Our survey extends the methodology of the Sloan Lens Advanced Camera for Surveys survey (SLACS) to higher redshift. We describe the details of the BOSS spectroscopic candidate detections, our HST ACS image processing and analysis methods, and our strong gravitational lens modeling procedure. We report BOSS spectroscopic parameters and ACS photometric parameters for all candidates, and mass-distribution parameters for the best-fit singular isothermal ellipsoid models of definite lenses. Our sample to date was selected using only the first six months of BOSS survey-quality spectroscopic data. The full five-year BOSS database should produce a sample of several hundred strong galaxy-galaxy lenses and in combination with SLACS lenses at lower redshift, strongly constrain the redshift evolution of the structure of elliptical, bulge-dominated galaxies as a function of luminosity, stellar mass, and rest-frame color, thereby providing a powerful test for competing theories of galaxy formation and evolution.

  6. The two-point correlation function for groups of galaxies in the Center for Astrophysics redshift survey

    NASA Technical Reports Server (NTRS)

    Ramella, Massimo; Geller, Margaret J.; Huchra, John P.

    1990-01-01

    The large-scale distribution of groups of galaxies selected from complete slices of the CfA redshift survey extension is examined. The survey is used to reexamine the contribution of group members to the galaxy correlation function. The relationship between the correlation function for groups and those calculated for rich clusters is discussed, and the results for groups are examined as an extension of the relation between correlation function amplitude and richness. The group correlation function indicates that groups and individual galaxies are equivalent tracers of the large-scale matter distribution. The distribution of group centers is equivalent to random sampling of the galaxy distribution. The amplitude of the correlation function for groups is consistent with an extrapolation of the amplitude-richness relation for clusters. The amplitude scaled by the mean intersystem separation is also consistent with results for richer clusters.

  7. A Survey of Star-forming Galaxies in the 1.4<~Z<~ 2.5 Redshift Desert: Overview

    NASA Astrophysics Data System (ADS)

    Steidel, Charles C.; Shapley, Alice E.; Pettini, Max; Adelberger, Kurt L.; Erb, Dawn K.; Reddy, Naveen A.; Hunt, Matthew P.

    2004-04-01

    The redshift interval 1.4<~z<~2.5 has been described by some as the ``redshift desert'' because of historical difficulties in spectroscopically identifying galaxies in that range. In fact, galaxies can be found in large numbers with standard broadband color selection techniques coupled with follow-up spectroscopy with UV and blue-sensitive spectrographs. In this paper we present the first results of a large-scale survey of such objects, carried out with the blue channel of the LRIS spectrograph (LRIS-B) on the Keck I Telescope. We introduce two samples of star-forming galaxies, ``BX'' galaxies at =2.20+/-0.32 and ``BM'' galaxies at =1.70+/-0.34. In seven survey fields we have spectroscopically confirmed 749 of the former and 114 of the latter. Interlopers (defined as objects at z<1) account for less than 10% of the photometric candidates, and the fraction of faint active galactic nuclei is ~3% in the combined BX/BM sample. Deep near-IR photometry of a subset of the BX sample indicates that, compared with a sample of similarly UV-selected galaxies at z~3, the z~2 galaxies are on average significantly redder in (R-Ks), indicating longer star formation histories, increased reddening by dust, or both. Using near-IR Hα spectra of a subset of BX/BM galaxies to define the galaxies' systemic redshifts, we show that the galactic-scale winds that are a feature of star-forming galaxies at z~3 are also common at later epochs and have similar bulk outflow speeds of 200-300 km s-1. We illustrate with examples the information that can be deduced on the stellar populations, metallicities, and kinematics of redshift desert galaxies from easily accessible rest-frame far-UV and rest-frame optical spectra. Far from being hostile to observations, the universe at z~2 is uniquely suited to providing information on the astrophysics of star-forming galaxies and the intergalactic medium, and the relationship between the two. Based, in part, on data obtained at the W. M. Keck

  8. Exploring the SDSS photometric galaxies with clustering redshifts

    NASA Astrophysics Data System (ADS)

    Rahman, Mubdi; Mendez, Alexander J.; Ménard, Brice; Scranton, Ryan; Schmidt, Samuel J.; Morrison, Christopher B.; Budavári, Tamás

    2016-07-01

    We apply clustering-based redshift inference to all extended sources from the Sloan Digital Sky Survey photometric catalogue, down to magnitude r = 22. We map the relationships between colours and redshift, without assumption of the sources' spectral energy distributions (SEDs). We identify and locate star-forming quiescent galaxies, and active galactic nuclei, as well as colour changes due to spectral features, such as the 4000 Å break, redshifting through specific filters. Our mapping is globally in good agreement with colour-redshift tracks computed with SED templates, but reveals informative differences, such as the need for a lower fraction of M-type stars in certain templates. We compare our clustering-redshift estimates to photometric redshifts and find these two independent estimators to be in good agreement at each limiting magnitude considered. Finally, we present the global clustering-redshift distribution of all Sloan extended sources, showing objects up to z ˜ 0.8. While the overall shape agrees with that inferred from photometric redshifts, the clustering-redshift technique results in a smoother distribution, with no indication of structure in redshift space suggested by the photometric-redshift estimates (likely artefacts imprinted by their spectroscopic training set). We also infer a higher fraction of high-redshift objects. The mapping between the four observed colours and redshift can be used to estimate the redshift probability distribution function of individual galaxies. This work is an initial step towards producing a general mapping between redshift and all available observables in the photometric space, including brightness, size, concentration, and ellipticity.

  9. Exploring the SDSS Photometric Galaxies with Clustering Redshifts

    NASA Astrophysics Data System (ADS)

    Rahman, Mubdi; Mendez, Alexander J.; Ménard, Brice; Scranton, Ryan; Schmidt, Samuel J.; Morrison, Christopher B.; Budavári, Tamás

    2016-04-01

    We apply clustering-based redshift inference to all extended sources from the Sloan Digital Sky Survey photometric catalogue, down to magnitude r = 22. We map the relationships between colours and redshift, without assumption of the sources' spectral energy distributions (SED). We identify and locate star-forming, quiescent galaxies, and AGN, as well as colour changes due to spectral features, such as the 4000 Å break, redshifting through specific filters. Our mapping is globally in good agreement with colour-redshift tracks computed with SED templates, but reveals informative differences, such as the need for a lower fraction of M-type stars in certain templates. We compare our clustering-redshift estimates to photometric redshifts and find these two independent estimators to be in good agreement at each limiting magnitude considered. Finally, we present the global clustering-redshift distribution of all Sloan extended sources, showing objects up to z ˜ 0.8. While the overall shape agrees with that inferred from photometric redshifts, the clustering redshift technique results in a smoother distribution, with no indication of structure in redshift space suggested by the photometric redshift estimates (likely artifacts imprinted by their spectroscopic training set). We also infer a higher fraction of high redshift objects. The mapping between the four observed colours and redshift can be used to estimate the redshift probability distribution function of individual galaxies. This work is an initial step towards producing a general mapping between redshift and all available observables in the photometric space, including brightness, size, concentration, and ellipticity.

  10. An integral field spectroscopic survey for high redshift damped Lyman-α galaxies

    NASA Astrophysics Data System (ADS)

    Christensen, L.; Wisotzki, L.; Roth, M. M.; Sánchez, S. F.; Kelz, A.; Jahnke, K.

    2007-06-01

    Aims:We search for galaxy counterparts to damped Lyman-α absorbers (DLAs) at z > 2 towards nine quasars, which have 14 DLAs and 8 sub-DLAs in their spectra. Methods: We use integral field spectroscopy to search for Lyα emission line objects at the redshifts of the absorption systems. Results: Besides recovering two previously confirmed objects, we find six statistically significant candidate Lyα emission line objects. The candidates are identified as having wavelengths close to the DLA line where the background quasar emission is absorbed. In comparison with the six currently known Lyα emitting DLA galaxies the candidates have similar line fluxes and line widths, while velocity offsets between the emission lines and systemic DLA redshifts are larger. The impact parameters are larger than 10 kpc, and lower column density systems are found at larger impact parameters. Conclusions: Assuming that a single gas cloud extends from the QSO line of sight to the location of the candidate emission line, we find that the average candidate DLA galaxy is surrounded by neutral gas with an exponential scale length of ~5 kpc. Based on observations collected at the Centro Astronómico Hispano Alemán (CAHA), operated by the Max-Planck Institut für Astronomie and the Instituto Astrofisica de Andalucia (CSIC). Full Fig. [see full text] is only available in electronic form at http://www.aanda.org

  11. See Change: First Results from the Supernova Cosmology Project High Redshift Cluster Supernova Survey

    NASA Astrophysics Data System (ADS)

    Hayden, Brian; Aldering, Greg Scott; Amanullah, Rahman; Barbary, Kyle H.; Boehringer, Hans; Brodwin, Mark; Cunha, Carlos E.; Deustua, Susana E.; Dixon, Samantha; Eisenhardt, Peter R.; Fagrelius, Parker; Fassbender, Rene; Fruchter, Andrew S.; Gladders, Michael; Gonzalez, Anthony H.; Goobar, Ariel; Hildebrandt, Hendrik; Hilton, Matt; Hoekstra, Henk; Hook, Isobel; Huang, Xiaosheng; Huterer, Dragan; Jee, James; Kim, Alex G.; Kowalski, Marek; Lidman, Chris; Linder, Eric; Luther, Kyle; Meyers, Joshua; Muzzin, Adam; Nordin, Jakob; Pain, Reynald; Perlmutter, Saul; Richard, Johan; Rosati, Piero; Rozo, Eduardo; Rubin, David; Rykoff, Eli S.; Santos, Joana; Saunders, Clare; Sofiatti, Caroline; Spadafora, Anthony L.; Stanford, S. Adam; Stern, Daniel; Suzuki, Nao; Wechsler, Risa H.; Willis, Jon; Wilson, Gillian; Yen, Mike

    2016-01-01

    Using the Hubble Space Telescope, the Supernova Cosmology Project is performing a type Ia supernova search in the highest-redshift, most massive clusters known to date. This large HST program spans Cycles 22-23. It will improve the constraint by a factor of 3 on the Dark Energy equation of state above z ~ 1, allowing an unprecedented probe of Dark Energy time variation. When combined with the improved cluster mass calibration from gravitational lensing provided by the deep WFC3-IR observations of the clusters, the SNe clusters observed also will triple the Dark Energy Task Force Figure of Merit. With Cycle 22 completed, we present preliminary supernova light curves above z=1.1 and discuss the number of supernovae discovered compared to our expectations from different SN rates models. Our HST imaging and extensive ground-based campaign are already producing unique results; we have spectroscopically confirmed several of the highest redshift cluster members to-date, and confirmed one of the most massive clusters at z~1.2 expected over the entire sky.

  12. Type-Ia supernova rates to redshift 2.4 from clash: The cluster lensing and supernova survey with Hubble

    SciTech Connect

    Graur, O.; Rodney, S. A.; Riess, A. G.; Medezinski, E.; Maoz, D.; Jha, S. W.; Holoien, T. W.-S.; McCully, C.; Patel, B.; Postman, M.; Dahlen, T.; Strolger, L.-G.; Coe, D.; Bradley, L.; Koekemoer, A.; Benítez, N.; Molino, A.; Jouvel, S.; Nonino, M.; Balestra, I.; and others

    2014-03-01

    We present the supernova (SN) sample and Type-Ia SN (SN Ia) rates from the Cluster Lensing And Supernova survey with Hubble (CLASH). Using the Advanced Camera for Surveys and the Wide Field Camera 3 on the Hubble Space Telescope (HST), we have imaged 25 galaxy-cluster fields and parallel fields of non-cluster galaxies. We report a sample of 27 SNe discovered in the parallel fields. Of these SNe, ∼13 are classified as SN Ia candidates, including four SN Ia candidates at redshifts z > 1.2. We measure volumetric SN Ia rates to redshift 1.8 and add the first upper limit on the SN Ia rate in the range 1.8 < z < 2.4. The results are consistent with the rates measured by the HST/GOODS and Subaru Deep Field SN surveys. We model these results together with previous measurements at z < 1 from the literature. The best-fitting SN Ia delay-time distribution (DTD; the distribution of times that elapse between a short burst of star formation and subsequent SN Ia explosions) is a power law with an index of −1.00{sub −0.06(0.10)}{sup +0.06(0.09)} (statistical){sub −0.08}{sup +0.12} (systematic), where the statistical uncertainty is a result of the 68% and 95% (in parentheses) statistical uncertainties reported for the various SN Ia rates (from this work and from the literature), and the systematic uncertainty reflects the range of possible cosmic star-formation histories. We also test DTD models produced by an assortment of published binary population synthesis (BPS) simulations. The shapes of all BPS double-degenerate DTDs are consistent with the volumetric SN Ia measurements, when the DTD models are scaled up by factors of 3-9. In contrast, all BPS single-degenerate DTDs are ruled out by the measurements at >99% significance level.

  13. Type-Ia Supernova Rates to Redshift 2.4 from Clash: The Cluster Lensing and Supernova Survey with Hubble

    NASA Technical Reports Server (NTRS)

    Graur, O.; Rodney, S. A.; Maoz, D.; Riess, A. G.; Jha, S. W.; Postman, M.; Dahlen, T.; Holoien, T. W.-S.; McCully, C.; Patel, B.; Strolger, L.-G.; Benitez, N.; Coe, D.; Jouvel, S.; Medezinski, E.; Molino, A.; Nonino, M.; Bradley, L.; Koehemoer, A.; Balestra, I.; Cenko, S. B.; Clubb, K. I.; Dickinson, M. E.; Filippenko, A. V.; Frederiksen, T. F.; Garnavich, P.; Hjorth, J.; Jones, D. O.; Leibundgut, B.; Matheson, T.; Mobasher, B.; Rosati, P.; Silverman, J. M.; U., V.; Jedruszczuk, K.

    2014-01-01

    We present the supernova (SN) sample and Type-Ia SN (SN Ia) rates from the Cluster Lensing And Supernova survey with Hubble (CLASH). Using the Advanced Camera for Surveys and the Wide Field Camera 3 on the Hubble Space Telescope (HST), we have imaged 25 galaxy-cluster fields and parallel fields of non-cluster galaxies. We report a sample of 27 SNe discovered in the parallel fields. Of these SNe, approximately 13 are classified as SN Ia candidates, including four SN Ia candidates at redshifts z greater than 1.2.We measure volumetric SN Ia rates to redshift 1.8 and add the first upper limit on the SN Ia rate in the range z greater than 1.8 and less than 2.4. The results are consistent with the rates measured by the HST/ GOODS and Subaru Deep Field SN surveys.We model these results together with previous measurements at z less than 1 from the literature. The best-fitting SN Ia delay-time distribution (DTD; the distribution of times that elapse between a short burst of star formation and subsequent SN Ia explosions) is a power law with an index of 1.00 (+0.06(0.09))/(-0.06(0.10)) (statistical) (+0.12/-0.08) (systematic), where the statistical uncertainty is a result of the 68% and 95% (in parentheses) statistical uncertainties reported for the various SN Ia rates (from this work and from the literature), and the systematic uncertainty reflects the range of possible cosmic star-formation histories. We also test DTD models produced by an assortment of published binary population synthesis (BPS) simulations. The shapes of all BPS double-degenerate DTDs are consistent with the volumetric SN Ia measurements, when the DTD models are scaled up by factors of 3-9. In contrast, all BPS single-degenerate DTDs are ruled out by the measurements at greater than 99% significance level.

  14. High-Redshift Galaxy Surveys and the Reionization of the Universe

    NASA Astrophysics Data System (ADS)

    Bouwens, Rychard

    Star-forming galaxies in the early universe provide us with perhaps the most natural way of explaining the reionization of the universe. Current observational results are sufficiently comprehensive, as to allow us to approximately calculate how the ionizing radiation from galaxies varies as a function of cosmic time. Important uncertainties in modeling reionization by galaxies revolve around the escape fraction and its luminosity and redshift dependence, a possible truncation of the galaxy luminosity function at the faint end, and an evolution in the production efficiency of Lyman-continuum photons with cosmic time. Despite these uncertainties, plausible choices for these parameters naturally predict a cosmic ionizing emissivity at z ˜ 6-10 whose evolution and overall normalization is in excellent agreement with that derived from current observational constraints. This strongly suggests that galaxies provide the necessary photons to reionize the universe.

  15. THE NEWFIRM MEDIUM-BAND SURVEY: PHOTOMETRIC CATALOGS, REDSHIFTS, AND THE BIMODAL COLOR DISTRIBUTION OF GALAXIES OUT TO z {approx} 3

    SciTech Connect

    Whitaker, Katherine E.; Van Dokkum, Pieter G.; Brammer, Gabriel; Muzzin, Adam; Bezanson, Rachel; Lee, Kyoung-Soo; Lundgren, Britt; Nelson, Erica J.; Tal, Tomer; Wake, David A.; Labbe, Ivo; Williams, Rik J.; Kriek, Mariska; Marchesini, Danilo; Quadri, Ryan F.; Franx, Marijn; Illingworth, Garth D.

    2011-07-10

    We present deep near-IR (NIR) medium-bandwidth photometry over the wavelength range 1-1.8 {mu}m in the All-wavelength Extended Groth strip International Survey (AEGIS) and Cosmic Evolution Survey (COSMOS) fields. The observations were carried out using the NOAO Extremely Wide-Field Infrared Imager (NEWFIRM) on the Mayall 4 m Telescope on Kitt Peak as part of the NEWFIRM Medium-Band Survey (NMBS), an NOAO survey program. In this paper, we describe the full details of the observations, data reduction, and photometry for the survey. We also present a public K-selected photometric catalog, along with accurate photometric redshifts. The redshifts are computed with 37 (20) filters in the COSMOS (AEGIS) fields, combining the NIR medium-bandwidth data with existing UV (Galaxy Evolution Explorer), visible and NIR (Canada-France-Hawaii Telescope and Subaru Telescope), and mid-IR (Spitzer/IRAC) imaging. We find excellent agreement with publicly available spectroscopic redshifts, with {sigma}{sub z}/(1 + z) {approx} 1%-2% for {approx}4000 galaxies at z = 0-3. The NMBS catalogs contain {approx}13,000 galaxies at z > 1.5 with accurate photometric redshifts and rest-frame colors. Due to the increased spectral resolution obtained with the five NIR medium-band filters, the median 68% confidence intervals of the photometric redshifts of both quiescent and star-forming galaxies are a factor of about two times smaller when comparing catalogs with medium-band NIR photometry to NIR broadband photometry. We show evidence for a clear bimodal color distribution between quiescent and star-forming galaxies that persists to z {approx} 3, a higher redshift than has been probed so far.

  16. The VIMOS Public Extragalactic Redshift Survey (VIPERS). Ωm0 from the galaxy clustering ratio measured at z ~ 1

    NASA Astrophysics Data System (ADS)

    Bel, J.; Marinoni, C.; Granett, B. R.; Guzzo, L.; Peacock, J. A.; Branchini, E.; Cucciati, O.; de la Torre, S.; Iovino, A.; Percival, W. J.; Steigerwald, H.; Abbas, U.; Adami, C.; Arnouts, S.; Bolzonella, M.; Bottini, D.; Cappi, A.; Coupon, J.; Davidzon, I.; De Lucia, G.; Fritz, A.; Franzetti, P.; Fumana, M.; Garilli, B.; Ilbert, O.; Krywult, J.; Le Brun, V.; Le Fèvre, O.; Maccagni, D.; Małek, K.; Marulli, F.; McCracken, H. J.; Paioro, L.; Polletta, M.; Pollo, A.; Schlagenhaufer, H.; Scodeggio, M.; Tasca, L. A. M.; Tojeiro, R.; Vergani, D.; Zanichelli, A.; Burden, A.; Di Porto, C.; Marchetti, A.; Mellier, Y.; Moscardini, L.; Nichol, R. C.; Phleps, S.; Wolk, M.; Zamorani, G.

    2014-03-01

    We use a sample of about 22 000 galaxies at 0.65 < z < 1.2 from the VIMOS Public Extragalactic Redshift Survey (VIPERS) Public Data Release 1 (PDR-1) catalogue, to constrain the cosmological model through a measurement of the galaxy clustering ratio ηg,R. This statistic has favourable properties, which is defined as the ratio of two quantities characterizing the smoothed density field in spheres of a given radius R: the value of its correlation function on a multiple of this scale, ξ(nR), and its variance σ2(R). For sufficiently large values of R, this is a universal number, which captures 2-point clustering information independently of the linear bias and linear redshift-space distortions of the specific galaxy tracers. In this paper, we discuss how to extend the application of ηg,R to quasi-linear scales and how to control and remove observational selection effects, which are typical of redshift surveys as VIPERS, in detail. We verify the accuracy and efficiency of these procedures using mock catalogues that match the survey selection process. These results show the robustness of ηg,R to non-linearities and observational effects, which is related to its very definition as a ratio of quantities that are similarly affected. At an effective redshift z = 0.93, we measured the value ηg,R(15) = 0.141 ± 0.013 at R = 5h-1 Mpc. Within a flat ΛCDM cosmology and by including the best available priors on H0, ns and baryon density, we obtain a matter density parameter at the current epoch Ωm,0 = 0.270-0.025+0.029. In addition to the great precision achieved on our estimation of Ωm using VIPERS PDR-1, this result is remarkable because it appears to be in good agreement with a recent estimate at z ≃ 0.3, which was obtained by applying the same technique to the SDSS-LRG catalogue. It, therefore, supports the robustness of the present analysis. Moreover, the combination of these two measurements at z ~ 0.3 and z ~ 0.9 provides us with a very precise estimate of Ωm,0

  17. MAPPING THE GALACTIC HALO WITH BLUE HORIZONTAL BRANCH STARS FROM THE TWO-DEGREE FIELD QUASAR REDSHIFT SURVEY

    SciTech Connect

    De Propris, Roberto; Harrison, Craig D.; Mares, Peter J.

    2010-08-20

    We use 666 blue horizontal branch stars from the 2Qz Redshift Survey to map the Galactic halo in four dimensions (position, distance, and velocity). We find that the halo extends to at least 100 kpc in Galactocentric distance, and obeys a single power-law density profile of index {approx}-2.5 in two different directions separated by about 150{sup 0} on the sky. This suggests that the halo is spherical. Our map shows no large kinematically coherent structures (streams, clouds, or plumes) and appears homogeneous. However, we find that at least 20% of the stars in the halo reside in substructures and that these substructures are dynamically young. The velocity dispersion profile of the halo appears to increase toward large radii while the stellar velocity distribution is non-Gaussian beyond 60 kpc. We argue that the outer halo consists of a multitude of low luminosity overlapping tidal streams from recently accreted objects.

  18. Errata: A Wide-Field Multicolor Survey for High-Redshift Quasars, Z >= 2.2. III. The Luminosity Function

    NASA Astrophysics Data System (ADS)

    Warren, Stephen J.; Hewett, Paul C.; Osmer, Patrick S.

    1995-01-01

    In the paper "A Wide-Field Multicolor Survey for High-Redshift Quasars, z >= 2.2. III. The Luminosity Function" by Stephen. Warren, Paul C. Hewett and Patrick S. Osmer (ApJ, 421,412 [1994]), two equations should be corrected: On page 419, column one, line 11, the expression following the words "the error,, should have an opening parenthesis just before the integral sign, to read: [{SIGMA} 1/({integral} ρ(z)dV_a_)^2^]^1/2^. On page 421, equation (15) is missing the asterisk (*) in the M_c_^*^ term just prior to (β + 1); that is, the exponent in the second term the denominator should read: 0.4(M_c_ - M_c_^*^)(β + 1). The authors wish to draw these errors to the attention of any readers who will be using the expression and equation.

  19. The VIMOS Public Extragalactic Redshift Survey (VIPERS). A support vector machine classification of galaxies, stars, and AGNs

    NASA Astrophysics Data System (ADS)

    Małek, K.; Solarz, A.; Pollo, A.; Fritz, A.; Garilli, B.; Scodeggio, M.; Iovino, A.; Granett, B. R.; Abbas, U.; Adami, C.; Arnouts, S.; Bel, J.; Bolzonella, M.; Bottini, D.; Branchini, E.; Cappi, A.; Coupon, J.; Cucciati, O.; Davidzon, I.; De Lucia, G.; de la Torre, S.; Franzetti, P.; Fumana, M.; Guzzo, L.; Ilbert, O.; Krywult, J.; Le Brun, V.; Le Fevre, O.; Maccagni, D.; Marulli, F.; McCracken, H. J.; Paioro, L.; Polletta, M.; Schlagenhaufer, H.; Tasca, L. A. M.; Tojeiro, R.; Vergani, D.; Zanichelli, A.; Burden, A.; Di Porto, C.; Marchetti, A.; Marinoni, C.; Mellier, Y.; Moscardini, L.; Nichol, R. C.; Peacock, J. A.; Percival, W. J.; Phleps, S.; Wolk, M.; Zamorani, G.

    2013-09-01

    Aims: The aim of this work is to develop a comprehensive method for classifying sources in large sky surveys and to apply the techniques to the VIMOS Public Extragalactic Redshift Survey (VIPERS). Using the optical (u∗,g',r',i') and near-infrared (NIR) data (z', Ks), we develop a classifier, based on broad-band photometry, for identifying stars, active galactic nuclei (AGNs), and galaxies, thereby improving the purity of the VIPERS sample. Methods: Support vector machine (SVM) supervised learning algorithms allow the automatic classification of objects into two or more classes based on a multidimensional parameter space. In this work, we tailored the SVM to classifying stars, AGNs, and galaxies and applied this classification to the VIPERS data. We trained the SVM using spectroscopically confirmed sources from the VIPERS and VVDS surveys. Results: We tested two SVM classifiers and concluded that including NIR data can significantly improve the efficiency of the classifier. The self-check of the best optical + NIR classifier has shown 97% accuracy in the classification of galaxies, 97% for stars, and 95% for AGNs in the 5-dimensional colour space. In the test of VIPERS sources with 99% redshift confidence, the classifier gives an accuracy equal to 94% for galaxies, 93% for stars, and 82% for AGNs. The method was applied to sources with low-quality spectra to verify their classification, hence increasing the security of measurements for almost 4900 objects. Conclusions: We conclude that the SVM algorithm trained on a carefully selected sample of galaxies, AGNs, and stars outperforms simple colour-colour selection methods and can be regarded as a very efficient classification method particularly suitable for modern large surveys. Based on observations collected at the European Southern Observatory, Cerro Paranal, Chile, using the Very Large Telescope under programme 182.A-0886 and partly 070.A-9007. Also based on observations obtained with MegaPrime/MegaCam, a joint

  20. The BOSS Emission-Line Lens Survey (BELLS). I. A Large Spectroscopically Selected Sample of Lens Galaxies at Redshift ~0.5

    NASA Astrophysics Data System (ADS)

    Brownstein, Joel R.; Bolton, Adam S.; Schlegel, David J.; Eisenstein, Daniel J.; Kochanek, Christopher S.; Connolly, Natalia; Maraston, Claudia; Pandey, Parul; Seitz, Stella; Wake, David A.; Wood-Vasey, W. Michael; Brinkmann, Jon; Schneider, Donald P.; Weaver, Benjamin A.

    2012-01-01

    We present a catalog of 25 definite and 11 probable strong galaxy-galaxy gravitational lens systems with lens redshifts 0.4 <~ z <~ 0.7, discovered spectroscopically by the presence of higher-redshift emission lines within the Baryon Oscillation Spectroscopic Survey (BOSS) of luminous galaxies, and confirmed with high-resolution Hubble Space Telescope (HST) images of 44 candidates. Our survey extends the methodology of the Sloan Lens Advanced Camera for Surveys survey (SLACS) to higher redshift. We describe the details of the BOSS spectroscopic candidate detections, our HST ACS image processing and analysis methods, and our strong gravitational lens modeling procedure. We report BOSS spectroscopic parameters and ACS photometric parameters for all candidates, and mass-distribution parameters for the best-fit singular isothermal ellipsoid models of definite lenses. Our sample to date was selected using only the first six months of BOSS survey-quality spectroscopic data. The full five-year BOSS database should produce a sample of several hundred strong galaxy-galaxy lenses and in combination with SLACS lenses at lower redshift, strongly constrain the redshift evolution of the structure of elliptical, bulge-dominated galaxies as a function of luminosity, stellar mass, and rest-frame color, thereby providing a powerful test for competing theories of galaxy formation and evolution. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with program 12209. Based on spectroscopic data from the Baryon Oscillation Spectroscopic Survey of the Sloan Digital Sky Survey III.

  1. Populating dark matter haloes with galaxies: comparing the 2dFGRS with mock galaxy redshift surveys

    NASA Astrophysics Data System (ADS)

    Yang, Xiaohu; Mo, H. J.; Jing, Y. P.; van den Bosch, Frank C.; Chu, YaoQuan

    2004-06-01

    In two recent papers, we developed a powerful technique to link the distribution of galaxies to that of dark matter haloes by considering halo occupation numbers as a function of galaxy luminosity and type. In this paper we use these distribution functions to populate dark matter haloes in high-resolution N-body simulations of the standard ΛCDM cosmology with Ωm= 0.3, ΩΛ= 0.7 and σ8= 0.9. Stacking simulation boxes of 100 h-1 Mpc and 300 h-1 Mpc with 5123 particles each we construct mock galaxy redshift surveys out to a redshift of z= 0.2 with a numerical resolution that guarantees completeness down to 0.01L*. We use these mock surveys to investigate various clustering statistics. The predicted two-dimensional correlation function ξ(rp, π) reveals clear signatures of redshift space distortions. The projected correlation functions for galaxies with different luminosities and types, derived from ξ(rp, π), match the observations well on scales larger than ~3 h-1 Mpc. On smaller scales, however, the model overpredicts the clustering power by about a factor two. Modelling the `finger-of-God' effect on small scales reveals that the standard ΛCDM model predicts pairwise velocity dispersions (PVD) that are ~400 km s-1 too high at projected pair separations of ~1 h-1 Mpc. A strong velocity bias in massive haloes, with bvel≡σgal/σdm~ 0.6 (where σgal and σdm are the velocity dispersions of galaxies and dark matter particles, respectively) can reduce the predicted PVD to the observed level, but does not help to resolve the overprediction of clustering power on small scales. Consistent results can be obtained within the standard ΛCDM model only when the average mass-to-light ratio of clusters is of the order of 1000 (M/L)solar in the B-band. Alternatively, as we show by a simple approximation, a ΛCDM model with σ8~= 0.75 may also reproduce the observational results. We discuss our results in light of the recent WMAP results and the constraints on σ8 obtained

  2. Saskatchewan Older Adult Literacy Survey. Final Report.

    ERIC Educational Resources Information Center

    Regina Univ. (Saskatchewan). Univ. Extension. Seniors Education Centre.

    The Saskatchewan Older Adult Literacy Survey involved 16 literacy programs offered by the regional colleges, public libraries, and technical institutes throughout the province of Saskatchewan, Canada. The 2-month survey acquired information for an overview of the current state of older adults and literacy in Saskatchewan through mailed…

  3. College Experiences Survey: Methodological Summary. Final Report

    ERIC Educational Resources Information Center

    DesRoches, David; Hall, John; Santos, Betsy

    2009-01-01

    In an effort to better understand the factors associated with college persistence and attrition, the Survey Research Center at Princeton University, with funding from the Andrew W. Mellon Foundation, is conducting the College Student Attrition Project. As part of that project, Mathematica Policy Research conducted the College Experiences Survey.…

  4. GAMMA-RAY BURST HOST GALAXY SURVEYS AT REDSHIFT z {approx}> 4: PROBES OF STAR FORMATION RATE AND COSMIC REIONIZATION

    SciTech Connect

    Trenti, Michele; Perna, Rosalba; Levesque, Emily M.; Shull, J. Michael; Stocke, John T.

    2012-04-20

    Measuring the star formation rate (SFR) at high redshift is crucial for understanding cosmic reionization and galaxy formation. Two common complementary approaches are Lyman break galaxy (LBG) surveys for large samples and gamma-ray burst (GRB) observations for sensitivity to SFR in small galaxies. The z {approx}> 4 GRB-inferred SFR is higher than the LBG rate, but this difference is difficult to understand, as both methods rely on several modeling assumptions. Using a physically motivated galaxy luminosity function model, with star formation in dark matter halos with virial temperature T{sub vir} {approx}> 2 Multiplication-Sign 10{sup 4} K (M{sub DM} {approx}> 2 Multiplication-Sign 10{sup 8} M{sub Sun }), we show that GRB- and LBG-derived SFRs are consistent if GRBs extend to faint galaxies (M{sub AB} {approx}< -11). To test star formation below the detection limit L{sub lim} {approx} 0.05L*{sub z=3} of LBG surveys, we propose to measure the fraction f{sub det}(L > L{sub lim}, z) of GRB hosts with L > L{sub lim}. This fraction quantifies the missing star formation fraction in LBG surveys, constraining the mass-suppression scale for galaxy formation, with weak dependence on modeling assumptions. Because f{sub det}(L > L{sub lim}, z) corresponds to the ratio of SFRs derived from LBG and GRB surveys, if these estimators are unbiased, measuring f{sub det}(L > L{sub lim}, z) also constrains the redshift evolution of the GRB production rate per unit mass of star formation. Our analysis predicts significant success for GRB host detections at z {approx} 5 with f{sub det}(L > L{sub lim}, z) {approx} 0.4, but rarer detections at z > 6. By analyzing the upper limits on host galaxy luminosities of six z > 5 GRBs from literature data, we infer that galaxies with M{sub AB} > -15 were present at z > 5 at 95% confidence, demonstrating the key role played by very faint galaxies during reionization.

  5. REDSHIFTS, SAMPLE PURITY, AND BCG POSITIONS FOR THE GALAXY CLUSTER CATALOG FROM THE FIRST 720 SQUARE DEGREES OF THE SOUTH POLE TELESCOPE SURVEY

    SciTech Connect

    Song, J.; Zenteno, A.; Desai, S.; Bazin, G.; Stalder, B.; Ashby, M. L. N.; Bayliss, M.; Bleem, L. E.; Benson, B. A.; Carlstrom, J. E.; Chang, C. L.; Crawford, T. M.; Crites, A. T.; Aird, K. A.; Armstrong, R.; Bertin, E.; Brodwin, M.; Cho, H. M.; Clocchiatti, A.; De Haan, T.; and others

    2012-12-10

    We present the results of the ground- and space-based optical and near-infrared (NIR) follow-up of 224 galaxy cluster candidates detected with the Sunyaev-Zel'dovich (SZ) effect in the 720 deg{sup 2} of the South Pole Telescope (SPT) survey completed in the 2008 and 2009 observing seasons. We use the optical/NIR data to establish whether each candidate is associated with an overdensity of galaxies and to estimate the cluster redshift. Most photometric redshifts are derived through a combination of three different cluster redshift estimators using red-sequence galaxies, resulting in an accuracy of {Delta}z/(1 + z) = 0.017, determined through comparison with a subsample of 57 clusters for which we have spectroscopic redshifts. We successfully measure redshifts for 158 systems and present redshift lower limits for the remaining candidates. The redshift distribution of the confirmed clusters extends to z = 1.35 with a median of z{sub med} = 0.57. Approximately 18% of the sample with measured redshifts lies at z > 0.8. We estimate a lower limit to the purity of this SPT SZ-selected sample by assuming that all unconfirmed clusters are noise fluctuations in the SPT data. We show that the cumulative purity at detection significance {xi} > 5({xi} > 4.5) is {>=}95% ({>=}70%). We present the red brightest cluster galaxy (rBCG) positions for the sample and examine the offsets between the SPT candidate position and the rBCG. The radial distribution of offsets is similar to that seen in X-ray-selected cluster samples, providing no evidence that SZ-selected cluster samples include a different fraction of recent mergers from X-ray-selected cluster samples.

  6. Redshifts, Sample Purity, and BCG Positions for the Galaxy Cluster Catalog from the First 720 Square Degrees of the South Pole Telescope Survey

    NASA Astrophysics Data System (ADS)

    Song, J.; Zenteno, A.; Stalder, B.; Desai, S.; Bleem, L. E.; Aird, K. A.; Armstrong, R.; Ashby, M. L. N.; Bayliss, M.; Bazin, G.; Benson, B. A.; Bertin, E.; Brodwin, M.; Carlstrom, J. E.; Chang, C. L.; Cho, H. M.; Clocchiatti, A.; Crawford, T. M.; Crites, A. T.; de Haan, T.; Dobbs, M. A.; Dudley, J. P.; Foley, R. J.; George, E. M.; Gettings, D.; Gladders, M. D.; Gonzalez, A. H.; Halverson, N. W.; Harrington, N. L.; High, F. W.; Holder, G. P.; Holzapfel, W. L.; Hoover, S.; Hrubes, J. D.; Joy, M.; Keisler, R.; Knox, L.; Lee, A. T.; Leitch, E. M.; Liu, J.; Lueker, M.; Luong-Van, D.; Marrone, D. P.; McDonald, M.; McMahon, J. J.; Mehl, J.; Meyer, S. S.; Mocanu, L.; Mohr, J. J.; Montroy, T. E.; Natoli, T.; Nurgaliev, D.; Padin, S.; Plagge, T.; Pryke, C.; Reichardt, C. L.; Rest, A.; Ruel, J.; Ruhl, J. E.; Saliwanchik, B. R.; Saro, A.; Sayre, J. T.; Schaffer, K. K.; Shaw, L.; Shirokoff, E.; Šuhada, R.; Spieler, H. G.; Stanford, S. A.; Staniszewski, Z.; Stark, A. A.; Story, K.; Stubbs, C. W.; van Engelen, A.; Vanderlinde, K.; Vieira, J. D.; Williamson, R.; Zahn, O.

    2012-12-01

    We present the results of the ground- and space-based optical and near-infrared (NIR) follow-up of 224 galaxy cluster candidates detected with the Sunyaev-Zel'dovich (SZ) effect in the 720 deg2 of the South Pole Telescope (SPT) survey completed in the 2008 and 2009 observing seasons. We use the optical/NIR data to establish whether each candidate is associated with an overdensity of galaxies and to estimate the cluster redshift. Most photometric redshifts are derived through a combination of three different cluster redshift estimators using red-sequence galaxies, resulting in an accuracy of Δz/(1 + z) = 0.017, determined through comparison with a subsample of 57 clusters for which we have spectroscopic redshifts. We successfully measure redshifts for 158 systems and present redshift lower limits for the remaining candidates. The redshift distribution of the confirmed clusters extends to z = 1.35 with a median of z med = 0.57. Approximately 18% of the sample with measured redshifts lies at z > 0.8. We estimate a lower limit to the purity of this SPT SZ-selected sample by assuming that all unconfirmed clusters are noise fluctuations in the SPT data. We show that the cumulative purity at detection significance ξ > 5(ξ > 4.5) is >=95% (>=70%). We present the red brightest cluster galaxy (rBCG) positions for the sample and examine the offsets between the SPT candidate position and the rBCG. The radial distribution of offsets is similar to that seen in X-ray-selected cluster samples, providing no evidence that SZ-selected cluster samples include a different fraction of recent mergers from X-ray-selected cluster samples.

  7. A redshift survey of the strong-lensing cluster ABELL 383

    SciTech Connect

    Geller, Margaret J.; Hwang, Ho Seong; Kurtz, Michael J.; Diaferio, Antonaldo; Coe, Dan; Rines, Kenneth J. E-mail: hhwang@cfa.harvard.edu E-mail: diaferio@ph.unito.it E-mail: kenneth.rines@wwu.edu

    2014-03-01

    Abell 383 is a famous rich cluster (z = 0.1887) imaged extensively as a basis for intensive strong- and weak-lensing studies. Nonetheless, there are few spectroscopic observations. We enable dynamical analyses by measuring 2360 new redshifts for galaxies with r {sub Petro} ≤ 20.5 and within 50' of the Brightest Cluster Galaxy (BCG; R.A.{sub 2000} = 42.°014125, decl.{sub 2000} = –03.°529228). We apply the caustic technique to identify 275 cluster members within 7 h {sup –1} Mpc of the hierarchical cluster center. The BCG lies within –11 ± 110 km s{sup –1} and 21 ± 56 h {sup –1} kpc of the hierarchical cluster center; the velocity dispersion profile of the BCG appears to be an extension of the velocity dispersion profile based on cluster members. The distribution of cluster members on the sky corresponds impressively with the weak-lensing contours of Okabe et al. especially when the impact of foreground and background structure is included. The values of R {sub 200} = 1.22 ± 0.01 h {sup –1} Mpc and M {sub 200} = (5.07 ± 0.09) × 10{sup 14} h {sup –1} M {sub ☉} obtained by application of the caustic technique agree well with recent completely independent lensing measures. The caustic estimate extends direct measurement of the cluster mass profile to a radius of ∼5 h {sup –1} Mpc.

  8. Measurements of the Rate of Type Ia Supernovae at Redshift z < ~0.3 from the SDSS-II Supernova Survey

    SciTech Connect

    Dilday, Benjamin; Smith, Mathew; Bassett, Bruce; Becker, Andrew; Bender, Ralf; Castander, Francisco; Cinabro, David; Filippenko, Alexei V.; Frieman, Joshua A.; Galbany, Lluis; Garnavich, Peter M.; /Notre Dame U. /Stockholm U., OKC /Stockholm U.

    2010-01-01

    We present a measurement of the volumetric Type Ia supernova (SN Ia) rate based on data from the Sloan Digital Sky Survey II (SDSS-II) Supernova Survey. The adopted sample of supernovae (SNe) includes 516 SNe Ia at redshift z {approx}< 0.3, of which 270 (52%) are spectroscopically identified as SNe Ia. The remaining 246 SNe Ia were identified through their light curves; 113 of these objects have spectroscopic redshifts from spectra of their host galaxy, and 133 have photometric redshifts estimated from the SN light curves. Based on consideration of 87 spectroscopically confirmed non-Ia SNe discovered by the SDSS-II SN Survey, we estimate that 2.04{sub -0.95}{sup +1.61}% of the photometric SNe Ia may be misidentified. The sample of SNe Ia used in this measurement represents an order of magnitude increase in the statistics for SN Ia rate measurements in the redshift range covered by the SDSS-II Supernova Survey. If we assume a SN Ia rate that is constant at low redshift (z < 0.15), then the SN observations can be used to infer a value of the SN rate of r{sub V} = (2.69{sub -0.30-0.01}{sup +0.34+0.21}) x 10{sup -5} SNe yr{sup -1} Mpc{sup -3} (H{sub 0}/(70 km s{sup -1} Mpc{sup -1})){sup 3} at a mean redshift of {approx} 0.12, based on 79 SNe Ia of which 72 are spectroscopically confirmed. However, the large sample of SNe Ia included in this study allows us to place constraints on the redshift dependence of the SN Ia rate based on the SDSS-II Supernova Survey data alone. Fitting a power-law model of the SN rate evolution, r{sub V} (z) = A{sub p} x ((1+z)/(1+z{sub 0})){sup {nu}}, over the redshift range 0.0 < z < 0.3 with z{sub 0} = 0.21, results in A{sub p} = (3.43{sub -0.15}{sup +0.15}) x 10{sup -5} SNe yr{sup -1} Mpc{sup -3} (H{sub 0}/(70 km s{sup -1} Mpc{sup -1})){sup 3} and {nu} = 2.04{sub -0.89}{sup +0.90}.

  9. The DEEP2 Galaxy Redshift Survey: The Evolution of Void Statistics from z ~ 1 to z ~ 0

    NASA Astrophysics Data System (ADS)

    Conroy, Charlie; Coil, Alison L.; White, Martin; Newman, Jeffrey A.; Yan, Renbin; Cooper, Michael C.; Gerke, Brian F.; Davis, Marc; Koo, David C.

    2005-12-01

    We present measurements of the void probability function (VPF) at z~1 using data from the Deep Extragalactic Evolutionary Probe 2 (DEEP2) Redshift Survey and its evolution to z~0 using data from the Sloan Digital Sky Survey (SDSS). We measure the VPF as a function of galaxy color and luminosity in both surveys and find that it mimics trends displayed in the two-point correlation function, ξ: namely, that samples of brighter, red galaxies have larger voids (i.e., are more strongly clustered) than fainter, blue galaxies. We also clearly detect evolution in the VPF with cosmic time, with voids being larger in comoving units at z~0. We find that the reduced VPF matches the predictions of a ``negative binomial'' model for galaxies of all colors, luminosities, and redshifts studied. This model lacks a physical motivation but produces a simple analytic prediction for sources of any number density and integrated two-point correlation function, ξ¯. This implies that differences in the VPF across different galaxy populations are consistent with being due entirely to differences in the population number density and ξ¯. We compare the VPF at z~1 to N-body ΛCDM simulations and find good agreement between the DEEP2 data and mock galaxy catalogs. Interestingly, we find that the dark matter particle reduced VPF follows the physically motivated ``thermodynamic'' model, while the dark matter halo reduced VPF more closely follows the negative binomial model. The robust result that all galaxy populations follow the negative binomial model appears to be due primarily to the clustering of dark matter halos. The reduced VPF is insensitive to changes in the parameters of the halo occupation distribution, in the sense that halo models with the same ξ¯ will produce the same VPF. For the wide range of galaxies studied, the VPF therefore does not appear to provide useful constraints on galaxy evolution models that cannot be gleaned from studies of ξ¯ alone.

  10. THE SLOAN DIGITAL SKY SURVEY QUASAR LENS SEARCH. V. FINAL CATALOG FROM THE SEVENTH DATA RELEASE

    SciTech Connect

    Inada, Naohisa; Oguri, Masamune; Kayo, Issha; Fukugita, Masataka; Shin, Min-Su; Strauss, Michael A.; Bahcall, Neta A.; Morokuma, Tomoki; Rusu, Cristian E.; Kochanek, Christopher S.; Richards, Gordon T.; Schneider, Donald P.; York, Donald G.; Frieman, Joshua A.; Hall, Patrick B.; White, Richard L.

    2012-05-15

    We present the final statistical sample of lensed quasars from the Sloan Digital Sky Survey (SDSS) Quasar Lens Search (SQLS). The well-defined statistical lens sample consists of 26 lensed quasars brighter than i = 19.1 and in the redshift range of 0.6 < z < 2.2 selected from 50,826 spectroscopically confirmed quasars in the SDSS Data Release 7 (DR7), where we restrict the image separation range to 1'' < {theta} < 20'' and the i-band magnitude differences in two images to be smaller than 1.25 mag. The SDSS DR7 quasar catalog also contains 36 additional lenses identified with various techniques. In addition to these lensed quasars, we have identified 81 pairs of quasars from follow-up spectroscopy, 26 of which are physically associated binary quasars. The statistical lens sample covers a wide range of image separations, redshifts, and magnitudes, and therefore is suitable for systematic studies of cosmological parameters and surveys of the structure and evolution of galaxies and quasars.

  11. A CRITICAL ASSESSMENT OF PHOTOMETRIC REDSHIFT METHODS: A CANDELS INVESTIGATION

    SciTech Connect

    Dahlen, Tomas; Ferguson, Henry C.; Mobasher, Bahram; Faber, Sandra M.; Barro, Guillermo; Guo, Yicheng; Finlator, Kristian; Fontana, Adriano; Gruetzbauch, Ruth; Johnson, Seth; Pforr, Janine; Dickinson, Mark E.; Salvato, Mara; Wuyts, Stijn; Wiklind, Tommy; Acquaviva, Viviana; Huang, Jiasheng; Huang, Kuang-Han; Newman, Jeffrey A.; and others

    2013-10-01

    We present results from the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS) photometric redshift methods investigation. In this investigation, the results from 11 participants, each using a different combination of photometric redshift code, template spectral energy distributions (SEDs), and priors, are used to examine the properties of photometric redshifts applied to deep fields with broadband multi-wavelength coverage. The photometry used includes U-band through mid-infrared filters and was derived using the TFIT method. Comparing the results, we find that there is no particular code or set of template SEDs that results in significantly better photometric redshifts compared to others. However, we find that codes producing the lowest scatter and outlier fraction utilize a training sample to optimize photometric redshifts by adding zero-point offsets, template adjusting, or adding extra smoothing errors. These results therefore stress the importance of the training procedure. We find a strong dependence of the photometric redshift accuracy on the signal-to-noise ratio of the photometry. On the other hand, we find a weak dependence of the photometric redshift scatter with redshift and galaxy color. We find that most photometric redshift codes quote redshift errors (e.g., 68% confidence intervals) that are too small compared to that expected from the spectroscopic control sample. We find that all codes show a statistically significant bias in the photometric redshifts. However, the bias is in all cases smaller than the scatter; the latter therefore dominates the errors. Finally, we find that combining results from multiple codes significantly decreases the photometric redshift scatter and outlier fraction. We discuss different ways of combining data to produce accurate photometric redshifts and error estimates.

  12. A Critical Assessment of Photometric Redshift Methods: A CANDELS Investigation

    NASA Astrophysics Data System (ADS)

    Dahlen, Tomas; Mobasher, Bahram; Faber, Sandra M.; Ferguson, Henry C.; Barro, Guillermo; Finkelstein, Steven L.; Finlator, Kristian; Fontana, Adriano; Gruetzbauch, Ruth; Johnson, Seth; Pforr, Janine; Salvato, Mara; Wiklind, Tommy; Wuyts, Stijn; Acquaviva, Viviana; Dickinson, Mark E.; Guo, Yicheng; Huang, Jiasheng; Huang, Kuang-Han; Newman, Jeffrey A.; Bell, Eric F.; Conselice, Christopher J.; Galametz, Audrey; Gawiser, Eric; Giavalisco, Mauro; Grogin, Norman A.; Hathi, Nimish; Kocevski, Dale; Koekemoer, Anton M.; Koo, David C.; Lee, Kyoung-Soo; McGrath, Elizabeth J.; Papovich, Casey; Peth, Michael; Ryan, Russell; Somerville, Rachel; Weiner, Benjamin; Wilson, Grant

    2013-10-01

    We present results from the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS) photometric redshift methods investigation. In this investigation, the results from 11 participants, each using a different combination of photometric redshift code, template spectral energy distributions (SEDs), and priors, are used to examine the properties of photometric redshifts applied to deep fields with broadband multi-wavelength coverage. The photometry used includes U-band through mid-infrared filters and was derived using the TFIT method. Comparing the results, we find that there is no particular code or set of template SEDs that results in significantly better photometric redshifts compared to others. However, we find that codes producing the lowest scatter and outlier fraction utilize a training sample to optimize photometric redshifts by adding zero-point offsets, template adjusting, or adding extra smoothing errors. These results therefore stress the importance of the training procedure. We find a strong dependence of the photometric redshift accuracy on the signal-to-noise ratio of the photometry. On the other hand, we find a weak dependence of the photometric redshift scatter with redshift and galaxy color. We find that most photometric redshift codes quote redshift errors (e.g., 68% confidence intervals) that are too small compared to that expected from the spectroscopic control sample. We find that all codes show a statistically significant bias in the photometric redshifts. However, the bias is in all cases smaller than the scatter; the latter therefore dominates the errors. Finally, we find that combining results from multiple codes significantly decreases the photometric redshift scatter and outlier fraction. We discuss different ways of combining data to produce accurate photometric redshifts and error estimates.

  13. Lao National Literacy Survey 2001: Final Report

    ERIC Educational Resources Information Center

    Online Submission, 2004

    2004-01-01

    Background: Adult literacy rates are an important indicator for describing the status of education and development within a country. The Lao national literacy survey was undertaken in 2001 to provide a reliable source of literacy data which in turn will determine if the country will reach Education For All (EFA) goals agreed upon at the World…

  14. Source category survey: perlite industry. Final report

    SciTech Connect

    Not Available

    1980-05-01

    Background information is presented on the perlite industry for the purpose of determining the need for a new source performance standard (NSPS). The industry is surveyed and categorized by plant, process, and other factors. Information is presented on processes, emissions and air pollution control equipment. State and local regulations are summarized. The impact of a potential NSPS on particulate emissions is calculated.

  15. Inmate Informational Needs Survey. Final Report.

    ERIC Educational Resources Information Center

    Vogel, Brenda

    A survey was conducted to identify the information needs of a five percent sample of men and women incarcerated in seven Maryland State Correctional Facilities for use in planning relevant library services to this population. Findings indicated a lack of basic information concerning rules for correct institutional behavior, with one third of the…

  16. Mass calibration of galaxy clusters at redshift 0.1-1.0 using weak lensing in the Sloan Digital Sky Survey Stripe 82 co-add

    NASA Astrophysics Data System (ADS)

    Wiesner, Matthew P.; Lin, Huan; Soares-Santos, Marcelle

    2015-09-01

    We present galaxy cluster mass-richness relations found in the Sloan Digital Sky Survey Stripe 82 co-add using clusters found using a Voronoi tessellation cluster finder. These relations were found using stacked weak lensing shear observed in a large sample of galaxy clusters. These mass-richness relations are presented for four redshift bins, 0.1 < z ≤ 0.4, 0.4 < z ≤ 0.7, 0.7 < z ≤ 1.0 and 0.1 < z ≤ 1.0. We describe the sample of galaxy clusters and explain how these clusters were found using a Voronoi tessellation cluster finder. We fit a Navarro-Frenk-White profile to the stacked weak lensing shear signal in redshift and richness bins in order to measure virial mass (M200). We describe several effects that can bias weak lensing measurements, including photometric redshift bias, the effect of the central BCG, halo miscentering, photometric redshift uncertainty and foreground galaxy contamination. We present mass-richness relations using richness measure NVT with each of these effects considered separately as well as considered altogether. We also examine redshift evolution of the mass-richness relation. As a result, we present measurements of the mass coefficient (M200|20) and the power-law slope (α) for power-law fits to the mass and richness values in each of the redshift bins. We find values of the mass coefficient of 8.49 ± 0.526, 14.1 ± 1.78, 30.2 ± 8.74 and 9.23 ± 0.525 × 1013 h-1 M⊙ for each of the four redshift bins, respectively. We find values of the power-law slope of 0.905 ± 0.0585, 0.948 ± 0.100, 1.33 ± 0.260 and 0.883 ± 0.0500, respectively.

  17. Cameron Station remedial investigation: Final asbestos survey report. Final report

    SciTech Connect

    1992-02-01

    Woodward-Clyde Federal Services (WCFS) conducted a comprehensive asbestos survey of the facilities at Cameron Station as part of its contract with the US Army Toxic and Hazardous Materials Agency (USATHAMA) to perform a remedial investigation and feasibility study (RI/FS) at the base. The purpose of the survey which was initiated August 23, 1990 in response to the Base Realignment And Closure Environmental Restoration Strategy (BRAC), was to identify friable and non-friable asbestos-containing material (ACM), provide options for abatement of asbestos, provide cost estimates for both abatement and operations and maintenance costs, and identifying actions requiring immediate action in Cameron Station`s 24 buildings. BRAC states that only friable asbestos which presents a threat to health and safety shall be removed; non-friable asbestos or friable asbestos which is encapsulated or in good repair shall be left in place and identified to the buyer per GSA agreement. The investigation followed protocols that met or exceeded the requirements of 40 CFR 763, the EPA regulations promulgated under the Asbestos Hazard Emergency Response Act (AHERA).

  18. Radiological Final Status Survey of the Hammond Depot, Hammond, Indiana

    SciTech Connect

    T.J. Vitkus

    2008-04-07

    ORISE conducted extensive scoping, characterization, and final status surveys of land areas and structures at the DNSC’s Hammond Depot located in Hammond, Indiana in multiple phases during 2005, 2006 and 2007.

  19. Texas Public School Technology Survey, 1988. Final Report.

    ERIC Educational Resources Information Center

    Denton, Jon; Davis, Trina; Strader, Arlen; Jessup, George

    The Texas Association of School Administrators (TASA) with technical support from the South Central Regional Technology in Education Consortia-Texas (SCR*TEC-TX) conducted a survey of the technology infrastructure in all public schools in Texas. This document provides the final report of the 1998 Texas Public School Technology Survey. Following…

  20. The Blanco Cosmology Survey: Data Reduction, Calibration and Photometric Redshift Estimation to Four Distant Galaxy Clusters Discovered by the South Pole Telescope

    NASA Astrophysics Data System (ADS)

    Ngeow, Chow Choong; Mohr, J.; Zenteno, A.; Data Management, DES; BCS; SPT Collaborations

    2009-01-01

    The Blanco Cosmology Survey (BCS) is designed to enable a study of the cosmic acceleration using multiple techniques. To date, BCS has acquired Sloan griz band imaging data from 60 nights (15 nights per year from 2005 to 2008) using the Blanco 4m Telescope located at CTIO. The astronomical imaging data taken from this survey have been processed on high performance computer TeraGrid platforms at NCSA, using the automated Dark Energy Survey (DES) data management (DM) system. The DES DM system includes (1) middlewares for controlling and managing the processing jobs, and serve as an application container encapsulating the scientific codes; and (2) DES archive, which includes filesystem nodes, a relational database and a data access framework, to support the pipeline processing, data storage and scientific analyzes. Photometric solution module (PSM) were run on photometric nights to determine the zeropoints (ZP) and other photometric solutions. We remapped and coadded the images that lie within the pre-defined coadd tiles in the sky. When running the coaddition pipeline, we determined the ZP for each images using the photometric ZP from PSM, the magnitude offsets between overlapping images, and the sky brightness ratio for CCDs within a given exposure. We also applied aperture correction and color-term correction to the coadded catalogs. Satisfactory photometric and astrometric precision were achieved. These enabled initial estimation of photometric redshifts using ANNz codes, trained from 5000 galaxies with spectroscopic redshifts. RMS in the photometric redshifts ranges from 0.05 to 0.1 in sigma_z/(1+z) for redshift extended to z=1. We used the BCS data to optically confirm and estimate redshifts for four of the highest S/N galaxy clusters discovered with the South Pole Telescope using the Sunyaev-Zel'dovich Effect.

  1. Bright Galaxies at Hubble's Detection Frontier: The redshift z~9-10 BoRG pure-parallel survey

    NASA Astrophysics Data System (ADS)

    Trenti, Michele

    2014-10-01

    Hubble/WFC3 observations transformed our view of early galaxy formation by building reliable samples of galaxies out to redshift z 8, 700 Myr after the Big Bang and hinting at a dramatic evolution in properties at yet earlier times. From z 8 to z 10 { 200Myr} the luminosity density seems to decrease by a factor ten, but bright galaxies may remain relatively common, based on the four z>9 objects detected so far with m_AB<27. To investigate this apparent conundrum, and study the formation of the most massive and luminous galaxies at 500 Myr without being affected by cosmic variance, we propose a random-pointing survey to detect 20+/-5 galaxies at z 9-10 as faint as m_AB=27.1 {5-sigma} at zero prime orbit cost. This request builds on our successful Cycle 17 & 19 Brightest of Reionizing Galaxies {BoRG} Survey, which found the largest sample of L>L* galaxies at z 8. BoRG[z8] demonstrated, by adding constraints from the Ultra Deep Field {UDF}, that the luminosity function follows a Schechter form, as at lower z, but with a steeper faint-end slope, leading to a photon production sufficient to complete reionization. BoRG[z9-10] will similarly complement the UDF and Frontier Fields datasets by imaging 550 arcmin^2 over 120 sightlines in five WFC3 bands {F350LP, F105W, F125W, F140W, F160W}. Besides twenty new catches at z>9, we will double {from 60 to 120} the number of bright z 8 galaxies within reach of spectroscopy, to tighten constraints on Ly-alpha emission and reionization obtained by our BoRG@Keck follow-up. This new public dataset will reveal the connection between massive dark matter halos and formation of first galaxies, and create a legacy of rare targets for JWST

  2. A Constant Bar Fraction out to Redshift z ~ 1 in the Advanced Camera for Surveys Field of the Tadpole Galaxy

    NASA Astrophysics Data System (ADS)

    Elmegreen, Bruce G.; Elmegreen, Debra Meloy; Hirst, Amelia C.

    2004-09-01

    Barlike structures were investigated in a sample of 186 disk galaxies larger than 0.5" that are in the I-band image of the Tadpole galaxy taken with the Hubble Space Telescope Advanced Camera for Surveys. We found 22 clear cases of barred galaxies, 21 galaxies with small bars that appear primarily as isophotal twists in a contour plot, and 11 cases of peculiar bars in clump-cluster galaxies, which are face-on versions of chain galaxies. The latter bars are probably young, as the galaxies contain only weak interclump emission. Four of the clearly barred galaxies at z~0.8-1.2 have grand-design spirals. The bar fraction was determined as a function of galaxy inclination and compared with the analogous distribution in the local universe. The bar fraction was also determined as a function of galaxy angular size. These distributions suggest that inclination and resolution effects obscure nearly half of the bars in our sample. The bar fraction was also determined as a function of redshift. We found a nearly constant bar fraction of 0.23+/-0.03 from z~0 to z=1.1. When corrected for inclination and size effects, this fraction is comparable to the bar fraction in the local universe, ~0.4, which we tabulated for all bar and Hubble types in the Third Reference Catalogue of Bright Galaxies. The average major axis of a barred galaxy in our sample is ~10 kpc after correcting for redshift with a Λ-dominated cold dark matter cosmology. The average exponential scale length is ~2 kpc. These are half the sizes of local barred galaxies and not likely to be influenced much by cosmological dimming, because the high-z galaxies are intrinsically brighter. We conclude that galaxy bars were present in normal abundance at least ~8 Gyr ago (z~1) the bars in clump-cluster galaxies may have formed from gaseous disk instabilities and star formation rather than stellar disk instabilities, and bar dissolution cannot be common during a Hubble time unless the bar formation rate is comparable to the

  3. The Richness Dependence of Galaxy Cluster Correlations: Results From A Redshift Survey Of Rich APM Clusters

    NASA Technical Reports Server (NTRS)

    Croft, R. A. C.; Dalton, G. B.; Efstathiou, G.; Sutherland, W. J.; Maddox, S. J.

    1997-01-01

    We analyze the spatial clustering properties of a new catalog of very rich galaxy clusters selected from the APM Galaxy Survey. These clusters are of comparable richness and space density to Abell Richness Class greater than or equal to 1 clusters, but selected using an objective algorithm from a catalog demonstrably free of artificial inhomogeneities. Evaluation of the two-point correlation function xi(sub cc)(r) for the full sample and for richer subsamples reveals that the correlation amplitude is consistent with that measured for lower richness APM clusters and X-ray selected clusters. We apply a maximum likelihood estimator to find the best fitting slope and amplitude of a power law fit to x(sub cc)(r), and to estimate the correlation length r(sub 0) (the value of r at which xi(sub cc)(r) is equal to unity). For clusters with a mean space density of 1.6 x 10(exp -6) h(exp 3) MpC(exp -3) (equivalent to the space density of Abell Richness greater than or equal to 2 clusters), we find r(sub 0) = 21.3(+11.1/-9.3) h(exp -1) Mpc (95% confidence limits). This is consistent with the weak richness dependence of xi(sub cc)(r) expected in Gaussian models of structure formation. In particular, the amplitude of xi(sub cc)(r) at all richnesses matches that of xi(sub cc)(r) for clusters selected in N-Body simulations of a low density Cold Dark Matter model.

  4. Phenomenology of dark energy: exploring the space of theories with future redshift surveys

    SciTech Connect

    Piazza, Federico; Steigerwald, Heinrich; Marinoni, Christian E-mail: heinrich.Steigerwald@cpt.univ-mrs.fr

    2014-05-01

    We use the effective field theory of dark energy to explore the space of modified gravity models which are capable of driving the present cosmic acceleration. We identify five universal functions of cosmic time that are enough to describe a wide range of theories containing a single scalar degree of freedom in addition to the metric. The first function (the effective equation of state) uniquely controls the expansion history of the universe. The remaining four functions appear in the linear cosmological perturbation equations, but only three of them regulate the growth history of large scale structures. We propose a specific parameterization of such functions in terms of characteristic coefficients that serve as coordinates in the space of modified gravity theories and can be effectively constrained by the next generation of cosmological experiments. We address in full generality the problem of the soundness of the theory against ghost-like and gradient instabilities and show how the space of non-pathological models shrinks when a more negative equation of state parameter is considered. This analysis allows us to locate a large class of stable theories that violate the null energy condition (i.e. super-acceleration models) and to recover, as particular subsets, various models considered so far. Finally, under the assumption that the true underlying cosmological model is the Λ Cold Dark Matter (ΛCDM) scenario, and relying on the figure of merit of EUCLID-like observations, we demonstrate that the theoretical requirement of stability significantly narrows the empirical likelihood, increasing the discriminatory power of data. We also find that the vast majority of these non-pathological theories generating the same expansion history as the ΛCDM model predict a different, lower, growth rate of cosmic structures.

  5. A New Determination of the High Redshift Type Ia Supernova Rateswith the Hubble Space Telescope Advanced Camera for Surveys

    SciTech Connect

    Kuznetsova, N.; Barbary, K.; Connolly, B.; Kim, A.G.; Pain, R.; Roe, N.A.; Aldering, G.; Amanullah, R.; Dawson, K.; Doi, M.; Fadeyev, V.; Fruchter, A.S.; Gibbons, R.; Goldhaber, G.; Goober, A.; Gude, A.; Knop,R.A.; Kowalski, M.; Lidman, C.; Morokuma, T.; Meyers, J.; Perlmutter, S.; Rubin, D.; Schlegel, D.J.; Spadafora, A.L.; Stanishev, V.; Strovink, M.; Suzuki, N.; Wang, L.; Yasuda, N.

    2007-10-01

    We present a new measurement of the volumetric rate of Type Ia supernova up to a redshift of 1.7, using the Hubble Space Telescope (HST) GOODS data combined with an additional HST dataset covering the North GOODS field collected in 2004. We employ a novel technique that does not require spectroscopic data for identifying Type Ia supernovae (although spectroscopic measurements of redshifts are used for over half the sample); instead we employ a Bayesian approach using only photometric data to calculate the probability that an object is a Type Ia supernova. This Bayesian technique can easily be modified to incorporate improved priors on supernova properties, and it is well-suited for future high-statistics supernovae searches in which spectroscopic follow up of all candidates will be impractical. Here, the method is validated on both ground- and space-based supernova data having some spectroscopic follow up. We combine our volumetric rate measurements with low redshift supernova data, and fit to a number of possible models for the evolution of the Type Ia supernova rate as a function of redshift. The data do not distinguish between a flat rate at redshift > 0.5 and a previously proposed model, in which the Type Ia rate peaks at redshift {approx} 1 due to a significant delay from star-formation to the supernova explosion. Except for the highest redshifts, where the signal to noise ratio is generally too low to apply this technique, this approach yields smaller or comparable uncertainties than previous work.

  6. The Star Formation History of BCGs to z = 1.8 from the SpARCS/SWIRE Survey: Evidence for Significant In Situ Star Formation at High Redshift

    NASA Astrophysics Data System (ADS)

    Webb, Tracy M. A.; Muzzin, Adam; Noble, Allison; Bonaventura, Nina; Geach, James; Hezevah, Yashar; Lidman, Chris; Wilson, Gillian; Yee, H. K. C.; Surace, Jason; Shupe, David

    2015-12-01

    We present the results of an MIPS-24 μm study of the brightest cluster galaxies (BCGs) of 535 high-redshift galaxy clusters. The clusters are drawn from the Spitzer Adaptation of the Red-Sequence Cluster Survey, which effectively provides a sample selected on total stellar mass, over 0.2 < z < 1.8 within the Spitzer Wide-Area Infrared Extragalactic (SWIRE) Survey fields. Twenty percent, or 106 clusters, have spectroscopically confirmed redshifts, and the rest have redshifts estimated from the color of their red sequence. A comparison with the public SWIRE images detects 125 individual BCGs at 24 μm ≳ 100 μJy, or 23%. The luminosity-limited detection rate of BCGs in similar richness clusters (Ngal > 12) increases rapidly with redshift. Above z ∼ 1, an average of ∼20% of the sample have 24 μm inferred infrared luminosities of LIR > 1012 L⊙, while the fraction below z ∼ 1 exhibiting such luminosities is <1%. The Spitzer-IRAC colors indicate the bulk of the 24 μm detected population is predominantly powered by star formation, with only 7/125 galaxies lying within the color region inhabited by active galactic nuclei (AGNs). Simple arguments limit the star formation activity to several hundred million years and this may therefore be indicative of the timescale for AGN feedback to halt the star formation. Below redshift z ∼ 1, there is not enough star formation to significantly contribute to the overall stellar mass of the BCG population, and therefore BCG growth is likely dominated by dry mergers. Above z ∼ 1, however, the inferred star formation would double the stellar mass of the BCGs and is comparable to the mass assembly predicted by simulations through dry mergers. We cannot yet constrain the process driving the star formation for the overall sample, though a single object studied in detail is consistent with a gas-rich merger.

  7. A direct probe of cosmological power spectra of the peculiar velocity field and the gravitational lensing magnification from photometric redshift surveys

    SciTech Connect

    Nusser, Adi; Feix, Martin; Branchini, Enzo E-mail: branchin@fis.uniroma3.it

    2013-01-01

    The cosmological peculiar velocity field (deviations from the pure Hubble flow) of matter carries significant information on dark energy, dark matter and the underlying theory of gravity on large scales. Peculiar motions of galaxies introduce systematic deviations between the observed galaxy redshifts z and the corresponding cosmological redshifts z{sub c{sub o{sub s}}}. A novel method for estimating the angular power spectrum of the peculiar velocity field based on observations of galaxy redshifts and apparent magnitudes m (or equivalently fluxes) is presented. This method exploits the fact that a mean relation between z{sub c{sub o{sub s}}} and m of galaxies can be derived from all galaxies in a redshift-magnitude survey. Given a galaxy magnitude, it is shown that the z{sub c{sub o{sub s}}}(m) relation yields its cosmological redshift with a 1σ error of σ{sub z} ∼ 0.3 for a survey like Euclid ( ∼ 10{sup 9} galaxies at z∼<2), and can be used to constrain the angular power spectrum of z−z{sub c{sub o{sub s}}}(m) with a high signal-to-noise ratio. At large angular separations corresponding to l∼<15, we obtain significant constraints on the power spectrum of the peculiar velocity field. At 15∼

  8. Baryon cycling in the low-redshift circumgalactic medium: a comparison of simulations to the COS-Halos survey

    NASA Astrophysics Data System (ADS)

    Ford, Amanda Brady; Werk, Jessica K.; Davé, Romeel; Tumlinson, Jason; Bordoloi, Rongmon; Katz, Neal; Kollmeier, Juna A.; Oppenheimer, Benjamin D.; Peeples, Molly S.; Prochaska, Jason X.; Weinberg, David H.

    2016-06-01

    We analyse the low-redshift (z ≈ 0.2) circumgalactic medium (CGM) by comparing absorption-line data from the COS-Halos survey to absorption around a matched galaxy sample from two cosmological hydrodynamic simulations. The models include different prescriptions for galactic outflows, namely hybrid energy/momentum driven wind (ezw), and constant winds (cw). We compare equivalent widths, covering factors, ion ratios, and kinematics. Both wind models show generally ≲ 1σ agreement with these observations for H I and certain low-ionization metal lines, but poorer agreement with higher ionization metal lines including Si III and O VI that are well observed by COS-Halos. This suggests that both models predict too much cool, metal-enriched gas and not enough hot gas, and / or that metals are not sufficiently mixed. This may reflect our model assumption of ejecting outflows as cool and unmixing gas. Our ezw simulation includes a heuristic prescription to quench massive galaxies by superheating interstellar medium gas. This produces low-ionization absorption broadly consistent with observations, but substantial O VI absorption inconsistent with data, suggesting that gas around quenched galaxies in the real Universe does not cool. At impact parameters of ≲ 50 kpc, recycling winds dominate the absorption of low ions and even H I, while O VI generally arises from metals ejected ≳ 1 Gyr ago. The similarity between the wind models is surprising, since they differ substantially in the amount and phase distribution of halo gas. We show that this similarity owes mainly to our comparison at fixed stellar (not halo) mass, suggesting that CGM properties are more closely tied to galaxy's stellar (versus halo) mass.

  9. Superclusters of galaxies in the 2dF redshift survey. 3. The properties of galaxies in superclusters

    SciTech Connect

    Einasto, Maret; Einasto, J.; Tago, E.; Saar, E.; Liivamagi, L.J.; oeveer, M.J; Hutsi, G.; Heinamaki, P.; Muller, V.; Tucker, D.; /Fermilab

    2006-09-01

    We use catalogues of superclusters of galaxies from the 2dF Galaxy Redshift Survey to study the properties of galaxies in superclusters. We compare the properties of galaxies in high and low density regions of rich superclusters, in poor superclusters and in the field, as well as in groups, and of isolated galaxies in superclusters of various richness. We show that in rich superclusters the values of the luminosity density smoothed on a scale of 8 h{sup -1} Mpc are higher than in poor superclusters: the median density in rich superclusters is {sigma} {approx} 7.5, in poor superclusters {delta} {approx} 6.0. Rich superclusters contain high density cores with densities {sigma} > 10 while in poor superclusters such high density cores are absent. The properties of galaxies in rich and poor superclusters and in the field are different: the fraction of early type, passive galaxies in rich superclusters is slightly larger than in poor superclusters, and is the smallest among the field galaxies. Most importantly, in high density cores of rich superclusters ({delta} > 10) there is an excess of early type, passive galaxies in groups and clusters, as well as among those which do not belong to groups or clusters. The main galaxies of superclusters have a rather limited range of absolute magnitudes. The main galaxies of rich superclusters have larger luminosities than those of poor superclusters and of groups in the field (the median values are correspondingly M{sub bj} = -21.02, M{sub bj} = -20.9 and M{sub bj} = -19.7 for rich and poor superclusters and groups in the field). Our results show that both the local (group/cluster) environments and global (supercluster) environments influence galaxy morphologies and their star formation activity.

  10. The Multiwavelength Survey by Yale-Chile (MUSYC): Deep Medium-band Optical Imaging and High-quality 32-band Photometric Redshifts in the ECDF-S

    NASA Astrophysics Data System (ADS)

    Cardamone, Carolin N.; van Dokkum, Pieter G.; Urry, C. Megan; Taniguchi, Yoshi; Gawiser, Eric; Brammer, Gabriel; Taylor, Edward; Damen, Maaike; Treister, Ezequiel; Cobb, Bethany E.; Bond, Nicholas; Schawinski, Kevin; Lira, Paulina; Murayama, Takashi; Saito, Tomoki; Sumikawa, Kentaro

    2010-08-01

    We present deep optical 18-medium-band photometry from the Subaru telescope over the ~30' × 30' Extended Chandra Deep Field-South, as part of the Multiwavelength Survey by Yale-Chile (MUSYC). This field has a wealth of ground- and space-based ancillary data, and contains the GOODS-South field and the Hubble Ultra Deep Field. We combine the Subaru imaging with existing UBVRIzJHK and Spitzer IRAC images to create a uniform catalog. Detecting sources in the MUSYC "BVR" image we find ~40,000 galaxies with R AB < 25.3, the median 5σ limit of the 18 medium bands. Photometric redshifts are determined using the EAzY code and compared to ~2000 spectroscopic redshifts in this field. The medium-band filters provide very accurate redshifts for the (bright) subset of galaxies with spectroscopic redshifts, particularly at 0.1 < z < 1.2 and at z >~ 3.5. For 0.1 < z < 1.2, we find a 1σ scatter in Δz/(1 + z) of 0.007, similar to results obtained with a similar filter set in the COSMOS field. As a demonstration of the data quality, we show that the red sequence and blue cloud can be cleanly identified in rest-frame color-magnitude diagrams at 0.1 < z < 1.2. We find that ~20% of the red sequence galaxies show evidence of dust emission at longer rest-frame wavelengths. The reduced images, photometric catalog, and photometric redshifts are provided through the public MUSYC Web site. Based (in part) on data collected at Subaru Telescope, which is operated by the National Astronomical Observatory of Japan.

  11. THE MULTIWAVELENGTH SURVEY BY YALE-CHILE (MUSYC): DEEP MEDIUM-BAND OPTICAL IMAGING AND HIGH-QUALITY 32-BAND PHOTOMETRIC REDSHIFTS IN THE ECDF-S

    SciTech Connect

    Cardamone, Carolin N.; Van Dokkum, Pieter G.; Urry, C. Megan; Brammer, Gabriel; Taniguchi, Yoshi; Gawiser, Eric; Bond, Nicholas; Taylor, Edward; Damen, Maaike; Treister, Ezequiel; Cobb, Bethany E.; Schawinski, Kevin; Lira, Paulina; Murayama, Takashi; Saito, Tomoki; Sumikawa, Kentaro

    2010-08-15

    We present deep optical 18-medium-band photometry from the Subaru telescope over the {approx}30' x 30' Extended Chandra Deep Field-South, as part of the Multiwavelength Survey by Yale-Chile (MUSYC). This field has a wealth of ground- and space-based ancillary data, and contains the GOODS-South field and the Hubble Ultra Deep Field. We combine the Subaru imaging with existing UBVRIzJHK and Spitzer IRAC images to create a uniform catalog. Detecting sources in the MUSYC 'BVR' image we find {approx}40,000 galaxies with R {sub AB} < 25.3, the median 5{sigma} limit of the 18 medium bands. Photometric redshifts are determined using the EAzY code and compared to {approx}2000 spectroscopic redshifts in this field. The medium-band filters provide very accurate redshifts for the (bright) subset of galaxies with spectroscopic redshifts, particularly at 0.1 < z < 1.2 and at z {approx}> 3.5. For 0.1 < z < 1.2, we find a 1{sigma} scatter in {Delta}z/(1 + z) of 0.007, similar to results obtained with a similar filter set in the COSMOS field. As a demonstration of the data quality, we show that the red sequence and blue cloud can be cleanly identified in rest-frame color-magnitude diagrams at 0.1 < z < 1.2. We find that {approx}20% of the red sequence galaxies show evidence of dust emission at longer rest-frame wavelengths. The reduced images, photometric catalog, and photometric redshifts are provided through the public MUSYC Web site.

  12. Mass calibration of galaxy clusters at redshift 0.1–1.0 using weak lensing in the Sloan Digital Sky Survey Stripe 82 co-add

    DOE PAGESBeta

    Wiesner, Matthew P.; Lin, Huan; Soares-Santos, Marcelle

    2015-07-08

    We present galaxy cluster mass–richness relations found in the Sloan Digital Sky Survey Stripe 82 co-add using clusters found using a Voronoi tessellation cluster finder. These relations were found using stacked weak lensing shear observed in a large sample of galaxy clusters. These mass–richness relations are presented for four redshift bins, 0.1 < z ≤ 0.4, 0.4 < z ≤ 0.7, 0.7 < z ≤ 1.0 and 0.1 < z ≤ 1.0. We describe the sample of galaxy clusters and explain how these clusters were found using a Voronoi tessellation cluster finder. We fit a Navarro-Frenk-White profile to the stackedmore » weak lensing shear signal in redshift and richness bins in order to measure virial mass (M200). We describe several effects that can bias weak lensing measurements, including photometric redshift bias, the effect of the central BCG, halo miscentering, photometric redshift uncertainty and foreground galaxy contamination. We present mass–richness relations using richness measure NVT with each of these effects considered separately as well as considered altogether. We also examine redshift evolution of the mass–richness relation. As a result, we present measurements of the mass coefficient (M200|20) and the power-law slope (α) for power-law fits to the mass and richness values in each of the redshift bins. We find values of the mass coefficient of 8.49 ± 0.526, 14.1 ± 1.78, 30.2 ± 8.74 and 9.23 ± 0.525 × 1013 h–1 M⊙ for each of the four redshift bins, respectively. As a result, we find values of the power-law slope of 0.905 ± 0.0585, 0.948 ± 0.100, 1.33 ± 0.260 and 0.883 ± 0.0500, respectively.« less

  13. Mass calibration of galaxy clusters at redshift 0.1–1.0 using weak lensing in the Sloan Digital Sky Survey Stripe 82 co-add

    SciTech Connect

    Wiesner, Matthew P.; Lin, Huan; Soares-Santos, Marcelle

    2015-07-08

    We present galaxy cluster mass–richness relations found in the Sloan Digital Sky Survey Stripe 82 co-add using clusters found using a Voronoi tessellation cluster finder. These relations were found using stacked weak lensing shear observed in a large sample of galaxy clusters. These mass–richness relations are presented for four redshift bins, 0.1 < z ≤ 0.4, 0.4 < z ≤ 0.7, 0.7 < z ≤ 1.0 and 0.1 < z ≤ 1.0. We describe the sample of galaxy clusters and explain how these clusters were found using a Voronoi tessellation cluster finder. We fit a Navarro-Frenk-White profile to the stacked weak lensing shear signal in redshift and richness bins in order to measure virial mass (M200). We describe several effects that can bias weak lensing measurements, including photometric redshift bias, the effect of the central BCG, halo miscentering, photometric redshift uncertainty and foreground galaxy contamination. We present mass–richness relations using richness measure NVT with each of these effects considered separately as well as considered altogether. We also examine redshift evolution of the mass–richness relation. As a result, we present measurements of the mass coefficient (M200|20) and the power-law slope (α) for power-law fits to the mass and richness values in each of the redshift bins. We find values of the mass coefficient of 8.49 ± 0.526, 14.1 ± 1.78, 30.2 ± 8.74 and 9.23 ± 0.525 × 1013 h–1 M for each of the four redshift bins, respectively. As a result, we find values of the power-law slope of 0.905 ± 0.0585, 0.948 ± 0.100, 1.33 ± 0.260 and 0.883 ± 0.0500, respectively.

  14. The DAFT/FADA survey. I.Photometric redshifts along lines of sight to clusters in the z=[0.4,0.9] interval

    SciTech Connect

    Guennou, L.; Adami, C.; Ulmer, M.P.; LeBrun, V.; Durret, F.; Johnston, D.; Ilbert, O.; Clowe, D.; Gavazzi, R.; Murphy, K.; Schrabback, T.; /Leiden Observ. /Fermilab

    2010-08-01

    As a contribution to the understanding of the dark energy concept, the Dark energy American French Team (DAFT, in French FADA) has started a large project to characterize statistically high redshift galaxy clusters, infer cosmological constraints from Weak Lensing Tomography, and understand biases relevant for constraining dark energy and cluster physics in future cluster and cosmological experiments. Aims. The purpose of this paper is to establish the basis of reference for the photo-z determination used in all our subsequent papers, including weak lensing tomography studies. This project is based on a sample of 91 high redshift (z {ge} 0.4), massive ({approx}> 3 x 10{sup 14} M{sub {circle_dot}}) clusters with existing HST imaging, for which we are presently performing complementary multi-wavelength imaging. This allows us in particular to estimate spectral types and determine accurate photometric redshifts for galaxies along the lines of sight to the first ten clusters for which all the required data are available down to a limit of I{sub AB} = 24./24.5 with the LePhare software. The accuracy in redshift is of the order of 0.05 for the range 0.2 {le} z {le} 1.5. We verified that the technique applied to obtain photometric redshifts works well by comparing our results to with previous works. In clusters, photo-z accuracy is degraded for bright absolute magnitudes and for the latest and earliest type galaxies. The photo-z accuracy also only slightly varies as a function of the spectral type for field galaxies. As a consequence, we find evidence for an environmental dependence of the photo-z accuracy, interpreted as the standard used Spectral Energy Distributions being not very well suited to cluster galaxies. Finally, we modeled the LCDCS 0504 mass with the strong arcs detected along this line of sight.

  15. The 3D-HST Survey: Hubble Space Telescope WFC3/G141 Grism Spectra, Redshifts, and Emission Line Measurements for ~ 100,000 Galaxies

    NASA Astrophysics Data System (ADS)

    Momcheva, Ivelina G.; Brammer, Gabriel B.; van Dokkum, Pieter G.; Skelton, Rosalind E.; Whitaker, Katherine E.; Nelson, Erica J.; Fumagalli, Mattia; Maseda, Michael V.; Leja, Joel; Franx, Marijn; Rix, Hans-Walter; Bezanson, Rachel; Da Cunha, Elisabete; Dickey, Claire; Förster Schreiber, Natascha M.; Illingworth, Garth; Kriek, Mariska; Labbé, Ivo; Ulf Lange, Johannes; Lundgren, Britt F.; Magee, Daniel; Marchesini, Danilo; Oesch, Pascal; Pacifici, Camilla; Patel, Shannon G.; Price, Sedona; Tal, Tomer; Wake, David A.; van der Wel, Arjen; Wuyts, Stijn

    2016-08-01

    We present reduced data and data products from the 3D-HST survey, a 248-orbit HST Treasury program. The survey obtained WFC3 G141 grism spectroscopy in four of the five CANDELS fields: AEGIS, COSMOS, GOODS-S, and UDS, along with WFC3 H 140 imaging, parallel ACS G800L spectroscopy, and parallel I 814 imaging. In a previous paper, we presented photometric catalogs in these four fields and in GOODS-N, the fifth CANDELS field. Here we describe and present the WFC3 G141 spectroscopic data, again augmented with data from GO-1600 in GOODS-N (PI: B. Weiner). We developed software to automatically and optimally extract interlaced two-dimensional (2D) and one-dimensional (1D) spectra for all objects in the Skelton et al. (2014) photometric catalogs. The 2D spectra and the multi-band photometry were fit simultaneously to determine redshifts and emission line strengths, taking the morphology of the galaxies explicitly into account. The resulting catalog has redshifts and line strengths (where available) for 22,548 unique objects down to {{JH}}{IR}≤slant 24 (79,609 unique objects down to {{JH}}{IR}≤slant 26). Of these, 5459 galaxies are at z\\gt 1.5 and 9621 are at 0.7\\lt z\\lt 1.5, where Hα falls in the G141 wavelength coverage. The typical redshift error for {{JH}}{IR}≤slant 24 galaxies is {σ }z≈ 0.003× (1+z), i.e., one native WFC3 pixel. The 3σ limit for emission line fluxes of point sources is 2.1× {10}-17 erg s‑1 cm‑2. All 2D and 1D spectra, as well as redshifts, line fluxes, and other derived parameters, are publicly available.18

  16. Clusters and groups of galaxies in the 2dF galaxy redshift survey: A new catalogue

    NASA Astrophysics Data System (ADS)

    Tago, E.; Einasto, J.; Saar, E.; Einasto, M.; Suhhonenko, I.; Jõeveer, M.; Vennik, J.; Heinämäki, P.; Tucker, D. L.

    2006-05-01

    We create a new catalogue of groups and clusters, applying the friends-of-friends method to the 2dF GRS final release. We investigate various selection effects due to the use of a magnitude limited sample. For this purpose we follow the changes in group sizes and mean galaxy number densities within groups when shifting nearby observed groups to larger distances. We study the distribution of sizes of dark matter haloes in N-body simulations and compare properties of these haloes and the 2dF groups. We show that at large distances from the observer luminous and intrinsically greater groups dominate, but in these groups only very bright members are seen, which form compact cores of the groups. These two effects almost cancel each other, so that the mean sizes and densities of groups do not change considerably with distance. Our final sample contains 10750 groups in the Northern part, and 14465 groups in the Southern part of the 2dF survey with membership N_gal ≥ 2. We estimate the total luminosities of our groups, correcting for group members fainter than the observational limit of the survey. The cluster catalogue is available at our web-site (\\texttt{http://www.aai.ee/˜maret/2dfgr.html}).

  17. The Chandra Deep Survey of the Hubble Deep Field-North Area. II. Results from the Caltech Faint Field Galaxy Redshift Survey Area

    NASA Astrophysics Data System (ADS)

    Hornschemeier, A. E.; Brandt, W. N.; Garmire, G. P.; Schneider, D. P.; Barger, A. J.; Broos, P. S.; Cowie, L. L.; Townsley, L. K.; Bautz, M. W.; Burrows, D. N.; Chartas, G.; Feigelson, E. D.; Griffiths, R. E.; Lumb, D.; Nousek, J. A.; Ramsey, L. W.; Sargent, W. L. W.

    2001-06-01

    A deep X-ray survey of the Hubble Deep Field-North (HDF-N) and its environs is performed using data collected by the Advanced CCD Imaging Spectrometer (ACIS) on board the Chandra X-Ray Observatory. Currently a 221.9 ks exposure is available, the deepest ever presented, and here we give results on X-ray sources located in the 8.6‧×8.7‧ area covered by the Caltech Faint Field Galaxy Redshift Survey (the ``Caltech area''). This area has (1) deep photometric coverage in several optical and near-infrared bands; (2) extensive coverage at radio, submillimeter, and mid-infrared wavelengths; and (3) some of the deepest and most complete spectroscopic coverage ever obtained. It is also where the X-ray data have the greatest sensitivity; the minimum detectable fluxes in the 0.5-2 keV (soft) and 2-8 keV (hard) bands are ~1.3×10-16 and ~6.5×10-16 ergs cm-2 s-1, respectively. More than ~80% of the extragalactic X-ray background in the hard band is resolved. The 82 Chandra sources detected in the Caltech area are correlated with more than 25 multiwavelength source catalogs, and the results of these correlations as well as spectroscopic follow-up results obtained with the Keck and Hobby-Eberly Telescopes are presented. All but nine of the Chandra sources are detected optically with R<~26.5. Redshifts are available for 39% of the Chandra sources, including 96% of the sources with R<23 the redshift range is 0.1-3.5, with most sources having z<1.5. Eight of the X-ray sources are located in the HDF-N itself, including two not previously reported. A population of X-ray faint, optically bright, nearby galaxies emerges at soft-band fluxes of <~3×10-16 ergs cm-2 s-1. Our multiwavelength correlations have set the tightest constraints to date on the X-ray emission properties of μJy radio sources, mid-infrared sources detected by the Infrared Space Observatory (ISO), and very red (R-Ks>5.0) objects. A total of 16 of the 67 1.4 GHz μJy sources in the Caltech area are detected in the

  18. [Wing 1 radiation survey and contamination report]. Final report

    SciTech Connect

    Olsen, K.

    1991-05-13

    We have completed the 5480.11 survey for Wing 1. All area(s)/item(s) requested by the 5480.11 committee have been thoroughly surveyed and documented. Decontamination/disposal of contaminated items has been accomplished. The wing 1 survey was started on 8/13/90 and completed 9/18/90. However, the follow-up surveys were not completed until 2/18/91. We received the final set of smear samples for wing 1 on 1/13/91. A total of 5,495 smears were taken from wing 1 and total of 465 smears were taken during the follow-up surveys. There were a total 122 items found to have fixed contamination and 4 items with smearable contamination in excess of the limits specified in DOE ORDER 5480.11 (AR 3-7). The following area(s)/item(s) were not included in the 5480.11 survey: Hallways, Access panels, Men`s and women`s change rooms, Janitor closets, Wall lockers and item(s) stored in wing 1 hallways and room 1116. If our contract is renewed, we will include those areas in our survey according to your request of April 15, 1991.

  19. Overconfidence in photometric redshift estimation

    NASA Astrophysics Data System (ADS)

    Wittman, David; Bhaskar, Ramya; Tobin, Ryan

    2016-04-01

    We describe a new test of photometric redshift performance given a spectroscopic redshift sample. This test complements the traditional comparison of redshift differences by testing whether the probability density functions p(z) have the correct width. We test two photometric redshift codes, BPZ and EAZY, on each of two data sets and find that BPZ is consistently overconfident (the p(z) are too narrow) while EAZY produces approximately the correct level of confidence. We show that this is because EAZY models the uncertainty in its spectral energy distribution templates, and that post-hoc smoothing of the BPZ p(z) provides a reasonable substitute for detailed modelling of template uncertainties. Either remedy still leaves a small surplus of galaxies with spectroscopic redshift very far from the peaks. Thus, better modelling of low-probability tails will be needed for high-precision work such as dark energy constraints with the Large Synoptic Survey Telescope and other large surveys.

  20. The DAFT/FADA survey. I. Photometric redshifts along lines of sight to clusters in the z = [0.4, 0.9] interval

    NASA Astrophysics Data System (ADS)

    Guennou, L.; Adami, C.; Ulmer, M. P.; Lebrun, V.; Durret, F.; Johnston, D.; Ilbert, O.; Clowe, D.; Gavazzi, R.; Murphy, K.; Schrabback, T.; Allam, S.; Annis, J.; Basa, S.; Benoist, C.; Biviano, A.; Cappi, A.; Kubo, J. M.; Marshall, P.; Mazure, A.; Rostagni, F.; Russeil, D.; Slezak, E.

    2010-11-01

    Context. As a contribution to the understanding of the dark energy concept, the Dark energy American French Team (DAFT, in French FADA) has started a large project to characterize statistically high redshift galaxy clusters, infer cosmological constraints from weak lensing tomography, and understand biases relevant for constraining dark energy and cluster physics in future cluster and cosmological experiments. Aims: The purpose of this paper is to establish the basis of reference for the photo-z determination used in all our subsequent papers, including weak lensing tomography studies. Methods: This project is based on a sample of 91 high redshift (z ≥ 0.4), massive (⪆3 × 1014 M_⊙) clusters with existing HST imaging, for which we are presently performing complementary multi-wavelength imaging. This allows us in particular to estimate spectral types and determine accurate photometric redshifts for galaxies along the lines of sight to the first ten clusters for which all the required data are available down to a limit of IAB = 24./24.5 with the LePhare software. The accuracy in redshift is of the order of 0.05 for the range 0.2 ≤ z ≤ 1.5. Results: We verified that the technique applied to obtain photometric redshifts works well by comparing our results to with previous works. In clusters, photo-z accuracy is degraded for bright absolute magnitudes and for the latest and earliest type galaxies. The photo-z accuracy also only slightly varies as a function of the spectral type for field galaxies. As a consequence, we find evidence for an environmental dependence of the photo-z accuracy, interpreted as the standard used spectral energy distributions being not very well suited to cluster galaxies. Finally, we modeled the LCDCS 0504 mass with the strong arcs detected along this line of sight. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained from the data archive at the Space Telescope Institute and the Space Telescope European

  1. The KMOS AGN Survey at High redshift (KASHz): the prevalence and drivers of ionized outflows in the host galaxies of X-ray AGN

    NASA Astrophysics Data System (ADS)

    Harrison, C. M.; Alexander, D. M.; Mullaney, J. R.; Stott, J. P.; Swinbank, A. M.; Arumugam, V.; Bauer, F. E.; Bower, R. G.; Bunker, A. J.; Sharples, R. M.

    2016-02-01

    We present the first results from the KMOS (K-band Multi-Object Spectrograph) AGN (active galactic nuclei) Survey at High redshift (KASHz), a VLT/KMOS integral-field spectroscopic (IFS) survey of z ≳ 0.6 AGN. We present galaxy-integrated spectra of 89 X-ray AGN (L2-10 keV = 1042-1045 erg s-1), for which we observed [O III] (z ≈ 1.1-1.7) or Hα emission (z ≈ 0.6-1.1). The targets have X-ray luminosities representative of the parent AGN population and we explore the emission-line luminosities as a function of X-ray luminosity. For the [O III] targets, ≈50 per cent have ionized gas velocities indicative of gas that is dominated by outflows and/or highly turbulent material (i.e. overall line widths ≳600 km s-1). The most luminous half (i.e. LX > 6 × 1043 erg s-1) have a ≳2 times higher incidence of such velocities. On the basis of our results, we find no evidence that X-ray obscured AGN are more likely to host extreme kinematics than unobscured AGN. Our KASHz sample has a distribution of gas velocities that is consistent with a luminosity-matched sample of z < 0.4 AGN. This implies little evolution in the prevalence of ionized outflows, for a fixed AGN luminosity, despite an order-of-magnitude decrease in average star formation rates over this redshift range. Furthermore, we compare our Hα targets to a redshift-matched sample of star-forming galaxies and despite a similar distribution of Hα luminosities and likely star formation rates, we find extreme ionized gas velocities are up to ≈10 times more prevalent in the AGN-host galaxies. Our results reveal a high prevalence of extreme ionized gas velocities in high-luminosity X-ray AGN and imply that the most powerful ionized outflows in high-redshift galaxies are driven by AGN activity.

  2. Final Status Survey for the Largest Decommissioning Project on Earth

    SciTech Connect

    Dubiel, R.W.; Miller, J.; Quayle, D.

    2006-07-01

    To assist the United States Department of Energy's (US DOE's) re-industrialization efforts at its gaseous diffusion site in Oak Ridge, Tennessee, known as the East Tennessee Technology Park (ETTP), the US DOE awarded a 6-year Decontamination and Decommissioning (D and D) contract to BNG America (formerly BNFL Inc.) in 1997. The ETTP 3-Building D and D Project included the removal and disposition of the materials and equipment from the K-33, K-31, and K-29 Gaseous Diffusion Plant buildings. The three buildings comprise more than 4.8 million square feet (446,000 square meters) of floor surface area and more than 350 million pounds (148 million kilograms) of hazardous and radioactively contaminated material, making it the largest nuclear D and D project in progress anywhere in the world. The logistical hurdles involved in a project of this scope and magnitude required an extensive amount of Engineering and Health Physics professionals. In order to accomplish the Final Status Survey (FSS) for a project of this scope, the speed and efficiency of automated survey equipment was essential. Surveys of floors, structural steel and ceilings up to 60 feet (18 meters) were required. The FSS had to be expanded to include additional remediation and surveys due to characterization surveys and assumptions regarding the nature and extent of contamination provided by the US DOE. Survey design and technical bases had to consider highly variable constituents; including uranium from depleted to low enrichment, variable levels of Technetium-99 and transuranic nuclides, which were introduced into the cascade during the 1960's when recycled uranium (RU) from Savannah River was re-enriched at the facility. The RU was transported to unexpected locations from leaks in the cascade by complex building ventilation patterns. The primary survey tool used for the post remediation and FSS was the Surface Contamination Monitor (SCM) and the associated Survey Information Management System (SIMS

  3. A GREEN BANK TELESCOPE SURVEY FOR H I 21 cm ABSORPTION IN THE DISKS AND HALOS OF LOW-REDSHIFT GALAXIES

    SciTech Connect

    Borthakur, Sanchayeeta; Tripp, Todd M.; Yun, Min S.; Meiring, Joseph D.; Bowen, David V.; York, Donald G.; Momjian, Emmanuel

    2011-01-20

    We present an H I 21 cm absorption survey with the Green Bank Telescope (GBT) of galaxy-quasar pairs selected by combining galaxy data from the Sloan Digital Sky Survey (SDSS) and radio sources from the Faint Images of the Radio Sky at Twenty-Centimeters (FIRST) survey. Our sample consists of 23 sight lines through 15 low-redshift foreground galaxy-background quasar pairs with impact parameters ranging from 1.7 kpc up to 86.7 kpc. We detected one absorber in the GBT survey from the foreground dwarf galaxy, GQ1042+0747, at an impact parameter of 1.7 kpc and another possible absorber in our follow-up Very Large Array (VLA) imaging of the nearby foreground galaxy UGC 7408. The line widths of both absorbers are narrow (FWHM of 3.6 and 4.8km s{sup -1}). The absorbers have sub-damped Ly{alpha} column densities, and most likely originate in the disk gas of the foreground galaxies. We also detected H I emission from three foreground galaxies including UGC 7408. Although our sample contains both blue and red galaxies, the two H I absorbers as well as the H I emissions are associated with blue galaxies. We discuss the physical conditions in the 21 cm absorbers and some drawbacks of the large GBT beam for this type of survey.

  4. Twenty-Three High-Redshift Supernovae from the Institute for Astronomy Deep Survey: Doubling the Supernova Sample at z > 0.7

    NASA Astrophysics Data System (ADS)

    Barris, Brian J.; Tonry, John L.; Blondin, Stéphane; Challis, Peter; Chornock, Ryan; Clocchiatti, Alejandro; Filippenko, Alexei V.; Garnavich, Peter; Holland, Stephen T.; Jha, Saurabh; Kirshner, Robert P.; Krisciunas, Kevin; Leibundgut, Bruno; Li, Weidong; Matheson, Thomas; Miknaitis, Gajus; Riess, Adam G.; Schmidt, Brian P.; Smith, R. Chris; Sollerman, Jesper; Spyromilio, Jason; Stubbs, Christopher W.; Suntzeff, Nicholas B.; Aussel, Hervé; Chambers, K. C.; Connelley, M. S.; Donovan, D.; Henry, J. Patrick; Kaiser, Nick; Liu, Michael C.; Martín, Eduardo L.; Wainscoat, Richard J.

    2004-02-01

    We present photometric and spectroscopic observations of 23 high-redshift supernovae (SNe) spanning a range of z=0.34-1.03, nine of which are unambiguously classified as Type Ia. These SNe were discovered during the IfA Deep Survey, which began in 2001 September and observed a total of 2.5 deg2 to a depth of approximately m~25-26 in RIZ over 9-17 visits, typically every 1-3 weeks for nearly 5 months, with additional observations continuing until 2002 April. We give a brief description of the survey motivations, observational strategy, and reduction process. This sample of 23 high-redshift SNe includes 15 at z>=0.7, doubling the published number of objects at these redshifts, and indicates that the evidence for acceleration of the universe is not due to a systematic effect proportional to redshift. In combination with the recent compilation of Tonry et al. (2003), we calculate cosmological parameter density contours that are consistent with the flat universe indicated by the cosmic microwave background (Spergel et al. 2003). Adopting the constraint that Ωtotal=1.0, we obtain best-fit values of (Ωm,ΩΛ)=(0.33,0.67) using 22 SNe from this survey augmented by the literature compilation. We show that using the empty-beam model for gravitational lensing does not eliminate the need for ΩΛ>0. Experience from this survey indicates great potential for similar large-scale surveys while also revealing the limitations of performing surveys for z>1 SNe from the ground. CFHT: Based in part on observations obtained at the Canada-France-Hawaii Telescope (CFHT), which is operated by the National Research Council of Canada, the Institut National des Science de l'Univers of the Centre National de la Recherche Scientifique of France, and the University of Hawaii. CTIO: Based in part on observations taken at the Cerro Tololo Inter-American Observatory. Keck: Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership

  5. COMOVING SPACE DENSITY AND OBSCURED FRACTION OF HIGH-REDSHIFT ACTIVE GALACTIC NUCLEI IN THE SUBARU/XMM-NEWTON DEEP SURVEY

    SciTech Connect

    Hiroi, Kazuo; Ueda, Yoshihiro; Akiyama, Masayuki; Watson, Mike G.

    2012-10-10

    We study the comoving space density of X-ray-selected luminous active galactic nuclei (AGNs) and the obscured AGN fraction at high redshifts (3 < z < 5) in the Subaru/XMM-Newton Deep Survey field. From an X-ray source catalog with high completeness of optical identification thanks to deep optical images, we select a sample of 30 AGNs at z > 3 with intrinsic (de-absorbed and rest-frame 2-10 keV) luminosities of L{sub X} = 10{sup 44-45} erg s{sup -1} detected in the 0.5-2 keV band, consisting of 20 and 10 objects with spectroscopic and photometric redshifts, respectively. Utilizing the 1/V{sub max} method, we confirm that the comoving space density of luminous AGNs decreases with redshift above z > 3. When combined with the Chandra-COSMOS result of Civano et al., the density decline of AGNs with L{sub X} = 10{sup 44-45} erg s{sup -1} is well represented by a power law of (1 + z){sup -6.2{+-}0.9}. We also determine the fraction of X-ray obscured AGNs with N{sub H} > 10{sup 22} cm{sup -2} in the Compton-thin population to be 0.54{sup +0.17}{sub -0.19}, by carefully taking into account observational biases including the effects of photon statistics for each source. This result is consistent with an independent determination of the type-2 AGN fraction based on optical properties, for which the fraction is found to be 0.59 {+-} 0.09. Comparing our result with that obtained in the local universe, we conclude that the obscured fraction of luminous AGNs increases significantly from z = 0 to z > 3 by a factor of 2.5 {+-} 1.1.

  6. A PARAMETERIZED GALAXY CATALOG SIMULATOR FOR TESTING CLUSTER FINDING, MASS ESTIMATION, AND PHOTOMETRIC REDSHIFT ESTIMATION IN OPTICAL AND NEAR-INFRARED SURVEYS

    SciTech Connect

    Song, Jeeseon; Mohr, Joseph J.; Barkhouse, Wayne A.; Rude, Cody; Warren, Michael S.; Dolag, Klaus

    2012-03-01

    We present a galaxy catalog simulator that converts N-body simulations with halo and subhalo catalogs into mock, multiband photometric catalogs. The simulator assigns galaxy properties to each subhalo in a way that reproduces the observed cluster galaxy halo occupation distribution, the radial and mass-dependent variation in fractions of blue galaxies, the luminosity functions in the cluster and the field, and the color-magnitude relation in clusters. Moreover, the evolution of these parameters is tuned to match existing observational constraints. Parameterizing an ensemble of cluster galaxy properties enables us to create mock catalogs with variations in those properties, which in turn allows us to quantify the sensitivity of cluster finding to current observational uncertainties in these properties. Field galaxies are sampled from existing multiband photometric surveys of similar depth. We present an application of the catalog simulator to characterize the selection function and contamination of a galaxy cluster finder that utilizes the cluster red sequence together with galaxy clustering on the sky. We estimate systematic uncertainties in the selection to be at the {<=}15% level with current observational constraints on cluster galaxy populations and their evolution. We find the contamination in this cluster finder to be {approx}35% to redshift z {approx} 0.6. In addition, we use the mock galaxy catalogs to test the optical mass indicator B{sub gc} and a red-sequence redshift estimator. We measure the intrinsic scatter of the B{sub gc}-mass relation to be approximately log normal with {sigma}{sub log10M}{approx}0.25 and we demonstrate photometric redshift accuracies for massive clusters at the {approx}3% level out to z {approx} 0.7.

  7. Is the misalignment of the Local Group velocity and the dipole generated by the 2MASS Redshift Survey typical in {lambda} cold dark matter and the halo model of galaxies?

    SciTech Connect

    Erdogdu, Pirin; Lahav, Ofer

    2009-08-15

    We predict the acceleration of the Local Group generated by the 2MASS Redshift Survey within the framework of {lambda} cold dark matter and the halo model of galaxies. We show that as the galaxy fluctuations derived from the halo model have more power on small scales compared with the mass fluctuations, the misalignment angle between the CMB velocity vector and the 2MASS Redshift Survey dipole is in reasonable agreement with the observed 21 deg. This statistical analysis suggests that it is not necessary to invoke a hypothetical nearby galaxy or a distant cluster to explain this misalignment.

  8. The Deep2 Galaxy Redshift Survey: Mean Ages and Metallicities ofRed Field Galaxies at Z ~; 0.9 from Stacked Keck/Deimos Spectra

    SciTech Connect

    Schiavon, Ricardo P.; Faber, S.M.; Konidaris, Nicholas; Graves,Genevieve; Willmer, Christopher N.A.; Weiner, Benjamin J.; Coil, AlisonL.; Cooper, Michael C.; Davis, Marc; Harker, Justin; Koo, David C.; Newman, Jeffrey A.; Yan, Renbin

    2006-10-19

    As part of the DEEP2 galaxy redshift survey, we analyze absorption line strengths in stacked Keck/DEIMOS spectra of red field galaxies with weak to no emission lines, at redshifts 0.7 {approx}< z {approx}< 1. Comparison with models of stellar population synthesis shows that red galaxies at z {approx} 0:9 have mean luminosity-weighted ages of the order of only 1 Gyr and at least solar metallicities. These ages cannot be reconciled with a scenario where all stars evolved passively after forming at very high z. Rather, a significant fraction of stars can be no more than 1 Gyr old, which means that some star formation in the stacked populations continued to at least z {approx} 1:2. Furthermore, a comparison of these distant galaxies with a local SDSS sample, using stellar populations synthesis models, shows that the drop in the equivalent width of H{delta} from z {approx} 0:9 to 0.1 is less than predicted by passively evolving models. This admits of two interpretations: either each individual galaxy experiences continuing low-level star formation, or the red-sequence galaxy population from z {approx} 0:9 to 0.1 is continually being added to by new galaxies with younger stars.

  9. Upper Bound of 0.28 eV on Neutrino Masses from the Largest Photometric Redshift Survey

    SciTech Connect

    Thomas, Shaun A.; Abdalla, Filipe B.; Lahav, Ofer

    2010-07-16

    We present a new limit of (95% CL) on the sum of the neutrino masses assuming a flat {Lambda}CDM cosmology. This relaxes slightly to and when quasinonlinear scales are removed and w{ne}-1, respectively. These are derived from a new photometric catalogue of over 700 000 luminous red galaxies (MegaZ DR7) with a volume of 3.3 (Gpc h{sup -1}){sup 3} and redshift range 0.45

  10. A DETERMINATION OF THE INTERGALACTIC REDSHIFT-DEPENDENT ULTRAVIOLET-OPTICAL-NIR PHOTON DENSITY USING DEEP GALAXY SURVEY DATA AND THE GAMMA-RAY OPACITY OF THE UNIVERSE

    SciTech Connect

    Stecker, Floyd W.; Scully, Sean T. E-mail: malkan@astro.ucla.edu

    2012-12-20

    We calculate the intensity and photon spectrum of the intergalactic background light (IBL) as a function of redshift using an approach based on observational data obtained in many different wavelength bands from local to deep galaxy surveys. This allows us to obtain an empirical determination of the IBL and to quantify its observationally based uncertainties. Using our results on the IBL, we then place 68% confidence upper and lower limits on the opacity of the universe to {gamma}-rays, free of the theoretical assumptions that were needed for past calculations. We compare our results with measurements of the extragalactic background light and upper limits obtained from observations made by the Fermi Gamma-ray Space Telescope.

  11. A Determination of the Intergalactic Redshift Dependent UV-Optical-NIR Photon Density Using Deep Galaxy Survey Data and the Gamma-ray Opacity of the Universe

    NASA Technical Reports Server (NTRS)

    Stecker, Floyd W.; Malkan, Matthew A.; Scully, Sean T.

    2012-01-01

    We calculate the intensity and photon spectrum of the intergalactic background light (IBL) as a function of redshift using an approach based on observational data obtained in many different wavelength bands from local to deep galaxy surveys. This allows us to obtain an empirical determination of the IBL and to quantify its observationally based uncertainties. Using our results on the IBL, we then place 68% confidence upper and lower limits on the opacity of the universe to gamma-rays, free of the theoretical assumptions that were needed for past calculations. We compare our results with measurements of the extragalactic background light and upper limits obtained from observations made by the Fermi Gamma-ray Space Telescope.

  12. The Carnegie-Spitzer-IMACS Redshift Survey: How the Universe Shaped Galaxies over the Past 8 Gyr and Why It Wasn't All Finished Before z~2

    NASA Astrophysics Data System (ADS)

    Kelson, Daniel David

    2015-08-01

    While the peak of cosmic star-formation occurs by z~2, hierarchical growth leads to the assembly of galaxy groups at much later times. The galaxies in these groups host a substantial fraction of the stellar mass at z~0. Probing the evolution of galaxies in these environments is therefore imperative for understanding the forces that shaped the distributions of galaxies we see today. The Carnegie-Spitzer-IMACS Spectrophotometric Redshift Survey, with its wide-field (total 15 degs^2) and near-IR selection, is uniquely positioned to trace the combined evolution of galaxies and their environments. The survey targets a flux-limited sample of galaxies selected from Spitzer IRAC 3.6µm imaging of SWIRE fields, in order to efficiently trace the stellar mass growth of average galaxies to z~1.5. Our unique methodology for analyzing low-dispersion spectra from IMACS, combined with panchromatic photometry from the ultraviolet to the IR, yielded high quality redshifts, stellar masses, emission line luminosities, and information on recent star-formation. For galaxies up to z~1, the redshift precision is sigma_z/(1+z)<1%, with a spectroscopic completeness sufficient to reliably detect galaxy groups M200 ~ 10^13 Msun. In the Chandra Deep Field South we combine the CSI data with the ultra-deep Chandra and XMM-Newton X-ray observations to make the first statistical measurements of the stellar mass-halo mass relation of low-mass X-ray groups at 0.5

  13. The VISTA Kilo-degree Infrared Galaxy (VIKING) Survey: Bridging the Gap between Low and High Redshift

    NASA Astrophysics Data System (ADS)

    Edge, A.; Sutherland, W.; Kuijken, K.; Driver, S.; McMahon, R.; Eales, S.; Emerson, J. P.

    2013-12-01

    VIKING is a medium-deep survey of 1500 square degrees over two areas of the extragalactic sky with VISTA in zYJHKs bands to sample the restframe optical for galaxies at z >~ 1. VIKING complements the two other surveys — VHS with its large area but shallower depth and VIDEO with its greater photometric depth and smaller spatial coverage. In addition to a 0.7 < z < 2 galaxy survey, the area and depth of VIKING enables other studies, such as detection of distant quasars and low-mass stars and many galaxy clusters and superclusters. The early results are summarised and future prospects presented.

  14. Upper bound of 0.28 eV on neutrino masses from the largest photometric redshift survey.

    PubMed

    Thomas, Shaun A; Abdalla, Filipe B; Lahav, Ofer

    2010-07-16

    We present a new limit of ∑m(v) ≤ 0.28 (95% CL) on the sum of the neutrino masses assuming a flat ΛCDM cosmology. This relaxes slightly to ∑m(ν) ≤ 0.34 and ∑m(v) ≤ 0.47 when quasinonlinear scales are removed and w≠ -1, respectively. These are derived from a new photometric catalogue of over 700,000 luminous red galaxies (MegaZ DR7) with a volume of 3.3  (Gpc h(-1))(3) and redshift range 0.45 < z < 0.65. The data are combined with WMAP 5-year CMB, baryon acoustic oscillations, supernovae, and a Hubble Space Telescope prior on h. When combined with WMAP these data are as constraining as adding all supernovae and baryon oscillation data available. The upper limit is one of the tightest constraints on the neutrino from cosmology or particle physics. Further, if these bounds hold, they all predict that current-to-next generation neutrino experiments, such as KATRIN, are unlikely to obtain a detection. PMID:20867754

  15. A CHANDRA SNAPSHOT SURVEY FOR 3C RADIO GALAXIES WITH REDSHIFTS BETWEEN 0.3 AND 0.5

    SciTech Connect

    Massaro, F.; Harris, D. E.; Paggi, A.; Tremblay, G. R.; Liuzzo, E.; Bonafede, A.

    2013-05-01

    This paper contains an analysis of short Chandra observations of 19 3C sources with redshifts between 0.3 and 0.5 not previously observed in the X-rays. This sample is part of a project to obtain Chandra data for all of the extragalactic sources in the 3C catalog. Nuclear X-ray intensities as well as any X-ray emission associated with radio jet knots, hotspots, or lobes have been measured in three energy bands: soft, medium, and hard. Standard X-ray spectral analysis for the four brightest nuclei has also been performed. X-ray emission was detected for all the nuclei of the radio sources in the current sample with the exception of 3C 435A. There is one compact steep spectrum source while all the others are FR II radio galaxies. X-ray emission from two galaxy clusters (3C 19 and 3C 320), from six hotspots in four radio galaxies (3C 16, 3C 19, 3C 268.2, 3C 313), and extended X-ray emission on kiloparsec scales in 3C 187 and 3C 313, has been detected.

  16. The VIMOS Public Extragalactic Redshift Survey (VIPERS). An unprecedented view of galaxies and large-scale structure at 0.5 < z < 1.2

    NASA Astrophysics Data System (ADS)

    Guzzo, L.; Scodeggio, M.; Garilli, B.; Granett, B. R.; Fritz, A.; Abbas, U.; Adami, C.; Arnouts, S.; Bel, J.; Bolzonella, M.; Bottini, D.; Branchini, E.; Cappi, A.; Coupon, J.; Cucciati, O.; Davidzon, I.; De Lucia, G.; de la Torre, S.; Franzetti, P.; Fumana, M.; Hudelot, P.; Ilbert, O.; Iovino, A.; Krywult, J.; Le Brun, V.; Le Fèvre, O.; Maccagni, D.; Małek, K.; Marulli, F.; McCracken, H. J.; Paioro, L.; Peacock, J. A.; Polletta, M.; Pollo, A.; Schlagenhaufer, H.; Tasca, L. A. M.; Tojeiro, R.; Vergani, D.; Zamorani, G.; Zanichelli, A.; Burden, A.; Di Porto, C.; Marchetti, A.; Marinoni, C.; Mellier, Y.; Moscardini, L.; Nichol, R. C.; Percival, W. J.; Phleps, S.; Wolk, M.

    2014-06-01

    We describe the construction and general features of VIPERS, the VIMOS Public Extragalactic Redshift Survey. This ESO Large Programme is using the Very Large Telescope with the aim of building a spectroscopic sample of ~ 100 000 galaxies with iAB< 22.5 and 0.5 survey covers a total area of ~ 24 deg2 within the CFHTLS-Wide W1 and W4 fields. VIPERS is designed to address a broad range of problems in large-scale structure and galaxy evolution, thanks to a unique combination of volume (~ 5 × 107h-3 Mpc3) and sampling rate (~ 40%), comparable to state-of-the-art surveys of the local Universe, together with extensive multi-band optical and near-infrared photometry. Here we present the survey design, the selection of the source catalogue and the development of the spectroscopic observations. We discuss in detail the overall selection function that results from the combination of the different constituents of the project. This includes the masks arising from the parent photometric sample and the spectroscopic instrumental footprint, together with the weights needed to account for the sampling and the success rates of the observations. Using the catalogue of 53 608 galaxy redshifts composing the forthcoming VIPERS Public Data Release 1 (PDR-1), we provide a first assessment of the quality of the spectroscopic data. The stellar contamination is found to be only 3.2%, endorsing the quality of the star-galaxy separation process and fully confirming the original estimates based on the VVDS data, which also indicate a galaxy incompleteness from this process of only 1.4%. Using a set of 1215 repeated observations, we estimate an rms redshift error σz/ (1 + z) = 4.7 × 10-4 and calibrate the internal spectral quality grading. Benefiting from the combination of size and detailed sampling of this dataset, we conclude by presenting a map showing in unprecedented detail the large-scale distribution of galaxies between 5 and 8 billion years ago. Based on observations

  17. The Muenster Redshift Project (MRSP).

    NASA Astrophysics Data System (ADS)

    Schuecker, P.; Horstmann, H.; Seitter, W. C.; Ott, H.-A.; Duemmler, R.; Tucholke, H.-J.; Teuber, D.; Meijer, J.; Cunow, B.

    The Astronomical Institute Muenster, in 1986, has started the Muenster Redshift Project (MRSP), where redshifts z are measured automatically from low-dispersion objective prism plates. The number of galaxy redshifts per square degree is approximately 250, the scale reached z = 0.3, compared to about 2 galaxies per square degree and z = 0.05 for currently available large-area surveys. This is a significant growth, gained, however, with the loss of resolution in redshift space: the low dispersion of the spectra gives redshift accuracies of dz = 0.01 or 30 h-1Mpc (H0 = 100 h km s-1Mpc-1, q0 = 0.5). Nevertheless, in most cases the large numbers of objects compensate for the statistical redshift errors, while the derivations of global and cosmological quantities are less affected by small-number statistics, are more representative, and thus lead to more reliable values. The detection of voids on scales z < 0.02 is not possible, unless the structures in redshift space are sharpened, using, e.g. deconvolution techniques.

  18. Aerial remote sensing surveys, geophysical characterization. Final report

    SciTech Connect

    Labson, V.F.; Pellerin, L.; Anderson, W.L.

    1998-06-01

    The application of helicopter electromagnetic (HEM) and magnetic methods to the requirements of the environmental restoration of the Oak Ridge Reservation (ORR) demand the use of advanced, nontraditional methods of data acquisition, processing and interpretation. The cooperative study by the U.S. Geological Survey (USGS), Oak Ridge National Laboratory (ORNL), and University of California (UCB) has resulted in the planning and supervision of data acquisition, the development of tools for data processing and interpretation, and an intensive application of the methods developed. This final report consists of a series of publications which the USGS collaborated with the ORNL technical staff. These reports represent the full scope of the USGS assistance. Copies of the reports and papers are included in the Appendix. The primary goals of this effort were to quantify the effectiveness of the geophysical methods applied in the survey of the ORR for the identification of buried waste, hydrogeologic pathways by which contamination could migrate through or off the site, and for the more accurate geologic mapping of the ORR. The objectives in buried waste identification are the accurate description of the source of the geophysical anomaly and the determination of the limits of resolution of the geophysical methods to acknowledge what we might have missed. The study of hydrogeologic pathways concentrated on the identification of karst features in the limestone underlying much of the ORR. Work in this study has indicated to the ORNL staff that these karst features can be located from the airborne geophysics. The defining characteristic of this helicopter geophysical study is the collaborative nature of the effort. Each task in which the USGS was involved has included a designated staff member from the Oak Ridge National Laboratory.

  19. The Subaru-XMM-Newton Deep Survey (SXDS). VIII. Multi-wavelength identification, optical/NIR spectroscopic properties, and photometric redshifts of X-ray sources†

    NASA Astrophysics Data System (ADS)

    Akiyama, Masayuki; Ueda, Yoshihiro; Watson, Mike G.; Furusawa, Hisanori; Takata, Tadafumi; Simpson, Chris; Morokuma, Tomoki; Yamada, Toru; Ohta, Kouji; Iwamuro, Fumihide; Yabe, Kiyoto; Tamura, Naoyuki; Moritani, Yuuki; Takato, Naruhisa; Kimura, Masahiko; Maihara, Toshinori; Dalton, Gavin; Lewis, Ian; Lee, Hanshin; Curtis-Lake, Emma; Macaulay, Edward; Clarke, Frazer; Silverman, John D.; Croom, Scott; Ouchi, Masami; Hanami, Hitoshi; Díaz Tello, Jorge; Yoshikawa, Tomohiro; Fujishiro, Naofumi; Sekiguchi, Kazuhiro

    2015-10-01

    We report on the multi-wavelength identification of the X-ray sources found in the Subaru-XMM-Newton Deep Survey (SXDS) using deep imaging data covering the wavelength range between the far-UV and mid-IR (MIR). We select a primary counterpart of each X-ray source by applying the likelihood ratio method to R-band, 3.6 μm, near-UV, and 24 μm source catalogs as well as matching catalogs of active galactic nucleus (AGN) candidates selected in 1.4 GHz radio and i '-band variability surveys. Once candidates for Galactic stars, ultra-luminous X-ray sources in a nearby galaxy, and clusters of galaxies are removed there are 896 AGN candidates in the sample. We conduct spectroscopic observations of the primary counterparts with multi-object spectrographs in the optical and NIR; 65% of the X-ray AGN candidates are spectroscopically identified. For the remaining X-ray AGN candidates, we evaluate their photometric redshift with photometric data in 15 bands. Utilizing the multi-wavelength photometric data of the large sample of X-ray-selected AGNs, we evaluate the stellar masses, M*, of the host galaxies of the narrow-line AGNs. The distribution of the stellar mass is remarkably constant from z = 0.1 to 4.0. The relation between M* and 2-10 keV luminosity can be explained with strong cosmological evolution of the relationship between the black hole mass and M*. We also evaluate the scatter of the UV-MIR spectral energy distribution (SED) of the X-ray AGNs as a function of X-ray luminosity and absorption by the nucleus. The scatter is compared with galaxies which have redshift and stellar mass distribution matched with the X-ray AGN. The UV-NIR (near-IR) SEDs of obscured X-ray AGNs are similar to those of the galaxies in the matched sample. In the NIR-MIR range, the median SEDs of X-ray AGNs are redder, but the scatter of the SEDs of the X-ray AGN broadly overlaps that of the galaxies in the matched sample.

  20. The large scale structure of the Universe revealed with high redshift emission-line galaxies: implications for future surveys

    NASA Astrophysics Data System (ADS)

    Antonino Orsi, Alvaro

    2015-08-01

    Nebular emission in galaxies trace their star-formation activity within the last 10 Myr or so. Hence, these objects are typically found in the outskirts of massive clusters, where otherwise environmental effects can effectively stop the star formation process. In this talk I discuss the nature of emission-line galaxies (ELGs) and its implications for their clustering properties. To account for the relevant physical ingredients that produce nebular emission, I combine semi-analytical models of galaxy formation with a radiative transfer code of Ly-alpha photons, and the photoionzation and shock code MAPPINGS-III. As a result, the clustering strength of ELGs is found to correlate weakly with the line luminosities. Also, their 2-d clustering displays a weak finger-of-god effect, and the clustering in linear scales is affected by assembly bias. I review the impact of the nature of this galaxy population for future spectroscopic large surveys targeting ELGs to extract cosmological results. In particular, I present forecasts for the ELG population in J-PAS, an 8000 deg^2 survey with 54 narrow-band filters covering the optical range, expected to start in 2016.

  1. The Subaru FMOS galaxy redshift survey (FastSound). II. The emission line catalog and properties of emission line galaxies

    NASA Astrophysics Data System (ADS)

    Okada, Hiroyuki; Totani, Tomonori; Tonegawa, Motonari; Akiyama, Masayuki; Dalton, Gavin; Glazebrook, Karl; Iwamuro, Fumihide; Ohta, Kouji; Takato, Naruhisa; Tamura, Naoyuki; Yabe, Kiyoto; Bunker, Andrew J.; Goto, Tomotsugu; Hikage, Chiaki; Ishikawa, Takashi; Okumura, Teppei; Shimizu, Ikkoh

    2016-06-01

    We present basic properties of ˜3300 emission line galaxies detected by the FastSound survey, which are mostly Hα emitters at z ˜ 1.2-1.5 in the total area of about 20 deg2, with the Hα flux sensitivity limit of ˜1.6 × 10-16 erg cm-2 s-1 at 4.5 σ. This paper presents the catalog of the FastSound emission lines and galaxies, which is open to the public. We also present basic properties of typical FastSound Hα emitters, which have Hα luminosities of 1041.8-1043.3 erg s-1, star formation rates (SFRs) of 20-500 M⊙ yr-1, and stellar masses of 1010.0-1011.3 M⊙. The 3D distribution maps for the four fields of Canada-France-Hawaii Telescope Legacy Survey (CFHTLS) W1-4 are presented, clearly showing large scale clustering of galaxies at the scale of ˜100-600 comoving Mpc. Based on 1105 galaxies with detections of multiple emission lines, we estimate that the contamination of non-Hα lines is about 4% in the single-line emission galaxies, which is mostly [O III]λ5007. This contamination fraction is also confirmed by the stacked spectrum of all the FastSound spectra, in which Hα, [N II]λλ6548,6583, [S II]λλ6717,6731, and [O I]λλ6300,6364 are seen.

  2. A WFC3 Grism Emission Line Redshift Catalog in the GOODS-South Field

    NASA Astrophysics Data System (ADS)

    Morris, Aaron M.; Kocevski, Dale D.; Trump, Jonathan R.; Weiner, Benjamin J.; Hathi, Nimish P.; Barro, Guillermo; Dahlen, Tomas; Faber, Sandra M.; Finkelstein, Steven L.; Fontana, Adriano; Ferguson, Henry C.; Grogin, Norman A.; Grützbauch, Ruth; Guo, Yicheng; Hsu, Li-Ting; Koekemoer, Anton M.; Koo, David C.; Mobasher, Bahram; Pforr, Janine; Salvato, Mara; Wiklind, Tommy; Wuyts, Stijn

    2015-06-01

    We combine Hubble Space Telescope (HST)/Wide Field Camera3 (WFC3) imaging and G141 grism observations from the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS) and 3D-HST surveys to produce a catalog of grism spectroscopic redshifts for galaxies in the CANDELS/GOODS-South field. The WFC3/G141 grism spectra cover a wavelength range of 1.1≤slant λ ≤slant 1.7 μm with a resolving power of R∼ 130 for point sources, thus providing rest-frame optical spectra for galaxies out to z∼ 3.5. The catalog is selected in the H-band (F160W) and includes both galaxies with and without previously published spectroscopic redshifts. Grism spectra are extracted for all H-band detected galaxies with H ≤slant 24 and a CANDELS photometric redshift {{z}phot}≥slant 0.6. The resulting spectra are visually inspected to identify emission lines, and redshifts are determined using cross-correlation with empirical spectral templates. To establish the accuracy of our redshifts, we compare our results against high-quality spectroscopic redshifts from the literature. Using a sample of 411 control galaxies, this analysis yields a precision of {{σ }NMAD}=0.0028 for the grism-derived redshifts, which is consistent with the accuracy reported by the 3D-HST team. Our final catalog covers an area of 153 arcmin2 and contains 1019 redshifts for galaxies in GOODS-S. Roughly 60% (608/1019) of these redshifts are for galaxies with no previously published spectroscopic redshift. These new redshifts span a range of 0.677≤slant z≤slant 3.456 and have a median redshift of z = 1.282. The catalog contains a total of 234 new redshifts for galaxies at z\\gt 1.5. In addition, we present 20 galaxy pair candidates identified for the first time using the grism redshifts in our catalog, including four new galaxy pairs at z∼ 2, nearly doubling the number of such pairs previously identified.

  3. The XXL survey. V. Detection of the Sunyaev-Zel'dovich effect of the redshift 1.9 galaxy cluster XLSSU J021744.1–034536 with CARMA

    SciTech Connect

    Mantz, A. B.; Abdulla, Z.; Carlstrom, J. E.; Leitch, E. M.; Greer, C. H.; Marrone, D. P.; Muchovej, S.; Adami, C.; Birkinshaw, M.; Bremer, M.; Giles, P.; Maughan, B.; Clerc, N.; Horellou, C.; Pacaud, F.; Pierre, M.; Willis, J.

    2014-10-20

    We report the detection of the Sunyaev-Zel'dovich (SZ) effect of galaxy cluster XLSSU J021744.1–034536, using 30 GHz Combined Array for Research in Millimeter-wave Astronomy (CARMA) data. This cluster was discovered via its extended X-ray emission in the XMM- Newton Large Scale Structure survey, the precursor to the XXL survey. It has a photometrically determined redshift z=1.91{sub −0.21}{sup +0.19}, making it among the most distant clusters known, and nominally the most distant for which the SZ effect has been measured. The spherically integrated Comptonization is Y {sub 500} = (3.0 ± 0.4) × 10{sup –12}, a measurement that is relatively insensitive to assumptions regarding the size and redshift of the cluster, as well as the background cosmology. Using a variety of locally calibrated cluster scaling relations extrapolated to z ∼ 2, we estimate a mass M {sub 500} ∼ (1-2) × 10{sup 14} M {sub ☉} from the X-ray flux and SZ signal. The measured properties of this cluster are in good agreement with the extrapolation of an X-ray luminosity-SZ effect scaling relation calibrated from clusters discovered by the South Pole Telescope at higher masses and lower redshifts. The full XXL-CARMA sample will provide a more complete, multi-wavelength census of distant clusters in order to robustly extend the calibration of cluster scaling relations to these high redshifts.

  4. The Highest Redshift Relativistic Jets

    SciTech Connect

    Cheung, C.C.; Stawarz, L.; Siemiginowska, A.; Harris, D.E; Schwartz, D.A.; Wardle, J.F.C.; Gobeille, D.; Lee, N.P.

    2007-12-18

    We describe our efforts to understand large-scale (10's-100's kpc) relativistic jet systems through observations of the highest-redshift quasars. Results from a VLA survey search for radio jets in {approx} 30 z > 3.4 quasars are described along with new Chandra observations of 4 selected targets.

  5. OVERDENSITIES OF Y-DROPOUT GALAXIES FROM THE BRIGHTEST-OF-REIONIZING GALAXIES SURVEY: A CANDIDATE PROTOCLUSTER AT REDSHIFT z Almost-Equal-To 8

    SciTech Connect

    Trenti, Michele; Shull, J. M.; Bradley, L. D.; Stiavelli, M.; Oesch, P.; Bouwens, R. J.; Munoz, J. A.; Romano-Diaz, E.; Shlosman, I.; Treu, T.; Carollo, C. M.

    2012-02-10

    Theoretical and numerical modeling of the assembly of dark-matter halos predicts that the most massive and luminous galaxies at high redshift are surrounded by overdensities of fainter companions. We test this prediction with Hubble Space Telescope observations acquired by our Brightest-of-Reionizing Galaxies (BoRG) survey, which identified four very bright z {approx} 8 candidates as Y{sub 098}-dropout sources in four of the 23 non-contiguous Wide Field Camera 3 fields observed. We extend here the search for Y{sub 098}-dropouts to fainter luminosities (M{sub *} galaxies with M{sub AB} {approx} -20), with detections at {>=}5{sigma} confidence (compared to the 8{sigma} confidence threshold adopted earlier) identifying 17 new candidates. We demonstrate that there is a correlation between number counts of faint and bright Y{sub 098}-dropouts at {>=}99.84% confidence. Field BoRG58, which contains the best bright z {approx} 8 candidate (M{sub AB} = -21.3), has the most significant overdensity of faint Y{sub 098}-dropouts. Four new sources are located within 70'' (corresponding to 3.1 comoving Mpc at z = 8) from the previously known brighter z {approx} 8 candidate. The overdensity of Y{sub 098}-dropouts in this field has a physical origin to very high confidence (p > 99.975%), independent of completeness and contamination rate of the Y{sub 098}-dropout selection. We modeled the overdensity by means of cosmological simulations and estimate that the principal dark-matter halo has mass M{sub h} Almost-Equal-To (4-7) Multiplication-Sign 10{sup 11} M{sub Sun} ({approx}5{sigma} density peak) and is surrounded by several M{sub h} Almost-Equal-To 10{sup 11} M{sub Sun} halos which could host the fainter dropouts. In this scenario, we predict that all halos will eventually merge into a M{sub h} > 2 Multiplication-Sign 10{sup 14} M{sub Sun} galaxy cluster by z = 0. Follow-up observations with ground- and space-based telescopes are required to secure the z {approx} 8 nature of the

  6. Overdensities of Y-dropout Galaxies from the Brightest-of-Reionizing Galaxies Survey: A Candidate Protocluster at Redshift z ≈ 8

    NASA Astrophysics Data System (ADS)

    Trenti, Michele; Bradley, L. D.; Stiavelli, M.; Shull, J. M.; Oesch, P.; Bouwens, R. J.; Muñoz, J. A.; Romano-Diaz, E.; Treu, T.; Shlosman, I.; Carollo, C. M.

    2012-02-01

    Theoretical and numerical modeling of the assembly of dark-matter halos predicts that the most massive and luminous galaxies at high redshift are surrounded by overdensities of fainter companions. We test this prediction with Hubble Space Telescope observations acquired by our Brightest-of-Reionizing Galaxies (BoRG) survey, which identified four very bright z ~ 8 candidates as Y 098-dropout sources in four of the 23 non-contiguous Wide Field Camera 3 fields observed. We extend here the search for Y 098-dropouts to fainter luminosities (M * galaxies with M AB ~ -20), with detections at >=5σ confidence (compared to the 8σ confidence threshold adopted earlier) identifying 17 new candidates. We demonstrate that there is a correlation between number counts of faint and bright Y 098-dropouts at >=99.84% confidence. Field BoRG58, which contains the best bright z ~ 8 candidate (M AB = -21.3), has the most significant overdensity of faint Y 098-dropouts. Four new sources are located within 70'' (corresponding to 3.1 comoving Mpc at z = 8) from the previously known brighter z ~ 8 candidate. The overdensity of Y 098-dropouts in this field has a physical origin to very high confidence (p > 99.975%), independent of completeness and contamination rate of the Y 098-dropout selection. We modeled the overdensity by means of cosmological simulations and estimate that the principal dark-matter halo has mass Mh ≈ (4-7) × 1011 M ⊙ (~5σ density peak) and is surrounded by several Mh ≈ 1011 M ⊙ halos which could host the fainter dropouts. In this scenario, we predict that all halos will eventually merge into a Mh > 2 × 1014 M ⊙ galaxy cluster by z = 0. Follow-up observations with ground- and space-based telescopes are required to secure the z ~ 8 nature of the overdensity, discover new members, and measure their precise redshift. Based on observations made with the NASA/ESA Hubble Space Telescope, which is operated by the Association of Universities for Research in

  7. THE COS-HALOS SURVEY: AN EMPIRICAL DESCRIPTION OF METAL-LINE ABSORPTION IN THE LOW-REDSHIFT CIRCUMGALACTIC MEDIUM

    SciTech Connect

    Werk, Jessica K.; Prochaska, J. Xavier; Tripp, Todd M.; O'Meara, John M.; Peeples, Molly S.

    2013-02-15

    We present the equivalent width and column density measurements for low and intermediate ionization states of the circumgalactic medium (CGM) surrounding 44 low-z, L Almost-Equal-To L* galaxies drawn from the COS-Halos survey. These measurements are derived from far-UV transitions observed in HST/COS and Keck/HIRES spectra of background quasars within an impact parameter R < 160 kpc to the targeted galaxies. The data show significant metal-line absorption for 33 of the 44 galaxies, including quiescent systems, revealing the common occurrence of a cool (T Almost-Equal-To 10{sup 4}-10{sup 5} K), metal-enriched CGM. The detection rates and column densities derived for these metal lines decrease with increasing impact parameter, a trend we interpret as a declining metal surface density profile for the CGM. A comparison of the relative column densities of adjacent ionization states indicates that the gas is predominantly ionized. The large surface density in metals demands a large reservoir of metals and gas in the cool CGM (very conservatively, M {sup cool} {sub CGM} > 10{sup 9} M {sub Sun }), which likely traces a distinct density and/or temperature regime from the highly ionized CGM traced by O{sup +5} absorption. The large dispersion in absorption strengths (including non-detections) suggests that the cool CGM traces a wide range of densities or a mix of local ionizing conditions. Lastly, the kinematics inferred from the metal-line profiles are consistent with the cool CGM being bound to the dark matter halos hosting the galaxies; this gas may serve as fuel for future star formation. Future work will leverage this data set to provide estimates on the mass, metallicity, dynamics, and origin of the cool CGM in low-z, L* galaxies.

  8. An HST/COS legacy survey of intervening Si III absorption in the extended gaseous halos of low-redshift galaxies

    NASA Astrophysics Data System (ADS)

    Richter, P.; Wakker, B. P.; Fechner, C.; Herenz, P.; Tepper-García, T.; Fox, A. J.

    2016-05-01

    Aims: Doubly ionized silicon (Si iii) is a powerful tracer of diffuse ionized gas inside and outside of galaxies. It can be observed in the local Universe in ultraviolet (UV) absorption against bright extragalactic background sources. We here present an extensive study of intervening Si iii-selected absorbers and study the properties of the warm circumgalactic medium (CGM) around low-redshift (z ≤ 0.1) galaxies. Methods: We analyzed the UV absorption spectra of 303 extragalactic background sources, as obtained with the Cosmic Origins Spectrograph (COS) on-board the Hubble Space Telescope (HST). We developed a geometrical model for the absorption-cross section of the CGM around the local galaxy population and compared the observed Si iii absorption statistics with predictions provided by the model. We also compared redshifts and positions of the absorbers with those of ~64 000 galaxies using archival galaxy-survey data to investigate the relation between intervening Si iii absorbers and the CGM. Results: Along a total redshift path of Δz ≈ 24, we identify 69 intervening Si iii systems that all show associated absorption from other low and high ions (e.g., H i, Si ii, Si iv, C ii, C iv). We derive a bias-corrected number density of dN/dz(Si iii)= 2.5 ± 0.4 for absorbers with column densities log N(Si iii) > 12.2, which is ~3 times the number density of strong Mg ii systems at z = 0. This number density matches the expected cross section of a Si iii absorbing CGM around the local galaxy population with a mean covering fraction of ⟨ fc ⟩ = 0.69. For the majority (~60 percent) of the absorbers, we identify possible host galaxies within 300 km s-1 of the absorbers and derive impact parameters ρ < 200 kpc, demonstrating that the spatial distributions of Si iii absorbers and galaxies are highly correlated. Conclusions: Our study indicates that the majority of Si iii-selected absorbers in our sample trace the CGM of nearby galaxies within their virial radii at a

  9. South Carolina Job Placement Services Effectiveness Survey. Final Technical Report.

    ERIC Educational Resources Information Center

    National Evaluation Systems, Inc., Amherst, MA.

    A survey was conducted to determine the effectiveness of job placement services provided to secondary vocational students in South Carolina high schools and vocational centers, to identify characteristics of effective placement service programs, and to identify efforts made by schools to overcome sex bias. Survey instruments consisting of a…

  10. Hartnell College 1999 Accreditation Employee Survey Final Report.

    ERIC Educational Resources Information Center

    Hartnell Coll., Salinas, CA. Institutional Research and Planning Office.

    This document describes the results of an employee survey conducted as part of an Accreditation Self-Study at Hartnell College (California). Approximately 70% of the college's employees responded to the survey during fall 1999, and the respondents' characteristics appeared to be representative of all Hartnell employees. Employees as a whole…

  11. Teaching and Learning International Survey TALIS 2013: Conceptual Framework. Final

    ERIC Educational Resources Information Center

    Rutkowski, David; Rutkowski, Leslie; Bélanger, Julie; Knoll, Steffen; Weatherby, Kristen; Prusinski, Ellen

    2013-01-01

    In 2008, the initial cycle of the OECD's Teaching and Learning International Survey (TALIS 2008) established, for the first time, an international, large-scale survey of the teaching workforce, the conditions of teaching, and the learning environments of schools in participating countries. The second cycle of TALIS (TALIS 2013) aims to continue…

  12. RANDOM FORESTS FOR PHOTOMETRIC REDSHIFTS

    SciTech Connect

    Carliles, Samuel; Szalay, Alexander S.; Budavari, Tamas; Heinis, Sebastien; Priebe, Carey

    2010-03-20

    The main challenge today in photometric redshift estimation is not in the accuracy but in understanding the uncertainties. We introduce an empirical method based on Random Forests to address these issues. The training algorithm builds a set of optimal decision trees on subsets of the available spectroscopic sample, which provide independent constraints on the redshift of each galaxy. The combined forest estimates have intriguing statistical properties, notable among which are Gaussian errors. We demonstrate the power of our approach on multi-color measurements of the Sloan Digital Sky Survey.

  13. THE SLOAN LENS ACS SURVEY. XI. BEYOND HUBBLE RESOLUTION: SIZE, LUMINOSITY, AND STELLAR MASS OF COMPACT LENSED GALAXIES AT INTERMEDIATE REDSHIFT

    SciTech Connect

    Newton, Elisabeth R.; Marshall, Philip J.; Treu, Tommaso; Auger, Matthew W.; Gavazzi, Raphaeel; Bolton, Adam S.; Koopmans, Leon V. E.; Moustakas, Leonidas A.

    2011-06-20

    We exploit the strong lensing effect to explore the properties of intrinsically faint and compact galaxies at intermediate redshift (z{sub s} {approx_equal} 0.4-0.8) at the highest possible resolution at optical wavelengths. Our sample consists of 46 strongly lensed emission line galaxies (ELGs) discovered by the Sloan Lens ACS Survey (SLACS). The galaxies have been imaged at high resolution with the Hubble Space Telescope (HST) in three bands (V{sub HST} , I{sub 814}, and H{sub 160}), allowing us to infer their size, luminosity, and stellar mass using stellar population synthesis models. Lens modeling is performed using a new fast and robust code, KLENS, which we test extensively on real and synthetic non-lensed galaxies, and also on simulated galaxies multiply imaged by SLACS-like galaxy-scale lenses. Our tests show that our measurements of galaxy size, flux, and Sersic index are robust and accurate, even for objects intrinsically smaller than the HST point-spread function. The median magnification is 8.8, with a long tail that extends to magnifications above 40. Modeling the SLACS sources reveals a population of galaxies with colors and Sersic indices (median n {approx} 1) consistent with the galaxies detected with HST in the Galaxy Evolution from Morphology and SEDs (GEMS) and Hubble Ultra Deep Field (HUDF) surveys, but that are (typically) {approx}2 mag fainter and {approx}5 times smaller in apparent size than GEMS and {approx}4 mag brighter than but similar in size to HUDF. The size-stellar-mass and size-luminosity relations for the SLACS sources are offset to smaller sizes with respect to both comparison samples. The closest analog are ultracompact ELGs identified by HST grism surveys. The lowest mass galaxies in our sample are comparable to the brightest Milky Way satellites in stellar mass (10{sup 7} M{sub sun}) and have well-determined half-light radii of 0.''05 ({approx}0.3 kpc).

  14. The Subaru FMOS Galaxy Redshift Survey (FastSound). III. The mass-metallicity relation and the fundamental metallicity relation at z ˜ 1.4*

    NASA Astrophysics Data System (ADS)

    Yabe, Kiyoto; Ohta, Kouji; Akiyama, Masayuki; Bunker, Andrew; Dalton, Gavin; Ellis, Richard; Glazebrook, Karl; Goto, Tomotsugu; Imanishi, Masatoshi; Iwamuro, Fumihide; Okada, Hiroyuki; Shimizu, Ikkoh; Takato, Naruhisa; Tamura, Naoyuki; Tonegawa, Motonari; Totani, Tomonori

    2015-12-01

    We present the results from a large near-infrared spectroscopic survey made with Subaru/FMOS (FastSound) consisting of ˜ 4000 galaxies at z ˜ 1.4 with significant Hα detection. We measure the gas-phase metallicity from the [N II]λ6583/Hα emission line ratio of the composite spectra in various stellar mass and star-formation rate bins. The resulting mass-metallicity relation generally agrees with previous studies obtained in a similar redshift range to that of our sample. No clear dependence of the mass-metallicity relation on star-formation rate is found. Our result at z ˜ 1.4 is roughly in agreement with the fundamental metallicity relation at z ˜ 0.1 with a fiber aperture corrected star-formation rate. We detect significant [S II]λλ6716,6731 emission lines from the composite spectra. The electron density estimated from the [S II]λλ6716,6731 line ratio ranges from 10-500 cm-3, which generally agrees with that of local galaxies. On the other hand, the distribution of our sample on [N II]λ6583/Hα vs. [S II]λλ6716,6731/Hα is different to that found locally. We estimate the nitrogen-to-oxygen abundance ratio (N/O) from the N2S2 index, and find that the N/O in galaxies at z ˜ 1.4 is significantly higher than the local values at a fixed metallicity and stellar mass. The metallicity at z ˜ 1.4 recalculated with this N/O enhancement taken into account decreases by 0.1-0.2 dex. The resulting metallicity is lower than the local fundamental metallicity relation.

  15. Electric utility survey of residential ventilation issues. Final report

    SciTech Connect

    Moraski, D.P.; Smit, K.L.; Tidball, R.K.

    1994-06-01

    Many utilities are promoting tightly-sealed homes to improve energy efficiency, and it is important to understand the implications of a well-sealed structure on indoor air quality (IAQ). With Electric Power Research Institute (EPRI) support, Energy International conducted a nationwide survey of electric utilities to determine utility understanding of IAQ and ventilation issues. A total of 35 utilities were contacted for this survey. Utilities known to be active in the ventilation area were specifically targeted. The remaining utilities were chosen to gain a balanced geographical and size representation. A survey form was completed for each utility, providing a consistent platform for the survey. The results of the survey indicate a mixed awareness and interest in ventilation issues. Of the 35 utilities contacted, 10 were concerned with IAQ issues and were taking steps to alleviate potential problems through ventilation. Eight of the utilities believed that IAQ issues may be important in the future but have not yet implemented ventilation requirements or recommendations. The remaining 17 utilities did not express a significant concern with IAQ and did not foresee future problems. The utilities surveyed had only moderate concern with detailed ventilation issues such as infiltration measurements, spot vs. Whole house ventilation, source control vs. dilution, and control strategies. The most important utility concerns appear to be questions about the basic need for IAQ controls, and the cost-benefit analysis of energy efficient homes that require additional ventilation equipment. The utilities contacted that are concerned with IAQ generally have several mechanical ventilation system options to meet recommendations.

  16. The Ohio Schools Pest Management Survey: A Final Report.

    ERIC Educational Resources Information Center

    2001

    In 2001, the Environmental Studies Senior Capstone Seminar class at Denison University helped the state of Ohio work to prevent harmful pesticide use in schools. In cooperation with Ohio State University's Integrated Pest Management (IPM) in Schools Program, Denison conducted a statewide survey of school districts to determine current pest…

  17. National Environmental Data Referral Service (NEDRES) User Survey. Final Report.

    ERIC Educational Resources Information Center

    MAXIMA Corp., Silver Spring, MD.

    A survey was conducted to assess environmental data users' interest in a referral system such as the National Environmental Data Referral Service (NEDRES) and to gauge user willingness to participate in a proposed NEDRES network and to comply with a system of NEDRES user fees. Twenty-one organizations were identified and 3,200 individuals were…

  18. Direct Minkowski Functional analysis of large redshift surveys: a new high-speed code tested on the luminous red galaxy Sloan Digital Sky Survey-DR7 catalogue

    NASA Astrophysics Data System (ADS)

    Wiegand, Alexander; Buchert, Thomas; Ostermann, Matthias

    2014-09-01

    As deeper galaxy catalogues are soon to come, it becomes even more important to measure large-scale fluctuations in the catalogues with robust statistics that cover all moments of the galaxy distribution. In this paper, we reinforce a direct analysis of galaxy data by employing the Germ-Grain method to calculate the family of Minkowski Functionals. We introduce a new code, suitable for the analysis of large data sets without smoothing and without the construction of excursion sets. We provide new tools to measure correlation properties, putting emphasis on explicitly isolating non-Gaussian correlations with the help of integral-geometric relations. As a first application, we present the analysis of large-scale fluctuations in the luminous red galaxy sample of Sloan Digital Sky Survey data release 7 data. We find significant deviations from the Λ cold dark matter mock catalogues on samples as large as 500 h- 1 Mpc (more than 3σ) and slight deviations of around 2σ on 700 h- 1 Mpc, and we investigate possible sources of these deviations.

  19. A Catalog of Candidate High-redshift Blazars for GLAST

    SciTech Connect

    Arias, Tersi M.; /SLAC /San Francisco State U.

    2006-09-27

    High-redshift blazars are promising candidates for detection by the Gamma-ray Large Area Space Telescope (GLAST). GLAST, expected to be launched in the Fall of 2007, is a high-energy gamma-ray observatory designed for making observations of celestial gamma-ray sources in the energy band extending from 10 MeV to more than 200 GeV. It is estimated that GLAST will find several thousand blazars. The motivations for measuring the gamma-ray emission from distant blazars include the study of the high-energy emission processes occurring in these sources and an indirect measurement of the extragalactic background light. In anticipation of the launch of GLAST we have compiled a catalog of candidate high-redshift blazars. The criteria for sources chosen for the catalog were: high radio emission, high redshift, and a flat radio spectrum. A preliminary list of 307 radio sources brighter than 70mJy with a redshift z {ge} 2.5 was acquired using data from the NASA Extragalactic Database. Flux measurements of each source were obtained at two or more radio frequencies from surveys and catalogs to calculate their radio spectral indices {alpha}. The sources with a flat-radio spectrum ({alpha} {le} 0.5) were selected for the catalog, and the final catalog includes about 200 sources.

  20. Dusty Quasars at High Redshifts

    NASA Astrophysics Data System (ADS)

    Weedman, Daniel; Sargsyan, Lusine

    2016-09-01

    A population of quasars at z ˜ 2 is determined based on dust luminosities νL ν (7.8 μm) that includes unobscured, partially obscured, and obscured quasars. Quasars are classified by the ratio νL ν (0.25 μm)/νL ν (7.8 μm) = UV/IR, assumed to measure obscuration of UV luminosity by the dust that produces IR luminosity. Quasar counts at rest-frame 7.8 μm are determined for quasars in the Boötes field of the NOAO Deep Wide Field Survey using 24 μm sources with optical redshifts from the AGN and Galaxy Evolution Survey (AGES) or infrared redshifts from the Spitzer Infrared Spectrograph. Spectral energy distributions are extended to far-infrared wavelengths using observations from the Herschel Space Observatory Spectral and Photometric Imaging Receiver (SPIRE), and new SPIRE photometry is presented for 77 high-redshift quasars from the Sloan Digital Sky Survey. It is found that unobscured and obscured quasars have similar space densities at rest-frame 7.8 μm, but the ratio L ν (100 μm)/L ν (7.8 μm) is about three times higher for obscured quasars than for unobscured, so that far-infrared or submillimeter quasar detections are dominated by obscured quasars. We find that only ˜5% of high-redshift submillimeter sources are quasars and that existing 850 μm surveys or 2 mm surveys should already have detected sources at z ˜ 10 if quasar and starburst luminosity functions remain the same from z = 2 until z = 10.

  1. Quasars, Redshifts and Controversies

    NASA Astrophysics Data System (ADS)

    Arp, Halton C.

    1988-09-01

    Introduction; 1. Distance of quasars; 2. The battle over statistics; 3. Galaxies visibly connected to quasars; 4. Certain galaxies with many quasars; 5. Distribution of quasars in space; 6. Galaxies with excess redshift; 7. Small excess redshifts, the local group of galaxies, and quantization of redshifts; 8. Correcting intrinsic redshifts and identifying hydrogen clouds within nearby groups of galaxies; 9. Ejection from galaxies; 10. The sociology of the controversy; 11. Interpretations; Glossary; Index.

  2. Real-time cosmography with redshift derivatives

    NASA Astrophysics Data System (ADS)

    Martins, C. J. A. P.; Martinelli, M.; Calabrese, E.; Ramos, M. P. L. P.

    2016-08-01

    The drift in the redshift of objects passively following the cosmological expansion has long been recognized as a key model-independent probe of cosmology. Here, we study the cosmological relevance of measurements of time or redshift derivatives of this drift, arguing that the combination of first and second redshift derivatives is a powerful test of the Λ CDM cosmological model. In particular, the latter can be obtained numerically from a set of measurements of the drift at different redshifts. We show that, in the low-redshift limit, a measurement of the derivative of the drift can provide a constraint on the jerk parameter, which is j =1 for flat Λ CDM , while generically j ≠1 for other models. We emphasize that such a measurement is well within the reach of the ELT-HIRES and SKA Phase 2 array surveys.

  3. WHERE DO WET, DRY, AND MIXED GALAXY MERGERS OCCUR? A STUDY OF THE ENVIRONMENTS OF CLOSE GALAXY PAIRS IN THE DEEP2 GALAXY REDSHIFT SURVEY

    SciTech Connect

    Lin, Lihwai; Cooper, Michael C.; Willmer, Christopher N. A.; Jian, Hung-Yu; Chiueh, Tzihong; Koo, David C.; Guhathakurta, Puragra; Yan, Renbin; Coil, Alison L.; Croton, Darren J.; Gerke, Brian F.; Newman, Jeffrey A.

    2010-08-01

    We study the environments of wet, dry, and mixed galaxy mergers at 0.75 < z < 1.2 using close pairs in the DEEP2 Galaxy Redshift Survey. We find that the typical environment of dry and mixed merger candidates is denser than that of wet mergers, mostly due to the color-density relation. While the galaxy companion rate (N{sub c}) is observed to increase with overdensity, using N-body simulations, we find that the fraction of pairs that will eventually merge decreases with the local density, predominantly because interlopers are more common in dense environments. After taking into account the merger probability of pairs as a function of local density, we find only marginal environment dependence of the galaxy merger rate for wet mergers. On the other hand, the dry and mixed merger rates increase rapidly with local density due to the increased population of red galaxies in dense environments, implying that the dry and mixed mergers are most effective in overdense regions. We also find that the environment distribution of K+A galaxies is similar to that of wet mergers alone and of wet+mixed mergers, suggesting a possible connection between K+A galaxies and wet and/or wet+mixed mergers. Based on our results, we therefore expect that the properties, including structures and masses, of red-sequence galaxies should be different between those in underdense regions and those in overdense regions since the dry mergers are significantly more important in dense environments. We conclude that, as early as z {approx} 1, high-density regions are the preferred environment in which dry mergers occur, and that present-day red-sequence galaxies in overdense environments have, on average, undergone 1.2 {+-} 0.3 dry mergers since this time, accounting for (38 {+-} 10)% of their mass accretion in the last 8 billion years. The main uncertainty in this finding is the conversion from the pair fraction to the galaxy merger rate, which is possibly as large as a factor of 2. Our findings

  4. Spitzer Space Telescope: Focal Plane Survey Final Report. Appendix B:; IRAC

    NASA Technical Reports Server (NTRS)

    Bayard, David S.; Kang, Bryan H.; Brugarolas, Paul B.; Boussalis, Dhemetrios

    2004-01-01

    This final report summarizes the results and accuracies of the Spitzer Space Telescope focal plane survey. Accuracies achieved are compared to the focal plane survey calibration requirements put forth in the SIRTF IOC-SV Mission Plan [14] and pre-flight predictions made in [2]. The results of this focal plane survey are presently being used to support in-flight precision pointing, precision incremental offsets, IRS peakup array calibration, and ground pointing reconstruction...

  5. TPZ: photometric redshift PDFs and ancillary information by using prediction trees and random forests

    NASA Astrophysics Data System (ADS)

    Carrasco Kind, Matias; Brunner, Robert J.

    2013-06-01

    With the growth of large photometric surveys, accurately estimating photometric redshifts, preferably as a probability density function (PDF), and fully understanding the implicit systematic uncertainties in this process, has become increasingly important. In this paper, we present a new, publicly available, parallel, machine learning algorithm that generates photometric redshift PDFs by using prediction trees and random forest techniques, which we have named TPZ.1 This new algorithm incorporates measurement errors into the calculation while also dealing efficiently with missing values in the data. In addition, our implementation of this algorithm provides supplementary information regarding the data being analysed, including unbiased estimates of the accuracy of the technique without resorting to a validation data set, identification of poor photometric redshift areas within the parameter space occupied by the spectroscopic training data, a quantification of the relative importance of the variables used to construct the PDF, and a robust identification of outliers. This extra information can be used to optimally target new spectroscopic observations and to improve the overall efficacy of the redshift estimation. We have tested TPZ on galaxy samples drawn from the Sloan Digital Sky Survey (SDSS) main galaxy sample and from the Deep Extragalactic Evolutionary Probe-2 (DEEP2) survey, obtaining excellent results in each case. We also have tested our implementation by participating in the PHAT1 project, which is a blind photometric redshift contest, finding that TPZ performs comparable to if not better than other empirical photometric redshift algorithms. Finally, we discuss the various parameters that control the operation of TPZ, the specific limitations of this approach and an application of photometric redshift PDFs.

  6. Survey of potential geopressured resource areas in California. Final report

    SciTech Connect

    Sanyal, S.K.; Robertson-Tait, A.; Kraemer, M.; Buening, N.

    1993-03-01

    This paper presents the initial results of a survey of the occurrence and characteristics of geopressured fluid resources in California using the publicly- available database involving more than 150,000 oil and gas wells drilled in the State. Of the 975 documented on-shore oil and gas pools studied, about 42% were identified as potentially geopressured. Geothermal gradients in California oil and gas fields lie within the normal range of 1 F to 2 F per 100 feet. Except for the Los Angeles Basin, there was no evidence of higher temperatures or temperature gradients in geopressured pools.

  7. Survey of medical waste incinerators and emissions control. Final report

    SciTech Connect

    Barton, R.G.; Hansell, D.W.; Furlong, D.; Hassell, G.R.; Lanier, W.S.

    1992-01-01

    The report contains two volumes. Volume I of the report assesses the state-of-the-art of medical waste thermal treatment. The program involved a survey of existing information on medical waste treatment. This information was combined with data from municipal and hazardous waste combustion to identify potential mechanisms responsible for toxic emissions. Manufacturers of combustion and flue gas cleaning equipment were contacted. Information on current design practice was obtained. Volume II was prepared to assist local air pollution management districts implement Section 93104, Title 17, of the California Code of Regulations. Section 93104 places restrictions on polychlorodibenzo-p-dioxins (PCDD) and polychlorodibenzofurans (PCDF) emission levels and medical waste incinerator operating parameters which may affect PCDD/PCDF emissions. Part I of Volume II provides direct guidance for implementing the regulations. Part II provides background information on the operation and capabilities of flue gas cleaning systems used to control particulate, acid gas, metals, and PCDD/PCDF emissions.

  8. Final report. Electro-Seise, Inc., Airborne Survey

    SciTech Connect

    Schulte, Ralph

    2001-06-01

    The Rocky Mountain Oilfield Testing Center (RMOTC) has recently completed a test of an airborne microgravity and electric field sensing technology developed by Electro-Seise, Inc. of Fort Worth, Texas. The test involved the use of a single engine airplane to gather data over the Teapot Dome oil field along a tight grid spacing and along thirty (30) survey lines. The resultant gravity structure maps, based on the field data, were found to overlay the known structure of Teapot Dome. In addition, fault maps, based on the field data, were consistent with the known fault strike at Teapot Dome. Projected hydrocarbon thickness maps corresponded to some of the known production histories at RMOTC. Exceptions to the hydrocarbon thickness maps were also found to be true.

  9. Final Report for the Advanced Camera for Surveys (ACS)

    NASA Technical Reports Server (NTRS)

    2004-01-01

    ACS was launched aboard the Space Shuttle Columbia just before dawn on March 1, 2002. At the time of liftoff, the Hubble Space Telescope (HST) was reflecting the early morning sun as it moved across the sky. After successfully docking with HST, several components were replaced. One of the components was the Advanced Camera for Surveys built by Ball Aerospace & Technologies Corp. (BATC) in Boulder, Colorado. Over the life of the HST contract at BATC, hundreds of employees had the pleasure of working on the concept, design, fabrication, assembly, and test of ACS. Those employees thank NASA - Goddard Space Flight Center and the science team at Johns Hopkins University (JHU) for the opportunity to participate in building a great science instrument for HST.

  10. A Survey of Metal Lines at High Redshift. II. SDSS Absorption Line Studies—O VI Line Density, Space Density, and Gas Metallicity at z abs ~ 3.0

    NASA Astrophysics Data System (ADS)

    Frank, S.; Mathur, S.; Pieri, M.; York, D. G.

    2010-09-01

    We have analyzed a large data set of O VI absorber candidates found in the spectra of 3702 Sloan Digital Sky Survey (SDSS) quasars, focusing on a subsample of 387 active galactic nuclei sight lines with an average S/N >=5.0, allowing for the detection of absorbers above a rest-frame equivalent width limit of W r >= 0.19 Å for the O VI 1032 Å component. Accounting for random interlopers mimicking an O VI doublet, we derive for the first time a secure lower limit for the redshift number density ΔN/Δz for redshifts z abs >= 2.8. With extensive Monte Carlo simulations, we quantify the losses of absorbers due to blending with the ubiquitous Lyα forest lines and estimate the success rate of retrieving each individual candidate as a function of its redshift, the emission redshift of the quasar, the strength of the absorber, and the measured signal-to-noise ratio (S/N) of the spectrum by modeling typical Lyman forest spectra. These correction factors allow us to derive the "incompleteness and S/N-corrected" redshift number densities of O VI absorbers: ΔN O VI,c /Δzc (2.8 < z < 3.2) = 4.6 ± 0.3, ΔN O VI,c /Δzc (3.2 < z < 3.6) = 6.7 ± 0.8, and ΔN O VI,c /Δzc (3.6 < z < 4.0) = 8.4 ± 2.9. We can place a secure lower limit for the contribution of O VI to the closure mass density at the redshifts probed here: ΩO VI (2.8 < z < 3.2) >= 1.9 × 10-8 h -1. We show that the strong lines we probe account for over 65% of the mass in the O VI absorbers; the weak absorbers, while dominant in line number density, do not contribute significantly to the mass density. Making a conservative assumption about the ionization fraction, {O VI}/{O}, and adopting the Anders & Grevesse solar abundance values, we derive the mean metallicity of the gas probed in our search: ζ(2.8 < z < 3.2) >= 3.6 × 10-4 h, in good agreement with other studies. These results demonstrate that large spectroscopic data sets such as SDSS can play an important role in QSO absorption line studies, in spite of

  11. An ALMA survey of submillimeter galaxies in the extended Chandra deep field south: The redshift distribution and evolution of submillimeter galaxies

    SciTech Connect

    Simpson, J. M.; Swinbank, A. M.; Smail, Ian; Alexander, D. M.; Danielson, A. L. R.; Thomson, A. P.; Brandt, W. N.; Bertoldi, F.; Karim, A.; De Breuck, C.; Chapman, S. C.; Coppin, K. E. K.; Da Cunha, E.; Hodge, J. A.; Schinnerer, E.; Dannerbauer, H.; Greve, T. R.; Ivison, R. J.; Knudsen, K. K.; Poggianti, B. M.; and others

    2014-06-20

    We present the first photometric redshift distribution for a large sample of 870 μm submillimeter galaxies (SMGs) with robust identifications based on observations with ALMA. In our analysis we consider 96 SMGs in the Extended Chandra Deep Field South, 77 of which have 4-19 band photometry. We model the SEDs for these 77 SMGs, deriving a median photometric redshift of z {sub phot} = 2.3 ± 0.1. The remaining 19 SMGs have insufficient photometry to derive photometric redshifts, but a stacking analysis of Herschel observations confirms they are not spurious. Assuming that these SMGs have an absolute H-band magnitude distribution comparable to that of a complete sample of z ∼ 1-2 SMGs, we demonstrate that they lie at slightly higher redshifts, raising the median redshift for SMGs to z {sub phot} = 2.5 ± 0.2. Critically we show that the proportion of galaxies undergoing an SMG-like phase at z ≥ 3 is at most 35% ± 5% of the total population. We derive a median stellar mass of M {sub *} = (8 ± 1) × 10{sup 10} M {sub ☉}, although there are systematic uncertainties of up to 5 × for individual sources. Assuming that the star formation activity in SMGs has a timescale of ∼100 Myr, we show that their descendants at z ∼ 0 would have a space density and M{sub H} distribution that are in good agreement with those of local ellipticals. In addition, the inferred mass-weighted ages of the local ellipticals broadly agree with the look-back times of the SMG events. Taken together, these results are consistent with a simple model that identifies SMGs as events that form most of the stars seen in the majority of luminous elliptical galaxies at the present day.

  12. Bifurcation and chaos in power systems: A survey. Final report

    SciTech Connect

    Varaiya, P.; Wu, F.; Chiang, H.D.

    1992-08-01

    The literature dealing with bifurcation and chaos in electric power systems is surveyed. A brief discussion of relevant mathematical concepts and results is included in order to make the presentation self-contained and readily accessible. The objective is to determine the extent and significance of power system behavior that can be understood by dynamic models exhibiting bifurcation and chaotic motion. Bifurcation denotes a qualitative change in system behavior. The study is divided into three parts dealing with static bifurcations, Hopf bifurcations, and chaos. Static bifurcation occurs when two or more equilibrium points coincide. Hopf bifurcation occurs when a periodic oscillation emerges from a stable equilibrium. These are both examples of local bifurcation - they are determined by the system behavior in a neighborhood of the equilibrium. Chaos emerges from a global bifurcation - a non-local change in the phase portrait of tile system. The following conclusions are reached. Even the simplest models of power systems exhibit both local and global bifurcations. Local bifurcations occur because power flow equations have multiple solutions. In models that only incorporate real power flow, the capacity of transmission systems is so large that local bifurcations although present are unlikely to be practically significant. However, in models where voltage is determined by reactive power flows, local bifurcations can dramatically shrink the stability region. These bifurcations may explain ``voltage collapse``. The simplest models also exhibit chaotic behavior. However, for analytical convenience, chaos has mostly been investigated in systems with unrealistic parameter values.

  13. The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey: mock galaxy catalogues for the BOSS Final Data Release

    NASA Astrophysics Data System (ADS)

    Kitaura, Francisco-Shu; Rodríguez-Torres, Sergio; Chuang, Chia-Hsun; Zhao, Cheng; Prada, Francisco; Gil-Marín, Héctor; Guo, Hong; Yepes, Gustavo; Klypin, Anatoly; Scóccola, Claudia G.; Tinker, Jeremy; McBride, Cameron; Reid, Beth; Sánchez, Ariel G.; Salazar-Albornoz, Salvador; Grieb, Jan Niklas; Vargas-Magana, Mariana; Cuesta, Antonio J.; Neyrinck, Mark; Beutler, Florian; Comparat, Johan; Percival, Will J.; Ross, Ashley

    2016-03-01

    We reproduce the galaxy clustering catalogue from the SDSS-III Baryon Oscillation Spectroscopic Survey Final Data Release (BOSS DR11&DR12) with high fidelity on all relevant scales in order to allow a robust analysis of baryon acoustic oscillations and redshift space distortions. We have generated (6000) 12 288 MultiDark PATCHY BOSS (DR11) DR12 light cones corresponding to an effective volume of ˜192 000 [h-1 Gpc]3 (the largest ever simulated volume), including cosmic evolution in the redshift range from 0.15 to 0.75. The mocks have been calibrated using a reference galaxy catalogue based on the halo abundance matching modelling of the BOSS DR11&DR12 galaxy clustering data and on the data themselves. The production follows three steps. First, we apply the PATCHY code to generate a dark matter field and an object distribution including non-linear stochastic galaxy bias. Secondly, we run the halo/stellar distribution reconstruction HADRON code to assign masses to the various objects. This step uses the mass distribution as a function of local density and non-local indicators (i.e. tidal field tensor eigenvalues and relative halo exclusion separation for massive objects) from the reference simulation applied to the corresponding patchy dark matter and galaxy distribution. Finally, we apply the SUGAR code to build the light cones. The resulting MultiDarkPATCHY mock light cones reproduce the number density, selection function, survey geometry, and in general within 1σ, for arbitrary stellar mass bins, the power spectrum up to k = 0.3 h Mpc-1, the two-point correlation functions down to a few Mpc scales, and the three-point statistics of the BOSS DR11&DR12 galaxy samples.

  14. A spectroscopic survey for lambda Bootis stars. III. Final results

    NASA Astrophysics Data System (ADS)

    Paunzen, E.

    2001-07-01

    In the third paper of a series dedicated to the spectroscopic survey for new lambda Bootis stars, we present all new and confirmed members of the group as well as a detailed analysis of the observed sample. The nature of this small group of chemically peculiar stars of the upper main sequence still challenges our understanding of processes like diffusion, mass-loss and accretion. The typical abundances pattern (nearly solar values for C, N, O and S whereas the Fe-peak elements are moderate to strong underabundant) can still not be explained by any proposed theory. Hence, the significant increase of new members gives the opportunity to investigate the group properties in more detail. We report the discovery of 26 new members of the group and the confirmation of 18 candidates from the literature. This almost triples the number of known lambda Bootis stars. The existence of one member in the young open cluster NGC 2264 and four members in the Orion OB1 association proves that the lambda Bootis phenomenon already works at very early stages of stellar evolution. Recent results from the Hipparcos mission have shown that the well established lambda Bootis stars of the Galactic field comprise the whole area from the Zero Age Main Sequence to the Terminal Age Main Sequence (~ 109 yr for an A-type star). There is a continuous transition between very young and rather evolved evolutionary stages. We find that the overall percentage of lambda Bootis type among all normal type stars in the spectral range from B8 to F4 is 2% in the Galactic field as well as in open clusters. Furthermore, 44 metal-weak objects are listed which might be connected with the lambda Bootis phenomenon. Our biased sample (chosen by photometric boxes) is not distinguished from all A-type stars in the corresponding spectral region by the rotational velocity distribution. Only for the luminosity classes IV and III (especially for the cooler program stars) the determined mean v sin i values are very high

  15. A new method to search for high-redshift clusters using photometric redshifts

    SciTech Connect

    Castignani, G.; Celotti, A.; Chiaberge, M.; Norman, C.

    2014-09-10

    We describe a new method (Poisson probability method, PPM) to search for high-redshift galaxy clusters and groups by using photometric redshift information and galaxy number counts. The method relies on Poisson statistics and is primarily introduced to search for megaparsec-scale environments around a specific beacon. The PPM is tailored to both the properties of the FR I radio galaxies in the Chiaberge et al. sample, which are selected within the COSMOS survey, and to the specific data set used. We test the efficiency of our method of searching for cluster candidates against simulations. Two different approaches are adopted. (1) We use two z ∼ 1 X-ray detected cluster candidates found in the COSMOS survey and we shift them to higher redshift up to z = 2. We find that the PPM detects the cluster candidates up to z = 1.5, and it correctly estimates both the redshift and size of the two clusters. (2) We simulate spherically symmetric clusters of different size and richness, and we locate them at different redshifts (i.e., z = 1.0, 1.5, and 2.0) in the COSMOS field. We find that the PPM detects the simulated clusters within the considered redshift range with a statistical 1σ redshift accuracy of ∼0.05. The PPM is an efficient alternative method for high-redshift cluster searches that may also be applied to both present and future wide field surveys such as SDSS Stripe 82, LSST, and Euclid. Accurate photometric redshifts and a survey depth similar or better than that of COSMOS (e.g., I < 25) are required.

  16. [Redshift estimation of galaxy spectra based on similarity measure].

    PubMed

    Liu, Rong; Qiao, Xue-Jun; Duan, Fu-Qing

    2008-01-01

    Automated spectra analysis is desirable and necessary for efficiency of large sky surveys such as SDSS (Sloan digital sky survey), 2DF (2 degree fields) and LAMOST (large sky area multi-object spectroscopic telescope). In the present paper, we present a method for redshift estimation of galaxy spectra based on similarity measure. Firstly, we extract the spectral lines of the observed spectrum using the feature constrains of spectral lines; secondly, the authors determine the redshift candidates of the observed spectrum by spectral line features; then, the similarity between the observed spectrum and the template spectra shifted by each redshift candidate is measured; finally, the candidate of the highest similarity is chosen as the estimated redshift. PCA (principal component analysis) is used to build the static galaxy template spectra. The authors perform PCA for the four template spectra E, S0, Sa and Sb of the normal galaxy and the seven template spectra Sc, Sb1, Sb2, Sb3, Sb4, Sb5 and Sb6 of the starburst galaxy respectively, where the eleven template spectra are presented by Kinney & Calzetti et al. Two eigen-spectra are produced with the variance contribution rate of 99%. The authors choose the two eigen-spectra as the galaxy templates. The similarity measure proposed, which is similar to the evidence accumulation, is defined as the weighted sum of several similarity evidences. It can reduce the influence caused by some error matching. The authors divide the observed spectrum and the template spectrum respectively into several parts, and measure the correlations of the corresponding parts of them, which is chosen as the similarity evidences in the proposed similarity measure. The principle of setting the weights is that the higher the correlation, the higher the corresponding weight. The proposed approach is compared with the method based on spectral line matching and the traditional cross correlation technique by experiments, the results show that the

  17. PHOTOMETRIC ESTIMATES OF REDSHIFTS AND DISTANCE MODULI FOR TYPE Ia SUPERNOVAE

    SciTech Connect

    Kessler, Richard; Frieman, Joshua A.; Cinabro, David; Bassett, Bruce; Smith, Mathew; Dilday, Benjamin; Jha, Saurabh; Garnavich, Peter M.; Marriner, John; Nichol, Robert C.; Sako, Masao; Bernstein, Joseph P.; Kuhlmann, Stephen; Bizyaev, Dmitry; Goobar, Ariel; Schneider, Donald P.; Stritzinger, Maximilian

    2010-07-01

    Large planned photometric surveys will discover hundreds of thousands of supernovae (SNe), outstripping the resources available for spectroscopic follow-up and necessitating the development of purely photometric methods to exploit these events for cosmological study. We present a light curve fitting technique for type Ia supernova (SN Ia) photometric redshift (photo-z) estimation in which the redshift is determined simultaneously with the other fit parameters. We implement this 'LCFIT+Z' technique within the frameworks of the MLCS2K2 and SALTII light curve fit methods and determine the precision on the redshift and distance modulus. This method is applied to a spectroscopically confirmed sample of 296 SNe Ia from the Sloan Digital Sky Survey-II (SDSS-II) SN Survey and 37 publicly available SNe Ia from the Supernova Legacy Survey (SNLS). We have also applied the method to a large suite of realistic simulated light curves for existing and planned surveys, including the SDSS, SNLS, and the Large Synoptic Survey Telescope. When intrinsic SN color fluctuations are included, the photo-z precision for the simulation is consistent with that in the data. Finally, we compare the LCFIT+Z photo-z precision with previous results using color-based SN photo-z estimates.

  18. Survey of protected terrestrial vertebrates on the Oak Ridge Reservation. Final report

    SciTech Connect

    Mitchell, J.M.; Vail, E.R.; Webb, J.W.; Evans, J.W.

    1996-07-01

    This document is the final report on surveys of protected terrestrial vertebrates on the Oak Ridge Reservation (ORR) conducted from October 1994 through May 1996. The surveys were undertaken to gain information that could help prevent or minimize the potential impacts of projects on the ORR to species listed by the state or federal government as endangered, threatened, or in need of management; federal species of concern were also included. The results of the survey will assist in the effective management of the natural resources of the ORR. Currently, there are 69 species of federal or state listed terrestrial vertebrates (20 reptiles and amphibians, 20 mammals, and 29 birds) that may occur in Tennessee. Listed animal species that might be present on the ORR were targeted for survey using a prioritization system based on historical and recent sightings, known species distributions, presence of suitable habitat, literature reviews, and personal communications. Survey methods included trapping, seining, monitoring of artificial covers, active searching, and avian surveys. Surveys were conducted during the time of year when each targeted species was most likely to be encountered. The surveys confirmed the presence of 20 threatened and endangered species on the ORR. This report also includes some ancillary information. Records are provided for nonlisted species (44 species of reptiles and amphibians, 155 species of birds, and 28 species of mammals). Categorization of survey sites into 1 or more of 19 habitat types, which are briefly described, is presented. Notes are summarized on the occurrence of threatened and endangered species on the ORR. Finally, this report also lists threatened and endangered species not found that might be located by additional surveys, recommends three survey areas for natural-area status due to wildlife value, and suggests several avenues for future work.

  19. CONSTRAINING SOURCE REDSHIFT DISTRIBUTIONS WITH GRAVITATIONAL LENSING

    SciTech Connect

    Wittman, D.; Dawson, W. A.

    2012-09-10

    We introduce a new method for constraining the redshift distribution of a set of galaxies, using weak gravitational lensing shear. Instead of using observed shears and redshifts to constrain cosmological parameters, we ask how well the shears around clusters can constrain the redshifts, assuming fixed cosmological parameters. This provides a check on photometric redshifts, independent of source spectral energy distribution properties and therefore free of confounding factors such as misidentification of spectral breaks. We find that {approx}40 massive ({sigma}{sub v} = 1200 km s{sup -1}) cluster lenses are sufficient to determine the fraction of sources in each of six coarse redshift bins to {approx}11%, given weak (20%) priors on the masses of the highest-redshift lenses, tight (5%) priors on the masses of the lowest-redshift lenses, and only modest (20%-50%) priors on calibration and evolution effects. Additional massive lenses drive down uncertainties as N{sub lens}{sup -1/2}, but the improvement slows as one is forced to use lenses further down the mass function. Future large surveys contain enough clusters to reach 1% precision in the bin fractions if the tight lens-mass priors can be maintained for large samples of lenses. In practice this will be difficult to achieve, but the method may be valuable as a complement to other more precise methods because it is based on different physics and therefore has different systematic errors.

  20. Infrared-faint radio sources are at high redshifts. Spectroscopic redshift determination of infrared-faint radio sources using the Very Large Telescope

    NASA Astrophysics Data System (ADS)

    Herzog, A.; Middelberg, E.; Norris, R. P.; Sharp, R.; Spitler, L. R.; Parker, Q. A.

    2014-07-01

    Context. Infrared-faint radio sources (IFRS) are characterised by relatively high radio flux densities and associated faint or even absent infrared and optical counterparts. The resulting extremely high radio-to-infrared flux density ratios up to several thousands were previously known only for high-redshift radio galaxies (HzRGs), suggesting a link between the two classes of object. However, the optical and infrared faintness of IFRS makes their study difficult. Prior to this work, no redshift was known for any IFRS in the Australia Telescope Large Area Survey (ATLAS) fields which would help to put IFRS in the context of other classes of object, especially of HzRGs. Aims: This work aims at measuring the first redshifts of IFRS in the ATLAS fields. Furthermore, we test the hypothesis that IFRS are similar to HzRGs, that they are higher-redshift or dust-obscured versions of these massive galaxies. Methods: A sample of IFRS was spectroscopically observed using the Focal Reducer and Low Dispersion Spectrograph 2 (FORS2) at the Very Large Telescope (VLT). The data were calibrated based on the Image Reduction and Analysis Facility (IRAF) and redshifts extracted from the final spectra, where possible. This information was then used to calculate rest-frame luminosities, and to perform the first spectral energy distribution modelling of IFRS based on redshifts. Results: We found redshifts of 1.84, 2.13, and 2.76, for three IFRS, confirming the suggested high-redshift character of this class of object. These redshifts and the resulting luminosities show IFRS to be similar to HzRGs, supporting our hypothesis. We found further evidence that fainter IFRS are at even higher redshifts. Conclusions: Considering the similarities between IFRS and HzRGs substantiated in this work, the detection of IFRS, which have a significantly higher sky density than HzRGs, increases the number of active galactic nuclei in the early universe and adds to the problems of explaining the formation of

  1. REDSHIFT CATALOG FOR SWIFT LONG GAMMA-RAY BURSTS

    SciTech Connect

    Xiao Limin; Schaefer, Bradley E.

    2011-04-20

    We present a catalog of the redshifts for most long-duration gamma-ray bursts (GRBs) by Swift from 2004 December 20 to 2008 July 23 (258 bursts in total). All available information is collected, including spectroscopic redshifts, photometric redshift limits, and redshifts calculated from various luminosity relations. Error bars for the redshifts derived from the luminosity relations are asymmetric, with tails extended to the high-redshift end, and this effect is evaluated by looking at the 30% of Swift bursts with spectroscopic redshifts. A simulation is performed to eliminate this asymmetric effect, and the resultant redshift distribution is deconvolved. We test and confirm this simulation on the sample of bursts with known spectroscopic redshifts and then apply it to the 70% of Swift bursts that do not have spectroscopic measures. A final intrinsic redshift distribution is then made for almost all Swift bursts, and the efficiency of the spectroscopic detections is evaluated. The efficiency of spectroscopic redshifts varies from near unity at low redshift to 0.5 at z = 1, to near 0.3 at z = 4, and to 0.1 at z = 6. We also find that the fraction of GRBs with z>5 is {approx}10%, and this fraction is compared with simulations from a cosmological model.

  2. Improving dark energy constraints with high-redshift Type Ia supernovae from CANDELS and CLASH

    NASA Astrophysics Data System (ADS)

    Salzano, Vincenzo; Rodney, Steven A.; Sendra, Irene; Lazkoz, Ruth; Riess, Adam G.; Postman, Marc; Broadhurst, Tom; Coe, Dan

    2013-09-01

    Aims: We investigated the degree of improvement in dark energy constraints that can be achieved by extending Type Ia supernova (SN Ia) samples to redshifts z > 1.5 with the Hubble Space Telescope (HST), particularly in the ongoing Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS) and the Cluster Lensing and Supernova survey with Hubble (CLASH) multi-cycle treasury programs. Methods: Using the popular Chevalier-Polarski-Linder (CPL) parametrization of the dark energy w = w0 + wa(1 - a) we generated mock SN Ia samples that can be projected out to higher redshifts. The synthetic datasets thus generated were fitted to the CPL model, and we evaluated the improvements that a high-z sample can add to improve the statistical and systematic uncertainties on cosmological parameters. Results: In an optimistic but still very achievable scenario, we find that extending the HST sample beyond CANDELS+CLASH to reach a total of 28 SN Ia at z > 1.0 could improve the uncertainty in the wa parameter σwaby up to 21%. The corresponding improvement in the figure of merit (FoM) would be as high as 28%. Finally, we consider the use of high-redshift SN Ia samples to detect non-cosmological evolution in SN Ia luminosities with redshift, finding that these tests could be undertaken by future space-based infrared surveys using the James Webb Space Telescope (JWST).

  3. Properties of the redshift

    NASA Technical Reports Server (NTRS)

    Tifft, William G.; Cocke, W. J.

    1990-01-01

    Central to any analysis of dynamical systems, or large scale motion, is the interpretation of redshifts of galaxies as classical Doppler velocity shifts. This is a testable assumption and for many years evidence has accumulated that is inconsistent with the assumption. Here, the authors review recent evidence suggesting systematic radial dependence and temporal variation of redshifts.

  4. HIGH-REDSHIFT COOL-CORE GALAXY CLUSTERS DETECTED VIA THE SUNYAEV-ZEL'DOVICH EFFECT IN THE SOUTH POLE TELESCOPE SURVEY

    SciTech Connect

    Semler, D. R.; Suhada, R.; Bazin, G.; Bocquet, S.; Desai, S.; Aird, K. A.; Ashby, M. L. N.; Bayliss, M.; Bautz, M.; Benson, B. A.; Bleem, L. E.; Carlstrom, J. E.; Chang, C. L.; Crawford, T. M.; Crites, A. T.; Brodwin, M.; Cho, H. M.; Clocchiatti, A.; De Haan, T.; Dobbs, M. A.; and others

    2012-12-20

    We report the first investigation of cool-core properties of galaxy clusters selected via their Sunyaev-Zel'dovich (SZ) effect. We use 13 galaxy clusters uniformly selected from 178 deg{sup 2} observed with the South Pole Telescope (SPT) and followed up by the Chandra X-ray Observatory. They form an approximately mass-limited sample (>3 Multiplication-Sign 10{sup 14} M{sub Sun} h {sup -1}{sub 70}) spanning redshifts 0.3 < z < 1.1. Using previously published X-ray-selected cluster samples, we compare two proxies of cool-core strength: surface brightness concentration (c{sub SB}) and cuspiness ({alpha}). We find that c{sub SB} is better constrained. We measure c{sub SB} for the SPT sample and find several new z > 0.5 cool-core clusters, including two strong cool cores. This rules out the hypothesis that there are no z > 0.5 clusters that qualify as strong cool cores at the 5.4{sigma} level. The fraction of strong cool-core clusters in the SPT sample in this redshift regime is between 7% and 56% (95% confidence). Although the SPT selection function is significantly different from the X-ray samples, the high-z c{sub SB} distribution for the SPT sample is statistically consistent with that of X-ray-selected samples at both low and high redshifts. The cool-core strength is inversely correlated with the offset between the brightest cluster galaxy and the X-ray centroid, providing evidence that the dynamical state affects the cool-core strength of the cluster. Larger SZ-selected samples will be crucial in understanding the evolution of cluster cool cores over cosmic time.

  5. High-redshift Cool-core Galaxy Clusters Detected via the Sunyaev-Zel'dovich Effect in the South Pole Telescope Survey

    NASA Astrophysics Data System (ADS)

    Semler, D. R.; Šuhada, R.; Aird, K. A.; Ashby, M. L. N.; Bautz, M.; Bayliss, M.; Bazin, G.; Bocquet, S.; Benson, B. A.; Bleem, L. E.; Brodwin, M.; Carlstrom, J. E.; Chang, C. L.; Cho, H. M.; Clocchiatti, A.; Crawford, T. M.; Crites, A. T.; de Haan, T.; Desai, S.; Dobbs, M. A.; Dudley, J. P.; Foley, R. J.; George, E. M.; Gladders, M. D.; Gonzalez, A. H.; Halverson, N. W.; Harrington, N. L.; High, F. W.; Holder, G. P.; Holzapfel, W. L.; Hoover, S.; Hrubes, J. D.; Jones, C.; Joy, M.; Keisler, R.; Knox, L.; Lee, A. T.; Leitch, E. M.; Liu, J.; Lueker, M.; Luong-Van, D.; Mantz, A.; Marrone, D. P.; McDonald, M.; McMahon, J. J.; Mehl, J.; Meyer, S. S.; Mocanu, L.; Mohr, J. J.; Montroy, T. E.; Murray, S. S.; Natoli, T.; Padin, S.; Plagge, T.; Pryke, C.; Reichardt, C. L.; Rest, A.; Ruel, J.; Ruhl, J. E.; Saliwanchik, B. R.; Saro, A.; Sayre, J. T.; Schaffer, K. K.; Shaw, L.; Shirokoff, E.; Song, J.; Spieler, H. G.; Stalder, B.; Staniszewski, Z.; Stark, A. A.; Story, K.; Stubbs, C. W.; van Engelen, A.; Vanderlinde, K.; Vieira, J. D.; Vikhlinin, A.; Williamson, R.; Zahn, O.; Zenteno, A.

    2012-12-01

    We report the first investigation of cool-core properties of galaxy clusters selected via their Sunyaev-Zel'dovich (SZ) effect. We use 13 galaxy clusters uniformly selected from 178 deg2 observed with the South Pole Telescope (SPT) and followed up by the Chandra X-ray Observatory. They form an approximately mass-limited sample (>3 × 1014 M ⊙ h -1 70) spanning redshifts 0.3 < z < 1.1. Using previously published X-ray-selected cluster samples, we compare two proxies of cool-core strength: surface brightness concentration (c SB) and cuspiness (α). We find that c SB is better constrained. We measure c SB for the SPT sample and find several new z > 0.5 cool-core clusters, including two strong cool cores. This rules out the hypothesis that there are no z > 0.5 clusters that qualify as strong cool cores at the 5.4σ level. The fraction of strong cool-core clusters in the SPT sample in this redshift regime is between 7% and 56% (95% confidence). Although the SPT selection function is significantly different from the X-ray samples, the high-z c SB distribution for the SPT sample is statistically consistent with that of X-ray-selected samples at both low and high redshifts. The cool-core strength is inversely correlated with the offset between the brightest cluster galaxy and the X-ray centroid, providing evidence that the dynamical state affects the cool-core strength of the cluster. Larger SZ-selected samples will be crucial in understanding the evolution of cluster cool cores over cosmic time.

  6. THE METALLICITY EVOLUTION OF STAR-FORMING GALAXIES FROM REDSHIFT 0 TO 3: COMBINING MAGNITUDE-LIMITED SURVEY WITH GRAVITATIONAL LENSING

    SciTech Connect

    Yuan, T.-T.; Kewley, L. J.; Richard, J.

    2013-01-20

    We present a comprehensive observational study of the gas-phase metallicity of star-forming galaxies from z {approx} 0 {yields} 3. We combine our new sample of gravitationally lensed galaxies with existing lensed and non-lensed samples to conduct a large investigation into the mass-metallicity (MZ) relation at z > 1. We apply a self-consistent metallicity calibration scheme to investigate the metallicity evolution of star-forming galaxies as a function of redshift. The lensing magnification ensures that our sample spans an unprecedented range of stellar mass (3 Multiplication-Sign 10{sup 7} to 6 Multiplication-Sign 10{sup 10} M {sub Sun }). We find that at the median redshift of z = 2.07, the median metallicity of the lensed sample is 0.35 dex lower than the local SDSS star-forming galaxies and 0.18 dex lower than the z {approx} 0.8 DEEP2 galaxies. We also present the z {approx} 2 MZ relation using 19 lensed galaxies. A more rapid evolution is seen between z {approx} 1 {yields} 3 than z {approx} 0 {yields} 1 for the high-mass galaxies (10{sup 9.5} M {sub Sun} < M {sub *} < 10{sup 11} M {sub Sun }), with almost twice as much enrichment between z {approx} 1 {yields} 3 than between z {approx} 1 {yields} 0. We compare this evolution with the most recent cosmological hydrodynamic simulations with momentum-driven winds. We find that the model metallicity is consistent with the observed metallicity within the observational error for the low-mass bins. However, for higher masses, the model overpredicts the metallicity at all redshifts. The overprediction is most significant in the highest mass bin of 10{sup 10}-10{sup 11} M {sub Sun }.

  7. Cosmological constraints from Sunyaev-Zeldovich cluster counts: An approach to account for missing redshifts

    SciTech Connect

    Bonaldi, A.; Battye, R. A.; Brown, M. L.

    2014-05-10

    The accumulation of redshifts provides a significant observational bottleneck when using galaxy cluster surveys to constrain cosmological parameters. We propose a simple method to allow the use of samples where there is a fraction of the redshifts that are not known. The simplest assumption is that the missing redshifts are randomly extracted from the catalog, but the method also allows one to take into account known selection effects in the accumulation of redshifts. We quantify the reduction in statistical precision of cosmological parameter constraints as a function of the fraction of missing redshifts for simulated surveys, and also investigate the impact of making an incorrect assumption for the distribution of missing redshifts.

  8. THE OBSERVATIONS OF REDSHIFT EVOLUTION IN LARGE-SCALE ENVIRONMENTS (ORELSE) SURVEY. I. THE SURVEY DESIGN AND FIRST RESULTS ON CL 0023+0423 AT z = 0.84 AND RX J1821.6+6827 AT z = 0.82

    SciTech Connect

    Lubin, L. M.; Lemaux, B. C.; Kocevski, D. D.; Gal, R. R.; Squires, G. K.

    2009-06-15

    We present the Observations of Redshift Evolution in Large-Scale Environments (ORELSE) Survey, a systematic search for structure on scales greater than 10 h {sup -1} {sub 70} Mpc around 20 well-known clusters at redshifts of 0.6 < z < 1.3. The goal of the survey is to examine a statistical sample of dynamically active clusters and large-scale structures in order to quantify galaxy properties over the full range of local and global environments. We describe the survey design, the cluster sample, and our extensive observational data covering at least 25' around each target cluster. We use adaptively smoothed red galaxy density maps from our wide-field optical imaging to identify candidate groups/clusters and intermediate-density large-scale filaments/walls in each cluster field. Because photometric techniques (such as photometric redshifts, statistical overdensities, and richness estimates) can be highly uncertain, the crucial component of this survey is the unprecedented amount of spectroscopic coverage. We are using the wide-field, multiobject spectroscopic capabilities of the Deep Multiobject Imaging Spectrograph to obtain 100-200+ confirmed cluster members in each field. Our survey has already discovered the Cl 1604 supercluster at z {approx} 0.9, a structure which contains at least eight groups and clusters and spans 13 Mpc x 100 Mpc. Here, we present the results on the large-scale environments of two additional clusters, Cl 0023+0423 at z = 0.84 and RX J1821.6+6827 at z = 0.82, which highlight the diversity of global properties at these redshifts. The optically selected Cl 0023+0423 is a four-way group-group merger with constituent groups having measured velocity dispersions between 206 and 479 km s{sup -1}. The galaxy population is dominated by blue, star-forming galaxies, with 80% of the confirmed members showing [O II] emission. The strength of the H{delta} line in a composite spectrum of 138 members indicates a substantial contribution from recent

  9. The Observations of Redshift Evolution in Large-Scale Environments (ORELSE) Survey. I. The Survey Design and First Results on CL 0023+0423 at z = 0.84 and RX J1821.6+6827 at z = 0.82

    NASA Astrophysics Data System (ADS)

    Lubin, L. M.; Gal, R. R.; Lemaux, B. C.; Kocevski, D. D.; Squires, G. K.

    2009-06-01

    We present the Observations of Redshift Evolution in Large-Scale Environments (ORELSE) Survey, a systematic search for structure on scales greater than 10 h -1 70 Mpc around 20 well-known clusters at redshifts of 0.6 < z < 1.3. The goal of the survey is to examine a statistical sample of dynamically active clusters and large-scale structures in order to quantify galaxy properties over the full range of local and global environments. We describe the survey design, the cluster sample, and our extensive observational data covering at least 25' around each target cluster. We use adaptively smoothed red galaxy density maps from our wide-field optical imaging to identify candidate groups/clusters and intermediate-density large-scale filaments/walls in each cluster field. Because photometric techniques (such as photometric redshifts, statistical overdensities, and richness estimates) can be highly uncertain, the crucial component of this survey is the unprecedented amount of spectroscopic coverage. We are using the wide-field, multiobject spectroscopic capabilities of the Deep Multiobject Imaging Spectrograph to obtain 100-200+ confirmed cluster members in each field. Our survey has already discovered the Cl 1604 supercluster at z ≈ 0.9, a structure which contains at least eight groups and clusters and spans 13 Mpc × 100 Mpc. Here, we present the results on the large-scale environments of two additional clusters, Cl 0023+0423 at z = 0.84 and RX J1821.6+6827 at z = 0.82, which highlight the diversity of global properties at these redshifts. The optically selected Cl 0023+0423 is a four-way group-group merger with constituent groups having measured velocity dispersions between 206 and 479 km s-1. The galaxy population is dominated by blue, star-forming galaxies, with 80% of the confirmed members showing [O II] emission. The strength of the Hδ line in a composite spectrum of 138 members indicates a substantial contribution from recent starbursts to the overall galaxy

  10. Redshift-space Enhancement of Line-of-sight Baryon Acoustic Oscillations in the Sloan Digital Sky Survey Main-galaxy Sample

    NASA Astrophysics Data System (ADS)

    Tian, H. J.; Neyrinck, Mark C.; Budavári, Tamás; Szalay, Alexander S.

    2011-02-01

    We show that redshift-space distortions of galaxy correlations have a strong effect on correlation functions with distinct, localized features, like the signature of the baryon acoustic oscillations (BAO). Near the line of sight, the features become sharper as a result of redshift-space distortions. We demonstrate this effect by measuring the correlation function in Gaussian simulations and the Millennium simulation. We also analyze the SDSS DR7 main-galaxy sample, splitting the sample into slices 2fdg5 on the sky in various rotations. Measuring two-dimensional correlation functions in each slice, we do see a sharp bump along the line of sight. Using Mexican-hat wavelets, we localize it to (110 ± 10) h -1 Mpc. Averaging only along the line of sight, we estimate its significance at a particular wavelet scale and location at 2.2σ. In a flat angular weighting in the (π, rp ) coordinate system, the noise level is suppressed, pushing the bump's significance to 4σ. We estimate that there is about a 0.2% chance of getting such a signal anywhere in the vicinity of the BAO scale from a power spectrum lacking a BAO feature. However, these estimates of the significances make some use of idealized Gaussian simulations, and thus are likely a bit optimistic.

  11. Redshift-Space Enhancement of Line-of-Sight Baryon Acoustic Oscillations in the Sloan Digital Sky Survey Main-Galaxy Sample

    NASA Astrophysics Data System (ADS)

    Tian, Haijun; Neyrinck, Mark C.; Budavari, Tamas; SZALAY, AlEXANDER

    2015-08-01

    We show that redshift-space distortions of galaxy correlations have a strong effect on correlation functions with distinct, localized features, like the signature of the baryon acoustic oscillations (BAO). Near the line of sight, the features become sharper as a result of redshift-space distortions. We demonstrate this effect by measuring the correlation function in Gaussian simulations and the Millennium simulation. We also analyze the SDSS DR7 main-galaxy sample, splitting the sample into slices 2.5 on the sky in various rotations. Measuring two-dimensional correlation functions in each slice, we do see a sharp bump along the line of sight. Using Mexican-hat wavelets, we localize it to (110 ± 10) Mpc/h. Averaging only along the line of sight, we estimate its significance at a particular wavelet scale and location at 2.2σ. In a flat angular weighting in the (π,rp) coordinate system, the noise level is suppressed, pushing the bump’s significance to 4σ . We estimate that there is about a 0.2% chance of getting such a signal anywhere in the vicinity of the BAO scale from a power spectrum lacking a BAO feature. However, these estimates of the significances make some use of idealized Gaussian simulations, and thus are likely a bit optimistic.

  12. Galaxy bispectrum, primordial non-Gaussianity and redshift space distortions

    NASA Astrophysics Data System (ADS)

    Tellarini, Matteo; Ross, Ashley J.; Tasinato, Gianmassimo; Wands, David

    2016-06-01

    Measurements of the non-Gaussianity of the primordial density field have the power to considerably improve our understanding of the physics of inflation. Indeed, if we can increase the precision of current measurements by an order of magnitude, a null-detection would rule out many classes of scenarios for generating primordial fluctuations. Large-scale galaxy redshift surveys represent experiments that hold the promise to realise this goal. Thus, we model the galaxy bispectrum and forecast the accuracy with which it will probe the parameter fNL, which represents the degree of primordial local-type non Gaussianity. Specifically, we address the problem of modelling redshift space distortions (RSD) in the tree-level galaxy bispectrum including fNL. We find novel contributions associated with RSD, with the characteristic large scale amplification induced by local-type non-Gaussianity. These RSD effects must be properly accounted for in order to obtain un-biased measurements of fNL from the galaxy bispectrum. We propose an analytic template for the monopole which can be used to fit against data on large scales, extending models used in the recent measurements. Finally, we perform idealised forecasts on σfNL—the accuracy of the determination of local non-linear parameter fNL—from measurements of the galaxy bispectrum. Our findings suggest that current surveys can in principle provide fNL constraints competitive with Planck, and future surveys could improve them further.

  13. Probing the dark ages: Observations of the high-redshift universe

    NASA Astrophysics Data System (ADS)

    Stevens, Daniel Keith

    This thesis attempts to describe some of the earliest phases in the collapse of galaxies from an observational standpoint. The work is composed of an assortment of projects which sample objects at very high redshift, probing the Universe 1-3 Gyr after the Big Bang. The first section of the thesis concerns high-redshift galaxies. Search techniques for identifying distant galaxies are extensively reviewed. Radio selection was once the primary vehicle to targeting the early Universe. Keck spectroscopy of high-redshift radio galaxies from the MIT-Greenbank radio catalog (S5GHz >~ 50 mJy) are discussed. We synthesize a composite radio galaxy spectrum, which we compare with other composite active galaxy spectra. Our data suggests a correlation between radio power and ionization state in high-redshift radio galaxies. The following three chapters detail individual galaxies confirmed at z > 5. These galaxies are among the half-dozen most distant sources known at the close of the 20th Century. Two of the galaxies were photometrically-selected from the Hubble Deep Field (HDF 4-473.0 at z = 5.60 and HDF 3-951.0 at z = 5.34 +/- 0.01). The third is TN J0924-2201, a radio galaxy at z = 5.19 selected on the basis of steep radio spectral index and faint K-band brightness. This source contains the most distant active galactic nucleus currently known, requiring early formation of supermassive blackholes within a Gyr after the Big Bang. The second section of the thesis concerns searches for high-redshift Lyα emission, identified either from deep, narrow-band imaging surveys or deep slit spectra. We discuss in detail one faint, high equivalent width line-emitter. Conventional wisdom would suggest identifying the 9185 Å line with Lyα at z = 6.55. We argue [O II] λ3727 at z = 1.46 is the more likely identification and discuss observational tests to distinguish Lyα-emitters at high redshift from foreground (active) sources. The final section of the thesis concerns high-redshift

  14. Energy savings opportunity survey, Energy Engineering Analysis Program, Fort Gordon, Georgia: Executive summary. Final report

    SciTech Connect

    1988-09-01

    This is the pre-final submittal of an Energy Savings Opportunity Survey (ESOS) performed at Fort Gordon, GA. This report presents potential energy conservation projects for this Installation. These projects, consisting of Energy Conservation Opportunities (ECOs), are summarized in Tables 1 and 2. The projects were developed based on project packaging instructions from the Installation and on follow-up phone calls with The Directorate of Installation Support (DIS). The ECOs have been extended to include buildings similar to those surveyed by the architect/engineer. Similarity was based on instructions from the Installation and on follow-up phone calls with DIS. Table 3 lists the buildings surveyed. Thirty nine buildings were surveyed totaling approximately 800,000 square feet. Of these, one was an example of Family Housing and 38 were examples of non-housing buildings. Over one hundred ECOs were considered at Fort Gordon. Of these 39 were applicable in non-housing and 5 in Family Housing.

  15. High Redshift Quasars

    NASA Technical Reports Server (NTRS)

    Elvis, Martin S.

    1996-01-01

    The report for this period includes three papers: 'Associated Absorption at Low and High Redshift'; 'Strong X-ray Absorption in a Broad Absorption Line Quasar: PHL5200'; and 'ASCA and ROSAT X-ray Spectra of High-Redshift Radio-Loud Quasars'. The first gives examples from both low and high redshift for combining information on absorbing material in active galactic nuclei from both x-ray and the UV. The second presents ASCA observations of the z = 1.98 prototype broad absorption line quasar (BALQSO): PHL 5200, detected with both the solid-state imaging spectrometers and the gas imaging spectometers. The third paper presents results on the x-ray properties of 9 high-redshift radio-loud quasars observed by ASCA and ROSAT, including ASCA observations of S5 0014+81 (z = 3.38) and S5 0836+71 (z = 2.17) and ROSAT observations of PKS 2126-158.

  16. Cost-benefit of final radiological survey versus radioactive waste disposal.

    PubMed

    Barroso, Jeff; Roberts, Sarah

    2003-02-01

    A significant portion of the cost for D&D is related to low-level waste disposal, decontamination, and final radiological survey. For that reason, a careful cost-benefit analysis must be performed weighing the cost of decontaminating and radiologically surveying the building media for release against the cost of disposing of the material as radioactive waste. This cost-benefit analysis visibly came into play at the Rocky Flats Environmental Technology Site during the recent D&D of two facilities. PMID:12564340

  17. Cost-Benefit of Final Radiological Survey Versus Radioactive Waste Disposal.

    PubMed

    Barroso, Jeff; Roberts, Sarah

    2003-02-01

    ABSTRACT A significant portion of the cost for D&D is related to low-level waste disposal, decontamination, and final radiological survey. For that reason, a careful cost-benefit analysis must be performed weighing the cost of decontaminating and radiologically surveying the building media for release against the cost of disposing of the material as radioactive waste. This cost-benefit analysis visibly came into play at the Rocky Flats Environmental Technology Site during the recent D&D of two facilities. PMID:12555030

  18. MARZ: Redshifting Program

    NASA Astrophysics Data System (ADS)

    Hinton, Samuel

    2016-05-01

    MARZ analyzes objects and produces high quality spectroscopic redshift measurements. Spectra not matched correctly by the automatic algorithm can be redshifted manually by cycling automatic results, manual template comparison, or marking spectral features. The software has an intuitive interface and powerful automatic matching capabilities on spectra, and can be run interactively or from the command line, and runs as a Web application. MARZ can be run on a local server; it is also available for use on a public server.

  19. Quasar clustering at intermediate redshift - Analysis of systematics and of luminosity effects

    NASA Astrophysics Data System (ADS)

    Eftekharzadeh, Sarah; Myers, Adam D.; Kourkchi, Ehsan; DiPompeo, Michael A.; White, Martin; Weinberg, David, H.; Font-Ribera, Andreu; Ge, Jian; Paris, Isabelle; Ross, Nicholas P.; Schneider, Donald P.; Shen, Yue; Streblyanska, Alina

    2016-01-01

    We measure the clustering of over 55,000 quasars at redshifts 2.2 < z < 3.4 drawn from the final sample of the Baryonic Oscillation Spectroscopic Survey (BOSS). This is by far the largest sample ever used to study quasar clustering at "intermediate" redshifts. We ameliorate the effect of observational systematics on our clustering analyses by weighting our control catalogues of random points by maps of how observational systematics correlate with the BOSS quasar target density. We find that there is no significant evolution in the quasar correlation length and bias over our studied redshift range, implying that the masses of the dark matter halos that host quasars decreases slightly from z~2.2 to z~3.4. Our result also contradicts a monotonic relation between the optical luminosity of quasars near redshift 2.5 and their host halo masses. To begin to study whether this contradiction holds for quasars' bolometric luminosity, we use data from the Wide-field Infra red Survey Explorer (WISE) to study whether the luminosity or detection of BOSS quasars in the mid-IR is correlated with the masses of quasars' host halos. This work was partially supported by NSF award 1211112.

  20. Plasma Redshift Cosmology

    NASA Astrophysics Data System (ADS)

    Brynjolfsson, Ari

    2011-04-01

    The newly discovered plasma redshift cross section explains a long range of phenomena; including the cosmological redshift, and the intrinsic redshift of Sun, stars, galaxies and quasars. It explains the beautiful black body spectrum of the CMB, and it predicts correctly: a) the observed XRB, b) the magnitude redshift relation for supernovae, and c) the surface- brightness-redshift relation for galaxies. There is no need for Big Bang, Inflation, Dark Energy, Dark Matter, Accelerated Expansion, and Black Holes. The universe is quasi-static and can renew itself forever (for details, see: http://www.plasmaredshift.org). There is no cosmic time dilation. In intergalactic space, the average electron temperature is T = 2.7 million K, and the average electron density is N = 0.0002 per cubic cm. Plasma redshift is derived theoretically from conventional axioms of physics by using more accurate methods than those conventionally used. The main difference is: 1) the proper inclusion of the dielectric constant, 2) more exact calculations of imaginary part of the dielectric constant, and as required 3) a quantum mechanical treatment of the interactions.

  1. New Tools for Analyzing Teaching, Curriculum and Standards in Mathematics & Science. Results from Survey of Enacted Curriculum Project. Final Report.

    ERIC Educational Resources Information Center

    Blank, Rolf K.; Porter, Andrew; Smithson, John

    The Council of Chief State School Officers has completed a 2-year project to develop and test Surveys of Enacted Curriculum in Mathematics and Science. This final report describes advances in survey methods and analyses of enacted curriculum data, highlights central findings of the research, and presents applications of the survey and data tools.…

  2. ANNz: Estimating Photometric Redshifts Using Artificial Neural Networks

    NASA Astrophysics Data System (ADS)

    Collister, Adrian A.; Lahav, Ofer

    2004-04-01

    We introduce ANNz, a freely available software package for photometric redshift estimation using artificial neural networks. ANNz learns the relation between photometry and redshift from an appropriate training set of galaxies for which the redshift is already known. Where a large and representative training set is available, ANNz is a highly competitive tool when compared with traditional template-fitting methods. The ANNz package is demonstrated on the Sloan Digital Sky Survey Data Release 1, and for this particular data set the rms redshift error in the range 0<~z<~0.7 is σrms=0.023. Nonideal conditions (spectroscopic sets that are small or brighter than the photometric set for which redshifts are required) are simulated, and the impact on the photometric redshift accuracy is assessed.2

  3. WISE × SuperCOSMOS Photometric Redshift Catalog: 20 Million Galaxies over 3/pi Steradians

    NASA Astrophysics Data System (ADS)

    Bilicki, Maciej; Peacock, John A.; Jarrett, Thomas H.; Cluver, Michelle E.; Maddox, Natasha; Brown, Michael J. I.; Taylor, Edward N.; Hambly, Nigel C.; Solarz, Aleksandra; Holwerda, Benne W.; Baldry, Ivan; Loveday, Jon; Moffett, Amanda; Hopkins, Andrew M.; Driver, Simon P.; Alpaslan, Mehmet; Bland-Hawthorn, Joss

    2016-07-01

    We cross-match the two currently largest all-sky photometric catalogs—mid-infrared Wide-field Infrared Survey Explorer and SuperCOSMOS scans of UKST/POSS-II photographic plates—to obtain a new galaxy sample that covers 3π steradians. In order to characterize and purify the extragalactic data set, we use external GAMA and Sloan Digital Sky Survey spectroscopic information to define quasar and star loci in multicolor space, aiding the removal of contamination from our extended source catalog. After appropriate data cleaning, we obtain a deep wide-angle galaxy sample that is approximately 95% pure and 90% complete at high Galactic latitudes. The catalog contains close to 20 million galaxies over almost 70% of the sky, outside the Zone of Avoidance and other confused regions, with a mean surface density of more than 650 sources per square degree. Using multiwavelength information from two optical and two mid-IR photometric bands, we derive photometric redshifts for all the galaxies in the catalog, using the ANNz framework trained on the final GAMA-II spectroscopic data. Our sample has a median redshift of {z}{med}=0.2, with a broad {dN}/{dz} reaching up to z > 0.4. The photometric redshifts have a mean bias of | δ z| ∼ {10}-3, a normalized scatter of σ z = 0.033, and less than 3% outliers beyond 3σ z . Comparison with external data sets shows no significant variation of photo-z quality with sky position. Together with the overall statistics, we also provide a more detailed analysis of photometric redshift accuracy as a function of magnitudes and colors. The final catalog is appropriate for “all-sky” three-dimensional (3D) cosmology to unprecedented depths, in particular through cross-correlations with other large-area surveys. It should also be useful for source preselection and identification in forthcoming surveys, such as TAIPAN or WALLABY.

  4. Multi-agency radiation survey and site investigation manual (MARSIM). Final report

    SciTech Connect

    1997-12-01

    The MARSSIM provides information on planning, conducting, evaluating, and documenting building surface and surface soil final status radiological surveys for demonstrating compliance with dose or risk-based regulations or standards. The MARSSIM is a multi-agency consensus document that was developed collaboratively by four Federal agencies having authority and control over radioactive materials: Department of Defense (DOD), Department of Energy (DOE), Environmental Protection Agency (EPA), and Nuclear Regulatory Commission (NRC). The MARSSIM`s objective is to describe a consistent approach for planning, performing, and assessing building surface and surface soil final status surveys to meet established dose or risk-based release criteria, while at the same time encouraging an effective use of resources.

  5. Challenges with Final Status Surveys at a Large Decommissioning Site - 13417

    SciTech Connect

    Downey, Heath; Collopy, Peter; Shephard, Eugene; Walter, Nelson; Conant, John

    2013-07-01

    As part of decommissioning a former nuclear fuel manufacturing site, one of the crucial final steps is to conduct Final Status Surveys (FSS) in order to demonstrate compliance with the release criteria. At this decommissioning site, the area for FSS was about 100 hectares (248 acres) and included varying terrain, wooded areas, ponds, excavations, buildings and a brook. The challenges in performing the FSS included determining location, identifying FSS units, logging gamma walkover survey data, determining sample locations, managing water in excavations, and diverting water in the brook. The approaches taken to overcome these challenges will be presented in the paper. The paper will present and discuss lessons learned that will aid others in the FSS process. (authors)

  6. The evolution of host mass and black hole mass in quasi-stellar objects from the 2dF QSO Redshift Survey

    NASA Astrophysics Data System (ADS)

    Fine, S.; Croom, S. M.; Miller, L.; Babic, A.; Moore, D.; Brewer, B.; Sharp, R. G.; Boyle, B. J.; Shanks, T.; Smith, R. J.; Outram, P. J.; Loaring, N. S.

    2006-12-01

    We investigate the relation between the mass of supermassive black holes (MBH) in quasi-stellar objects (QSOs) and the mass of the dark matter haloes hosting them (MDH). We measure the widths of broad emission lines (MgII λ2798, CIV λ1549) from QSO composite spectra as a function of redshift. These widths are then used to determine virial black hole mass estimates. We compare our virial black hole mass estimates to dark matter halo masses for QSO hosts derived by Croom et al. based on measurements of QSO clustering. This enables us to trace the MBH-MDH relation over the redshift range z = 0.5-2.5. We calculate the mean zero-point of the MBH-MDH relation to be MBH = 108.4+/-0.2Msolar for an MDH = 1012.5Msolar. These data are then compared with several models connecting MBH and MDH as well as recent hydrodynamical simulations of galaxy evolution. We note that the flux-limited nature of QSO samples can cause a Malmquist-type bias in the measured zero-point of the MBH-MDH relation. The magnitude of this bias depends on the scatter in the MBH-MDH relation, and we re-evaluate the zero-point assuming three published values for this scatter. We create a subsample of our data defined by a constant magnitude interval around L* and find (1 + z)3.3+/-1.3 evolution in MBH between z ~ 0.5 and 2.5 for typical, L* QSOs. We also determine the Eddington ratios (L/LEdd) for the same subsample and find no significant evolution: (1 + z)-0.4+/-1.1. Taken at face value, our data suggest that a decrease in active black hole mass since z ~ 2.5 is the driving force behind luminosity evolution of typical, L*, optically selected QSOs. However, we note that our data are also consistent with a picture in which reductions in both black hole mass and accretion rate contribute equally to luminosity evolution. In addition, we find that these evolution results are strongly affected by the virial black hole mass estimators used. Changes to the calibration of these have a significant effect on the

  7. Photometric Redshift Techniques in Big-data Era

    NASA Astrophysics Data System (ADS)

    Zhang, Yan-Xia; Zhao, Yong-Heng

    Photometric data increase with large survey projects running. The huge volume of data influences the means and methods to deal with them. As such, the techniques of photometric redshift estimation based on photometric data must be developed and improved.

  8. Testing dark matter clustering with redshift space distortions

    SciTech Connect

    Linder, Eric V.

    2013-04-01

    The growth rate of large scale structure can probe whether dark matter clusters at gravitational strength or deviates from this, e.g. due to self interactions. Measurement of the growth rate through redshift space distortions in galaxy redshift surveys constrains the clustering strength, and its redshift dependence. We compare such effects on growth to those from high redshift deviations (e.g. early dark energy) or modified gravity, and give a simple, highly accurate analytic prescription. Current observations can constrain the dark matter clustering strength to F{sub cl} = 0.99±0.02 of standard, if all other parameters are held fixed, but substantial covariances exist. Future galaxy redshift surveys may constrain an evolving clustering strength to 28%, marginalizing over the other parameters, or 4% if the dark energy parameters are held fixed while fitting for dark matter growth. Tighter constraints on the nature of dark matter could be obtained by combining cosmological and astrophysical probes.

  9. Can We Detect the Color–Density Relation with Photometric Redshifts?

    NASA Astrophysics Data System (ADS)

    Lai, Chuan-Chin; Lin, Lihwai; Jian, Hung-Yu; Chiueh, Tzi-Hong; Merson, Alex; Baugh, Carlton M.; Foucaud, Sebastien; Chen, Chin-Wei; Chen, Wen-Ping

    2016-07-01

    A variety of methods have been proposed to define and to quantify galaxy environments. While these techniques work well in general with spectroscopic redshift samples, their application to photometric redshift surveys remains uncertain. To investigate whether galaxy environments can be robustly measured with photo-z samples, we quantify how the density measured with the nearest-neighbor approach is affected by photo-z uncertainties by using the Durham mock galaxy catalogs in which the 3D real-space environments and the properties of galaxies are known exactly. Furthermore, we present an optimization scheme in the choice of parameters used in the 2D projected measurements that yield the tightest correlation with respect to the 3D real-space environments. By adopting the optimized parameters in the density measurements, we show that the correlation between the 2D projected optimized density and the real-space density can still be revealed, and the color–density relation is also visible out to z ˜ 0.8 even for a photo-z uncertainty ({σ }{{{Δ }}z/(1+z)}) up to 0.06. We find that at redshifts 0.3 < z < 0.5 a deep (i ˜ 25) photometric redshift survey with {σ }{{{Δ }}z/(1+z)} = 0.02 yields a performance in small-scale density measurement that is comparable to a shallower i ˜ 22.5 spectroscopic sample with ˜10% sampling rate. Finally, we discuss the application of the local density measurements to the Pan-STARRS1 Medium Deep Survey (PS-MDS), one of the largest deep optical imaging surveys. Using data from ˜5 square degrees of survey area, our results show that it is possible to measure local density and to probe the color–density relation with 3σ confidence level out to z ˜ 0.8 in the PS-MDS. The color–density relation, however, quickly degrades for data covering smaller areas.

  10. Cluster redshifts in five suspected superclusters

    NASA Technical Reports Server (NTRS)

    Ciardullo, R.; Ford, H.; Harms, R.

    1985-01-01

    Redshift surveys for rich superclusters were carried out in five regions of the sky containing surface-density enhancements of Abell clusters. While several superclusters are identified, projection effects dominate each field, and no system contains more than five rich clusters. Two systems are found to be especially interesting. The first, field 0136 10, is shown to contain a superposition of at least four distinct superclusters, with the richest system possessing a small velocity dispersion. The second system, 2206 - 22, though a region of exceedingly high Abell cluster surface density, appears to be a remarkable superposition of 23 rich clusters almost uniformly distributed in redshift space between 0.08 and 0.24. The new redshifts significantly increase the three-dimensional information available for the distance class 5 and 6 Abell clusters and allow the spatial correlation function around rich superclusters to be estimated.

  11. Dusty Galaxies at the Highest Redshifts

    NASA Astrophysics Data System (ADS)

    Clements, David L.

    2015-08-01

    Galaxies with very high star formation rates are usually shrouded in substantial amounts of dust obscuration, making their discovery impossible through optical and/or near-IR observations. Observations in the far-IR/submm in contrast can identify such objects from their colours, allowing these rare objects to be followup up in detail. Herschel surveys have found a significant population of such objects at 4redshift record holder lying at z=6.34. Such objects are a challenge for all current models of galaxy formation and evolution. We here present the latest results from the HerMES consortium's ongoing work on this population, including new imaging and spectroscopic redshifts from ALMA, analysis of lensing for bright z>5 sources, and progress in the search for dusty star forming galaxies at still higher redshifts.

  12. The GAMA Panchromatic Survey

    NASA Astrophysics Data System (ADS)

    Driver, Simon P.

    2013-07-01

    The Galaxy And Mass Assembly Survey (GAMA) has now been operating for almost 5 years gathering spectroscopic redshifts for five regions of sky spanning 300 sq degrees in total to a depth of r < 19.8 mag. The survey has amassed over 225,000 redshifts making it the third largest redshift campaign after the SDSS and BOSS surveys. The survey has two novel features that set it apart: (1) complete and uniform sampling to a fixed flux limit (r < 19.8 mag) regardless of galaxy clustering due to multiple-visits to each sky region, enabling the construction of high-fidelity catalogues of groups and pairs, (2) co-ordination with diverse imaging campaigns which together sample an extremely broad range along the electro-magnetic spectrum from the UV (GALEX) through optical (VST KIDs), near-IR (VISTA VIKING), mid-IR (WISE), far-IR (Herschel-Atlas), 1m (GMRT), and eventually 20cm continuum and rest-frame 21cm line measurements (ASKAP DINGO). Apart from the ASKAP campaign all multi-wavelength programmes are either complete or in the final stages of observations and the UV-far-IR data are expected to be fully merged by the end of 2013. This article provides a brief flavour of the coming panchromatic database which will eventually include measurements or upper-limits across 27 wavebands for 380,000 galaxies. GAMA DR2 is scheduled for the end of January 2013.

  13. The 2QDES Pilot: the luminosity and redshift dependence of quasar clustering

    NASA Astrophysics Data System (ADS)

    Chehade, Ben; Shanks, T.; Findlay, J.; Metcalfe, N.; Sawangwit, U.; Irwin, M.; González-Solares, E.; Fine, S.; Drinkwater, M. J.; Croom, S.; Jurek, R. J.; Parkinson, D.; Bielby, R.

    2016-06-01

    We present a new redshift survey, the 2dF Quasar Dark Energy Survey pilot (2QDESp), which consists of ≈10 000 quasars from ≈150 deg2 of the southern sky, based on VST-ATLAS imaging and 2dF/AAOmega spectroscopy. Combining our optical photometry with the WISE (W1,W2) bands we can select essentially contamination free quasar samples with 0.8 < z < 2.5 and g < 20.5. At fainter magnitudes, optical UVX selection is still required to reach our g ≈ 22.5 limit. Using both these techniques we observed quasar redshifts at sky densities up to 90 deg-2. By comparing 2QDESp with other surveys (SDSS, 2QZ and 2SLAQ) we find that quasar clustering is approximately luminosity independent, with results for all four surveys consistent with a correlation scale of r0 = 6.1 ± 0.1 h-1 Mpc, despite their decade range in luminosity. We find a significant redshift dependence of clustering, particularly when BOSS data with r0 = 7.3 ± 0.1 h-1 Mpc are included at z ≈ 2.4. All quasars remain consistent with having a single host halo mass of ≈2 ± 1 × 1012 h-1 M⊙. This result implies that either quasars do not radiate at a fixed fraction of the Eddington luminosity or AGN black hole and dark matter halo masses are weakly correlated. No significant evidence is found to support fainter, X-ray selected quasars at low redshift having larger halo masses as predicted by the `hot halo' mode AGN model of Fanidakis et al. (2013). Finally, although the combined quasar sample reaches an effective volume as large as that of the original SDSS LRG sample, we do not detect the BAO feature in these data.

  14. MARZ: Manual and automatic redshifting software

    NASA Astrophysics Data System (ADS)

    Hinton, S. R.; Davis, Tamara M.; Lidman, C.; Glazebrook, K.; Lewis, G. F.

    2016-04-01

    The Australian Dark Energy Survey (OzDES) is a 100-night spectroscopic survey underway on the Anglo-Australian Telescope using the fibre-fed 2-degree-field (2dF) spectrograph. We have developed a new redshifting application MARZ with greater usability, flexibility, and the capacity to analyse a wider range of object types than the RUNZ software package previously used for redshifting spectra from 2dF. MARZ is an open-source, client-based, Javascript web-application which provides an intuitive interface and powerful automatic matching capabilities on spectra generated from the AAOmega spectrograph to produce high quality spectroscopic redshift measurements. The software can be run interactively or via the command line, and is easily adaptable to other instruments and pipelines if conforming to the current FITS file standard is not possible. Behind the scenes, a modified version of the AUTOZ cross-correlation algorithm is used to match input spectra against a variety of stellar and galaxy templates, and automatic matching performance for OzDES spectra has increased from 54% (RUNZ) to 91% (MARZ). Spectra not matched correctly by the automatic algorithm can be easily redshifted manually by cycling automatic results, manual template comparison, or marking spectral features.

  15. Medicare and Medicaid programs: revisions to deeming authority survey, certification, and enforcement procedures. Final rule.

    PubMed

    2015-05-22

    This final rule revises the survey, certification, and enforcement procedures related to CMS oversight of national accrediting organizations (AOs). The revisions implement certain provisions under the Medicare Improvements for Patients and Providers Act of 2008 (MIPPA). The revisions also clarify and strengthen our oversight of AOs that apply for, and are granted, recognition and approval of an accreditation program in accordance with the statute. The rule also extends some provisions, which are applicable to Medicare-participating providers, to Medicare-participating suppliers subject to certification requirements, and clarifies the definition of "immediate jeopardy." PMID:26003965

  16. Host galaxy spectra and consequences for supernova typing from the SDSS SN survey

    SciTech Connect

    Olmstead, Matthew D.; Brown, Peter J.; Brownstein, Joel R.; Dawson, Kyle S.; Sako, Masao; Gupta, Ravi R.; Bassett, Bruce; Kunz, Martin; Bizyaev, Dmitry; Brinkmann, J.; Brewington, Howard; Ebelke, Garrett L.; Campbell, Heather; D'Andrea, Chris B.; Lampeitl, Hubert; Frieman, Joshua A.; Galbany, Lluís; Garnavich, Peter; Hlozek, Renee; Jha, Saurabh W.; and others

    2014-04-01

    We present the spectroscopy from 5254 galaxies that hosted supernovae (SNe) or other transient events in the Sloan Digital Sky Survey II (SDSS-II). Obtained during SDSS-I, SDSS-II, and the Baryon Oscillation Spectroscopic Survey, this sample represents the largest systematic, unbiased, magnitude limited spectroscopic survey of SN host galaxies. Using the host galaxy redshifts, we test the impact of photometric SN classification based on SDSS imaging data with and without using spectroscopic redshifts of the host galaxies. Following our suggested scheme, there are a total of 1166 photometrically classified SNe Ia when using a flat redshift prior and 1126 SNe Ia when the host spectroscopic redshift is assumed. For 1024 (87.8%) candidates classified as likely SNe Ia without redshift information, we find that the classification is unchanged when adding the host galaxy redshift. Using photometry from SDSS imaging data and the host galaxy spectra, we also report host galaxy properties for use in future analysis of SN astrophysics. Finally, we investigate the differences in the interpretation of the light curve properties with and without knowledge of the redshift. Without host galaxy redshifts, we find that SALT2 light curve fits are systematically biased toward lower photometric redshift estimates and redder colors in the limit of low signal-to-noise data. The general improvements in performance of the light curve fitter and the increased diversity of the host galaxy sample highlights the importance of host galaxy spectroscopy for current photometric SN surveys such as the Dark Energy Survey and future surveys such as the Large Synoptic Survey Telescope.

  17. The impact of foregrounds on redshift space distortion measurements with the highly redshifted 21-cm line

    NASA Astrophysics Data System (ADS)

    Pober, Jonathan C.

    2015-02-01

    The highly redshifted 21-cm line of neutral hydrogen has become recognized as a unique probe of cosmology from relatively low redshifts (z ˜ 1) up through the Epoch of Reionization (EoR) (z ˜ 8) and even beyond. To date, most work has focused on recovering the spherically averaged power spectrum of the 21-cm signal, since this approach maximizes the signal to noise in the initial measurement. However, like galaxy surveys, the 21-cm signal is affected by redshift space distortions, and is inherently anisotropic between the line of sight and transverse directions. A measurement of this anisotropy can yield unique cosmological information, potentially even isolating the matter power spectrum from astrophysical effects. However, in interferometric measurements, foregrounds also have an anisotropic footprint between the line of sight and transverse directions: the so-called foreground `wedge'. Although foreground subtraction techniques are actively being developed, a `foreground avoidance' approach of simply ignoring contaminated modes has arguably proven most successful to date. In this work, we analyse the effect of this foreground anisotropy in recovering the redshift space distortion signature in 21-cm measurements at both high and intermediate redshifts. We find the foreground wedge corrupts nearly all of the redshift space signal for even the largest proposed EoR experiments (Hydrogen Epoch of Reionization Array and the Square Kilometre Array), making cosmological information unrecoverable without foreground subtraction. The situation is somewhat improved at lower redshifts, where the redshift-dependent mapping from observed coordinates to cosmological coordinates significantly reduces the size of the wedge. Using only foreground avoidance, we find that a large experiment like Canadian Hydrogen Intensity Mapping Experiment can place non-trivial constraints on cosmological parameters.

  18. A Determination of the Intergalactic Redshift Dependent UV-Optical-NIR Photon Density Using Deep Galaxy Survey Data and the Gamma-Ray Opacity of the Universe

    NASA Technical Reports Server (NTRS)

    Stecker, Floyd W.

    2012-01-01

    We calculate the intensity and photon spectrum of the intergalactic background light (IBL) as a function of red shift using an approach based on observational data obtained at in different wavelength bands from local to deep galaxy surveys. Our empirically based approach allows us, for the firs.t time, to obtain a completely model independent determination of the IBL and to quantify its uncertainties. Using our results on the IBL, we then place upper and lower limits on the opacity of the universe to gamma-rays, independent of previous constraints.

  19. Naked into the World: IT Teaching Experiences on a Final Primary School Teaching Practice--A Second Survey.

    ERIC Educational Resources Information Center

    Dunn, S.; Ridgway, J.

    1991-01-01

    Describes results of a survey of student teachers in the United Kingdom who described their experiences with information technology (IT) during their final primary teaching practice. Data are related to an earlier survey of the same students during their first teaching practice to explore changes in their practices and beliefs about IT. (14…

  20. Primordial alignment of elliptical galaxies in intermediate redshift clusters

    NASA Astrophysics Data System (ADS)

    Rong, Yu; Zhang, Shuang-Nan; Liao, Jin-Yuan

    2015-10-01

    We measure primordial alignments for the red galaxies in the sample of eight massive galaxy clusters in the southern sky from the Cluster Lensing And Supernova survey with Hubble-Very Large Telescope (CLASH-VLT) Large Programme, at a median redshift of 0.375. We find primordial alignment with about 3σ significance in the four dynamically young clusters, but null detection of primordial alignment in the four highly relaxed clusters. The observed primordial alignment is not dominated by any single one of the four dynamically young clusters, and is primarily due to a population of bright galaxies (Mr < -20.5)residing in the region 300-810 kpc from the cluster centres. For the first time, we point out that the combination of radial alignment and halo alignment can cause fake primordial alignment. Finally, we find that the detected alignment for the dynamically young clusters is real rather than fake primordial alignment.

  1. The infrared database of extragalactic observables from Spitzer - I. The redshift catalogue

    NASA Astrophysics Data System (ADS)

    Hernán-Caballero, Antonio; Spoon, Henrik W. W.; Lebouteiller, Vianney; Rupke, David S. N.; Barry, Donald P.

    2016-01-01

    This is the first of a series of papers on the Infrared Database of Extragalactic Observables from Spitzer (IDEOS). In this work, we describe the identification of optical counterparts of the infrared sources detected in Spitzer Infrared Spectrograph (IRS) observations, and the acquisition and validation of redshifts. The IDEOS sample includes all the spectra from the Cornell Atlas of Spitzer/IRS Sources (CASSIS) of galaxies beyond the Local Group. Optical counterparts were identified from correlation of the extraction coordinates with the NASA Extragalactic Database (NED). To confirm the optical association and validate NED redshifts, we measure redshifts with unprecedented accuracy on the IRS spectra (σ(Δz/(1+z)) ˜ 0.0011) by using an improved version of the maximum combined pseudo-likelihood method (MCPL). We perform a multistage verification of redshifts that considers alternate NED redshifts, the MCPL redshift, and visual inspection of the IRS spectrum. The statistics is as follows: the IDEOS sample contains 3361 galaxies at redshift 0 < z < 6.42 (mean: 0.48, median: 0.14). We confirm the default NED redshift for 2429 sources and identify 124 with incorrect NED redshifts. We obtain IRS-based redshifts for 568 IDEOS sources without optical spectroscopic redshifts, including 228 with no previous redshift measurements. We provide the entire IDEOS redshift catalogue in machine-readable formats. The catalogue condenses our compilation and verification effort, and includes our final evaluation on the most likely redshift for each source, its origin, and reliability estimates.

  2. The first analytical expression to estimate photometric redshifts suggested by a machine

    NASA Astrophysics Data System (ADS)

    Krone-Martins, A.; Ishida, E. E. O.; de Souza, R. S.

    2014-09-01

    We report the first analytical expression purely constructed by a machine to determine photometric redshifts (zphot) of galaxies. A simple and reliable functional form is derived using 41 214 galaxies from the Sloan Digital Sky Survey Data Release 10 (SDSS-DR10) spectroscopic sample. The method automatically dropped the u and z bands, relying only on g, r and i for the final solution. Applying this expression to other 1417 181 SDSS-DR10 galaxies, with measured spectroscopic redshifts (zspec), we achieved a mean <(zphot - zspec)/(1 + zspec)> ≲ 0.0086 and a scatter σ(zphot - zspec)/(1 + zspec) ≲ 0.045 when averaged up to z ≲ 1.0. The method was also applied to the PHAT0 data set, confirming the competitiveness of our results when faced with other methods from the literature. This is the first use of symbolic regression in cosmology, representing a leap forward in astronomy-data-mining connection.

  3. Study of a quadratic redshift-based correction in f(R) gravity with Baryonic matter

    NASA Astrophysics Data System (ADS)

    Masoudi, Mozhgan; Saffari, Reza

    2015-08-01

    This paper is considered as a second-order redshift-based corrections in derivative of modified gravitational action, f(R), to explain the late time acceleration which is appeared by Supernova Type Ia (SNeIa) without considering the dark components. Here, we obtained the cosmological dynamic parameters of universe for this redshift depended corrections. Next, we used the recent data of SNeIa Union2, shift parameter of the cosmic background radiation, Baryon acoustic oscillation from sloan digital sky survey (SDSS), and combined analysis of these observations to put constraints on the parameters of the selected F(z) model. It is very interesting that the well-known age problem of the three old objects for combined observations can be alleviated in this model. Finally, the reference action will be constructed in terms of its Taylor expansion. Also, we show that the reconstructed action definitely pass the solar system and stability of the cosmological solution tests.

  4. High-redshift QSOs in GOODS

    NASA Astrophysics Data System (ADS)

    Fontanot, Fabio; Monaco, Pierluigi; Cristiani, Stefano; Nonino, Mario; Vanzella, Eros

    2004-12-01

    Multiwavelenght surveys are a key instrument in detecting AGNs. AGNs are recognizable from their color properties and/or their infrared/X-ray emission. We discuss the recent developments of the GOODS survey and our selection of candidates based on optical color criteria and on the matching of the optical ACS database with infrared and X-rays counterparts. We pay particular attention to the high-z QSOs search in those fields. From these observation we obtain a sample of QSOs at redshifts from 3.5 to 5.2 and we put new constraints on the faint end of the Luminosity Function at those redshift, which is particularly important to understand the interplay between the formation of galaxies and super-massive black holes inside Dark Matter Halos and to measure the QSOs contribution to the UV ionizing background.

  5. Final Report for the Advanced Camera for Surveys (ACS) from Ball Aerospace and Technologies Corporation

    NASA Technical Reports Server (NTRS)

    Volmer, Paul; Sullivan, Pam (Technical Monitor)

    2003-01-01

    The Advanced Camera for Surveys ACS was launched aboard the Space Shuttle Columbia just before dawn on March 1, 2002. After successfully docking with the Hubble Space Telescope (HST), several components were replaced. One of the components was the Advanced Camera for Surveys built by Ball Aerospace & Technologies Corp. (BATC) in Boulder, Colorado. Over the life of the HST contract at BATC hundreds of employees had the pleasure of working on the concept, design, fabrication, assembly and test of ACS. Those employees thank NASA - Goddard Space Flight Center and the science team at Johns Hopkins University (JHU) for the opportunity to participate in building a great science instrument for HST. After installation in HST a mini-functional test was performed and later a complete functional test. ACS performed well and has continued performing well since then. One of the greatest rewards for the BATC employees is a satisfied science team. Following is an excerpt from the JHU final report, "The foremost promise of ACS was to increase Hubble's capability for surveys in the near infrared by a factor of 10. That promise was kept. "

  6. Redshifts of southern radio sources. VII

    NASA Technical Reports Server (NTRS)

    White, Graeme L.; Jauncey, David L.; Wright, Alan E.; Batty, Michael J.; Savage, Ann; Peterson, Bruce A.; Gulkis, Sam

    1988-01-01

    Redshifts and low-resolution spectral data are presented for 47 objects, most of which are QSOs identified with flat-spectrum radio sources from the Parkes 2.7 GHz survey. These data were taken with the 3.9 m Anglo-Australian Telescope using both the IPCS and FORS spectrographs. The total spectral coverage is 3200-9500 A. Three objects are optical counterparts identified with IRAS sources.

  7. Metals at high redshifts

    NASA Astrophysics Data System (ADS)

    Petitjean, Patrick

    The amount of metals present in the Universe and its cosmological evolution is a key issue for our understanding of how star formation proceeds from the collapse of the first objects to the formation of present day galaxies. We discuss here recent results at the two extremes of the density scale. 1. Part of the tenuous intergalactic medium (IGM) revealed by neutral hydrogen absorptions in the spectra of remote quasars (the so-called Lyman-α forest) contains metals. This is not surprising as there is a close interplay between the formation of galaxies and the evolution of the IGM. The IGM acts as the baryonic reservoir from which galaxies form, while star formation in the forming galaxies strongly influences the IGM by enrichment with metals and the emission of ionizing radiation. The spatial distribution of metals in the IGM is largely unknown however. The possibility remains that metals are associated with the filaments and sheets of the dark matter spatial distribution where stars are expected to form, whereas the space delineated by these features remains unpolluted. 2. Damped Lyman-α (DLA) systems observed in the spectra of high-redshift quasars are considered as the progenitors of present-day galaxies. Indeed, the large neutral hydrogen column densities observed and the presence of metals imply that the gas is somehow closely associated with regions of star formation. The nature of the absorbing objects is unclear however. It is probable that very different objects contribute to this population of absorption systems. Here we concentrate on summarizing the properties of the gas: presence of dust in small amount; nucleosynthesis signature and lack of H_2 molecules. The presence of H_2 molecules has been investigated in the course of a mini-survey with UVES at the VLT. The upper limits on the molecular fraction, f = 2N(H_2)/(2N(H_2)+N(HI)), derived in eight systems are in the range 1.2 ×10^-7 - 1.6 × 10^-5. There is no evidence in this sample for any

  8. High redshift GRBs

    NASA Astrophysics Data System (ADS)

    Gehrels, Neil; Cannizzo, John K.

    2012-09-01

    The Swift mission has opened a new, high redshift window on the universe. In this review we provide an overview of gamma-ray burst (GRB) science, describe the Swift mission, discuss high-z GRBs and tools for high-z studies, and look forward at future capabilities. A new mission concept - Lobster - is described that would monitor the X-ray sky at order of magnitude higher sensitivity than current missions.

  9. High Redshift GRBs

    NASA Technical Reports Server (NTRS)

    Gehrels, Neil; Cannizzo, John K.

    2012-01-01

    The Swift mission has opened a new, high redshift window on the universe. In this review we provide an overview of gamma-ray burst (GRB) science, describe the Swift mission, discuss high-z GRBs and tools for high-z studies, and look forward at future capabilities. A new mission concept - Lobster - is described that would monitor the X-ray sky at order of magnitude higher sensitivity than current missions.

  10. The number density of quiescent compact galaxies at intermediate redshift

    SciTech Connect

    Damjanov, Ivana; Hwang, Ho Seong; Geller, Margaret J.; Chilingarian, Igor

    2014-09-20

    Massive compact systems at 0.2 < z < 0.6 are the missing link between the predominantly compact population of massive quiescent galaxies at high redshift and their analogs and relics in the local volume. The evolution in number density of these extreme objects over cosmic time is the crucial constraining factor for the models of massive galaxy assembly. We select a large sample of ∼200 intermediate-redshift massive compacts from the Baryon Oscillation Spectroscopic Survey (BOSS) spectroscopy by identifying point-like Sloan Digital Sky Survey photometric sources with spectroscopic signatures of evolved redshifted galaxies. A subset of our targets have publicly available high-resolution ground-based images that we use to augment the dynamical and stellar population properties of these systems by their structural parameters. We confirm that all BOSS compact candidates are as compact as their high-redshift massive counterparts and less than half the size of similarly massive systems at z ∼ 0. We use the completeness-corrected numbers of BOSS compacts to compute lower limits on their number densities in narrow redshift bins spanning the range of our sample. The abundance of extremely dense quiescent galaxies at 0.2 < z < 0.6 is in excellent agreement with the number densities of these systems at high redshift. Our lower limits support the models of massive galaxy assembly through a series of minor mergers over the redshift range 0 < z < 2.

  11. Final Status Survey Report for Corrective Action Unit 117 - Pluto Disassembly Facility, Building 2201, Nevada National Security Site, Nevada

    SciTech Connect

    Jeremy Gwin and Douglas Frenette

    2010-09-30

    This document contains the process knowledge, radiological data and subsequent statistical methodology and analysis to support approval for the radiological release of Corrective Action Unit (CAU) 117 – Pluto Disassembly Facility, Building 2201 located in Area 26 of the Nevada National Security Site (NNSS). Preparations for release of the building began in 2009 and followed the methodology described in the Multi-Agency Radiation Survey and Site Investigation Manual (MARSSIM). MARSSIM is the DOE approved process for release of Real Property (buildings and landmasses) to a set of established criteria or authorized limits. The pre-approved authorized limits for surface contamination values and corresponding assumptions were established by DOE O 5400.5. The release criteria coincide with the acceptance criteria of the U10C landfill permit. The U10C landfill is the proposed location to dispose of the radiologically non-impacted, or “clean,” building rubble following demolition. However, other disposition options that include the building and/or waste remaining at the NNSS may be considered providing that the same release limits apply. The Final Status Survey was designed following MARSSIM guidance by reviewing historical documentation and radiological survey data. Following this review a formal radiological characterization survey was performed in two phases. The characterization revealed multiple areas of residual radioactivity above the release criteria. These locations were remediated (decontaminated) and then the surface activity was verified to be less than the release criteria. Once remediation efforts had been successfully completed, a Final Status Survey Plan (10-015, “Final Status Survey Plan for Corrective Action Unit 117 – Pluto Disassembly Facility, Building 2201”) was developed and implemented to complete the final step in the MARSSIM process, the Final Status Survey. The Final Status Survey Plan consisted of categorizing each individual room

  12. The MOSDEF Survey: Measurements of Balmer Decrements and the Dust Attenuation Curve at Redshifts z ~ 1.4–2.6

    NASA Astrophysics Data System (ADS)

    Reddy, Naveen A.; Kriek, Mariska; Shapley, Alice E.; Freeman, William R.; Siana, Brian; Coil, Alison L.; Mobasher, Bahram; Price, Sedona H.; Sanders, Ryan L.; Shivaei, Irene

    2015-06-01

    We present results on the dust attenuation curve of z ∼ 2 galaxies using early observations from the MOSFIRE Deep Evolution Field survey. Our sample consists of 224 star-forming galaxies with zspec = 1.36–2.59 and high signal-to-noise ratio measurements of Hα and Hβ obtained with Keck/MOSFIRE. We construct composite spectral energy distributions (SEDs) of galaxies in bins of Balmer decrement to measure the attenuation curve. We find a curve that is similar to the SMC extinction curve at λ ≳ 2500 Å. At shorter wavelengths, the shape is identical to that of the Calzetti et al. relation, but with a lower normalization. Hence, the new attenuation curve results in star formation rates (SFRs) that are ≈ 20% lower, and stellar masses that are {Δ }{log}({M}*{/M}ȯ )≃ 0.16 dex lower, than those obtained with the Calzetti relation. We find that the difference in the total attenuation of the ionized gas and stellar continuum correlates strongly with SFR, such that for dust-corrected SFRs ≳ 20 M⊙ yr‑1, assuming a Chabrier initial mass function, the nebular emission lines suffer an increasing degree of obscuration relative to the continuum. A simple model that can account for these trends is one in which the UV through optical stellar continuum is dominated by a population of less-reddened stars, while the nebular line and bolometric luminosities become increasingly dominated by dustier stellar populations for galaxies with large SFRs, as a result of the increased dust enrichment that accompanies such galaxies. Consequently, UV- and SED-based SFRs may underestimate the total SFR at even modest levels of ≈20 M⊙ yr‑1. Based on data obtained at the W.M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and NASA, and was made possible by the generous financial support of the W.M. Keck Foundation.

  13. Spatial clustering in the ESO-Sculptor survey: two-point correlation functions by galaxy type at redshifts 0.1-0.5

    NASA Astrophysics Data System (ADS)

    de Lapparent, V.; Slezak, E.

    2007-09-01

    Context: Galaxy clustering shows segregation effects with galaxy type, color and luminosity, which bring clues on the relationship with the underlying density field. Aims: We explore these effects among the populations of giant and dwarf galaxies detected in the ESO-Sculptor survey. Methods: We calculate the spatial two-point auto and cross-correlation functions for the 765 galaxies with R_c≤ 21.5 and 0.1 ≤ z ≤ 0.51 and for subsets by spectral type and luminosity. Results: At separation of 0.3 h-1 Mpc, pairs of early-type galaxies dominate the clustering over all the other types of pairs. At intermediate scales, 0.3-5 h-1 Mpc, mixed pairs of dwarf and giant galaxies contribute equally as pairs of giant galaxies, whereas the latter dominate at ≃10 h-1 Mpc. Moreover, the correlation functions per galaxy type display the expected transition between the 1-halo and 2-halo regimes in the scenario of hierarchical merging of dark matter halos. The 1-halo component of the early-type galaxies largely outdoes that for the late spiral galaxies, and that for the dwarf galaxies is intermediate between both. In contrast, the 2-halo component of the early-type galaxies and late spiral galaxies are comparable, whereas that for the dwarf galaxies is consistent with null clustering. Conclusions: We link the clustering segregation of the early-type and late spiral galaxies to their spatial distribution within the underlying dark matter halos. The early-type galaxies are preferentially located near the centers of the most massive halos, whereas late spiral galaxies tend to occupy their outskirts or the centers of less massive halos. This appears to be independent of luminosity for the early-type galaxies, whereas faint late spiral galaxies might reside in less dense regions than their bright analogs. The present analysis also unveils unprecedented results on the contribution from dwarf galaxies: at the scale at which they significantly cluster inside the halos (≤0.3 h-1 Mpc

  14. Bayesian photometric redshifts with empirical training sets

    NASA Astrophysics Data System (ADS)

    Wolf, Christian

    2009-07-01

    We combine in a single framework the two complementary benefits of χ2 template fits and empirical training sets used e.g. in neural nets: χ2 is more reliable when its probability density functions (PDFs) are inspected for multiple peaks, while empirical training is more accurate when calibration and priors of query data and training set match. We present a χ2 empirical method that derives PDFs from empirical models as a subclass of kernel regression methods, and apply it to the Sloan Digital Sky Survey Data Release 5 sample of >75000 quasi-stellar objects, which is full of ambiguities. Objects with single-peak PDFs show <1 per cent outliers, rms redshift errors <0.05 and vanishing redshift bias. At z > 2.5, these figures are two times better. Outliers result purely from the discrete nature and limited size of the model, and rms errors are dominated by the intrinsic variety of object colours. PDFs classed as ambiguous provide accurate probabilities for alternative solutions and thus weights for using both solutions and avoiding needless outliers. E.g. the PDFs predict 78.0 per cent of the stronger peaks to be correct, which is true for 77.9 per cent of them. Redshift incompleteness is common in faint spectroscopic surveys and turns into a massive undetectable outlier risk above other performance limitations, but we can quantify residual outlier risks stemming from size and completeness of the model. We propose a matched χ2 error scale for noisy data and show that it produces correct error estimates and redshift distributions accurate within Poisson errors. Our method can easily be applied to future large galaxy surveys, which will benefit from the reliability in ambiguity detection and residual risk quantification.

  15. A survey of interventional radiology awareness among final-year medical students in a European country.

    PubMed

    Leong, Sum; Keeling, Aoife N; Lee, Michael J

    2009-07-01

    Interventional radiology (IR) is a rapidly expanding specialty that is facing the challenges of turf wars and personnel shortages. Appropriate exposure of medical students to this field can be vital to recruitment of potential future trainees or referring physicians. The aim of this study was to determine the knowledge and views of final-year medical students in a single EU country regarding various aspects of IR. An electronic survey was sent via e-mail to all final-year medical students in a European country. The students were given a month to respond to the questionnaire. A total of 234 students of 675 (34.5%) replied to the survey. Of the respondents, 35% had previously completed an attachment to the radiology department. The majority of students (63%) thought their knowledge in radiology in general was poor. The percentage of students who correctly identified procedures performed by interventional radiologists was 69% for Hickman line insertion, 79% for fibroid embolization, and 67.5% for lower limb angioplasty. Sixty percent, 30%, and 47% thought that interventional radiologists perform cardiac angioplasties, perform arterial bypasses, and create AV fistulas, respectively. Forty-nine percent felt that interventional radiologists are surgically trained. Eighty-three percent of students were first made aware of angioplasty by a cardiologist. Thirty-one percent thought that interventional radiologists do ward rounds, 24% thought that interventional radiologists have admitting rights, and 26% felt that interventional radiologists run an outpatient practice. A significant number of students (76%) thought that the job prospects in IR are good or excellent but only 40.5% were willing to consider a career in IR. In conclusion, this study indicates that IR remains a nascent but attractive specialty to the majority of medical students. Further development of the existing informal undergraduate curriculum to address shortcomings will ensure that IR continues to attract

  16. Redshift-space distortions in massive neutrino and evolving dark energy cosmologies

    NASA Astrophysics Data System (ADS)

    Upadhye, Amol; Kwan, Juliana; Pope, Adrian; Heitmann, Katrin; Habib, Salman; Finkel, Hal; Frontiere, Nicholas

    2016-03-01

    Large-scale structure surveys in the coming years will measure the redshift-space power spectrum to unprecedented accuracy, allowing for powerful new tests of the Λ cold dark matter (Λ CDM ) picture as well as measurements of particle physics parameters such as the neutrino masses. We extend the time-renormalization-group (RG) perturbative framework to redshift space, computing the power spectrum Ps(k ,μ ) in massive neutrino cosmologies with time-dependent dark energy equations of state w (z ). Time-RG is uniquely capable of incorporating scale-dependent growth into the Ps(k ,μ ) computation, which is important for massive neutrinos as well as modified gravity models. Although changes to w (z ) and the neutrino mass fraction both affect the late-time scale dependence of the nonlinear power spectrum, we find that the two effects depend differently on the line-of-sight angle μ . Finally, we use the hacc N-body code to quantify errors in the perturbative calculations. For a Λ CDM model at redshift z =1 , our procedure predicts the monopole (quadrupole) to 1% accuracy up to a wave number 0.19 h /Mpc (0.28 h /Mpc ), compared to 0.08 h /Mpc (0.07 h /Mpc ) for the Kaiser approximation and 0.19 h /Mpc (0.16 h /Mpc ) for the current state-of-the-art perturbation scheme. Our calculation agrees with the simulated redshift-space power spectrum even for neutrino masses above the current bound, and for rapidly evolving dark energy equations of state, |d w /d z |˜1 . Along with this article, we make our redshift-space time-RG implementation publicly available as the code redtime.

  17. The evolution of neutral gas in damped Lyman α systems from the XQ-100 survey

    NASA Astrophysics Data System (ADS)

    Sánchez-Ramírez, R.; Ellison, S. L.; Prochaska, J. X.; Berg, T. A. M.; López, S.; D'Odorico, V.; Becker, G. D.; Christensen, L.; Cupani, G.; Denney, K. D.; Pâris, I.; Worseck, G.; Gorosabel, J.

    2016-03-01

    We present a sample of 38 intervening damped Lyman α (DLA) systems identified towards 100 z > 3.5 quasars, observed during the XQ-100 survey. The XQ-100 DLA sample is combined with major DLA surveys in the literature. The final combined sample consists of 742 DLAs over a redshift range approximately 1.6 < zabs < 5.0. We develop a novel technique for computing Ω_{H I}^DLA as a continuous function of redshift, and we thoroughly assess and quantify the sources of error therein, including fitting errors and incomplete sampling of the high column density end of the column density distribution function. There is a statistically significant redshift evolution in Ω_{H I}^DLA (≥3σ) from z ˜ 2 to z ˜ 5. In order to make a complete assessment of the redshift evolution of Ω_{H I}, we combine our high-redshift DLA sample with absorption surveys at intermediate redshift and 21-cm emission line surveys of the local universe. Although Ω_{H I}^DLA, and hence its redshift evolution, remains uncertain in the intermediate-redshift regime (0.1 < zabs < 1.6), we find that the combination of high-redshift data with 21-cm surveys of the local universe all yield a statistically significant evolution in Ω_{H I} from z ˜ 0 to z ˜ 5 (≥3σ). Despite its statistical significance, the magnitude of the evolution is small: a linear regression fit between Ω_{H I} and z yields a typical slope of ˜0.17 × 10-3, corresponding to a factor of ˜4 decrease in Ω_{H I} between z = 5 and z = 0.

  18. ALHAMBRA survey: morphological classification

    NASA Astrophysics Data System (ADS)

    Pović, M.; Huertas-Company, M.; Márquez, I.; Masegosa, J.; Aguerri, J. A. López; Husillos, C.; Molino, A.; Cristóbal-Hornillos, D.

    2015-03-01

    The Advanced Large Homogeneous Area Medium Band Redshift Astronomical (ALHAMBRA) survey is a photometric survey designed to study systematically cosmic evolution and cosmic variance (Moles et al. 2008). It employs 20 continuous medium-band filters (3500 - 9700 Å), plus JHK near-infrared (NIR) bands, which enable measurements of photometric redshifts with good accuracy. ALHAMBRA covers > 4 deg2 in eight discontinuous regions (~ 0.5 deg2 per region), of theseseven fields overlap with other extragalactic, multiwavelength surveys (DEEP2, SDSS, COSMOS, HDF-N, Groth, ELAIS-N1). We detect > 600.000 sources, reaching the depth of R(AB) ~ 25.0, and photometric accuracy of 2-4% (Husillos et al., in prep.). Photometric redshifts are measured using the Bayesian Photometric Redshift (BPZ) code (Benítez et al. 2000), reaching one of the best accuracies up to date of δz/z <= 1.2% (Molino et al., in prep.). To deal with the morphological classification of galaxies in the ALHAMBRA survey (Pović et al., in prep.), we used the galaxy Support Vector Machine code (galSVM; Huertas-Company 2008, 2009), one of the new non-parametric methods for morphological classification, specially useful when dealing with low resolution and high-redshift data. To test the accuracy of our morphological classification we used a sample of 3000 local, visually classified galaxies (Nair & Abraham 2010), moving them to conditions typical of our ALHAMBRA data (taking into account the background, redshift and magnitude distributions, etc.), and measuring their morphology using galSVM. Finally, we measured the morphology of ALHAMBRA galaxies, obtaining for each source seven morphological parameters (two concentration indexes, asymmetry, Gini, M20 moment of light, smoothness, and elongation), probability if the source belongs to early- or late-type, and its error. Comparing ALHAMBRA morph COSMOS/ACS morphology (obtained with the same method) we expect to have qualitative separation in two main morphological

  19. Quasar redshifts: the intrinsic component

    NASA Astrophysics Data System (ADS)

    Hansen, Peter M.

    2016-09-01

    The large observed redshift of quasars has suggested large cosmological distances and a corresponding enormous energy output to explain the brightness or luminosity as seen at earth. Alternative or complementary sources of redshift have not been identified by the astronomical community. This study examines one possible source of additional redshift: an intrinsic component based on the plasma characteristics of high temperature and high electron density which are believed to be present.

  20. Morphologies at High Redshift from Galaxy Zoo

    NASA Astrophysics Data System (ADS)

    Masters, Karen; Melvin, Tom; Simmons, Brooke; Willett, Kyle; Lintott, Chris

    2015-08-01

    I will present results from Galaxy Zoo classification of galaxies observed in public observed frame optical HST surveys (e.g. COSMOS, GOODS) as well as in observed frame NIR with (ie. CANDELS). Early science results from these classifications have investigated the changing bar fraction in disc galaxies as a function of redshift (to z~1 in Melvin et al. 2014; and at z>1 in Simmons et al. 2015), as well as how the morphologies of galaxies on the red sequence have been changing since z~1 (Melvin et al. in prep.). These unique dataset of quantitative visual classifications for high redshift galaxies will be made public in forthcoming publications (planned as Willett et al. for Galaxy Zoo Hubble, and Simmons et al. for Galaxy Zoo CANDELS).

  1. EZ: A Tool For Automatic Redshift Measurement

    NASA Astrophysics Data System (ADS)

    Garilli, B.; Fumana, M.; Franzetti, P.; Paioro, L.; Scodeggio, M.; Le Fèvre, O.; Paltani, S.; Scaramella, R.

    2010-07-01

    We present EZ (Easy redshift), a tool we have developed within the VVDS project to help in redshift measurement from optical spectra. EZ has been designed with large spectroscopic surveys in mind, and in its development particular care has been given to the reliability of the results obtained in an automatic and unsupervised mode. Nevertheless, the possibility of running it interactively has been preserved, and a graphical user interface for results inspection has been designed. EZ has been successfully used within the VVDS project, as well as the zCosmos one. In this article we describe its architecture and the algorithms used, and evaluate its performances both on simulated and real data. EZ is an open-source program, freely downloadable from the Pandora Web Site.1

  2. Comparison of the National Survey of Compensation with other surveys of research and development professionals. Final report on universe update

    SciTech Connect

    Newborg, J.; Spurgeon, M.; Price, B.; Evans, P.

    1981-10-01

    The National Survey of Compensation Paid Scientists and Engineers Engaged in Research and Development (NSC) has been conducted for the Department of Energy since 1967. During this time the NSC has come to be considered the most comprehensive survey of its kind available in the United States. Its methodology and results are reliable and highly useful to compensation personnel in research and development (R and D) establishments. Each year project staff pinpoint areas of improvement which are necessary and desirable. The three tasks that are the subject of this report have been undertaken to maintain and improve the NSC and increase its usefulness to participants. The three tasks are: an update of the universe listing; comparison of NSC survey methodology and results with other surveys of research and development professionals; and development of a methodology to project salaries for the near-term. Each task is described.

  3. Photometric redshifts for the SDSS Data Release 12

    NASA Astrophysics Data System (ADS)

    Beck, Róbert; Dobos, László; Budavári, Tamás; Szalay, Alexander S.; Csabai, István

    2016-08-01

    We present the methodology and data behind the photometric redshift data base of the Sloan Digital Sky Survey (SDSS) Data Release 12. We adopt a hybrid technique, empirically estimating the redshift via local regression on a spectroscopic training set, then fitting a spectrum template to obtain K-corrections and absolute magnitudes. The SDSS spectroscopic catalogue was augmented with data from other, publicly available spectroscopic surveys to mitigate target selection effects. The training set is comprised of 1976 978 galaxies, and extends up to redshift z ≈ 0.8, with a useful coverage of up to z ≈ 0.6. We provide photometric redshifts and realistic error estimates for the 208 474 076 galaxies of the SDSS primary photometric catalogue. We achieve an average bias of overline{Δ z_{norm}} = {5.84 × 10^{-5}}, a standard deviation of σ(Δznorm) = 0.0205, and a 3σ outlier rate of Po = 4.11 per cent when cross-validating on our training set. The published redshift error estimates and photometric error classes enable the selection of galaxies with high-quality photometric redshifts. We also provide a supplementary error map that allows additional, sophisticated filtering of the data.

  4. Tuning target selection algorithms to improve galaxy redshift estimates

    NASA Astrophysics Data System (ADS)

    Hoyle, Ben; Paech, Kerstin; Rau, Markus Michael; Seitz, Stella; Weller, Jochen

    2016-06-01

    We showcase machine learning (ML) inspired target selection algorithms to determine which of all potential targets should be selected first for spectroscopic follow-up. Efficient target selection can improve the ML redshift uncertainties as calculated on an independent sample, while requiring less targets to be observed. We compare seven different ML targeting algorithms with the Sloan Digital Sky Survey (SDSS) target order, and with a random targeting algorithm. The ML inspired algorithms are constructed iteratively by estimating which of the remaining target galaxies will be most difficult for the ML methods to accurately estimate redshifts using the previously observed data. This is performed by predicting the expected redshift error and redshift offset (or bias) of all of the remaining target galaxies. We find that the predicted values of bias and error are accurate to better than 10-30 per cent of the true values, even with only limited training sample sizes. We construct a hypothetical follow-up survey and find that some of the ML targeting algorithms are able to obtain the same redshift predictive power with 2-3 times less observing time, as compared to that of the SDSS, or random, target selection algorithms. The reduction in the required follow-up resources could allow for a change to the follow-up strategy, for example by obtaining deeper spectroscopy, which could improve ML redshift estimates for deeper test data.

  5. Photometric redshifts for the SDSS Data Release 12

    NASA Astrophysics Data System (ADS)

    Beck, Róbert; Dobos, László; Budavári, Tamás; Szalay, Alexander S.; Csabai, István

    2016-04-01

    We present the methodology and data behind the photometric redshift database of the Sloan Digital Sky Survey Data Release 12 (SDSS DR12). We adopt a hybrid technique, empirically estimating the redshift via local regression on a spectroscopic training set, then fitting a spectrum template to obtain K-corrections and absolute magnitudes. The SDSS spectroscopic catalog was augmented with data from other, publicly available spectroscopic surveys to mitigate target selection effects. The training set is comprised of 1, 976, 978 galaxies, and extends up to redshift z ≈ 0.8, with a useful coverage of up to z ≈ 0.6. We provide photometric redshifts and realistic error estimates for the 208, 474, 076 galaxies of the SDSS primary photometric catalog. We achieve an average bias of overline{Δ z_{norm}} = 5.84 × 10^{-5}, a standard deviation of σ(Δznorm) = 0.0205, and a 3σ outlier rate of Po = 4.11% when cross-validating on our training set. The published redshift error estimates and photometric error classes enable the selection of galaxies with high quality photometric redshifts. We also provide a supplementary error map that allows additional, sophisticated filtering of the data.

  6. Final report of the radiological release survey of Building 11 at the Grand Junction Office Facility

    SciTech Connect

    Johnson, R.K.; Corle, S.G.

    1997-09-01

    The U.S. Department of Energy (DOE) Grand Junction Office (GJO) occupies a 61.7-acre facility along the Gunnison River near Grand Junction, Colorado. This site was contaminated with uranium ore concentrates and mill tailings during vanadium refining activities of the Manhattan Engineer District, and during sampling, assaying, pilot milling, storage, and brokerage activities conducted for the U.S. Atomic Energy Commission`s domestic uranium procurement program. The DOE Defense Decontamination and Decommissioning Program established the GJO Remedial Action Project (GJORAP) to clean up and restore the facility lands, improvements, and underlying aquifer. WASTREN-Grand Junction is the site contractor for the facility and the remedial action contractor for GJORAP. Building 11 and the underlying soil were found not to be radiologically contaminated; therefore, the building can be released for unrestricted use. Placards have been placed at the building entrances indicating the completion of the radiological release survey and prohibiting the introduction of any radioactive materials within the building without written approvals from the GJO Facilities Operations Manager. This document was prepared in response to a DOE-GJO request for an individual final release report for each GJO building.

  7. New Mexico cloud super cooled liquid water survey final report 2009.

    SciTech Connect

    Beavis, Nick; Roskovensky, John K.; Ivey, Mark D.

    2010-02-01

    Los Alamos and Sandia National Laboratories are partners in an effort to survey the super-cooled liquid water in clouds over the state of New Mexico in a project sponsored by the New Mexico Small Business Assistance Program. This report summarizes the scientific work performed at Sandia National Laboratories during the 2009. In this second year of the project a practical methodology for estimating cloud super-cooled liquid water was created. This was accomplished through the analysis of certain MODIS sensor satellite derived cloud products and vetted parameterizations techniques. A software code was developed to analyze multiple cases automatically. The eighty-one storm events identified in the previous year effort from 2006-2007 were again the focus. Six derived MODIS products were obtained first through careful MODIS image evaluation. Both cloud and clear-sky properties from this dataset were determined over New Mexico. Sensitivity studies were performed that identified the parameters which most influenced the estimation of cloud super-cooled liquid water. Limited validation was undertaken to ensure the soundness of the cloud super-cooled estimates. Finally, a path forward was formulized to insure the successful completion of the initial scientific goals which include analyzing different of annual datasets, validation of the developed algorithm, and the creation of a user-friendly and interactive tool for estimating cloud super-cooled liquid water.

  8. Dust survey following the final shutdown of TEXTOR: metal particles and fuel retention

    NASA Astrophysics Data System (ADS)

    Fortuna-Zaleśna, E.; Weckmann, A.; Grzonka, J.; Rubel, M.; Esser, H. G.; Freisinger, M.; Kreter, A.; Sergienko, G.; Ström, P.

    2016-02-01

    The work presents results of a broad TEXTOR dust survey in terms of its composition, structure, distribution and fuel content. The dust particles were collected after final shutdown of TEXTOR in December 2013. Fuel retention, as determined by thermal desorption, varied significantly, even by two orders of magnitude, dependent on the dust location in the machine. Dust structure was examined by means of scanning electron microscopy combined with energy-dispersive x-ray spectroscopy, focused ion beam and scanning transmission electron microscopy. Several categories of dust have been identified. Carbon-based stratified and granular deposits were dominating, but the emphasis in studies was on metal dust. They were found in the form of small particles, small spheres, flakes and splashes which formed ‘comet’-like structures, clearly indicating directional effects in the impact on surfaces of plasma-facing components. Nickel-rich alloys from the Inconel liner and iron-based ones from various diagnostic holders were the main components of metal-containing dust, but also molybdenum and tungsten debris were detected. Their origin is discussed.

  9. OzDES multifibre spectroscopy for the Dark Energy Survey: first-year operation and results

    NASA Astrophysics Data System (ADS)

    Yuan, Fang; Lidman, C.; Davis, T. M.; Childress, M.; Abdalla, F. B.; Banerji, M.; Buckley-Geer, E.; Carnero Rosell, A.; Carollo, D.; Castander, F. J.; D'Andrea, C. B.; Diehl, H. T.; Cunha, C. E.; Foley, R. J.; Frieman, J.; Glazebrook, K.; Gschwend, J.; Hinton, S.; Jouvel, S.; Kessler, R.; Kim, A. G.; King, A. L.; Kuehn, K.; Kuhlmann, S.; Lewis, G. F.; Lin, H.; Martini, P.; McMahon, R. G.; Mould, J.; Nichol, R. C.; Norris, R. P.; O'Neill, C. R.; Ostrovski, F.; Papadopoulos, A.; Parkinson, D.; Reed, S.; Romer, A. K.; Rooney, P. J.; Rozo, E.; Rykoff, E. S.; Sako, M.; Scalzo, R.; Schmidt, B. P.; Scolnic, D.; Seymour, N.; Sharp, R.; Sobreira, F.; Sullivan, M.; Thomas, R. C.; Tucker, D.; Uddin, S. A.; Wechsler, R. H.; Wester, W.; Wilcox, H.; Zhang, B.; Abbott, T.; Allam, S.; Bauer, A. H.; Benoit-Lévy, A.; Bertin, E.; Brooks, D.; Burke, D. L.; Carrasco Kind, M.; Covarrubias, R.; Crocce, M.; da Costa, L. N.; DePoy, D. L.; Desai, S.; Doel, P.; Eifler, T. F.; Evrard, A. E.; Fausti Neto, A.; Flaugher, B.; Fosalba, P.; Gaztanaga, E.; Gerdes, D.; Gruen, D.; Gruendl, R. A.; Honscheid, K.; James, D.; Kuropatkin, N.; Lahav, O.; Li, T. S.; Maia, M. A. G.; Makler, M.; Marshall, J.; Miller, C. J.; Miquel, R.; Ogando, R.; Plazas, A. A.; Roodman, A.; Sanchez, E.; Scarpine, V.; Schubnell, M.; Sevilla-Noarbe, I.; Smith, R. C.; Soares-Santos, M.; Suchyta, E.; Swanson, M. E. C.; Tarle, G.; Thaler, J.; Walker, A. R.

    2015-09-01

    The Australian Dark Energy Survey (OzDES) is a five-year, 100-night, spectroscopic survey on the Anglo-Australian Telescope, whose primary aim is to measure redshifts of approximately 2500 Type Ia supernovae host galaxies over the redshift range 0.1 < z < 1.2, and derive reverberation-mapped black hole masses for approximately 500 active galactic nuclei and quasars over 0.3 < z < 4.5. This treasure trove of data forms a major part of the spectroscopic follow-up for the Dark Energy Survey for which we are also targeting cluster galaxies, radio galaxies, strong lenses, and unidentified transients, as well as measuring luminous red galaxies and emission line galaxies to help calibrate photometric redshifts. Here, we present an overview of the OzDES programme and our first-year results. Between 2012 December and 2013 December, we observed over 10 000 objects and measured more than 6 000 redshifts. Our strategy of retargeting faint objects across many observing runs has allowed us to measure redshifts for galaxies as faint as mr = 25 mag. We outline our target selection and observing strategy, quantify the redshift success rate for different types of targets, and discuss the implications for our main science goals. Finally, we highlight a few interesting objects as examples of the fortuitous yet not totally unexpected discoveries that can come from such a large spectroscopic survey.

  10. Sky Mining - Application to Photomorphic Redshift Estimation

    NASA Astrophysics Data System (ADS)

    Nayak, Pragyansmita

    The field of astronomy has evolved from the ancient craft of observing the sky. In it's present form, astronomers explore the cosmos not just by observing through the tiny visible window used by our eyes, but also by exploiting the electromagnetic spectrum from radio waves to gamma rays. The domain is undoubtedly at the forefront of data-driven science. The data growth rate is expected to be around 50%--100% per year. This data explosion is attributed largely to the large-scale wide and deep surveys of the different regions of the sky at multiple wavelengths (both ground and space-based surveys). This dissertation describes the application of machine learning methods to the estimation of galaxy redshifts leveraging such a survey data. Galaxy is a large system of stars held together by mutual gravitation and isolated from similar systems by vast regions of space. Our view of the universe is closely tied to our understanding of galaxy formation. Thus, a better understanding of the relative location of the multitudes of galaxies is crucial. The position of each galaxy can be characterized using three coordinates. Right Ascension (ra) and Declination (dec) are the two coordinates that locate the galaxy in two dimensions on the plane of the sky. It is relatively straightforward to measure them. In contrast, fixing the third coordinate that is the galaxy's distance from the observer along the line of sight (redshift 'z') is considerably more challenging. "Spectroscopic redshift" method gives us accurate and precise measurements of z. However, it is extremely time-intensive and unusable for faint objects. Additionally, the rate at which objects are being identified via photometric surveys far exceeds the rate at which the spectroscopic redshift measurements can keep pace in determining their distance. As the surveys go deeper into the sky, the proportion of faint objects being identified also continues to increase. In order to tackle both these drawbacks increasing in

  11. Probabilistic Photometric Redshifts in the Era of Petascale Astronomy

    SciTech Connect

    Carrasco Kind, Matias

    2014-01-01

    With the growth of large photometric surveys, accurately estimating photometric redshifts, preferably as a probability density function (PDF), and fully understanding the implicit systematic uncertainties in this process has become increasingly important. These surveys are expected to obtain images of billions of distinct galaxies. As a result, storing and analyzing all of these photometric redshift PDFs will be non-trivial, and this challenge becomes even more severe if a survey plans to compute and store multiple different PDFs. In this thesis, we have developed an end-to-end framework that will compute accurate and robust photometric redshift PDFs for massive data sets by using two new, state-of-the-art machine learning techniques that are based on a random forest and a random atlas, respectively. By using data from several photometric surveys, we demonstrate the applicability of these new techniques, and we demonstrate that our new approach is among the best techniques currently available. We also show how different techniques can be combined by using novel Bayesian techniques to improve the photometric redshift precision to unprecedented levels while also presenting new approaches to better identify outliers. In addition, our framework provides supplementary information regarding the data being analyzed, including unbiased estimates of the accuracy of the technique without resorting to a validation data set, identification of poor photometric redshift areas within the parameter space occupied by the spectroscopic training data, and a quantification of the relative importance of the variables used during the estimation process. Furthermore, we present a new approach to represent and store photometric redshift PDFs by using a sparse representation with outstanding compression and reconstruction capabilities. We also demonstrate how this framework can also be directly incorporated into cosmological analyses. The new techniques presented in this thesis are crucial

  12. Filling in the 2MASX Redshift Zone of Avoidance

    NASA Astrophysics Data System (ADS)

    Kraan-Korteweg, Renee; Staveley-Smith, Lister; Jarrett, Thomas; Schroeder, Anja; Henning, Trish; van Driel, Wim; Said, Khaled

    2014-04-01

    Despite nearly 20 years of concerted effort, the dynamics of the local Universe remain poorly understood. This in part is due to the lack of data in the Zone of Avoidance (ZOA). The current most homogeneous "all-sky'' redshift survey is the 2MASX Redshift Survey (2MRS). However, 2MASX galaxies in the ZOA were excluded from the Redshift follow-up Survey. To fill in the 2MASX redshift gap and map the hidden large-scale structures we started a systematic HI redshift follow-up programme of the brightest 2MASX galaxies, i.e. complement the 2MRS and the 2MASX Tully-Fisher survey (2MTF). A thousand galaxies without previous redshift measurement and Dec > -38 deg have been observed with the Nancay Radio Telescope (NRT). For the remaining southern ZOA we started using the Parkes Radio Telescope. 121 hours of observing time were allocated in the previous semesters (2012OCTS and 2013OCTS/P831). The TAC rating for our previous semester 2013OCT/P831 was 4.1 and they suggest to resubmit for the remainder of the remaining time in 2014APR, with the expectation those observations will be scheduled at the beginning of April. To complete the survey, a further 94 hours with the Parkes MultiBeam System are needed. With the here proposed observations, the ZoA will have systematic coverage from the northern to southern end, providing a unique TF data set to map the important flow fields that cross the ZOA, including the Great Attractor (GA), Perseus-Pisces(PP), Puppis, and the Local Void (LV).

  13. Final Report - Independent Confirmatory Survey Summary and Results for the Hematite Decommissioning Project

    SciTech Connect

    E.N. Bailey

    2009-03-18

    The objectives of the confirmatory surveys were to provide independent contractor field data reviews and to generate independent radiological data for use by the NRC in evaluating the adequacy and accuracy of the licensee’s procedures and survey results.

  14. Dust Emission from High-Redshift QSOs.

    PubMed

    Carilli; Bertoldi; Menten; Rupen; Kreysa; Fan; Strauss; Schneider; Bertarini; Yun; Zylka

    2000-04-10

    We present detections of emission at 250 GHz (1.2 mm) from two high-redshift QSOs from the Sloan Digital Sky Survey sample using the bolometer array at the IRAM 30 m telescope. The sources are SDSSp 015048.83+004126.2 at z=3.7 and SDSSp J033829.31+002156.3 at z=5.0; the latter is the third highest redshift QSO known and the highest redshift millimeter-emitting source yet identified. We also present deep radio continuum imaging of these two sources at 1.4 GHz using the Very Large Array. The combination of centimeter and millimeter observations indicate that the 250 GHz emission is most likely thermal dust emission, with implied dust masses approximately 108 M middle dot in circle. We consider possible dust heating mechanisms, including UV emission from the active galactic nucleus (AGN) and a massive starburst concurrent with the AGN, with implied star formation rates greater than 103 M middle dot in circle yr-1. PMID:10727380

  15. Relativistic redshifts in quasar broad lines

    SciTech Connect

    Tremaine, Scott; Shen, Yue; Liu, Xin; Loeb, Abraham E-mail: yshen@obs.carnegiescience.edu E-mail: aloeb@cfa.harvard.edu

    2014-10-10

    The broad emission lines commonly seen in quasar spectra have velocity widths of a few percent of the speed of light, so special- and general-relativistic effects have a significant influence on the line profile. We have determined the redshift of the broad Hβ line in the quasar rest frame (determined from the core component of the [O III] line) for over 20,000 quasars from the Sloan Digital Sky Survey Data Release 7 quasar catalog. The mean redshift as a function of line width is approximately consistent with the relativistic redshift that is expected if the line originates in a randomly oriented Keplerian disk that is obscured when the inclination of the disk to the line of sight exceeds ∼30°-45°, consistent with simple active galactic nucleus unification schemes. This result also implies that the net line-of-sight inflow/outflow velocities in the broad-line region are much less than the Keplerian velocity when averaged over a large sample of quasars with a given line width.

  16. American College Freshman; 1984 Survey; Final Merged File [machine-readable data file].

    ERIC Educational Resources Information Center

    California Univ., Los Angeles. Higher Education Research Inst.

    The Cooperative Institutional Research Program (CIRP) is a continuing longitudinal study of the American higher educational system. CIRP annually conducts a survey of students entering college as first-time, full-time freshmen. The freshman surveys began in 1966; the 1984 survey is the nineteenth in the series. All institutions responding to the…

  17. Phase 1 Final status survey plan for the West Valley demonstration project.

    SciTech Connect

    Johnson, R. L.

    2011-05-31

    This plan provides the technical basis and associated protocols to support Phase 1 final status survey (FSS) data collection and interpretation as part of the West Valley Demonstration Project Phase 1 Decommissioning Plan process. This plan is consistent with the Multi-Agency Radiation Survey and Site Investigation Manual (MARSSIM). The Phase 1 Decommissioning Plan provides the relevant derived concentration guideline levels (DCGLs) for the Phase 1 radionuclides of interest. This plan includes protocols that will be applied to the deep excavations planned for Waste Management Area (WMA) 1 and WMA 2, for surface soils outside the WMA 1 and WMA 2 excavations that do not have contamination impacts at depths greater than one meter, and for areas that are used for Phase 1 contaminated soil lay-down purposes. All excavated and lay-down areas will be classified as MARSSIM Class 1 areas. Surface soils that have not been excavated, are not expected to exceed DCGLs, and do not have contamination impacts at depths greater than one meter will be divided into either Class 1 or Class 2 areas depending on the expected potential for surface soil contamination in those areas. The plan uses gamma scans combined with biased soil samples to address DCGLemc concerns. The plan uses systematic soil sampling combined with area factors to address DCGLw and DCGLemc concerns. The Sign test will be used to statistically evaluate DCGLw compliance. If the results from the characterization sampling and analysis plan (CSAP) data collection indicate that background may be a significant issue for Sign test implementation, the Wilcoxon rank sum (WRS) test will be used instead to demonstrate DCGLw compliance. A reference area will be selected on the basis of CSAP data results if the WRS test becomes a necessity. The WMA 1 excavation footprint includes approximately 476 foundation pilings that will be trimmed and left in place. Piling-specific systematic and biased sampling will be conducted to

  18. Energy savings opportunity survey, Energy Engineering Analysis Program (EEAP), Fort Campbell, Kentucky, final report - phase I. Executive summary. Final report

    SciTech Connect

    1993-11-12

    Systems Corp surveyed and completed energy analyses for 98 buildings, fifteen chiller plants, and roadway lighting. The energy conservation opportunities (ECOs) evaluated were lighting efficiency improvements, instantaneous water heaters, heat recovery from hot refrigerant gases, absorption chiller replacements, and ground water coupled heat pumps. Cost estimates were prepared using M-CACES. Life cycle cost analyses were performed using the Life Cycle Cost in Design (LCCID) computer program. Project development brochures (PDBs) and DD1391 forms were prepared for Energy Conservation Investment Program (ECIP) projects. The projects that were developed represent $2,257,000 in annual savings with favorable simple paybacks and saving to investment ratios (SIRs).

  19. Maine State Planning Office, 1990--1991 heating season home heating fuels price survey. Final report

    SciTech Connect

    Not Available

    1991-12-31

    The 1990--1991 heating season was the first time in Maine that the Home Heating Fuels Survey was conducted for the United States Department of Energy by the Maine State Planning Office. This season also marked the first time that dealers were surveyed for a price for propane. Under a late agreement, the State of Maine was picked up by the regional survey of the Energy Information Agency in the beginning of October. This accounted for the weekly survey of the traditional participants in the State`s Home Heating Fuels Price Survey being supplemented by biweekly DOE surveys of separate survey samples of oil and propane dealers. The SPO sample identifies 36 dealers in the State of Maine, while the DOE sample was constructed around 22 oil dealers in Maine and New Hampshire and 29 propane dealers in Maine.

  20. Wastewater characterization survey, Victor Valley Wastewater Reclamation Authority and hazardous-waste survey at George AFB, California. Final report

    SciTech Connect

    Binovi, R.D.; Ng, E.K.; Tetla, R.A.

    1987-01-01

    This is a report of a survey of the Victor Wastewater Reclamation Authority Sewerage system, the sewage treatment plant, and effluent from the various operations at George AFB, California. The scope of work included the characterization of the wastewater from George AFB, as well as characterization of effluents from 29 oil/water separators servicing industrial operations on base, flow measurements at three locations on base, a microbiological evaluation of aeration basin foam, bench-scale activated-sludge studies, and a review of results from previous surveys. Recommendations: (1) AFFF (Aqueous Film Forming Foam) should never be discharged to the sewer. (2) Programming for pretreatment should proceed at selected operations. (3) More waste and wastestream analysis be performed. (4) Upgrade waste accumulation points. (5) Implement an aggressive inspection program for oil/water separators. (6) Cut down on nonessential washing.

  1. Exhausting the information: novel Bayesian combination of photometric redshift PDFs

    NASA Astrophysics Data System (ADS)

    Carrasco Kind, Matias; Brunner, Robert J.

    2014-08-01

    The estimation and utilization of photometric redshift probability density functions (photo-z PDFs) have become increasingly important over the last few years and currently there exist a wide variety of algorithms to compute photo-z's, each with their own strengths and weaknesses. In this paper, we present a novel and efficient Bayesian framework that combines the results from different photo-z techniques into a more powerful and robust estimate by maximizing the information from the photometric data. To demonstrate this, we use a supervised machine learning technique based on random forest, an unsupervised method based on self-organizing maps, and a standard template-fitting method but can be easily extended to other existing techniques. We use data from the DEEP2 survey and the Sloan Digital Sky Survey to explore different methods for combining the predictions from these techniques. By using different performance metrics, we demonstrate that we can improve the accuracy of our final photo-z estimate over the best input technique, that the fraction of outliers is reduced, and that the identification of outliers is significantly improved when we apply a naïve Bayes classifier to this combined information. Our more robust and accurate photo-z PDFs will allow even more precise cosmological constraints to be made by using current and future photometric surveys. These improvements are crucial as we move to analyse photometric data that push to or even past the limits of the available training data, which will be the case with the Large Synoptic Survey Telescope.

  2. Steep radio spectra in high-redshift radio galaxies

    NASA Technical Reports Server (NTRS)

    Krolik, Julian H.; Chen, Wan

    1991-01-01

    The generic spectrum of an optically thin synchrotron source steepens by 0.5 in spectral index from low frequencies to high whenever the source lifetime is greater than the energy-loss timescale for at least some of the radiating electrons. Three effects tend to decrease the frequency nu(b) of this spectral bend as the source redshift increases: (1) for fixed bend frequency nu* in the rest frame, nu(b) = nu*/(1 + z); (2) losses due to inverse Compton scattering the microwave background rise with redshift as (1 + z) exp 4, so that, for fixed residence time in the radiating region, the energy of the lowest energy electron that can cool falls rapidly with increasing redshift; and (3) if the magnetic field is proportional to the equipartition field and the emitting volume is fixed or slowly varying, flux-limited samples induce a selection effect favoring low nu* at high z because higher redshift sources require higher emissivity to be included in the sample, and hence have stronger implied fields and more rapid synchrotron losses. A combination of these effects may explain the trend observed in the 3CR sample for higher redshift radio galaxies to have steeper spectra, and the successful use of ultrasteep spectrum surveys to locate high-redshift galaxies.

  3. Quasar probabilities and redshifts from WISE mid-IR through GALEX UV photometry

    NASA Astrophysics Data System (ADS)

    DiPompeo, M. A.; Bovy, J.; Myers, A. D.; Lang, D.

    2015-09-01

    Extreme deconvolution (XD) of broad-band photometric data can both separate stars from quasars and generate probability density functions for quasar redshifts, while incorporating flux uncertainties and missing data. Mid-infrared photometric colours are now widely used to identify hot dust intrinsic to quasars, and the release of all-sky WISE data has led to a dramatic increase in the number of IR-selected quasars. Using forced photometry on public WISE data at the locations of Sloan Digital Sky Survey (SDSS) point sources, we incorporate this all-sky data into the training of the XDQSOz models originally developed to select quasars from optical photometry. The combination of WISE and SDSS information is far more powerful than SDSS alone, particularly at z > 2. The use of SDSS+WISE photometry is comparable to the use of SDSS+ultraviolet+near-IR data. We release a new public catalogue of 5537 436 (total; 3874 639 weighted by probability) potential quasars with probability PQSO > 0.2. The catalogue includes redshift probabilities for all objects. We also release an updated version of the publicly available set of codes to calculate quasar and redshift probabilities for various combinations of data. Finally, we demonstrate that this method of selecting quasars using WISE data is both more complete and efficient than simple WISE colour-cuts, especially at high redshift. Our fits verify that above z ˜ 3 WISE colours become bluer than the standard cuts applied to select quasars. Currently, the analysis is limited to quasars with optical counterparts, and thus cannot be used to find highly obscured quasars that WISE colour-cuts identify in significant numbers.

  4. Redshift Distributions of Galaxies in the DES Science Verification Shear Catalogue and Implications for Weak Lensing

    SciTech Connect

    Bonnett, C.

    2015-07-21

    We present photometric redshift estimates for galaxies used in the weak lensing analysis of the Dark Energy Survey Science Verification (DES SV) data. Four model- or machine learning-based photometric redshift methods { annz2, bpz calibrated against BCC-U fig simulations, skynet, and tpz { are analysed. For training, calibration, and testing of these methods, we also construct a catalogue of spectroscopically confirmed galaxies matched against DES SV data. The performance of the methods is evalu-ated against the matched spectroscopic catalogue, focusing on metrics relevant for weak lensing analyses, with additional validation against COSMOS photo-zs. From the galaxies in the DES SV shear catalogue, which have mean redshift 0.72 ±0.01 over the range 0:3 < z < 1:3, we construct three tomographic bins with means of z = {0.45; 0.67,1.00g}. These bins each have systematic uncertainties δz ≲ 0.05 in the mean of the fiducial skynet photo-z n(z). We propagate the errors in the redshift distributions through to their impact on cosmological parameters estimated with cosmic shear, and find that they cause shifts in the value of σ8 of approx. 3%. This shift is within the one sigma statistical errors on σ8 for the DES SV shear catalog. We also found that further study of the potential impact of systematic differences on the critical surface density, Σcrit, contained levels of bias safely less than the statistical power of DES SV data. We recommend a final Gaussian prior for the photo-z bias in the mean of n(z) of width 0:05 for each of the three tomographic bins, and show that this is a sufficient bias model for the corresponding cosmology analysis.

  5. Survey of Postdoctorates at FFRDCs: Final Report [Federally Funded Research and Development Centers

    SciTech Connect

    Mulrow, Jeri

    2010-06-30

    The 2009 FFRDC survey collected the total number of postdocs employed by FFRDCs in the United States—categorized by source of support, citizenship, sex, and field of research—as of October 1, 2009. The universe for the 2009 GSS-FFRDC survey was the Master Government List of Federally Funded Research and Development Centers. The 2009 survey also contacted the NIH’s Intramural Research Program because it employs the largest number of postdocs in the federal government. The FFRDC survey collected data via a web instrument. Topics included the type of support the postdocs received (federal and nonfederal), their sex, citizenship, race/ethnicity, and field of research.

  6. High redshift QSOs and the x ray background

    NASA Technical Reports Server (NTRS)

    Impey, Chris

    1993-01-01

    ROSAT pointed observations were made of 9 QSO's from the Large Bright Quasar Survey (LBQS). The LBQS is based on machine measurement of objective prism plates taken with the UK Schmidt Telescope. Software has been used to select QSO's by both color and by the presence of spectral features and continuum breaks. The probability of detection can be calculated as a function of magnitude, redshift and spectral features, and the completeness of the survey can be accurately estimated. Nine out of 1040 QSO's in the LBQS have z greater than 3. The observations will provide an important data point in the X-ray luminosity function of QSO's at high redshift. The QSO's with z greater than 3 span less than a magnitude in M(sub B), so can be combined as a homogeneous sample. This analysis is only possible with a sample drawn from a large and complete catalog such as the LBQS. Four of the 9 QSO's that were observed with the ROSAT PSPC for this proposal were detected, including one of the most luminous X-ray sources ever observed. The April 1992 version of the PROS DETECT package was used to reduce the data. The results have been used to search for evolution of the X-ray properties of QSO's in redshift. The 9 QSO's lie in the range -28.7 less than M(sub B) less than -27.8. When combined with data for 16 QSO's in a similar luminosity range at lower redshift correlations with luminosity and redshift can be separated out. The LBQS sample also yields a new constraint on the contribution of high redshift QSO's to the X-ray background. An initial requirement is knowledge of the X-ray properties (alpha(sub OX)) as a function of redshift. Integration over the evolving luminosity function of the LBQS then gives the QSO contribution to the source counts.

  7. A sparse Gaussian process framework for photometric redshift estimation

    NASA Astrophysics Data System (ADS)

    Almosallam, Ibrahim A.; Lindsay, Sam N.; Jarvis, Matt J.; Roberts, Stephen J.

    2016-01-01

    Accurate photometric redshifts are a lynchpin for many future experiments to pin down the cosmological model and for studies of galaxy evolution. In this study, a novel sparse regression framework for photometric redshift estimation is presented. Synthetic data set simulating the Euclid survey and real data from SDSS DR12 are used to train and test the proposed models. We show that approaches which include careful data preparation and model design offer a significant improvement in comparison with several competing machine learning algorithms. Standard implementations of most regression algorithms use the minimization of the sum of squared errors as the objective function. For redshift inference, this induces a bias in the posterior mean of the output distribution, which can be problematic. In this paper, we directly minimize the target metric Δz = (zs - zp)/(1 + zs) and address the bias problem via a distribution-based weighting scheme, incorporated as part of the optimization objective. The results are compared with other machine learning algorithms in the field such as artificial neural networks (ANN), Gaussian processes (GPs) and sparse GPs. The proposed framework reaches a mean absolute Δz = 0.0026(1 + zs), over the redshift range of 0 ≤ zs ≤ 2 on the simulated data, and Δz = 0.0178(1 + zs) over the entire redshift range on the SDSS DR12 survey, outperforming the standard ANNz used in the literature. We also investigate how the relative size of the training sample affects the photometric redshift accuracy. We find that a training sample of >30 per cent of total sample size, provides little additional constraint on the photometric redshifts, and note that our GP formalism strongly outperforms ANNz in the sparse data regime for the simulated data set.

  8. Very high redshift radio galaxies

    SciTech Connect

    van Breugel, W.J.M., LLNL

    1997-12-01

    High redshift radio galaxies (HzRGs) provide unique targets for the study of the formation and evolution of massive galaxies and galaxy clusters at very high redshifts. We discuss how efficient HzRG samples ae selected, the evidence for strong morphological evolution at near-infracd wavelengths, and for jet-induced star formation in the z = 3 800 HzRG 4C41 17

  9. PHOTOMETRIC REDSHIFTS OF SUBMILLIMETER GALAXIES

    SciTech Connect

    Chakrabarti, Sukanya; Magnelli, Benjamin; Lutz, Dieter; Berta, Stefano; Popesso, Paola; McKee, Christopher F.; Pozzi, Francesca

    2013-08-20

    We use the photometric redshift method of Chakrabarti and McKee to infer photometric redshifts of submillimeter galaxies with far-IR (FIR) Herschel data obtained as part of the PACS Evolutionary Probe program. For the sample with spectroscopic redshifts, we demonstrate the validity of this method over a large range of redshifts (4 {approx}> z {approx}> 0.3) and luminosities, finding an average accuracy in (1 + z{sub phot})/(1 + z{sub spec}) of 10%. Thus, this method is more accurate than other FIR photometric redshift methods. This method is different from typical FIR photometric methods in deriving redshifts from the light-to-gas mass (L/M) ratio of infrared-bright galaxies inferred from the FIR spectral energy distribution, rather than dust temperatures. To assess the dependence of our photometric redshift method on the data in this sample, we contrast the average accuracy of our method when we use PACS data, versus SPIRE data, versus both PACS and SPIRE data. We also discuss potential selection effects that may affect the Herschel sample. Once the redshift is derived, we can determine physical properties of infrared-bright galaxies, including the temperature variation within the dust envelope, luminosity, mass, and surface density. We use data from the GOODS-S field to calculate the star formation rate density (SFRD) of submillimeter bright sources detected by AzTEC and PACS. The AzTEC-PACS sources, which have a threshold 850 {mu}m flux {approx}> 5 mJy, contribute 15% of the SFRD from all ultraluminous infrared galaxies (L{sub IR} {approx}> 10{sup 12} L{sub Sun }), and 3% of the total SFRD at z {approx} 2.

  10. Finding high-redshift voids using Lyman α forest tomography

    NASA Astrophysics Data System (ADS)

    Stark, Casey W.; Font-Ribera, Andreu; White, Martin; Lee, Khee-Gan

    2015-11-01

    We present a new method of finding cosmic voids using tomographic maps of Lyα forest flux. We identify cosmological voids with radii of 2-12 h-1 Mpc in a large N-body simulation at z = 2.5, and characterize the signal of the high-redshift voids in density and Lyα forest flux. The void properties are similar to what has been found at lower redshifts, but they are smaller and have steeper radial density profiles. Similarly to what has been found for low-redshift voids, the radial velocity profiles have little scatter and agree very well with the linear theory prediction. We run the same void finder on an ideal Lyα flux field and tomographic reconstructions at various spatial samplings. We compare the tomographic map void catalogues to the density void catalogue and find good agreement even with modest-sized voids (r > 6 h-1 Mpc). Using our simple void-finding method, the configuration of the ongoing COSMOS Lyman Alpha Mapping And Tomography Observations (CLAMATO) survey covering 1 deg2 would provide a sample of about 100 high-redshift voids. We also provide void-finding forecasts for larger area surveys, and discuss how these void samples can be used to test modified gravity models, study high-redshift void galaxies, and to make an Alcock-Paczynski measurement. To aid future work in this area, we provide public access to our simulation products, catalogues, and sample tomographic flux maps.

  11. Redshift distortions of clustering: a Lagrangian approach.

    NASA Astrophysics Data System (ADS)

    Hivon, E.; Bouchet, F. R.; Colombi, S.; Juszkiewicz, R.

    1995-06-01

    We study the effects of peculiar velocities on statistical measures of galaxy clustering. These effects occur when distances to the galaxies are estimated from their redshifts. It is assumed that the clustering pattern results from the gravitational instability of initially Gaussian, small-amplitude perturbations of a Friedman-Lemaitre cosmological model. Explicit expressions are given for an arbitrary density parameter {OMEGA} of the model, both when the cosmological constant, {LAMBDA}, is zero, and when the model is spatially flat, {OMEGA}+ {LAMBDA}/3H^2^ =1. Kaiser (1987) had analyzed the redshift distortion of the two-point correlation function. This function determines the variance of the density field distribution function and can be computed using linear perturbation theory. We show here how to compute higher order moments in redshift space, paying special attention to the skewness, or third moment of the density field, and its Fourier space counterpart, the bispectrum. This calls for a weakly non-linear analysis. We rely on a perturbative expansion of particle trajectories in Lagrangian coordinates, using the formalism introduced by Moutarde et al. (1991) and further developed by Bouchet et al. (1992, 1994). This formalism extends to higher orders the Zel'dovich first order (i.e. linear) solution (1970). The lowest non-vanishing contribution to the skewness comes from the first and second-order terms in perturbation theory. Therefore, using Zel'dovich approximation would not be self-consistent and would yield inaccurate results. We show that a physically consistent and quantitatively accurate analysis of the growth skewness in redshift space can be obtained from second-order Lagrangian theory. With practical applications to redshift surveys in mind, we also study the effects of spatial smoothing of the evolved density field. The necessary formalism was developed by Juszkiewicz & Bouchet (1991) and Juszkiewicz et al. (1993a). Here we give the first complete

  12. Redshifts distribution in A262

    NASA Astrophysics Data System (ADS)

    Hassan, M. S. R.; Abidin, Z. Z.; Ibrahim, U. F. S. U.; Hashim, N.; Lee, D. A. A.

    2016-05-01

    Galaxy clusters are the largest virialized systems in the Universe containing a collection of galaxies of different redshifts. The redshift distribution of galaxies in galaxy clusters is concentrated at a certain redshift range which remarkably tells us that only the galaxies in a certain radial range belong to the galaxy cluster. This leads to a boundary estimation of the cluster. Background and foreground systems are represented by a histogram that determines whether some of the galaxies are too far or too high in redshift to be counted as the member of the cluster. With the recent advances in multifibre spectroscopy, it has become possible to perform detailed analysis of the redshift distribution of several galaxy clusters in the Abell Catalogue. This has given rise to significantly improved estimates of cluster membership, extent and dynamical history. Here we present a spectroscopic analysis of the galaxy cluster A262. We find 55 galaxies fall within z = 0.0143 and 0.0183 with velocity range 4450-5300 km s-1, and are therefore members of the cluster. We derived a new mean redshift of z = 0.016 173 ± 0.000 074 (4852 ± 22 km s-1) for the system of which we compare with our neutral hydrogen (H I) detection which peaks at 4970 ± 0.5 km s-1. It is found that the distribution of H I tends to be located at the edge of the cluster since most of spiral rich galaxies were away from cluster centre.

  13. A Survey of Viewership of Television Series Sponsored by ESAA Legislation. Final Report.

    ERIC Educational Resources Information Center

    Hebbeler, Kathleen; Cosgrove, Michael

    Results are presented of a national survey of in-school students, teachers, and principals to determine the viewership and availability of 11 television series which have been produced and distributed through funding provided by the Emergency School Aid Act (ESAA) to reduce cultural isolation among minority group members. In-home surveys were also…

  14. Survey of Speech-Language Pathology Services in School-Based Settings National Study Final Report.

    ERIC Educational Resources Information Center

    Peters-Johnson, Cassandra

    1998-01-01

    This paper reports on a survey of 1,718 school-based speech language pathologists in 1995. Survey questions addressed such topics as caseload characteristics, service delivery, bilingual/bicultural services, supervision, support personnel, shortages of speech-language pathologists, substitutes, and demographic characteristics, and activities. (DB)

  15. Survey of Foreign Language Course Registrations and Student Contact Hours in Final Report.

    ERIC Educational Resources Information Center

    Brod, Richard I.

    This report is based on a questionnaire survey sent to the registrars of all two-year and four-year colleges and universities in the United States. Replies were received from 2,494 institutions, of which 2,313 reported registrations in one or more foreign languages. The fall 1974 survey shows a decline of 6.2% in total foreign language…

  16. Final Report Bald and Golden Eagle Territory Surveys for the Lawrence Livermore National Laboratory

    SciTech Connect

    Fratanduono, M. L.

    2014-11-25

    Garcia and Associates (GANDA) was contracted by the Lawrence Livermore National Laboratory (LLNL) to conduct surveys for bald eagles (Haliaeetus leucocephalus) and golden eagles (Aquila chrysaetos) at Site 300 and in the surrounding area out to 10-miles. The survey effort was intended to document the boundaries of eagle territories by careful observation of eagle behavior from selected viewing locations throughout the study area.

  17. Initiation Rites in American High Schools: A National Survey. Final Report.

    ERIC Educational Resources Information Center

    Hoover, Nadine C.; Pollard, Norman J.

    Noting that high school students are just learning to distinguish between appropriate and inappropriate behavior and that without healthy adult supervision, initiation rites may become hazing incidents, this study surveyed students' experiences with hazing and initiation activities. Participating in the survey were 1,541 students from a random…

  18. Final Report on the Mississippi Project CLEAR Voice Teacher Working Conditions Survey

    ERIC Educational Resources Information Center

    Berry, Barnett; Fuller, Ed

    2008-01-01

    In 2007, the state of Mississippi conducted a web-based survey of all school-based licensed educators in which they were asked to share their perceptions of the state of teacher working conditions in Mississippi. This report of the Mississippi Teacher Working Conditions Survey, Project CLEAR Voice (Cultivate Learning Environments to Accelerate…

  19. Manpower Requirements for Scientific and Technical Communication: An Occupational Survey of Information Professionals. Final Report.

    ERIC Educational Resources Information Center

    Debons, Anthony; And Others

    The first phase of a three-phase program, this study determined the functions entailed in information work and identified the number of individuals who exercise these functions in a survey of 1,193 establishments in state and local government, industry, and academia. The survey revealed that there were over 1.64 million information professionals…

  20. Energy Efficiency for Florida Educational Facilities: The 1996 Energy Survey of Florida Schools. Final Report.

    ERIC Educational Resources Information Center

    Callahan, Michael P.; Parker, Danny S.; Dutton, Wanda L.; McIlvaine, Janet E. R.

    Florida has recently completed a survey of energy use and related physical and operational characteristics of the state's public schools. This report presents results from 1,298 surveys received (680 providing matching utility data) revealing that total energy costs for the Florida school system totaled $205 million in 1995. Other data show that…

  1. Final Report: LSAC Skills Analysis. Law School Task Survey. LSAC Research Report Series.

    ERIC Educational Resources Information Center

    Luebke, Stephen W.; Swygert, Kimberly A.; McLeod, Lori D.; Dalessandro, Susan P.; Roussos, Louis A.

    The Law School Admission Council (LSAC) Skills Analysis Survey identifies the skills that are important for success in law school. This information provides validity evidence for the current Law School Admission Test (LSAT) and guides the development of new test items and test specifications. The key question of the survey is "what academic tasks…

  2. Canadian Attitudes toward Labour Market Issues: A Survey of Canadian Opinion. Final Report

    ERIC Educational Resources Information Center

    Human Resources and Social Development Canada, 2008

    2008-01-01

    In 2007, Human Resources and Social Development Canada commissioned Environics Research Group Limited to conduct a public opinion survey on labour market issues among 3,000 adult Canadians. The objective of the public opinion survey was to better understand the perceptions of Canadians regarding labour market challenges and opportunities in order…

  3. SDSS-IV eBOSS emission-line galaxy pilot survey

    NASA Astrophysics Data System (ADS)

    Comparat, J.; Delubac, T.; Jouvel, S.; Raichoor, A.; Kneib, J.-P.; Yèche, C.; Abdalla, F. B.; Le Cras, C.; Maraston, C.; Wilkinson, D. M.; Zhu, G.; Jullo, E.; Prada, F.; Schlegel, D.; Xu, Z.; Zou, H.; Bautista, J.; Bizyaev, D.; Bolton, A.; Brownstein, J. R.; Dawson, K. S.; Escoffier, S.; Gaulme, P.; Kinemuchi, K.; Malanushenko, E.; Malanushenko, V.; Mariappan, V.; Newman, J. A.; Oravetz, D.; Pan, K.; Percival, W. J.; Prakash, A.; Schneider, D. P.; Simmons, A.; Abbott, T. M. C.; Allam, S.; Banerji, M.; Benoit-Lévy, A.; Bertin, E.; Brooks, D.; Capozzi, D.; Carnero Rosell, A.; Carrasco Kind, M.; Carretero, J.; Castander, F. J.; Cunha, C. E.; da Costa, L. N.; Desai, S.; Doel, P.; Eifler, T. F.; Estrada, J.; Flaugher, B.; Fosalba, P.; Frieman, J.; Gaztanaga, E.; Gerdes, D. W.; Gruen, D.; Gruendl, R. A.; Gutierrez, G.; Honscheid, K.; James, D. J.; Kuehn, K.; Kuropatkin, N.; Lahav, O.; Lima, M.; Maia, M. A. G.; March, M.; Marshall, J. L.; Miquel, R.; Plazas, A. A.; Reil, K.; Roe, N.; Romer, A. K.; Roodman, A.; Rykoff, E. S.; Sako, M.; Sanchez, E.; Scarpine, V.; Sevilla-Noarbe, I.; Soares-Santos, M.; Sobreira, F.; Suchyta, E.; Swanson, M. E. C.; Tarle, G.; Thaler, J.; Thomas, D.; Walker, A. R.; Zhang, Y.

    2016-08-01

    The Sloan Digital Sky Survey IV extended Baryonic Oscillation Spectroscopic Survey (SDSS-IV/eBOSS) will observe 195 000 emission-line galaxies (ELGs) to measure the baryonic acoustic oscillation (BAO) standard ruler at redshift 0.9. To test different ELG selection algorithms, 9000 spectra were observed with the SDSS spectrograph as a pilot survey based on data from several imaging surveys. First, using visual inspection and redshift quality flags, we show that the automated spectroscopic redshifts assigned by the pipeline meet the quality requirements for a reliable BAO measurement. We also show the correlations between sky emission, signal-to-noise ratio in the emission lines, and redshift error. Then we provide a detailed description of each target selection algorithm we tested and compare them with the requirements of the eBOSS experiment. As a result, we provide reliable redshift distributions for the different target selection schemes we tested. Finally, we determine an target selection algorithms that is best suited to be applied on DECam photometry because they fulfill the eBOSS survey efficiency requirements. The catalog is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/592/A121

  4. Nevada Test Site Area 25. Radiological survey and cleanup project, 1974-1983. Final report

    SciTech Connect

    McKnight, R.K.; Rosenberry, C.E.; Orcutt, J.A.

    1984-01-01

    This report describes radiological survey, decontamination and decommissioning of the Nevada Test Site (NTS) Area 25 facilities and land areas incorporated in the Nuclear Rocket Development Station (NRDS). Buildings, facilities and support systems used after 1959 for nuclear reactor and engine testing were surveyed for the presence of radioactive contamination. The cleanup was part of the Surplus Facilities Management Program funded by the Department of Energy's Richland Operations Office. The radiological survey portion of the project encompassed portable instrument surveys and removable contamination surveys (swipe) for alpha and beta plus gamma radiation contamination of facilities, equipment and land areas. Soil sampling was also accomplished. The majority of Area 25 facilities and land areas have been returned to unrestricted use. Remaining radiologically contaminated areas are posted with warning signs and barricades. 12 figures.

  5. Prevalence and Associated Factors of Smoking Among Final Year Medical Students: A Multicentric Survey From Pakistan.

    PubMed

    Khubaib, Mohammad U; Shahid, Zuhaib Y; Lodhi, Sameed K; Malik, Hamza; Jan, Mohsin M

    2016-01-01

    Introduction Smoking is the leading cause of lung cancer around the world. In a developing country like Pakistan with low levels of literacy and general awareness about adverse effects of smoking, doctors play a pivotal role in educating the masses about its harmful consequences and providing support for smoking cessation. However, their efficacy is affected if they smoke themselves, and oftentimes the habits cultivated during educational recourse are carried into the professional careers. The aim of this study was to document the prevalence of smoking among final year medical students of Lahore, Pakistan, and the factors associated with it. Methodology Study approval was obtained from Combined Military Hospital (CMH) Lahore Medical College, Ethics Review Committee. A cross-sectional survey was carried out in four medical colleges and hospitals of Lahore, Pakistan. A questionnaire consisting of 14 questions related to basic demographics and smoking was used after being pilot tested on 20 students of CMH. The overall response rate was 74.89%. Data was collected from 337 respondents, of which 38 forms were discarded and 299 forms were analyzed by SPSS V21. Results Among the 299 respondents, there were 128 males (42.81%) and 171 females (57.19%) with 32 (10.70%) smokers. Male students reported smoking (n = 27, 21.09%) more than their female counterparts (n = 5, 0.02%). The mean age of participants was 23.01 years. Students having an active smoker at home had statistically significant positive correlations with current smoking status and the number of cigarettes smoked per day. Students with household smoking contacts were also more likely to smoke if they belonged to the male gender. Conclusion Prevalence of smoking in medical students is lower than in the general population but still considerable in the male students. There is a need to target this particular population with interactive counseling sessions, education campaigns, and anti-smoking rules to decrease

  6. Prevalence and Associated Factors of Smoking Among Final Year Medical Students: A Multicentric Survey From Pakistan

    PubMed Central

    Shahid, Zuhaib Y; Lodhi, Sameed K; Malik, Hamza; Jan, Mohsin M

    2016-01-01

    Introduction Smoking is the leading cause of lung cancer around the world. In a developing country like Pakistan with low levels of literacy and general awareness about adverse effects of smoking, doctors play a pivotal role in educating the masses about its harmful consequences and providing support for smoking cessation. However, their efficacy is affected if they smoke themselves, and oftentimes the habits cultivated during educational recourse are carried into the professional careers. The aim of this study was to document the prevalence of smoking among final year medical students of Lahore, Pakistan, and the factors associated with it. Methodology Study approval was obtained from Combined Military Hospital (CMH) Lahore Medical College, Ethics Review Committee. A cross-sectional survey was carried out in four medical colleges and hospitals of Lahore, Pakistan. A questionnaire consisting of 14 questions related to basic demographics and smoking was used after being pilot tested on 20 students of CMH. The overall response rate was 74.89%. Data was collected from 337 respondents, of which 38 forms were discarded and 299 forms were analyzed by SPSS V21. Results Among the 299 respondents, there were 128 males (42.81%) and 171 females (57.19%) with 32 (10.70%) smokers. Male students reported smoking (n = 27, 21.09%) more than their female counterparts (n = 5, 0.02%). The mean age of participants was 23.01 years. Students having an active smoker at home had statistically significant positive correlations with current smoking status and the number of cigarettes smoked per day. Students with household smoking contacts were also more likely to smoke if they belonged to the male gender. Conclusion Prevalence of smoking in medical students is lower than in the general population but still considerable in the male students. There is a need to target this particular population with interactive counseling sessions, education campaigns, and anti-smoking rules to decrease

  7. Survey of protected terrestrial vertebrates on the Oak Ridge Reservation. Final report

    SciTech Connect

    Mitchell, J.M.; Vail, E.R.; Webb, J.W.; King, A.L.; Hamlett, P.A.

    1996-05-01

    Surveys of protected terrestrial vertebrates on the Oak Ridge Reservation (ORR) were conducted from October 1994 through May 1996. The surveys were undertaken to help avoid or minimize the potential impacts of projects on the ORR to species listed by the state or federal government as endangered, threatened, or in need-of-management; federal species of concern were included. Results of the survey will also assist in effectively managing the ORR. Currently, there are 69 species of federal- or state-listed terrestrial vertebrates (20 reptiles and amphibians, 20 mammals, and 29 birds) that may occur in Tennessee. Listed animal species that might be present on the ORR were targeted for survey using a prioritization system based on historical and recent sightings, known species distributions, presence of suitable habitat, literature reviews, and personal communications. Survey methods included trapping, seining, monitoring artificial covers, active searching, and avian surveys. Surveys were conducted during the time of year when each targeted species was most likely to be encountered. The report also includes ancillary information. Records are provided for nonlisted species (44 species of reptiles and amphibians, 155 species of birds, and 28 species of mammals). Categorization of survey sites into 1 or more of 19 habitat types, which are briefly described, is presented. Notes are summarized on the occurrence of threatened and endangered species on the ORR. The report also lists threatened and endangered species not found that might be located by additional surveys, recommends three survey areas for natural-area status due to wildlife value, and suggests several avenues for future work.

  8. MARSSIM vs. DOE Order 5400.5: the Final Status Survey plan at the Rocky Flats Environmental Technology Site.

    PubMed

    Roberts, Sarah J; Stevens, Jeff

    2003-06-01

    A challenge unique to the decommissioning of Department of Energy (DOE) facilities involves the compromise between the existing and newly recommended standards for the unrestricted release of property and materials. The Rocky Flats Environmental Technology Site (RFETS) is currently decommissioning numerous plutonium contaminated facilities. The default DOE standard for unrestricted release, Order 5400.5, defines surface activity guidelines as averaged over a 1-square-meter area with a maximum value defined for any given 100-square-centimeter area. While the Order was initially developed to release property and materials from an operating site, it is restrictive in its use when performing Final Status Survey and, to date, no new complex wide standard has been developed. However, the RFETS stakeholders selected the MARSSIM, which provides a progressive method to demonstrate compliance with the defined "dose-based" limits for a specific site, as the governing document in developing a final survey method. The end result is a hybrid final status survey plan that incorporates the requirements of both documents. This plan represents several years of development and negotiation between the contractor, the DOE, the Colorado Department of Public Health and Environment, the Rocky Flats stakeholders, and other interested parties. PMID:12792399

  9. Leveraging Spitzer's Legacy: Quasars and Feedback at High Redshift

    NASA Astrophysics Data System (ADS)

    Richards, Gordon; Anderson, Scott; Bauer, Franz; Deo, Rajesh; Fan, Xiaohui; Gallagher, Sarah; Myers, Adam; Strauss, Michael; Zakamska, Nadia

    2009-04-01

    Recent research efforts to understand the evolution of galaxies and quasars are beginning to form a consistent picture. Galaxies and their supermassive black holes grow through mergers, but with decreasing characteristic mass scales over time. Much less, however, is known about the evolution of galaxies at high redshifts and the role played by energy injection from the onset of active black hole growth. Understanding these events requires investigating a statistically significant number of high-redshift quasars and crossing the L* boundary in luminosity. To construct an appropriate data set requires both relatively wide-areas (to find these rare objects) and moderate-depth imaging (to probe below L* in luminosity). Unfortunately, existing optical and MIR surveys fail to meet both of these requirements. Furthermore, both optical and MIR quasar selection are blindest at the most crucial redshifts. Here we propose to address these gaps with targeted IRAC observations of a few hundred high-redshift quasars from the Sloan Digital Sky Survey. Such a sample will enable the construction of a proper training set for the discovery of 2.5redshift quasars in other fields over a large range in luminosity. With this knowledge, we will crack open the high-z quasar discovery space within existing IRAC legacy surveys (SWIRE, XFLS, Bootes, COSMOS). With a large sample of high-redshift quasars spanning a large range in luminosity, we can turn the quasar luminosity function and quasar clustering analysis into tools for distinguishing between different evolutionary models and feedback prescriptions. In all, we will observe 330 SDSS quasars using 307 pointings/AORs, totaling 48.5 hours of IRAC time.

  10. Final report on the radiological surveys of designated DX firing sites at Los Alamos National Laboratory

    SciTech Connect

    1996-09-09

    CHEMRAD was contracted by Los Alamos National Laboratory to perform USRADS{reg_sign} (UltraSonic Ranging And Data System) radiation scanning surveys at designated DX Sites at the Los Alamos National Laboratory. The primary purpose of these scanning surveys was to identify the presence of Depleted Uranium (D-38) resulting from activities at the DX Firing Sites. This effort was conducted to update the most recent surveys of these areas. This current effort was initiated with site orientation on August 12, 1996. Surveys were completed in the field on September 4, 1996. This Executive Summary briefly presents the major findings of this work. The detail survey results are presented in the balance of this report and are organized by Technical Area and Site number in section 2. This organization is not in chronological order. USRADS and the related survey methods are described in section 3. Quality Control issues are addressed in section 4. Surveys were conducted with an array of radiation detectors either mounted on a backpack frame for man-carried use (Manual mode) or on a tricycle cart (RadCart mode). The array included radiation detectors for gamma and beta surface near surface contamination as well as dose rate at 1 meter above grade. The radiation detectors were interfaced directly to an USRADS 2100 Data Pack.

  11. Redshift weights for baryon acoustic oscillations: application to mock galaxy catalogues

    NASA Astrophysics Data System (ADS)

    Zhu, Fangzhou; Padmanabhan, Nikhil; White, Martin; Ross, Ashley J.; Zhao, Gongbo

    2016-09-01

    Large redshift surveys capable of measuring the baryon acoustic oscillation (BAO) signal have proven to be an effective way of measuring the distance-redshift relation in cosmology. Building off the work in Zhu et al., we develop a technique to directly constrain the distance-redshift relation from BAO measurements without splitting the sample into redshift bins. We apply the redshift weighting technique in Zhu et al. to the clustering of galaxies from 1000 Quick particle mesh (QPM) mock simulations after reconstruction and achieve a 0.75 per cent measurement of the angular diameter distance DA at z = 0.64 and the same precision for Hubble parameter H at z = 0.29. These QPM mock catalogues mimic the clustering and noise level of the Baryon Oscillation Spectroscopic Survey Data Release 12 (DR12). We compress the correlation functions in the redshift direction on to a set of weighted correlation functions. These estimators give unbiased DA and H measurements across the entire redshift range of the combined sample. We demonstrate the effectiveness of redshift weighting in improving the distance and Hubble parameter estimates. Instead of measuring at a single `effective' redshift as in traditional analyses, we report our DA and H measurements at all redshifts. The measured fractional error of DA ranges from 1.53 per cent at z = 0.2 to 0.75 per cent at z = 0.64. The fractional error of H ranges from 0.75 per cent at z = 0.29 to 2.45 per cent at z = 0.7. Our measurements are consistent with a Fisher forecast to within 10-20 per cent depending on the pivot redshift. We further show the results are robust against the choice of fiducial cosmologies, galaxy bias models, and redshift-space distortions streaming parameters.

  12. Energy Efficiency and Renewable Energy Network (EREN) customer satisfaction survey, 1997. Final report

    SciTech Connect

    Anderson, A.V.; Henderson, D.P.

    1997-07-01

    the EREN Customer Satisfaction Survey 1997 was designed to follow up the results of the 1995-96 Surveys, enabling comparison to the 1995- 96 baseline, and to provide additional qualitative feedback about EREN. Both the 1995-96 and 1997 Surveys had these objectives: Identify and define actual EREN users; Determine the value or benefits derived from the use of EREN; Determine the kind and quality of services that users want; Determine the users` levels of satisfaction with existing services; Determine users` preferences in both the sources of service and means of delivery; and Establish continuous quality improvement measures. This report presents the methodology used, scope and limitations of the study, description of the survey instrument, and findings regarding demographics, technical capabilities, usage patterns, general use, importance of and satisfaction with resources, and additional information and comments.

  13. Long-life cable development. Cable-processing survey. Final report

    SciTech Connect

    Mangaraj, D.; Preston, J.R.

    1985-09-01

    A survey of cable manufacturers in North America, Europe, and Japan identified state-of-the-art techniques for processing extruded dielectric cables. The review highlights optimal approaches to such process operations as materials handling, extrusion, and vulcanization.

  14. Compact Nuclei in Galaxies at Moderate Redshift

    NASA Astrophysics Data System (ADS)

    Sarajedini, Vicki Lynn

    The purpose of this study is to understand the space density and properties of active galaxies to z ≃ 0.8. We have investigated the frequency and nature of unresolved nuclei in galaxies at moderate redshift as indicators of nuclear activity such as Active Galactic Nuclei (AGN) or starbursts. Candidates are selected by fitting imaged galaxies with multi-component models using maximum likelihood estimate techniques to determine the best model fit. We select those galaxies requiring an unresolved, point source component in the galaxy nucleus, in addition to a disk and/or bulge component, to adequately model the galaxy light. We have searched 70 WFPC2 images primarily from the Medium Deep Survey for galaxies containing compact nuclei. In our survey of 1033 galaxies, the fraction containing an unresolved nuclear component ≥3% of the total galaxy light is 16±3% corrected for incompleteness and 9±1% for nuclei ≥5% of the galaxy light. Most of the nuclei are ~<20% of the total galaxy light. The majority of the host galaxies are spirals with little or no bulge component. The V-I colors of the nuclei are compared with synthetic colors for Seyferts and starburst nuclei to help differentiate between AGNs and starbursts in our sample. Spectroscopic redshifts have been obtained for 35 of our AGN/starburst candidates and photometric redshifts are estimated to an accuracy of σz≃0.1 for the remaining sample. We present the upper limit luminosity function (LF) for low-luminosity AGN (LLAGN) in two redshift bins to z = 0.8. We detect mild number density evolution of the form φ∝ (1+z)1.9 for nuclei at -18 ~

  15. Reconstructing the galaxy density field with photometric redshifts. I. Methodology and validation on stellar mass functions

    NASA Astrophysics Data System (ADS)

    Malavasi, N.; Pozzetti, L.; Cucciati, O.; Bardelli, S.; Cimatti, A.

    2016-01-01

    Context. Measuring environment for large numbers of galaxies in the distant Universe is an open problem in astrophysics, as environment is important in determining many properties of galaxies during their formation and evolution. In order to measure galaxy environments, we need galaxy positions and redshifts. Photometric redshifts are more easily available for large numbers of galaxies, but at the price of larger uncertainties than spectroscopic redshifts. Aims: We study how photometric redshifts affect the measurement of galaxy environment and how the reconstruction of the density field may limit an analysis of the galaxy stellar mass function (GSMF) in different environments. Methods: Through the use of mock galaxy catalogues, we measured galaxy environment with a fixed aperture method, using each galaxy's true and photometric redshifts. We varied the parameters defining the fixed aperture volume and explored different configurations. We also used photometric redshifts with different uncertainties to simulate the case of various surveys. We then computed GSMF of the mock galaxy catalogues as a function of redshift and environment to see how the environmental estimate based on photometric redshifts affects their analysis. Results: We found that the most extreme environments can be reconstructed in a fairly accurate way only when using high-precision photometric redshifts with σΔz/ (1 + z) ≲ 0.01, with a fraction ≥ 60 ÷ 80% of galaxies placed in the correct density quartile and a contamination of ≤10% by opposite quartile interlopers. A length of the volume in the radial direction comparable to the ±1.5σ error of photometric redshifts and a fixed aperture radius of a size similar to the physical scale of the studied environment grant a better reconstruction than other volume configurations. When using this kind of an estimate of the density field, we found that any difference between the starting GSMF (divided accordingly to the true galaxy environment

  16. Durability and reliability of solar domestic hot water heaters: Survey results. Final report, Part 1

    SciTech Connect

    Ramirez-Vargas, R.; Whitfield, K.; Hicks, B.; Wood, B.D.

    1998-03-01

    An unresolved barrier for consumer acceptance of SDWH systems is the perception that they are unreliable and that their service life is significantly less than that claimed by the manufacturers/dealers. A comprehensive survey was developed to identify and define the relevant durability and reliability issues that affect the long term performance of SDWH systems. The survey was directed towards installers and service contractors with significant field experience.

  17. Michigan residential heating oil and propane price survey: 1995--1996 heating season. Final report

    SciTech Connect

    Moriarty, C.

    1996-05-01

    This report summarizes the results of a survey of residential No. 2 distillate fuel (home heating oil) and liquefied petroleum gas (pro