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Sample records for 2df redshift survey

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  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. 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.

  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. 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.

  3. 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

  4. 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

  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. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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

  18. 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

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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

  7. 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

  8. 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.

  9. 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.

  10. 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.

  11. 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

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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 .

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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

  13. 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.

  14. 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.

  15. 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.

  16. 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

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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}.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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

  1. 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.

  2. 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.

  3. 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.

  4. 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

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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

  18. 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.

  19. 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.

  20. 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

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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

  8. 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.

  9. 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.

  10. 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

  11. 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.

  12. 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

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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

  20. 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

  1. 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).

  2. 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.

  3. 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.

  4. 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.

  5. 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

  6. 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.

  7. 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.

  8. 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

  9. 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.

  10. 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.

  11. 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.

  12. 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

  13. 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

  14. 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.

  15. 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

  16. 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.

  17. 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

  18. 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

  19. 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.

  20. 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

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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

  11. 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.

  12. 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).

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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

  18. Adjusting the Adjusted X[superscript 2]/df Ratio Statistic for Dichotomous Item Response Theory Analyses: Does the Model Fit?

    ERIC Educational Resources Information Center

    Tay, Louis; Drasgow, Fritz

    2012-01-01

    Two Monte Carlo simulation studies investigated the effectiveness of the mean adjusted X[superscript 2]/df statistic proposed by Drasgow and colleagues and, because of problems with the method, a new approach for assessing the goodness of fit of an item response theory model was developed. It has been previously recommended that mean adjusted…

  19. 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).

  20. [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

  1. 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

  2. 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.

  3. 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.

  4. 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/

  5. 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

  6. 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

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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

  13. 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.

  14. 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

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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

  2. 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.

  3. 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

  4. 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.

  5. 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

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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}.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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

  17. 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.

  18. 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

  19. 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

  20. 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.

  1. 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.

  2. 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∼

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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

  9. 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.

  10. 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