WorldWideScience

Sample records for 2df redshift survey

  1. The XMM-2df Cluster Survey

    Gaga, T; Georgantopoulos, I; Georgakakis, A; Basilakos, S; Stewart, G C; Kolokotronis, V G; Stobbart, A M

    2003-01-01

    We present the results from a shallow (2-10 ksec) XMM/2dF survey. Our survey covers 18 XMM fields ($\\sim 5 {\\rm deg}^2$) previously spectroscopically followed up with the Anglo-Australian telescope 2-degree field facility. About half of the fields are also covered by the Sloan Digital Sky Survey (SDSS). We are searching for extended sources using the XMM SAS maximum likelihood algorithm in the 0.3-2 keV band and we have detected 14 candidate clusters down to a flux of $\\sim2\\times10^{-14} cgs$. Our preliminary results show that: i) the redshift distribution peaks at relatively high redshifts ($\\sim0.4$) as expected from the Rosati et al. $\\Phi(L)$, ii) some of our X-ray clusters appear to have optical counterparts.

  2. Redshift Survey Strategies

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

    1994-12-01

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

  3. Cosmology with photometric redshift surveys

    Blake, C; Blake, Chris; Bridle, Sarah

    2004-01-01

    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 two complementary types of analysis: (1) We quantify the statistical confidence and 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. For example, we show that a 10000 sq deg imaging survey with depth r = 22.5 and photometric redshift accuracy dz/(1+z) = 0.03 will detect the acoustic oscillations with 99.9% confidence, measuring the associated cosmological scale with 2% precision. Such a survey will also detect the turnover with 95% confidence, determining the corresponding scale with 20% accuracy. (2) By assuming a Lambda-CDM cosmology we calculate the confidence with which a non-zero baryon fraction can be deduced from such future surveys. After margi...

  4. The Redshift Distribution of the TOUGH Survey

    Jakobsson, P.; Chapman, R; Hjorth, J.; Malesani, D.; Fynbo, J. P. U.; Milvang-Jensen, B.; Kruhler, T.; Tanvir, N. R.

    2013-01-01

    We present the redshift results from a Very Large Telescope program aimed at optimizing the legacy value of the Swift mission: to characterize a homogeneous, X-ray selected, sample of 69 GRB host galaxies. 19 new redshifts have been secured, resulting in a 83% (57/69) redshift completion, making the survey the most comprehensive in terms of redshift completeness of any sample to the full Swift depth, available to date. We present the cumulative redshift distribution and derive a conservative,...

  5. The redshift distribution of the TOUGH survey

    Jakobsson, P.; Hjorth, J.; Malesani, D.;

    2013-01-01

    We present the redshift results from a Very Large Telescope (VLT) program aimed at optimizing the legacy value of the Swift mission: to characterize a homogeneous, X-ray selected, sample of 69 GRB host galaxies. Fifteen new redshifts have been secured, resulting in a 77% (53/69) redshift completion......, making the survey the most comprehensive in terms of redshift completeness of any sample to the full Swift depth, available to date. We present the cumulative redshift distribution and derive a conservative, yet small, associated uncertainty. We constrain the fraction of Swift GRBs at high redshift to a...

  6. Lensing convergence in galaxy redshift surveys

    Cardona, Wilmar; Kunz, Martin; Montanari, Francesco

    2016-01-01

    In this letter we demonstrate the importance of including the lensing contribution in galaxy clustering analyses with large galaxy redshift surveys. It is well known that radial cross-correlations between different redshift bins of galaxy surveys are dominated by lensing. But we show here that also neglecting lensing in the auto-correlations within one bin severely biases cosmological parameter estimation with redshift surveys. It leads to significant shifts for several cosmological parameters, most notably the scalar amplitude, the scalar spectral index and in particular the neutrino mass scale. Especially the latter parameter is one of the main targets of future galaxy surveys.

  7. Measuring our Universe from Galaxy Redshift Surveys

    Lahav Ofer

    2004-07-01

    Full Text Available Galaxy redshift surveys have achieved significant progress over the last couple of decades. Those surveys tell us in the most straightforward way what our local Universe looks like. While the galaxy distribution traces the bright side of the Universe, detailed quantitative analyses of the data have even revealed the dark side of the Universe dominated by non-baryonic dark matter as well as more mysterious dark energy (or Einstein's cosmological constant. We describe several methodologies of using galaxy redshift surveys as cosmological probes, and then summarize the recent results from the existing surveys. Finally we present our views on the future of redshift surveys in the era of precision cosmology.

  8. The Redshift Distribution of the TOUGH Survey

    Jakobsson, P; Malesani, D; Chapman, R; Fynbo, J P U; Milvang-Jensen, B; Kruhler, T; Tanvir, N R

    2013-01-01

    We present the redshift results from a Very Large Telescope program aimed at optimizing the legacy value of the Swift mission: to characterize a homogeneous, X-ray selected, sample of 69 GRB host galaxies. 19 new redshifts have been secured, resulting in a 83% (57/69) redshift completion, making the survey the most comprehensive in terms of redshift completeness of any sample to the full Swift depth, available to date. We present the cumulative redshift distribution and derive a conservative, yet small, associated uncertainty. We constrain the fraction of Swift GRBs at high redshift to a maximum of 10% (5%) for z > 6 (z > 7). The mean redshift of the host sample is assessed to be > 2.2. Using this more complete sample, we confirm previous findings that the GRB rate at high redshift (z > 3) appears to be in excess of predictions based on assumptions that it should follow conventional determinations of the star formation history of the universe, combined with an estimate of its likely metallicity dependence. T...

  9. Photometric Redshifts in the IRAC Shallow Survey

    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.

  10. Local redshift surveys and galaxy evolution

    De Propris, Roberto; Colless, Matthew; Croton, Darren

    2003-01-01

    We present observations of galaxy environmental dependencies using data from the 2dF Galaxy Redshift Survey. From a combined analysis of the luminosity function, Butcher-Oemler effect and trends in H$\\alpha$ line strengths we find support for a model where galaxy properties are mainly set by initial conditions at the time of their formation.

  11. An extended galaxy redshift survey: Pt. 1

    Redshifts and blue magnitudes are presented for a sample of 264 'field' galaxies virtually complete to a limiting magnitude of bj ∼ 16.80 mag. The galaxies were selected by sampling one galaxy in every three in order of apparent magnitude on each of nine high-latitude UK Schmidt (UKST) fields. Photometric data were provided by COSMOS machine measures of UKST plates, zero-pointed with CCD photometry. The spectral data came from observations with the 1.9-m telescope at the South African Astronomical Observatory (SAAO), and the resulting radial velocities have a precision of ∼ ± 130 km s-1. This survey augments substantially the Durham/AAT redshift survey. (author)

  12. Searching for X-ray luminous 'normal' galaxies in 2dfGRS

    Tzanavaris, P; Georgakakis, A

    2006-01-01

    We cross-correlated the Chandra XASSIST and XMM-Newton Serendipitous Source Catalogues with the 2 degree Field Galaxy Redshift Survey (2dfGRS) database. Our aim was to identify the most X-ray luminous (L_X > 10^42 erg s^-1) examples of galaxies in the local Universe whose X-ray emission is dominated by stellar processes rather than AGN activity ('normal' galaxies) as well as to test the empirical criterion log(f_X/f_O) -2. We performed a similar search in two nearby-galaxy samples from the literature. All 44 galaxies in the Zezas (2001) sample have log(f_X/f_O) -2, the majority of which are massive ellipticals. Three of these have L_X > 10^42 erg s^-1 .

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

    Kitaura, Francisco-Shu; Angulo, Raul E; Chuang, Chia-Hsun; Rodriguez-Torres, Sergio; Monteagudo, Carlos Hernandez; Prada, Francisco; Yepes, Gustavo

    2015-01-01

    We present a Bayesian reconstruction method which maps a galaxy distribution from redshift-space 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 given by the negative binomial distribution function modelling stochastic bias. We assume a deterministic bias given by a power law relating the dark matter density field to the expected halo or galaxy field. Coherent redshift-space distortions are corrected in a Gibbs-sampling procedure by moving the galaxies from redshift-space to real-space according to the peculiar motions derived from the recovered density field using linear theory with the option to include tidal field corrections from second order Lagrangian perturbation theory. The virialised distortions are corrected by sampling candidate real-space positions (being in the neighbourhood of the observations along the line of sight), which are compatible with the bulk flow corrected redshift-space posi...

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

    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.

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

    Leistedt, Boris; Peiris, Hiranya V

    2016-01-01

    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 photometri...

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

    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.

  17. Color-redshift Relations and Photometric Redshift Estimations of Quasars in Large Sky Surveys

    Wu, X B; Zhou, X; Wu, Xue-Bing; Zhang, Wei; Zhou, Xu

    2004-01-01

    With a recently constructed composite quasar spectrum and the \\chi^2 minimization technique, we demonstrated a general method to estimate the photometric redshifts of a large sample of quasars by deriving the theoretical color-redshift relations and comparing the theoretical colors with the observed ones. We estimated the photometric redshifts from the 5-band SDSS photometric data of 18678 quasars in the first major data release of SDSS and compare them with the spectroscopic redshifts. The redshift difference is smaller than 0.1 for 47% of quasars and 0.2 for 68 % of them. Based on the calculation of the theoretical color-color diagrams of stars, galaxies and quasars in both the SDSS and BATC photometric systems, we expected that with the BATC system of 15 intermediate filters we would be able to select candidates of high redshift quasars more efficiently than in the SDSS, provided the BATC survey could detect objects with magnitude fainter than 21.

  18. Mapping the Galaxy Color-Redshift Relation: Optimal Photometric Redshift Calibration Strategies for Cosmology Surveys

    Masters, Daniel; 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

    2015-01-01

    Calibrating the photometric redshifts of >10^9 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 whe...

  19. Redshift Accuracy Requirements for Future Supernova and Number Count Surveys

    Huterer, D; Krauss, L M; Broderick, T; Huterer, Dragan; Kim, Alex; Krauss, Lawrence M.; Broderick, Tamara

    2004-01-01

    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 z1) clusters.

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

    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.

  1. The Feasibility of Constraining Dark Energy Using LAMOST Redshift Survey

    2006-01-01

    We consider using future redshift surveys with the Large Sky Area MultiObject Fiber Spectroscopic Telescope (LAMOST) to constrain the equation of state of dark energy ω. We analyze the Alcock & Paczynski (AP) effect imprinted on the two-point correlation function of galaxies in redshift space. The Fisher matrix analysis is applied to estimate the expected error bounds of ω0 and ωa from galaxy redshift surveys, ω0 and ωa being the two parameters in the equation of state parametrization ω(z) = ω0 + ωaz/(1 -+ z). Strong degeneracies between ω0 and ωa are found. The direction of the degeneracy in ω0 - ωa plane, however, rotates counter-clockwise as the redshift increases. LAMOST can potentially contribute in the redshift range up to 0.5. In combination with other high redshift surveys, such as the proposed KiloAperture Optical Spectrograph project (KAOS), the joint constraint derived from galaxy surveys at different redshift ranges is likely to efficiently break the degeneracy of ω0 and ωa. We do not anticipate that the nature of dark energy can be well constrained with LAMOST alone, but it may help to reduce the error bounds expected from other observations, such as the Supernova/Acceleration Probe (SNAP).

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

    Geller, Margaret J; Dell'Antonio, Ian P; Zahid, Harus Jabran; Kurtz, Michael J; Fabricant, Daniel G

    2016-01-01

    The SHELS (Smithsonian Hectospec Lensing Survey) is a complete redshift survey covering two well-separated fields (F1 and F2) of the Deep Lens Survey. Both fields are more than 94% complete to a Galactic extinction corrected R0 = 20.2. Here we describe the redshift survey of the F1 field centered at R.A. = 00h53m25.3s and Decl = 12d33m55s; like F2, the F1 field covers 4 sq deg. 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 D4000 as a function of stellar mass and redshift for the two fields. The mass-metallicity relations differ by an insignificant 1.6 sigma. For galaxies in the stellar mass range 1.e10 to 1.e11 MSun, 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 w...

  3. Correcting cosmological parameter biases for all redshift surveys induced by estimating and reweighting redshift distributions

    Rau, Markus Michael; Paech, Kerstin; Seitz, Stella

    2016-01-01

    Photometric redshift uncertainties are a major source of systematic error for ongoing and future photometric surveys. We study different sources of redshift error caused by common suboptimal binning techniques and propose methods to resolve them. The selection of a too large bin width is shown to oversmooth small scale structure of the radial distribution of galaxies. This systematic error can significantly shift cosmological parameter constraints by up to $6 \\, \\sigma$ for the dark energy equation of state parameter $w$. Careful selection of bin width can reduce this systematic by a factor of up to 6 as compared with commonly used current binning approaches. We further discuss a generalised resampling method that can correct systematic and statistical errors in cosmological parameter constraints caused by uncertainties in the redshift distribution. This can be achieved without any prior assumptions about the shape of the distribution or the form of the redshift error. Our methodology allows photometric surve...

  4. Galaxy clustering with photometric surveys using PDF redshift information

    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.

  5. Peculiar Velocity Decomposition, Redshift Space Distortion and Velocity Reconstruction in Redshift Surveys - I. The Methodology

    Zhang, Pengjie; Zheng, Yi

    2013-01-01

    Massive spectroscopic surveys will open a new era of precision redshift space distortion (RSD) cosmology. We develop a new method to improve the RSD modeling and to carry out robust reconstruction of the 3D peculiar velocity through spectroscopic redshift surveys. (1) We propose a mathematically unique and physically motivated decomposition of peculiar velocity into three eigen-components. 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. We derive a new formula for the redshift space power spectrum. Under the velocity decomposition scheme, all high order Gaussian corrections and non-Gaussian correction of order $\\delta^3$ can be taken into account without introducing extra model uncertainties. We also identify a significant systematical error causing underestimation of the structure growth parameter f by as much as $O(10%)$ even at relatively large scale k=0.1h/Mpc. (3) The ...

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

    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. 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 artifacts that in some cases remain after data reduction. Redshift errors and catastrophic failure rates are assessed

  7. Real and Redshift-Space Clustering in the ESP Galaxy Redshift Survey

    Guzzo, L; Cappi, A

    1998-01-01

    We discuss the two-point correlation properties of galaxies in the ESO Slice Project (ESP) redshift survey, both in redshift and real space. The redshift-space correlation function xi(s) for the whole magnitude-limited survey is well described by a power law with \\gamma ~ 1.55 between 3 and ~40/h Mpc, where it smoothly breaks down, crossing the zero value on scales as large as ~80/h Mpc. On smaller scales (0.2-2/h Mpc), the slope is shallower, mostly due to redshift-space depression by virialized structures. This effect is found to be enhanced by the J3 optimal-weighting estimator for xi. We explicitly evidence these effects by computing xi(r_p,pi) and the projected function w_p(r_p). In this way we recover the real-space correlation function xi(r), which we fit below 10/h Mpc with a power-law model. This gives a reasonable fit, with r_o=4.15^{+0.20}_{-0.21} /h Mpc and \\gamma=1.67^{+0.07}_{-0.09}. This results on xi(r) and xi(s), and the comparison with other surveys, clearly confirm how the shape of spatial ...

  8. Caltech Faint Galaxy Redshift Survey X A Redshift Survey in the Region of the Hubble Deep Field North

    Cohen, J; Blandford, R D; Cowie, L L; Hu, E; Songaila, A; Shopbell, P l; Richberg, K; Cohen, Judith; Hogg, David; Blandford, Roger; Cowie, Lennox; Hu, Esther; Songaila, Antoinette; Shopbell, Patrick; Richberg, Kevin

    1999-01-01

    A redshift survey has been carried out in the region of the Hubble Deep Field North using the Low Resolution Imaging Spectrograph at the Keck Observatory. The resulting redshift catalog, which contains 671 entries, is a compendium of our own data together with published LRIS/Keck data. It is more than 92% complete for objects, irrespective of morphology, to $R = 24$ mag in the HDF itself and to $R = 23$ mag in the Flanking Fields within a diameter of 8 arcmin centered on the HDF, an unusually high completion for a magnitude limited survey performed with a large telescope. A median redshift $z = 1.0$ is reached at $R \\sim 23.8$. Strong peaks in the redshift distribution, which arise when a group or poor cluster of galaxies intersect the area surveyed, can be identified to $z \\sim 1.2$ in this dataset. More than 68% of the galaxies are members of these redshift peaks. In a few cases, closely spaced peaks in $z$ can be resolved into separate groups of galaxies that can be distinguished in both velocity and locat...

  9. The 2dF Galaxy Redshift Survey: Preliminary Results

    Maddox, S.

    1997-01-01

    Spectroscopic observations for a new survey of 250 000 galaxy redshifts are underway, using the 2dF instrument at the AAT. The input galaxy catalogue and commissioning data are described. The first result from the preliminary data is a new estimate of the galaxy luminosity function at =0.1.

  10. Galaxy redshift surveys with sparse sampling

    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., Vsurvey ∼ 10Gpc3) 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, Vsurvey, 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 Vsurvey (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 Vsurvey (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

  11. The Synergy between Weak Lensing and Galaxy Redshift Surveys

    de Putter, Roland; Takada, Masahiro

    2013-01-01

    We study the complementarity of weak lensing (WL) and spectroscopic galaxy clustering (GC) surveys, by forecasting dark energy and modified gravity constraints for three upcoming survey combinations: SuMIRe (Subaru Measurement of Images and Redshifts, the combination of the Hyper Suprime-Cam lensing survey and the Prime Focus Spectrograph redshift survey), EUCLID and WFIRST. From the WL surveys, we take into account both the shear and clustering of the source galaxies and from the GC surveys, we use the three-dimensional clustering of spectroscopic galaxies, including redshift space distortions. A CMB prior is included in all cases. Focusing on the large-scale, two-point function information, we find strong synergy between the two probes. The dark energy figure of merit from WL+GC is up to a factor ~2.5 larger than from either probe alone. Considering modified gravity, if the growth factor f(z) is treated as a free function, it is very poorly constrained by WL or GC alone, but can be measured at the few perce...

  12. Power Spectrum Analysis of Three-Dimensional Redshift Surveys

    Feldman, H A; Peacock, J A; Feldman, Hume A.; Kaiser, Nick; Peacock, John A.

    1994-01-01

    We develop a general method for power spectrum analysis of three dimensional redshift surveys. We present rigorous analytical estimates for the statistical uncertainty in the power and we are able to derive a rigorous optimal weighting scheme under the reasonable (and largely empirically verified) assumption that the long wavelength Fourier components are Gaussian distributed. We apply the formalism to the updated 1-in-6 QDOT IRAS redshift survey, and compare our results to data from other probes: APM angular correlations; the CfA and the Berkeley 1.2Jy IRAS redshift surveys. Our results bear out and further quantify the impression from e.g.\\ counts-in-cells analysis that there is extra power on large scales as compared to the standard CDM model with $\\Omega h\\simeq 0.5$. We apply likelihood analysis using the CDM spectrum with $\\Omega h$ as a free parameter as a phenomenological family of models; we find the best fitting parameters in redshift space and transform the results to real space. Finally, we calcul...

  13. The optical redshift survey sample selection and the galaxy distribution

    Santiago, B X; Lahav, O; Davis, M; Dressler, A; Huchra, J P

    1994-01-01

    This is the first in a series of papers describing the {\\it Optical Redshift Survey} (ORS), a redshift survey of optically selected galaxies covering 98\\% of the sky above |b| = 20^\\circ (8.09 ster). The survey is drawn from the UGC, ESO, and ESGC galaxy catalogues, and contains two sub-samples, one complete to a B magnitude of 14.5, the other complete to a B major axis diameter of 1.9^\\prime. The entire sample consists of 8457 objects, of which redshifts are now available for 8286; 171 objects remain without measured redshifts. The ORS provides the most detailed and homogeneous sampling of the large-scale galaxy distribution to date in these areas. The density field of bright optical galaxies is well-defined to 8000 \\kms, and is dominated by the Virgo, Telescopium-Pavo-Indus, Hydra-Centaurus, Pisces-Perseus, and Coma-A1367 Superclusters. The dense sampling provided by ORS allows a detailed analysis of the galaxy density field, and will be used to test its dependence on morphology and other galaxy parameters.

  14. High redshift galaxies in the ALHAMBRA survey: I. selection method and number counts based on redshift PDFs

    Viironen, K; López-Sanjuan, C; Varela, J; Chaves-Montero, J; Cristóbal-Hornillos, D; Molino, A; Fernández-Soto, A; 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; Delgado, R M González; Husillos, C; Infante, L; Martínez, V J; Perea, J; Prada, F; Quintana, J M

    2015-01-01

    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-alpha selection. However, the availability of multifilter data allows now replacing the dropout selections 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 in the study of the brightest, less 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, reach...

  15. The VIMOS Public Extragalactic Redshift Survey - Searching for Cosmic Voids

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

    2014-01-01

    The characterisation of cosmic voids gives unique information about the large-scale distribution of galaxies, their evolution and the cosmological model. We identify and characterise cosmic voids in the VIMOS Public Extragalactic Redshift Survey (VIPERS) at redshift 0.55 < z < 0.9. A new void search method is developed based upon the identification of empty spheres that fit between galaxies. The method can be used to characterise the cosmic voids despite the presence of complex survey boundaries and internal gaps. We investigate the impact of systematic observational effects and validate the method against mock catalogues. We measure the void size distribution and the void-galaxy correlation function. We construct a catalogue of voids in VIPERS. The distribution of voids is found to agree well with the distribution of voids found in mock catalogues. The void-galaxy correlation function shows indications of outflow velocity from the voids.

  16. Redshift

    Clark, Stuart

    1997-01-01

    The light emitted by celestial objects can have its wavelength "stretched" in different ways before it is observed by astronomers. These stretching phenomena are collectively called "redshift". They influence virtually all aspects of astronomy and even underpin the "Big Bang" theory of the creation of the universe. This book details the types of redshift and explains their myriad of uses. It begins by introducing the nature of light and the problems involved in measuring its properties. After explaining the redshift phenomena and their uses, the book touches on the age and size of the universe; two subjects embroiled in controversy because of our current interpretation of the redshift. Less conventional theories are then expressed. As a by-product of the explanation of redshift, the book offers the reader a basic understanding of Einstein's theory of relativity. Mathematical treatments of the concepts introduced in the text are boxed off and should not detract from the book's readibility, but allow it to be u...

  17. Recovering a redshift-extended VSL signal from galaxy surveys

    Salzano, Vincenzo

    2016-01-01

    We investigate a new method to recover (if any) a possible varying speed of light (VSL) signal from cosmological data. It comes as an upgrade of [1,2], where it was argued that such signal could be detected at a single redshift location only. Here, we show how it is possible to extract information on a VSL signal on an extended redshift range. We use mock cosmological data from future galaxy surveys (BOSS, DESI, \\emph{WFirst-2.4} and SKA): the sound horizon at decoupling imprinted in the clustering of galaxies (BAO) as an angular diameter distance, and the expansion rate derived from those galaxies recognized as cosmic chronometers. We find that, given the forecast sensitivities of such surveys, a $\\sim1\\%$ VSL signal can be detected at $3\\sigma$ confidence level in the redshift interval $z \\in [0.,1.55]$. Smaller signals $(\\sim0.1\\%)$ will be hardly detected (even if some lower possibility for a $1\\sigma$ detection is still possible). Finally, we discuss the degeneration between a VSL signal and a non-null s...

  18. Comparing Dense Galaxy Cluster Redshift Surveys with Weak Lensing Maps

    Hwang, Ho Seong; Diaferio, Antonaldo; Rines, Kenneth J; Zahid, H Jabran

    2014-01-01

    We use dense redshift surveys of nine galaxy clusters at $z\\sim0.2$ 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 0.5$z_{\\rm cl}$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 th...

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

    Labini, Francesco Sylos; Baryshev, Yurij V

    2014-01-01

    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 determine 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 effect...

  20. Survey of galaxy redshifts. I. Data reduction techniques

    We are currently undertaking a magnitude limited redshift survey of galaxies having m/sub B/ or =40, delta> or =0. In this paper, we present in some detail our methods of data reduction, which are based on cross correlation against filtered templates. We present expressions for the uncertainty of a measured redshift, for the internal broadening of the object, and for the uncertainty of this broadening. Comparison of our optical data with previously published 21 cm data shows no systematic errors and yields excellent agreement with our internal error analysis. The method of analyzing velocity dispersions is new and quite promising for further application. A series of spectra are presented as examples to show the power and limitations of the correlation techniques

  1. PHOTOMETRIC REDSHIFTS FOR QUASARS IN MULTI-BAND SURVEYS

    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 Δznorm (i.e., (zspec – zphot)/(1 + zspec)), to an average of Δznorm = 0.004, a standard deviation of σ = 0.069, and a median absolute deviation, MAD = 0.02, over the whole redshift range (i.e., zspec ≤ 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

  2. Photometric Redshifts for Quasars in Multi-band Surveys

    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 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.

  3. The DEEP2 Galaxy Redshift Survey: Redshift Identification of Single-Line Emission Galaxies

    Kirby, E N; Faber, S M; Koo, D C; Weiner, B J; Cooper, M C

    2007-01-01

    We present two methods for determining spectroscopic redshifts of galaxies in the \\deep survey which display only one identifiable feature, an emission line, in the observed spectrum ("single-line galaxies"). First, we assume each single line is one of the four brightest lines accessible to DEEP2: Halpha, [OIII] 5007, Hbeta, or [OII] 3727. Then, we supplement spectral information with BRI photometry. The first method, parameter space proximity (PSP), calculates the distance of a single-line galaxy to galaxies of known redshift in (B-R), (R-I), R, observed wavelength parameter space. The second method is an artificial neural network (ANN). Prior information, such as allowable line widths and ratios, rules out one or more of the four lines for some galaxies in both methods. Based on analyses of evaluation sets, both methods are nearly perfect at identifying blended [OII] doublets. Of the lines identified as Halpha in the PSP and ANN methods, 91.4% and 94.2% respectively are accurate. Although the methods are no...

  4. ALMA redshifts of millimeter-selected galaxies from the SPT survey: The redshift distribution of dusty star-forming galaxies

    Weiss, A; Marrone, D P; Vieira, J D; Aguirre, J E; Aird, K A; Aravena, M; Ashby, M L N; Bayliss, M; Benson, B A; Bethermin, M; Biggs, A D; Bleem, L E; Bock, J J; Bothwell, M; Bradford, C M; Brodwin, M; Carlstrom, J E; Chang, C L; Chapman, S C; Crawford, T M; Crites, A T; de Haan, T; Dobbs, M A; Downes, T P; Fassnacht, C D; George, E M; Gladders, M D; Gonzalez, A H; Greve, T R; Halverson, N W; Hezaveh, Y D; High, F W; Holder, G P; Holzapfel, W L; Hoover, S; Hrubes, J D; Husband, K; Keisler, R; Lee, A T; Leitch, E M; Lueker, M; Luong-Van, D; Malkan, M; McIntyre, V; McMahon, J J; Mehl, J; Menten, K M; Meyer, S S; Murphy, E J; Padin, S; Plagge, T; Reichardt, C L; Rest, A; Rosenman, M; Ruel, J; Ruhl, J E; Schaffer, K K; Shirokoff, E; Spilker, J S; Stalder, B; Staniszewski, Z; Stark, A A; Story, K; Vanderlinde, K; Welikala, N; Williamson, R

    2013-01-01

    Using the Atacama Large Millimeter/submillimeter Array (ALMA), we have conducted a blind redshift survey in the 3 mm atmospheric transmission window for 26 strongly lensd dusty star-forming galaxies (DSFGs) selected with the South Pole Telescope (SPT). The sources were selected to have S_1.4mm>20 mJy and a dust-like spectrum and, to remove low-z sources, not have bright radio (S_843MHz=3.5. This finding is in contrast to the redshift distribution of radio-identified DSFGs, which have a significantly lower mean redshift of =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.

  5. A faint galaxy redshift survey behind massive clusters

    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.

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

    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

  7. Tracing The Sound Horizon Scale With Photometric Redshift Surveys

    Sanchez, E; Garcia-Bellido, J; Gaztanaga, E; de Simoni, F; Crocce, M; Cabre, A; Fosalba, P; Alonso, D

    2010-01-01

    We propose a new method for cosmological parameters extraction using the baryon acoustic oscillation scale as a standard ruler in deep galaxy surveys with photometric determination of redshifts. The method consists in a simple empirical parametric fit to the angular 2-point correlation function w(theta). It is parametrized as a power law to describe the continuum plus a Gaussian to describe the BAO bump. The location of the Gaussian is used as the basis for the measurement of the sound horizon scale. This method, although simple, actually provides a robust estimation, since the inclusion of the power law and the use of the Gaussian removes the shifts which affect the local maximum. We discuss the effects of projection bias, non-linearities, redshift space distortions and photo-z precision, and apply our method to a mock catalog of the Dark Energy Survey, built upon a large N-body simulation provided by the MICE collaboration. We discuss the main systematic errors associated to our method and show that they ar...

  8. Effective Theory of Dark Energy at Redshift Survey Scales

    Gleyzes, Jérôme; Mancarella, Michele; Vernizzi, Filippo

    2016-01-01

    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 $\\Lambda$CDM 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 $\\sigma\\sim10^{-2}$--$10^{-3}$. We also consider two other fiducial models. A nonminimal coupling of CDM enhances the effects of modified gravit...

  9. Redshift and Shear Calibration: Impact on Cosmic Shear Studies and Survey Design

    Waerbeke, V

    2006-01-01

    The cosmological interpretation of weak lensing by large-scale structures requires knowledge of the redshift distribution of the source galaxies. Current lensing surveys are often calibrated using external redshift samples which span a significantly smaller sky area in comparison to the lensing survey, and are thus subject to sample variance. Some future lensing surveys are expected to be calibrated in the same way, in particular the fainter galaxy populations where the entire color coverage, and hence photometric redshift estimate, could be challenging to obtain. Using N-body simulations, we study the impact of this sample variance on cosmic shear analysis and show that, to first approximation, it behaves like a shear calibration error 1+/-epsilon. Using the Hubble Deep Field as a redshift calibration survey could therefore be a problem for current lensing surveys. We discuss the impact of the redshift distribution sampling error and a shear calibration error on the design of future lensing surveys, and find...

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

    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.

  11. Chandra Survey of Radio-quiet, High-redshift Quasars

    Bechtold, J; Shields, J; Czerny, B; Janiuk, A; Hamann, F; Aldcroft, T L; Elvis, M; Dobrzycki, A; Bechtold, Jill; Siemiginowska, Aneta; Shields, Joseph; Czerny, Bozena; Janiuk, Agnieszka; Hamann, Fred; Aldcroft, Thomas L.; Elvis, Martin; Dobrzycki, Adam

    2003-01-01

    We observed 17 optically-selected, radio-quiet high-redshift quasars with the Chandra Observatory ACIS, and detected 16 of them. The quasars have redshift between 3.70 and 6.28 and include the highest redshift quasars known. When compared to low-redshift quasars observed with ROSAT, these high redshift quasars are significantly more X-ray quiet. We also find that the X-ray spectral index of the high redshift objects is flatter than the average at lower redshift. These trends confirm the predictions of models where the accretion flow is described by a cold, optically-thick accretion disk surrounded by a hot, optically thin corona, provided the viscosity parameter alpha >= 0.02. The high redshift quasars have supermassive black holes with masses ~10^{10} M_{sun}, and are accreting material at ~0.1 the Eddington limit. We detect 10 X-ray photons from the z=6.28 quasar SDS 1030+0524, which may have a Gunn-Peterson trough and be near the redshift of reionization of the intergalactic medium. The X-ray data place an...

  12. Morphological Redshift Estimates for Galaxy Clusters in a Sunyaev-Zel'dovich Effect Survey

    Diego-Rodriguez, J M; Silk, J; Bryan, G

    2003-01-01

    We develop a new method to estimate the redshift of galaxy clusters through resolved images of the Sunyaev-Zel'dovich effect (SZE). Our method is based on morphological observables which can be measured by actual and future SZE experiments. We test the method with a set of high resolution hydrodynamical simulations of galaxy clusters at different redshifts. Our method combines the observables in a principal component analysis. After calibrating the method with an independent redshift estimation for some of the clusters, we show - using a Bayesian approach - how the method can give an estimate of the redshift of the galaxy clusters. Although the error bars given by the morphological redshift estimation are large, it should be useful for future SZE surveys where thousands of clusters are expected to be detected; a first preselection of the high redshift candidates could be done using our proposed morphological redshift estimator. Although not considered in this work, our method should also be useful to give an ...

  13. Galaxy groups in the 2MASS Redshift Survey

    Lu, Yi; Shi, Feng; Mo, H J; Tweed, Dylan; Wang, Huiyuan; Zhang, Youcai; Li, Shijie; Lim, S H

    2016-01-01

    A galaxy group catalog is constructed from the 2MASS Redshift Survey (2MRS) with the use of a halo-based group finder. The halo mass associated with a group is estimated using a `GAP' method based on the luminosity of the central galaxy and its gap with other member galaxies. Tests using mock samples shows that this method is reliable, particularly for poor systems containing only a few members. On average 80% of all the groups have completeness >0.8, and about 65% of the groups have zero contamination. Halo masses are estimated with a typical uncertainty $\\sim 0.35\\,{\\rm dex}$. The application of the group finder to the 2MRS gives 29,904 groups from a total of 43,246 galaxies at $z \\leq 0.08$, with 5,286 groups having two or more members. Some basic properties of this group catalog is presented, and comparisons are made with other groups catalogs in overlap regions. With a depth to $z\\sim 0.08$ and uniformly covering about 91% of the whole sky, this group catalog provides a useful data base to study galaxies...

  14. Getting leverage on inflation with a large photometric redshift survey

    Basse, Tobias; Hannestad, Steen; Wong, Yvonne Y Y

    2015-01-01

    We assess the potential of a future large-volume photometric redshift survey to constrain observational inflationary parameters using three large-scale structure observables: the angular shear and galaxy power spectra, and the cluster mass function measured through weak lensing. When used in combination with Planck-like CMB measurements, we find that the spectral index n_s can be constrained to a 1 sigma precision of up to 0.0025. The sensitivity to the running of the spectral index can potentially improve to 0.0017, roughly a factor of five better than the present 1 sigma~constraint from Planck and auxiliary CMB data, allowing us to test the assumptions of the slow-roll scenario with unprecedented accuracy. Interestingly, neither CMB+shear nor CMB+galaxy nor CMB+clusters alone can achieve this level of sensitivity; it is the combined power of all three probes that conspires to break the different parameter degeneracies inherent in each type of observations. We make our forecast software publicly available vi...

  15. Clusters and Superclusters in the Las Campanas Redshift Survey

    Einasto, J; Hütsi, G; Saar, E; Tucker, D L; Tago, E; Müller, V; Heinämäki, P; Allam, S S

    2003-01-01

    Two-dimensional high-resolution density field of galaxies of the Las Campanas Redshift Survey (LCRS) with a smoothing length 0.8 Mpc/h is used to extract clusters and groups of galaxies, and a low-resolution field with a smoothing length 10 Mpc/h to find superclusters of galaxies. Properties of these density field (DF) clusters and superclusters are studied and compared with the properties of Abell clusters and superclusters, and LCRS loose groups. We calculate the DF-cluster luminosity function, and show that most luminous clusters in high-density environments are about ten times brighter than most luminous clusters in low-density environments. We present a catalogue of DF-superclusters and show that superclusters that contain Abell clusters are richer and more luminous than superclusters without Abell clusters. A pdf file of the paper with high-resolution figures is available in Tartu Observatory web-site (http://www.aai.ee/~maret/cosmoweb.html)

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

    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.

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

    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.; J. Gorosabel; Greiner, J.; Jakobsson, P.

    2015-01-01

    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 obs...

  18. Redshift and Shear Calibration: Impact on Cosmic Shear Studies and Survey Design

    Van Waerbeke, Ludovic; White, Martin; Hoekstra, Henk; Heymans, Catherine

    2006-01-01

    The cosmological interpretation of weak lensing by large-scale structures requires knowledge of the redshift distribution of the source galaxies. Current lensing surveys are often calibrated using external redshift samples which span a significantly smaller sky area in comparison to the lensing survey, and are thus subject to sample variance. Some future lensing surveys are expected to be calibrated in the same way, in particular the fainter galaxy populations where the entire color coverage,...

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

    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° and –30°) 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.

  20. The 2dF Galaxy Redshift Survey : Wiener reconstruction of the cosmic web

    Erdogdu, P; Lahav, O; Zaroubi, S; Efstathiou, G; Moody, S; Peacock, JA; Colless, M; Baldry, IK; Baugh, CM; Bland-Hawthorn, J; Bridges, T; Cannon, R; Cole, S; Collins, C; Couch, W; Dalton, G; De Propris, R; Driver, SP; Ellis, RS; Frenk, CS; Glazebrook, K; Jackson, C; Lewis, [No Value; Lumsden, S; Maddox, S; Madgwick, D; Norberg, P; Peterson, BA; Sutherland, W; Taylor, K

    2004-01-01

    We reconstruct the underlying density field of the Two-degree Field Galaxy Redshift Survey (2dFGRS) for the redshift range 0.035

  1. The Team Keck Treasury Redshift Survey of the GOODS-North Field

    Wirth, G D; Amico, P; Chaffee, F H; Goodrich, R W; Kwok, S; Lyke, J E; Mader, J A; Tran, H D; Barger, A J; Cowie, L L; Capak, P; Cooper, M C; Conrad, A; Davis, M; Faber, S M; Hu, E M; Koo, D C; Le Mignant, D; Newman, J A; Songaila, A; Wirth, Gregory D.; Willmer, Christopher N. A.; Amico, Paola; Chaffee, Frederic H.; Goodrich, Robert W.; Kwok, Shui; Lyke, James E.; Mader, Jeff A.; Tran, Hien D.; Barger, Amy J.; Cowie, Lennox L.; Capak, Peter; Cooper, Michael C.; Conrad, Al; Davis, Marc; Hu, Esther M.; Koo, David C.; Mignant, David Le; Newman, Jeffrey A.; Songaila, Antoinette

    2004-01-01

    We report the results of an extensive imaging and spectroscopic survey in the GOODS-North field completed using DEIMOS on the Keck II telescope. Observations of 2018 targets in a magnitude-limited sample of 2911 objects to R=24.4 yield secure redshifts for a sample of 1440 galaxies and AGN plus 96 stars. In addition to redshifts and associated quality assessments, our catalog also includes photometric and astrometric measurements for all targets detected in our R-band imaging survey of the GOODS-North region. We investigate various sources of incompleteness and find the redshift catalog to be 53% complete at its limiting magnitude. The median redshift of z=0.65 is lower than in similar deep surveys because we did not select against low-redshift targets. Comparison with other redshift surveys in the same field, including a complementary Hawaii-led DEIMOS survey, establishes that our velocity uncertainties are as low as 40 km/s for red galaxies and that our redshift confidence assessments are accurate. The dist...

  2. Topological analysis of the CfA redshift survey

    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

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

    Pursimo, Tapio; 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 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 FS...

  4. The effects of spatial resolution on Integral Field Spectrograph surveys at different redshifts. The CALIFA perspective

    Mast, D; Sanchez, S F; Vílchez, J M; Iglesias-Paramo, J; Walcher, C J; Husemann, B; Marquez, I; Marino, R A; Kennicutt, R C; Monreal-Ibero, A; Galbany, L; de Lorenzo-Caceres, A; Mendez-Abreu, J; Kehrig, C; del Olmo, A; Relano, M; Wisotzki, L; Marmol-Queralto, E; Bekeraite, S; Papaderos, P; Wild, V; Aguerri, J A L; Falcon-Barroso, J; Bomans, D J; Ziegler, B; García-Lorenzo, B; Bland-Hawthorn, J; Lopez-Sanchez, A R; van de Ven, G

    2013-01-01

    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 ($z\\sim0.02$) 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. 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 resolut...

  5. Optimizing baryon acoustic oscillation surveys II: curvature, redshifts, and external datasets

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

    2009-01-01

    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 anal...

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

    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.

  7. Gravitational Redshift of Galaxies in Clusters from the Sloan Digital Sky Survey and the Baryon Oscillation Spectroscopic Survey

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

    2014-01-01

    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 w...

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

    Geller, Margaret J.; Hwang, Ho Seong; Fabricant, Daniel G.; Kurtz, Michael J. [Smithsonian Astrophysical Observatory, 60 Garden Street, Cambridge, MA 02138 (United States); Dell' Antonio, Ian P. [Department of Physics, Brown University, Box 1843, Providence, RI 02912 (United States); Zahid, Harus Jabran, E-mail: mgeller@cfa.harvard.edu, E-mail: hhwang@cfa.harvard.edu, E-mail: dfabricant@cfa.harvard.edu, E-mail: mkurtz@cfa.harvard.edu, E-mail: ian@het.brown.edu, E-mail: jabran@ifa.hawaii.edu [Institute for Astronomy, University of Hawaii at Manoa, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States)

    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.

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

    Cool, Richard J. [MMT Observatory, Tucson, AZ 85721 (United States); Moustakas, John [Department of Physics, Siena College, 515 Loudon Rd., Loudonville, NY 12211 (United States); Blanton, Michael R.; Hogg, David W. [Center for Cosmology and Particle Physics, Department of Physics, New York University, 4 Washington Place, New York, NY 10003 (United States); Burles, Scott M. [D.E. Shaw and Co. L.P, 20400 Stevens Creek Blvd., Suite 850, Cupertino, CA 95014 (United States); Coil, Alison L.; Aird, James; Mendez, Alexander J. [Department of Physics, Center for Astrophysics and Space Sciences, University of California, 9500 Gilman Dr., La Jolla, San Diego, CA 92093 (United States); Eisenstein, Daniel J. [Harvard-Smithsonian Center for Astrophysics, 60 Garden St, MS 20, Cambridge, MA 02138 (United States); Wong, Kenneth C. [Steward Observatory, The University of Arizona, 933 N. Cherry Ave., Tucson, AZ 85721 (United States); Zhu, Guangtun [Center for Astrophysical Sciences, Department of Physics and Astronomy, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218 (United States); Bernstein, Rebecca A. [Department of Astronomy and Astrophysics, UCA/Lick Observatory, University of California, 1156 High Street, Santa Cruz, CA 95064 (United States); Bolton, Adam S. [Department of Physics and Astronomy, University of Utah, Salt Lake City, UT 84112 (United States)

    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.

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

    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 σz/(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.

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

    Cool, Richard J; 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

    2013-01-01

    The PRIsm MUti-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 ~2,500 objects over 0.18 square degrees. The final PRIMUS catalog includes ~130,000 robust redshifts over 9.1 sq. deg. 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 2010. Comparisons to existing higher-resolution spectroscopic measurements show a typical precision of sigma_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 AGNs and their hosts, the effects of environment on galaxy evolution, and the build up of galactic systems over t...

  12. Narrow-band surveys for very high redshift Lyman-alpha emitters

    Nilsson, Kim K; Lacey, Cedric G; Baugh, Carlton M; Thommes, Eduard

    2007-01-01

    Context: Many current and future surveys aim to detect the highest redshift (z >~ 7) sources through their Lyman-alpha (Ly-alpha) 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 Ly-alpha emitters at z >~ 7 based on a variety of approaches. 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 num...

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

    Raichoor, A.; Mei, S.; Huertas-Company, M.; Licitra, R. [GEPI, Observatoire de Paris, CNRS, Université Paris Diderot, 61 Avenue de l' Observatoire, F-75014 Paris (France); Erben, T.; Hildebrandt, H. [Argelander-Institut für Astronomie, University of Bonn, Auf dem Hügel 71, D-53121 Bonn (Germany); Ilbert, O.; Boissier, S.; Boselli, A. [Aix Marseille Université, CNRS, Laboratoire d' Astrophysique de Marseille, UMR 7326, F-13388 Marseille (France); Ball, N. M.; Côté, P.; Ferrarese, L.; Gwyn, S. D. J.; Kavelaars, J. J. [Herzberg Institute of Astrophysics, National Research Council of Canada, Victoria, BC V9E 2E7 (Canada); Chen, Y.-T. [Insitute of Astronomy and Astrophysics, Academia Sinica, P.O. Box 23-141, Taipei 106, Taiwan (China); Cuillandre, J.-C. [Canada-France-Hawaïi Telescope Corporation, Kamuela, HI 96743 (United States); Duc, P. A. [Laboratoire AIM Paris-Saclay, CEA/IRFU/SAp, CNRS/INSU, Université Paris Diderot, F-91191 Gif-sur-Yvette Cedex (France); Durrell, P. R. [Department of Physics and Astronomy, Youngstown State University, Youngstown, OH 44555 (United States); Guhathakurta, P. [UCO/Lick Observatory, Department of Astronomy and Astrophysics, University of California Santa Cruz, 1156 High Street, Santa Cruz, CA 95064 (United States); Lançon, A., E-mail: anand.raichoor@obspm.fr [Observatoire Astronomique de Strasbourg, Université de Strasbourg, CNRS, UMR 7550, 11 rue de l' Université, F-67000 Strasbourg (France); 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.

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

    Kanekar, N.; Gupta, A. [National Centre for Radio Astrophysics, TIFR, Ganeshkhind, Pune 411007 (India); Carilli, C. L. [National Radio Astronomy Observatory, 1003 Lopezville Road, Socorro, NM 87801 (United States); Stocke, J. T. [CASA, Department of Astrophysical and Planetary Sciences, University of Colorado, 389-UCB, Boulder, CO 80309 (United States); Willett, K. W., E-mail: nkanekar@ncra.tifr.res.in [School of Physics and Astronomy, University of Minnesota, 116 Church Street SE, Minneapolis, MN 55455 (United States)

    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}.

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

    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.

  16. A Photometric Redshift Galaxy Catalog from the Red-Sequence Cluster Survey

    Hsieh, B C; Lin, H; Gladders, M D

    2005-01-01

    The Red-Sequence Cluster Survey (RCS) provides a large and deep photometric catalog of galaxies in the $z'$ and $R_c$ bands for ~90 square degrees of sky, and supplemental $V$ and $B$ data have been obtained for 33.6 deg$^{2}$. We 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 $R_c < 24$, giving an rms scatter $\\sigma(\\Delta{z}) < 0.06$ within the redshift range $0.2 < z < 0.5$ and $\\sigma(\\Delta{z}) < 0.11$ for galaxies at $0.0 < z < 1.5$. We describe the empirical quadratic polynomial photometric redshift fitting technique which we use to determine the relation between redshift and photometry. A kd-tree algorithm is used to divide up our sample to improve the accuracy of our cat...

  17. High-Redshift Quasars Found in Sloan Digital Sky Survey Commissioning Data

    SDSS Collaboration; Fan, X

    1999-01-01

    We present photometric and spectroscopic observations of 15 high-redshift quasars (z > 3.6) discovered from ~140 deg^2 of five-color (u'g'r'i'z') imaging data taken by the Sloan Digital Sky Survey (SDSS) during its commissioning phase. The quasars are selected by their distinctive colors in SDSS multicolor space. Four of the quasars have redshifts higher than 4.6 (z=4.63, 4.75, 4.90 and 5.00, the latter being the highest redshift quasar yet known). In addition, two previously known z > 4 obje...

  18. Measuring redshift-space distortions with future SKA surveys

    Raccanelli, Alvise; Camera, Stefano; Bacon, David; Blake, Chris; Dore, Olivier; Ferreira, Pedro; Maartens, Roy; Santos, Mario; Viel, Matteo; Zhao, Gong-bo

    2015-01-01

    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 measu...

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

    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 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 pr...

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

    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.

  1. Quantifying the Cosmic Web in the New Era of Redshift Surveys

    Lahav, Ofer

    2004-01-01

    Two main strategies have been implemented in mapping the local universe: whole-sky 'shallow' surveys and 'deep' surveys over limited parts of the sky. The two approaches complement each other in studying cosmography and statistical properties of the Universe. We summarise some results on the power spectrum of fluctuations and Wiener reconstruction of the density field from the 2dF Galaxy Redshift Survey (2dFGRS) of 230,000 redshifts. We then discuss future challenges in quantifying the web of...

  2. Redshift Space Distortions of the Correlation Function in Wide Angle Galaxy Surveys

    Szalay, Alexander S.; Matsubara, Takahiko; Landy, Stephen D.

    1997-01-01

    Using a novel two-dimensional coordinate system, we have derived a particularly simple way to express the redshift distortions in galaxy redshift surveys with arbitrary geometry in closed form. This method provides an almost ideal way to measure the value of $\\beta=\\Omega_0^{0.6}/b$ in wide area surveys, since all pairs in the survey can be used for the analysis. In the limit of small angles, this result straightforwardly reduces to the plane-parallel approximation. This expansion can also be...

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

    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 ∼> 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 ∼> 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.

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

    There is an ∼150 km s–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–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 Ks = 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 –1 Mpc. Deeper redshift surveys are needed to reach the 'convergence scale' of ≈250 h –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–1. Finally, we show that deviations from linear galaxy biasing and shot noise errors provide a minor contribution to the total error budget.

  5. Using gamma regression for photometric redshifts of survey galaxies

    Elliott, J; Krone-Martins, A; Cameron, E; Ishida, E E O; Hilbe, J

    2015-01-01

    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.

  6. Photometric redshifts and K-corrections for Sloan Digital Sky Survey Seven Data Release

    O'Mill, Ana Laura; Lambas, Diego García; Sodré, Laerte

    2010-01-01

    We present a catalogue of galaxy photometric redshifts and k-corrections for the Sloan Digital Sky Survey Seven Data Release (SDSS-DR7), available on the World Wide Web. The photometric redshifts were estimated with an artificial neural network using five ugriz bands, concentration indices and Petrosian radii in the g and r bands. We have explored our redshift estimates with different training set concluding that the best choice to improve redshift accuracy comprises the Main Galaxies Sample (MGS), the Luminous Red Galaxies, and galaxies of active galactic nuclei covering the redshift range 0redshift estimates agree with the spectroscopic values within rms=0.0227. The derived distribution of photometric redshifts in the range 0

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

    Pursimo, Tapio [Nordic Optical Telescope, Apartado 474, 38700 Santa Cruz de La Palma (Spain); Ojha, Roopesh [NVI Inc./U. S. Naval Observatory, 3450 Massachusetts Ave NW, Washington DC (United States); Jauncey, David L. [CSIRO Astronomy and Space Science and Mount Stromlo Observatory, Canberra ACT 0200 (Australia); Rickett, Barney J. [Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, CA 92093 (United States); Dutka, Michael S. [The Catholic University of America, 620 Michigan Ave., N.E., Washington DC 20064 (United States); Koay, Jun Yi; Bignall, Hayley E.; Macquart, Jean-Pierre [ICRAR, Curtin University, Bentley, WA 6845 (Australia); Lovell, James E. J. [School of Mathematics and Physics, University of Tasmania, TAS 7001 (Australia); Kedziora-Chudczer, Lucyna, E-mail: tpursimo@not.iac.es [School of Physics and Astrophysics, UNSW, Sydney NSW 2052 (Australia)

    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.

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

    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.

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

    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.

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

    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 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.

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

    Perley, D A; Schulze, S; Postigo, A de Ugarte; 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; 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 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, multi-color optical/NIR photometry, plus spectroscopy of events without pre-existing 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>5.5. Using this sample we estimate the redshift-depen...

  12. Optical Confirmation and Redshift Estimation of the Planck Cluster Candidates overlapping the Pan-STARRS Survey

    Liu, J; Desai, S; Hoyle, B; Koppenhoefer, J; Mohr, J J; Paech, K; Burgett, W S; Chambers, K C; Cole, S; Draper, P W; Kaiser, N; Metcalfe, N; Morgan, J S; Price, P A; Stubbs, C W; Tonry, J L; Wainscoat, R J; Waters, C

    2014-01-01

    We report results of a study of Planck Sunyaev-Zel'dovich effect (SZE) selected galaxy cluster candidates using the Panoramic Survey Telescope & Rapid Response System (Pan-STARRS) imaging data. We first examine 150 Planck confirmed galaxy clusters with spectroscopic redshifts to test our algorithm for identifying optical counterparts and measuring their redshifts; our redshifts have a typical accuracy of $\\sigma_{z/(1+z)} \\sim 0.022$ for this sample. We then examine an additional 237 Planck galaxy cluster candidates that have no redshift in the source catalogue. Of these 237 unconfirmed cluster candidates we are able to confirm 60 galaxy clusters and measure their redshifts. A further 83 candidates are so heavily contaminated by stars due to their location near the Galactic plane that we do not attempt to identify counterparts. For the remaining 94 candidates we find no optical counterpart but use the depth of the Pan-STARRS1 data to estimate a redshift lower limit $z_{\\text{lim}(10^{15})}$ beyond which w...

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

    Coupon, Jean; Umetsu, Keiichi [Institute of Astronomy and Astrophysics, Academia Sinica, P.O. Box 23-141, Taipei 10617, Taiwan (China); Broadhurst, Tom, E-mail: coupon@asiaa.sinica.edu.tw [Department of Theoretical Physics, University of Basque Country UPV/EHU, P.O. Box 644, E-48080 Bilbao (Spain)

    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.

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

    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 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.

  15. A Redshift Survey of the Strong Lensing Cluster Abell 383

    Geller, Margaret J; Diaferio, Antonaldo; Kurtz, Michael J; Coe, Dan; Rines, Kenneth J

    2014-01-01

    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$_{petro} \\leq 20.5$ and within 50$^\\prime$ of the BCG (Brightest Cluster Galaxy: R.A.$_{2000} = 42.014125^\\circ$, Decl$_{2000} = -03.529228^\\circ$). We apply the caustic technique to identify 275 cluster members within 7$h^{-1}$ Mpc of the hierarchical cluster center. The BCG lies within $-11 \\pm 110$ km s$^{-1}$ and 21 $\\pm 56 h^{-1}$ 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. (2010) especially when the impact of foreground and background structure is included. The values of R$_{200}$ = $1.22\\pm 0.01 h^{-1}$ Mp...

  16. The VIMOS Public Extragalactic Redshift Survey (VIPERS). Star formation history of passive galaxies

    Siudek, M; Scodeggio, M; Garilli, B; Pollo, A; Haines, C P; Fritz, A; Bolzonella, M; de la Torre, S; Granett, B R; Guzzo, L; Abbas, U; Adami, C; Bottini, D; Cappi, A; Cucciati, O; De Lucia, G; Davidzon, I; Franzetti, P; Iovino, A; Krywult, J; Brun, V Le; Fèvre, O Le; Maccagni, D; Marchetti, A; Marulli, F; Polletta, M; Tasca, L A M; Tojeiro, R; Vergani, D; Zanichelli, A; Arnouts, S; Bel, J; Branchini, E; Ilbert, O; Gargiulo, A; Moscardini, L; Takeuchi, T T; Zamorani, G

    2016-01-01

    We trace the evolution and the star formation history of passive galaxies, using a subset of the VIMOS Public Extragalactic Redshift Survey (VIPERS). We extracted from the VIPERS survey a sample of passive galaxies in the redshift range 0.4redshift-stellar mass relation for intermediate-redshift passive galaxies. We find that at $z\\sim1$ stellar populations in low-mass passive galaxies are younger than in high-mass passive galaxies, similarly to what is observed at the present epoch. Over the full analyzed redshift and stellar mass range, the...

  17. High-Redshift Quasars Found in Sloan Digital Sky Survey Commissioning Data

    Fan, X

    1999-01-01

    We present photometric and spectroscopic observations of 15 high-redshift quasars (z > 3.6) discovered from ~140 deg^2 of five-color (u'g'r'i'z') imaging data taken by the Sloan Digital Sky Survey (SDSS) during its commissioning phase. The quasars are selected by their distinctive colors in SDSS multicolor space. Four of the quasars have redshifts higher than 4.6 (z=4.63, 4.75, 4.90 and 5.00, the latter being the highest redshift quasar yet known). In addition, two previously known z > 4 objects were recovered from the data. The quasars all have i* < 20 and have luminosities comparable to that of 3C273. The spectra of the quasars have similar features (strong, broad emission lines and substantial absorption blueward of the Ly alpha emission line) seen in previously known high-redshift quasars. Although the photometric accuracy and image quality fail to meet the final survey requirements, our success rate for identifying high-redshift quasars (17 quasars from 27 candidates) is much higher than that of previ...

  18. Optimizing baryon acoustic oscillation surveys II: curvature, redshifts, and external datasets

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

    2009-01-01

    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 (Parkinson et al. 2007). 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. We go beyond our earlier analysis by examining the effect of including curvature on the optimal survey configuration, using the Seo & Eisenstein (2007) fitting formula for the accuracies of the BAO measurements, and updating the expected `prior' constraints from Planck. 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 z=2. We find that when assuming a flat universe the optimal survey makes measurements in the redshift range 0.1 <...

  19. Discovery of Nine Intermediate Redshift Compact Quiescent Galaxies in the Sloan Digital Sky Survey

    Damjanov, Ivana; Hwang, Ho Seong; Geller, Margaret J

    2013-01-01

    We identify nine galaxies with dynamical masses of M_dyn>10^10 M_sol 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 (HST) images. Surface brightness profile fitting confirms that all nine galaxies are extremely compact (with circularized half-light radii between 0.4 and 6.6 kpc and the median value of 0.74 kpc) for their velocity dispersion (1101 galaxies and the other eight objects follow the high-redshift dynamical size-mass relation.

  20. The power spectrum of galaxies in the 2dF 100k redshift survey

    Tegmark, Max; Hamilton, Andrew J. S.; Xu, Yongzhong

    2001-01-01

    We compute the real-space power spectrum and the redshift-space distortions of galaxies in the 2dF 100k galaxy redshift survey using pseudo-Karhunen-Loeve eigenmodes and the stochastic bias formalism. Our results agree well with those published by the 2dFGRS team, and have the added advantage of producing easy-to-interpret uncorrelated minimum-variance measurements of the galaxy-galaxy, galaxy-velocity and velocity-velocity power spectra in 27 k-bands, with narrow and well-behaved window func...

  1. I. Apples to apples $A^2$: photometric redshift predictions for next-generation surveys

    Ascaso, Begoña; Benítez, Narciso

    2015-01-01

    This is the first of a series of papers where we compare the expected performance of two of the largest stage IV next-generation surveys in the optical and infrared (LSST and Euclid), with a particular focus on cluster surveys. In this first paper, we introduce the mock catalogues we have utilized in this work, an N-body simulation+semi-analytical cone with a posterior modification with PhotReal, a technique which modifies the original photometry to make it more realistic by using an empirical library of spectral templates. We have confirmed the reliability of the mock catalogue by comparing the obtained color-magnitude relation, the luminosity and mass function and the angular correlation function with those of real data. We also analyze the behavior of the expected photometric redshifts for each different survey, in terms of photometric redshift resolution, photometric redshift bias and fraction of outliers. In addition, we discuss the benefits of using the BPZ \\emph{odds} photometric redshift quality param...

  2. A Sunyaev-Zel'dovich Effect Survey for High Redshift Clusters

    Mohr, J J; Holder, G P; Holzapfel, W L; Joy, M K; Leitch, E M; Reese, E D

    1999-01-01

    Interferometric observations of the Sunyaev-Zel'dovich Effect (SZE) toward clusters of galaxies provide sensitive cosmological probes. We present results from 1 cm observations (at BIMA and OVRO) of a large, intermediate redshift cluster sample. In addition, we describe a proposed, higher sensitivity array which will enable us to survey large portions of the sky. Simulated observations indicate that we will be able to survey one square degree of sky per month to sufficient depth that we will detect all galaxy clusters more massive than 2x10^{14} h^{-1}_{50}M_ødot, regardless of their redshift. We describe the cluster yield and resulting cosmological constraints from such a survey.

  3. Cosmology with high-redshift galaxy survey: Neutrino mass and inflation

    High-z galaxy redshift surveys open up exciting possibilities for precision determinations of neutrino masses and inflationary models. The high-z surveys are more useful for cosmology than low-z ones owing to much weaker nonlinearities in matter clustering, redshift-space distortion, and galaxy bias, which allows us to use the galaxy power spectrum down to the smaller spatial scales that are inaccessible by low-z surveys. We can then utilize the two-dimensional information of the linear power spectrum in angular and redshift space to measure the scale-dependent suppression of matter clustering due to neutrino free-streaming as well as the shape of the primordial power spectrum. To illustrate capabilities of high-z surveys for constraining neutrino masses and the primordial power spectrum, we compare three future redshift surveys covering 300 square degrees at 0.5ν,tot)=0.059, 0.043, and 0.025 eV, respectively, thus yielding a positive detection of the neutrino mass rather than an upper limit, as σ(mν,tot) is smaller than the lower limits to the neutrino masses implied from the neutrino oscillation experiments, by up to a factor of 4 for the highest redshift survey. The accuracies of constraining the tilt and running index of the primordial power spectrum, σ(ns)=(3.8,3.7,3.0)x10-3 and σ(αs)=(5.9,5.7,2.4)x10-3 at k0=0.05 Mpc-1, respectively, are smaller than the current uncertainties by more than an order of magnitude, which will allow us to discriminate between candidate inflationary models. In particular, the error on αs from the future highest redshift survey is not very far away from the prediction of a class of simple inflationary models driven by a massive scalar field with self-coupling, αs=-(0.8-1.2)x10-3

  4. Using the 2dF galaxy redshift survey to detect gravitationally-lensed quasars

    Mortlock, D J; Mortlock, Daniel J.; Webster, Rachel L.

    2001-01-01

    Galaxy redshift surveys can be used to detect gravitationally-lensed quasars if the spectra obtained are searched for the quasars' emission lines. Previous investigations of this possibility have used simple models to show that the 2 degree Field (2dF) redshift survey could yield several tens of new lenses, and that the larger Sloan Digital Sky Survey should contain an order of magnitude more. However the particular selection effects of the samples were not included in these calculations, limiting the robustness of the predictions; thus a more detailed simulation of the 2dF survey was undertaken here. The use of an isophotal magnitude limit reduces both the depth of the sample and the expected number of lenses, but more important is the Automatic Plate Measuring survey's star-galaxy separation algorithm, used to generate the 2dF input catalogue. It is found that most quasar lenses are classed as merged stars, with only the few lenses with low-redshift deflectors likely to be classified as galaxies. Explicit i...

  5. Photometric redshift analysis in the Dark Energy Survey Science Verification data

    Sánchez, C; Lin, H; Miquel, R; Abdalla, F B; Amara, A; Banerji, M; Bonnett, C; Brunner, R; Capozzi, D; Carnero, A; Castander, F J; da Costa, L A N; Cunha, C; Fausti, A; Gerdes, D; Greisel, N; Gschwend, J; Hartley, W; Jouvel, S; Lahav, O; Lima, M; Maia, M A G; Martí, P; Ogando, R L C; Ostrovski, F; Pellegrini, P; Rau, M M; Sadeh, I; Seitz, S; Sevilla-Noarbe, I; Sypniewski, A; de Vicente, J; Abbot, T; Allam, S S; Atlee, D; Bernstein, G; Bernstein, J P; Buckley-Geer, E; Burke, D; Childress, M J; Davis, T; DePoy, D L; Dey, A; Desai, S; Diehl, H T; Doel, P; Estrada, J; Evrard, A; Fernández, E; Finley, D; Flaugher, B; Gaztanaga, E; Glazebrook, K; Honscheid, K; Kim, A; Kuehn, K; Kuropatkin, N; Lidman, C; Makler, M; Marshall, J L; Nichol, R C; Roodman, A; Sánchez, E; Santiago, B X; Sako, M; Scalzo, R; Smith, R C; Swanson, M E C; Tarle, G; Thomas, D; Tucker, D L; Uddin, S A; Valdés, F; Walker, A; Yuan, F; Zuntz, J

    2014-01-01

    We present results from a study of the photometric redshift performance of the Dark Energy Survey (DES), using the early data from a Science Verification (SV) period of observations in late 2012 and early 2013 that provided science-quality images for almost 200 sq.~deg.~at the nominal depth of the survey. We assess the photometric redshift performance using about 15000 galaxies with spectroscopic redshifts available from other surveys. These galaxies are used, in different configurations, as a calibration sample, and photo-$z$'s are obtained and studied using most of the existing photo-$z$ codes. A weighting method in a multi-dimensional color-magnitude space is applied to the spectroscopic sample in order to evaluate the photo-$z$ performance with sets that mimic the full DES photometric sample, which is on average significantly deeper than the calibration sample due to the limited depth of spectroscopic surveys. Empirical photo-$z$ methods using, for instance, Artificial Neural Networks or Random Forests, y...

  6. The 160 Square Degree ROSAT Survey: The revised catalog of 201 clusters with spectroscopic redshifts

    Mullis, C.R.; McNamara, B.R.; Quintana, H.;

    2003-01-01

    We present the revised catalog of galaxy clusters detected as extended X-ray sources in the 160 Square Degree ROSAT Survey, including spectroscopic redshifts and X-ray luminosities for 200 of the 201 members. The median redshift is z(median) = 0.25, and the median X-ray luminosity is L-X......,L-median = 4.2 x 10(43) h(50)(-2) s(-1) (0.5 - 2.0 keV). This is the largest high-redshift sample of X-ray - selected clusters published to date. There are 73 objects at z > 0.3 and 22 objects at z > 0.5 drawn from a statistically complete flux-limited survey with a median object flux of 1.4 x 10(-13) ergs cm......-complete spectroscopic coverage for our survey. We discuss the final optical identifications for the extended X-ray sources in the survey region and compare our results to similar X-ray cluster searches....

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

    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.

  8. The 2dF Galaxy Redshift Survey: Wiener Reconstruction of the Cosmic Web

    Erdogdu, P; Zaroubi, S; Efstathiou, G P; Moody, S; Peacock, J A; Colless, M; Baldry, I K; Baugh, C M; Bland-Hawthorn, J; Bridges, T J; Cannon, R; Cole, S; Collins, C; Couch, W; Dalton, G B; De Propris, R; Driver, S P; Ellis, Richard S; Frenk, C S; Glazebrook, K; Jackson, C; Lewis, I; Lumsden, S; Maddox, S; Madgwick, D; Norberg, P; Peterson, B A; Sutherland, W; Taylor, K; Erdogdu, Pirin; Lahav, Ofer; Zaroubi, Saleem; Efstathiou, George; Moody, Steve; Peacock, John A.; Colless, Matthew; Baldry, Ivan K.; Baugh, Carlton M.; Bland-Hawthorn, Joss; Bridges, Terry; Cannon, Russell; Cole, Shaun; Collins, Chris; Couch, Warrick; Dalton, Gavin; Propris, Roberto De; Driver, Simon P.; Ellis, Richard S.; Frenk, Carlos S.; Glazebrook, Karl; Jackson, Carole; Lewis, Ian; Lumsden, Stuart; Maddox, Steve; Madgwick, Darren; Norberg, Peder; Peterson, Bruce A.; Sutherland, Will; Taylor, Keith

    2003-01-01

    We reconstruct the underlying density field of the 2 degree Field Galaxy Redshift Survey (2dFGRS) for the redshift range 0.0352dF power spectrum of fluctuations and the combination of matter density and bias parameters however the results are only slightly affected by changes to these parameters. We present maps of the density field in two different resolutions: 5 Mpc/h and 10 Mpc/h. We identify all major superclusters and voids in the survey. In particular, we find two large superclusters and two large local voids. A version of this paper with full set of colour maps can be found at http://www.ast.cam.ac.uk/~pirin.

  9. THE EGNoG SURVEY: MOLECULAR GAS IN INTERMEDIATE-REDSHIFT STAR-FORMING GALAXIES

    Bauermeister, A.; Blitz, L.; Wright, M. [Department of Astronomy and Radio Astronomy Laboratory, University of California at Berkeley, B-20 Hearst Field Annex, Berkeley, CA 94720 (United States); Bolatto, A.; Teuben, P. [Department of Astronomy and Laboratory for Millimeter-wave Astronomy, University of Maryland, College Park, MD 20742 (United States); Bureau, M. [Sub-department of Astrophysics, Department of Physics, University of Oxford, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH (United Kingdom); Leroy, A. [National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903 (United States); Ostriker, E. [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States); Wong, T., E-mail: amberb@astro.berkeley.edu [Department of Astronomy, University of Illinois, MC-221, 1002 W. Green Street, Urbana, IL 61801 (United States)

    2013-05-10

    We present the Evolution of molecular Gas in Normal Galaxies (EGNoG) survey, an observational study of molecular gas in 31 star-forming galaxies from z = 0.05 to z = 0.5, with stellar masses of (4-30) Multiplication-Sign 10{sup 10} M{sub Sun} and star formation rates of 4-100 M{sub Sun} yr{sup -1}. This survey probes a relatively un-observed redshift range in which the molecular gas content of galaxies is expected to have evolved significantly. To trace the molecular gas in the EGNoG galaxies, we observe the CO(J = 1 {yields} 0) and CO(J = 3 {yields} 2) rotational lines using the Combined Array for Research in Millimeter-wave Astronomy (CARMA). We detect 24 of 31 galaxies and present resolved maps of 10 galaxies in the lower redshift portion of the survey. We use a bimodal prescription for the CO to molecular gas conversion factor, based on specific star formation rate, and compare the EGNoG galaxies to a large sample of galaxies assembled from the literature. We find an average molecular gas depletion time of 0.76 {+-} 0.54 Gyr for normal galaxies and 0.06 {+-} 0.04 Gyr for starburst galaxies. We calculate an average molecular gas fraction of 7%-20% at the intermediate redshifts probed by the EGNoG survey. By expressing the molecular gas fraction in terms of the specific star formation rate and molecular gas depletion time (using typical values), we also calculate the expected evolution of the molecular gas fraction with redshift. The predicted behavior agrees well with the significant evolution observed from z {approx} 2.5 to today.

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

    Gerke, Brian F.; /UC, Berkeley; Newman, Jeffrey A.; /LBNL, NSD; Davis, Marc; /UC, Berkeley /UC, Berkeley, Astron.Dept.; Marinoni, Christian; /Brera Observ.; Yan, Renbin; Coil, Alison L.; Conroy, Charlie; Cooper, Michael C.; /UC, Berkeley, Astron.Dept.; Faber, S.M.; /Lick Observ.; Finkbeiner, Douglas P.; /Princeton U. Observ.; Guhathakurta, Puragra; /Lick Observ.; Kaiser, Nick; /Hawaii U.; Koo, David C.; Phillips, Andrew C.; /Lick Observ.; 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.

  11. The Subaru FMOS galaxy redshift survey (FastSound). IV. New constraint on gravity theory from redshift space distortions at $z\\sim 1.4$

    Okumura, Teppei; 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

    2015-01-01

    We measure the redshift-space correlation function from a spectroscopic sample of 2830 emission line galaxies from the FastSound survey. The survey, which uses the Subaru Telescope and covers the redshift ranges of $1.19redshifts. 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 LCDM cosmology, and using the RSD measurements on scales above 8Mpc/h, we obtain the first constraint on the growth rate at the redshift, $f(z)\\sigma_8(z)=0.482\\pm 0.116$ at $z\\sim 1.4$. This corresponds to $4.2\\sigma$ detection of RSD, after marginalizing over the galaxy bias parameter $b(z)\\sigma_8(z)$. Our constraint is consistent with the prediction of general relativity $f\\sigma_8\\sim 0.392$ within the $1-\\sigma$ co...

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

    SDSS Collaboration; Fan, Xiaohui

    1999-01-01

    This is the second paper in a series aimed at finding high-redshift quasars from five-color (u'g'r'i'z') 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 ~250 deg^2 of data in the spring Equatorial Stripe, plus photometry for two previously known high-redshift quasars in the same region of sky. Our success rate of identifying high-redshift quasars is ...

  13. Estimating Photometric Redshifts of Quasars via K-nearest Neighbor Approach Based on Large Survey Databases

    Yanxia, Zhang; Nanbo, Peng; Yongheng, Zhao; Xue-bing, Wu

    2013-01-01

    We apply one of lazy learning methods named k-nearest neighbor algorithm (kNN) to estimate the photometric redshifts of quasars, based on various datasets from the Sloan Digital Sky Survey (SDSS), UKIRT Infrared Deep Sky Survey (UKIDSS) and 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 arrives at the best performance when k is different with a special input pattern for a special dataset. The best result belongs to the SDSS-UKIDSS-WISE sample. The experimental results show that generally 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. By comparing the performance of various m...

  14. Cosmology with photometric weak lensing surveys: constraints with redshift tomography of convergence peaks and moments

    Petri, Andrea; Haiman, Zoltán

    2016-01-01

    Weak gravitational lensing is becoming a mature technique for constraining cosmological parameters, and future surveys will be able to constrain the dark energy equation of state $w$. When analyzing galaxy surveys, redshift information has proven to be a valuable addition to angular shear correlations. We forecast parameter constraints on the triplet $(\\Omega_m,w,\\sigma_8)$ for an LSST-like photometric galaxy survey, using tomography of the shear-shear power spectrum, convergence peak counts and higher convergence moments. We find that redshift tomography with the power spectrum reduces the area of the $1\\sigma$ confidence interval in $(\\Omega_m,w)$ space by a factor of 8 with respect to the case of the single highest redshift bin. We also find that adding non-Gaussian information from the peak counts and higher-order moments of the convergence field and its spatial derivatives further reduces the constrained area in $(\\Omega_m,w)$ by a factor of 3 and 4, respectively. When we add cosmic microwave background ...

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

    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 ≤ zDeep Survey (VVDS). We measure the lowest bias b = 1.47 ± 0.18 for galaxies with MB(z = 1.1) - 5log (h) ≤ -19.5 in the first redshift bin (0.5 ≤ zweb site is http://www.vipers.inaf.it

  16. On the recovery of Local Group motion from galaxy redshift surveys

    Nusser, Adi; Branchini, Enzo

    2014-01-01

    There is a $\\sim 150 km s^{-1}$ discrepancy between the measured motion of the Local Group of galaxies (LG) with respect to the CMB 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 $150-200 km s^{-1}$ in amplitude and within a $\\approx10^\\circ$ 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 $K_s=11.75$ Two-Mass Galaxy Redshift Survey, which provides the deepest, widest and most complete spatial distribution of galaxies available so 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 2MRS that prevents a proper sa...

  17. Intrinsic galaxy alignments from the 2SLAQ and SDSS surveys: luminosity and redshift scalings and implications for weak lensing surveys

    Hirata, C M; Ishak, M; Seljak, U; Nichol, R; Pimbblet, K A; Ross, N P; Wake, D; Hirata, Christopher M.; Mandelbaum, Rachel; Ishak, Mustapha; Seljak, Uros; Nichol, Robert; Pimbblet, Kevin A.; Ross, Nicholas P.; Wake, David

    2007-01-01

    Correlations between intrinsic shear and the density field on large scales, a potentially important contaminant for cosmic shear surveys, have been robustly detected at low redshifts with bright galaxies in SDSS data. Here we present a more detailed characterization of this effect, which can cause anti-correlations between gravitational lensing shear and intrinsic ellipticity (GI correlations). This measurement uses 36278 Luminous Red Galaxies (LRGs) from the SDSS spectroscopic sample with 0.153sigma detections of the effect for all galaxy subsamples within the SDSS LRG sample; for the 2SLAQ sample, we find a 2sigma detection for a bright subsample, and no detection for a fainter subsample. Fitting formulae are provided for the scaling of the GI correlations with luminosity, transverse separation, and redshift. We estimate contamination in the measurement of sigma_8 for future cosmic shear surveys on the basis of the fitted dependence of GI correlations on galaxy properties. We find contamination to the power...

  18. The redshift distribution of dusty star forming galaxies from the SPT survey

    Strandet, M L; 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

    2016-01-01

    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 1.4mm continuum emission in the South Pole Telescope (SPT) survey. We present ALMA 3mm spectral scans between 84-114GHz for 15 galaxies and targeted ALMA 1mm observations for an additional eight sources. Our observations yield 30 new line detections from CO, [CI] , [NII] , H_2O and NH_3. We further present APEX [CII] 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 mm/submm 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 redsh...

  19. Studying large-scale structure with the 2dF Galaxy Redshift Survey

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

    2002-01-01

    The 2dF Galaxy Redshift Survey is the first to observe more than 100,000 redshifts. This allows precise measurements of many of the key statistics of galaxy clustering, in particular redshift-space distortions and the large-scale power spectrum. This paper presents the current 2dFGRS results in these areas. Redshift-space distortions are detected with a high degree of significance, confirming the detailed Kaiser distortion from large-scale infall velocities, and measuring the distortion parameter beta equiv Omega_m^{0.6}/b = 0.43 +- 0.07. The power spectrum is measured to 0.02 h Mpc^{-1}, and is well fitted by a CDM model with Omega_m h = 0.20 +- 0.03 and a baryon fraction of 0.15 +- 0.07. A joint analysis with CMB data requires Omega_m = 0.29 +- 0.05, assuming scalar fluctuations, but no priors on other parameters. Two methods are used to determine the large-scale bias parameter: an internal bispectrum analysis yields b= 1.04 +- 0.11, in very good agreement with the b=1.00 +- 0.09 obtained from a joint 2dFG...

  20. Four quasars above redshift 6 discovered by the Canada-France High-z Quasar Survey

    Willott, Chris J.; Delorme, Philippe; Omont, Alain; Bergeron, Jacqueline; Delfosse, Xavier; Forveille, Thierry; Albert, Loic; Reyle, Celine; Hill, Gary J.; Gully-Santiago, Michael; Vinten, Phillip; Crampton, David; Hutchings, John B.; Schade, David; Simard, Luc

    2007-01-01

    The Canada-France High-z Quasar Survey (CFHQS) is an optical survey designed to locate quasars during the epoch of reionization. In this paper we present the discovery of the first four CFHQS quasars at redshift greater than 6, including the most distant known quasar, CFHQS J2329-0301 at z=6.43. We describe the observational method used to identify the quasars and present optical, infrared, and millimeter photometry and optical and near-infrared spectroscopy. We investigate the dust propertie...

  1. 200 Mpc Sized Structure in the 2dF QSO Redshift Survey

    Miller, L; Boyle, B J; Loaring, N S; Smith, R J; Shanks, T; Outram, P J

    2004-01-01

    The completed 2dF QSO Redshift (2QZ) Survey has been used to search for extreme large-scale cosmological structure (around 200 Mpc) over the redshift range 0100Mpc are in the linear or only weakly non-linear regime and do not represent collapsed non-linear structures. We compare the measurements with the expectation of a standard LCDM model by measuring the variance of counts in cells and find that, provided the distribution of QSOs on large scales exhibits a mild bias with respect to the distribution of dark matter, the observed fluctuations are found to be in good agreement with the model. There is no evidence on such scales for any extreme structures that might require, for example, departures from the assumption of Gaussian initial perturbations. Thus the power-spectrum derived from the 2QZ Survey appears to provide a complete description of the distribution of QSOs. The amount of bias and its redshift dependence that is required is consistent with that found from studying the clustering of 2QZ QSOs on 10...

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

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

    2015-01-01

    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 MOSFIRE, an infrared multi-object spectrometer 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 o...

  3. A 21 cm redshift survey and the large scale distribution of dwarf galaxies

    The first results of an all-sky 21-cm redshift survey of all 1849 galaxies classified as dwarf, magellanic irregular or irregular are presented. The detection rate is∼85 %. The survey reveals a broad continuum of galaxies with absolute blue luminosities. Detailed comparison of the spatial distributions of dwarf and bright galaxies shows that there is no difference between the two distributions. Dwarf galaxies do not fill the voids seen in the bright galaxy distribution. This rules out a certain class of biased galaxy formation theories. If biasing occurs, the dark matter which is in the voids cannot be traced by dwarf and LSB galaxies, and biasing must be equally effective for both bright and faint galaxies. The dwarf redshift sample has been used in conjunction with other redshift samples to measure the topology of the universe out to∼21 000 km s-1. The universe shows a sponge-like topology, which implies random phase Gaussian initial density fluctuations. This topology is inconsistent with explosive amplification or cosmic string galaxy formation models. The cold dark matter model withω=1 and H=50 km s-1 Mpc-1 fits best the topology of the universe on different length scales

  4. Constraining galaxy cluster temperatures and redshifts with eROSITA survey data

    Borm, Katharina; Mohammed, Irshad; Lovisari, Lorenzo

    2014-01-01

    The nature of dark energy is imprinted in the large-scale structure of the Universe and thus in the mass and redshift distribution of galaxy clusters. The upcoming eROSITA mission will exploit this method of probing dark energy by detecting roughly 100,000 clusters of galaxies in X-rays. For a precise cosmological analysis the various galaxy cluster properties need to be measured with high precision and accuracy. To predict these characteristics of eROSITA galaxy clusters and to optimise optical follow-up observations, we estimate the precision and the accuracy with which eROSITA will be able to determine galaxy cluster temperatures and redshifts from X-ray spectra. Additionally, we present the total number of clusters for which these two properties will be available from the eROSITA survey directly. During its four years of all-sky surveys, eROSITA will determine cluster temperatures with relative uncertainties of Delta(T)/T<10% at the 68%-confidence level for clusters up to redshifts of z~0.16 which corr...

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

    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_=-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_blue luminosity densities in these three cases are ρ_LUM_=(2.0, 2.2, 2.3)x10^8^hLsun_/Mpc^3^, respectively. Large over- and under- densities are clearly seen in our data. In particular, we find evidence for a "local" under-density (n~0.5n

  6. A Comparison of the PSCz and Stromlo-APM Redshift Surveys

    Seaborne, M D; Tadros, H; Efstathiou, G P; Frenk, C S; Keeble, O; Maddox, S J; McMahon, R G; Oliver, S; Rowan-Robinson, M; Saunders, W J; White, S D M

    1999-01-01

    We present a direct comparison of the clustering properties of two redshift surveys covering a common volume of space: the recently completed IRAS Point Source Catalogue redshift survey (PSCz) containing 14500 galaxies with a limiting flux of 0.6 Jy at 60 microns, and the optical Stromlo-APM survey containing 1787 galaxies in a region of 4300 deg^2 in the southern Galactic cap. We use three methods to compare the clustering properties: the counts-in-cells comparison of Efstathiou (1995), the two-point cross correlation function, and the Tegmark (1998) `null-buster' test. We find that the Stromlo variances are systematically higher than those of PSCz, as expected due to the deficit of early-type galaxies in IRAS samples. However we find that the differences between the cell counts are consistent with a linear bias between the two surveys, with a relative bias parameter b_rel = b_Stromlo/b_PSCz \\approx 1.3 which appears approximately scale-independent. The correlation coefficient R between optical and IRAS dens...

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

    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

  8. High-Redshift Quasars Found in Sloan Digital Sky Survey Commissioning Data VI. Sloan Digital Sky Survey Spectrograph Observations

    Anderson, S F; Richards, G T; Schneider, D P; Strauss, M A; Vanden Berk, Daniel E; Gunn, J E; Anderson, Scott F.; Fan, Xiaohui; Richards, Gordon T.; Schneider, Donald P.; Strauss, Michael A.; Berk, Daniel E. Vanden; Gunn, James E.

    2001-01-01

    We present results on over 100 high-redshift quasars found in the Sloan Digital Sky Survey (SDSS), using automated selection algorithms applied to SDSS imaging data and with spectroscopic confirmation obtained during routine spectroscopic operations of the Sloan 2.5-m telescope. The SDSS spectra cover the wavelength range 3900--9200 Angstroms at a spectral resolution of 1800, and have been obtained for 116 quasars with redshifts greater than 3.94; 92 of these objects were previously uncataloged, significantly increasing the current tally of published z>4 quasars. The paper also reports observations of five additional new z>4.6 quasars; all were found from the SDSS imaging survey and spectroscopically confirmed with data from the Apache Point Observatory's 3.5-m telescope. The i' magnitudes of the quasars range from 18.03 to 20.56. Of the 97 new objects in this paper, 13 are Broad Absorption Line quasars. Five quasars, including one object at a redshift of 5.11, have 20 cm peak flux densities greater than 1 mJ...

  9. Gravitational Redshift of Galaxies in Clusters from the Sloan Digital Sky Survey and the Baryon Oscillation Spectroscopic Survey

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

    2015-02-01

    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 1014 M⊙ . 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.

  10. The WiggleZ Dark Energy Survey: mapping the distance–redshift relation with baryon acoustic oscillations

    Blake, Chris; Forster, Karl; Martin, D. Christopher; Wyder, Ted K.

    2011-01-01

    We present measurements of the baryon acoustic peak at redshifts z= 0.44, 0.6 and 0.73 in the galaxy correlation function of the final data set of the WiggleZ Dark Energy Survey. We combine our correlation function with lower redshift measurements from the 6-degree Field Galaxy Survey and Sloan Digital Sky Survey, producing a stacked survey correlation function in which the statistical significance of the detection of the baryon acoustic peak is 4.9σ relative to a zero-baryon model with no pe...

  11. A step towards testing general relativity using weak gravitational lensing and redshift surveys

    Using the linear theory of perturbations in General Relativity, we express a set of consistency relations that can be observationally tested with current and future large scale structure surveys. We then outline a stringent model-independent program to test gravity on cosmological scales. We illustrate the feasibility of such a program by jointly using several observables like peculiar velocities, galaxy clustering and weak gravitational lensing. After addressing possible observational or astrophysical caveats like galaxy bias and redshift uncertainties, we forecast in particular how well one can predict the lensing signal from a cosmic shear survey using an over-lapping galaxy survey. We finally discuss the specific physics probed this way and illustrate how f(R) gravity models would fail such a test

  12. Early-type galaxies in the PEARS survey: Probing the stellar populations at moderate redshift

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

    2009-01-01

    Using HST/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 (F775W<24 ABmag) out to z~1.3 over 320 arcmin2, with a median redshift zM=0.75. This work significantly increases our previous sample from the GRAPES survey in the HUDF (18 galaxies over ~11 arcmin2; Pasquali et al. 2006b). 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 parameterising 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 RMS of the distribution) is ro...

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

    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.

  14. Planck's Dusty GEMS: Gravitationally lensed high-redshift galaxies discovered with the Planck survey

    Canameras, R; Guery, D; McKenzie, T; Koenig, S; Petitpas, G; Dole, H; Frye, B; Flores-Cacho, I; Montier, L; Negrello, M; Beelen, A; Boone, F; Dicken, D; Lagache, G; Floch, E Le; Altieri, B; Bethermin, M; Chary, R; De Zotti, G; Giard, M; Kneissl, R; Krips, M; Malhotra, S; Martinache, C; Omont, A; Pointecouteau, E; Puget, J -L; Scott, D; Soucail, G; Valtchanov, I; Welikala, N; Yan, L

    2015-01-01

    We present an analysis of 11 bright far-IR/submm sources discovered through a combination of the Planck survey and follow-up Herschel-SPIRE imaging. Each source has a redshift z=2.2-3.6 obtained through a blind redshift search with EMIR at the IRAM 30-m telescope. Interferometry obtained at IRAM and the SMA, and optical/near-infrared imaging obtained at the CFHT and the VLT reveal morphologies consistent with strongly gravitationally lensed sources. Additional photometry was obtained with JCMT/SCUBA-2 and IRAM/GISMO at 850 um and 2 mm, respectively. All objects are bright, isolated point sources in the 18 arcsec beam of SPIRE at 250 um, with spectral energy distributions peaking either near the 350 um or the 500 um bands of SPIRE, and with apparent far-infrared luminosities of up to 3x10^14 L_sun. Their morphologies and sizes, CO line widths and luminosities, dust temperatures, and far-infrared luminosities provide additional empirical evidence that these are strongly gravitationally lensed high-redshift gala...

  15. SUBLUMINOUS TYPE Ia SUPERNOVAE AT HIGH REDSHIFT FROM THE SUPERNOVA LEGACY SURVEY

    The rate evolution of subluminous Type Ia supernovae (SNe Ia) is presented using data from the Supernova Legacy Survey. This sub-sample represents the faint and rapidly declining light curves of the observed SN Ia population here defined by low-stretch values (s ≤ 0.8). Up to redshift z = 0.6, we find 18 photometrically identified subluminous SNe Ia, of which six have spectroscopic redshift (and three are spectroscopically confirmed SNe Ia). The evolution of the subluminous volumetric rate is constant or slightly decreasing with redshift, in contrast to the increasing SN Ia rate found for the normal stretch population, although a rising behavior is not conclusively ruled out. The subluminous sample is mainly found in early-type galaxies with little or no star formation, so that the rate evolution is consistent with a galactic mass-dependent behavior: r(z) = A x Mg , with A = (1.1 ± 0.3) x 10-14 SNe yr-1 M-1sun.

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

    We present the high-redshift (3 phot phot + 1σ > 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(2-10keV) > 44.15 erg s–1) space density up to z ∼ 5 and a fainter luminosity range (43.5 erg s–1 (2-10keV) –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.

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

    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

  18. Will Kinematic Sunyaev-Zel'dovich Measurements Enhance the Science Return from Galaxy Redshift Surveys?

    Sugiyama, Naonori S; Spergel, David N

    2016-01-01

    Yes. Future CMB experiments such as Advanced ACTPol and CMB-S4 should achieve measurements with S/N of $> 0.1$ for the typical galaxies in redshift surveys. These measurements will provide complementary measurements of the growth rate of large scale structure $f$ and the expansion rate of the Universe $H$ to galaxy clustering measurements. This paper emphasizes that there is significant information in the anisotropy of the relative pairwise kSZ measurements. We expand the relative pairwise kSZ power spectrum in Legendre polynomials and consider up to its octopole. Assuming that the noise in the filtered maps is uncorrelated between the positions of galaxies in the survey, we derive a simple analytic form for the power spectrum covariance of the relative pairwise kSZ temperature in redshift space. While many previous studies have assumed optimistically that the optical depth of the galaxies $\\tau_{\\rm T}$ in the survey is known, we marginalize over $\\tau_{\\rm T}$, to compute constraints on the growth rate $f$ ...

  19. The EGNoG Survey: Molecular Gas in Intermediate-Redshift Star-Forming Galaxies

    Bauermeister, Amber; Bolatto, Alberto D; Bureau, Martin; Leroy, Adam; Ostriker, Eve; Teuben, Peter J; Wong, Tony; Wright, Melvyn C H

    2013-01-01

    We present the Evolution of molecular Gas in Normal Galaxies (EGNoG) survey, an observational study of molecular gas in 31 star-forming galaxies from z=0.05 to z=0.5, with stellar masses of (4-30)x10^10 M_Sun and star formation rates of 4-100 M_Sun yr^-1. This survey probes a relatively un-observed redshift range in which the molecular gas content of galaxies is expected to have evolved significantly. To trace the molecular gas in the EGNoG galaxies, we observe the CO(1-0) and CO(3-2) rotational lines using the Combined Array for Research in Millimeter-wave Astronomy (CARMA). We detect 24 of 31 galaxies and present resolved maps of 10 galaxies in the lower redshift portion of the survey. We use a bimodal prescription for the CO to molecular gas conversion factor, based on specific star formation rate, and compare the EGNoG galaxies to a large sample of galaxies assembled from the literature. We find an average molecular gas depletion time of 0.76 \\pm 0.54 Gyr for normal galaxies and 0.06 \\pm 0.04 Gyr for star...

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

    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.

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

    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 ∼13 million objects classified as galaxies in the co-add with r 68 = 0.031. After presenting our results and quality tests, we provide a short guide for users accessing the public data.

  2. The KMOS Redshift One Spectroscopic Survey (KROSS) : the Tully–Fisher relation at z ∼ 1.

    Tiley, AL; Stott, JP; Swinbank, AM; Bureau, M.; Harrison, CM; Bower, R.; Johnson, HL; Bunker, AJ; Jarvis, MJ; Magdis, G.; Sharples, R.; Smail, I.; Sobral, D.; Best, P.

    2016-01-01

    We present the stellar mass ($M_{*}$), and K-corrected $K$-band absolute magnitude ($M_{K}$) Tully-Fisher relations (TFRs) for sub-samples of the 584 galaxies spatially resolved in H$\\alpha$ 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, $V_{80}$ at a radius equal to the major axis of an ellipse containing 80% of the total integrated H$\\alpha$ flux. The large sample si...

  3. Compression and Classification Methods for Galaxy Spectra in Large Redshift Surveys

    Lahav, Ofer

    2000-01-01

    Methods for compression and classification of galaxy spectra, which are useful for large galaxy redshift surveys (such as the SDSS, 2dF, 6dF and VIRMOS), are reviewed. In particular, we describe and contrast three methods: (i) Principal Component Analysis, (ii) Information Bottleneck, and (iii) Fisher Matrix. We show applications to 2dF galaxy spectra and to mock semi-analytic spectra, and we discuss how these methods can be used to study physical processes of galaxy formation, clustering and...

  4. The 6dF Galaxy Survey: Final Redshift Release (DR3) and Southern Large-Scale Structures

    Jones, D Heath; Saunders, Will; Colless, Matthew; Jarrett, Tom; Parker, Quentin; Fairall, Anthony; Mauch, Thomas; Sadler, Elaine; Watson, Fred; Burton, Donna; Campbell, Lachlan; Cass, Paul; Croom, Scott; Dawe, John; Fiegert, Kristin; Frankcombe, Leela; Hartley, Malcolm; Huchra, John; James, Dionne; Kirby, Emma; Lahav, Ofer; Lucey, John; Mamon, Gary; Moore, Lesa; Peterson, Bruce; Prior, Sayuri; Proust, Dominique; Russell, Ken; Safouris, Vicky; Wakamatsu, Ken-ichi; Westra, Eduard; Williams, Mary

    2009-01-01

    We report the final redshift release of the 6dF Galaxy Survey, a combined redshift and peculiar velocity survey over the southern sky (|b|>10 deg). Its 136,304 spectra have yielded 110,256 new extragalactic redshifts and a new catalogue of 125,071 galaxies making near-complete samples with (K, H, J, r_F, b_J) <= (12.65, 12.95, 13.75, 15.60, 16.75). The median redshift of the survey is 0.053. Survey data, including images, spectra, photometry and redshifts, are available through an online database. We describe changes to the information in the database since earlier interim data releases. Future releases will include velocity dispersions, distances and peculiar velocities for the brightest early-type galaxies, comprising about 10% of the sample. Here we provide redshift maps of the southern local universe with z<=0.1, showing nearby large-scale structures in hitherto unseen detail. A number of regions known previously to have a paucity of galaxies are confirmed as significantly underdense regions. The UR...

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

    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 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. High-Redshift Quasars Found in Sloan Digital Sky Survey Commissioning Data V. Hobby-Eberly Telescope Observations

    Schneider, Donald P.; Fan, Xiaohui; Strauss, Michael A.; Gunn, James E.; Richards, Gordon T.; Hill, Gary J.; MacQueen, Phillip J.; Ramsey, Lawrence W.

    2000-01-01

    We report the discovery of 27 quasars with redshifts between 3.58 and 4.49. The objects were identified as high-redshift candidates based on their colors in Sloan Digital Sky Survey commissioning data. The redshifts were confirmed with low resolution spectra obtained at the Hobby-Eberly Telescope. The quasars' $i^*$ magnitudes range from 18.55 to 20.97. Nearly 60% of the quasar candidates observed are confirmed spectroscopically as quasars. Two of the objects are Broad Absorption Line quasars...

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

    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.

  8. TWO MICRON ALL SKY SURVEY PHOTOMETRIC REDSHIFT CATALOG: A COMPREHENSIVE THREE-DIMENSIONAL CENSUS OF THE WHOLE SKY

    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

  9. The 2dF Galaxy Redshift Survey: stochastic relative biasing between galaxy populations

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

    2004-01-01

    It is well known that the clustering of galaxies depends on galaxy type. Such relative bias complicates the inference of cosmological parameters from galaxy redshift surveys, and is a challenge to theories of galaxy formation and evolution. In this paper we perform a joint counts-in-cells analysis on galaxies in the 2dF Galaxy Redshift Survey, classified by both colour and spectral type, eta, as early or late type galaxies. We fit three different models of relative bias to the joint probability distribution of the cell counts, assuming Poisson sampling of the galaxy density field. We investigate the nonlinearity and stochasticity of the relative bias, with cubical cells of side 10Mpc \\leq L \\leq 45Mpc (h=0.7). Exact linear bias is ruled out with high significance on all scales. Power law bias gives a better fit, but likelihood ratios prefer a bivariate lognormal distribution, with a non-zero `stochasticity' - i.e. scatter that may result from physical effects on galaxy formation other than those from the loca...

  10. Faint 1.4 GHz sources in the 2dF Galaxy Redshift Survey

    Chan, B H P; Sadler, E M; Killeen, N E B; Jackson, C A; Mobasher, B; Ekers, R D

    2003-01-01

    The Australia Telescope Compact Array (ATCA) has been used to survey at 1.4GHz, a small region ( 0.001 lying within the surveyed region, of which 316 have reliable spectral classification. Following Sadler et al. 2002 (MNRAS, 329, 227), we visually classified 176 as AGN or early-type galaxies, and 140 as star-forming galaxies. We derived radio flux density measurement or upperlimits for each of the 365 2dFGRS sources. The fraction of radio detected 2dFGRS star-forming galaxies increases from ~ 50% at ~ 0.7mJy up to ~ 60% at ~ 0.2mJy. The mean redshift for the fraction of radio detected star-forming galaxies increases with increasing radio detection sensitivity, while the mean redshift is fairly constant for the AGN/early-type fraction. We found very similar radio detection rates of 2dFGRS galaxies for both the AGN/early-type and star-forming components. The radio detection rate increases approximately linearly with respect to the rate of increase in radio detection sensitivity. We derived the radio luminosity...

  11. The VLT LBG Redshift Survey - IV. Gas and galaxies at z~3 in observations and simulations

    Tummuangpak, P; Bielby, R; Crighton, N H M; Francke, H; Infante, L; Theuns, T

    2013-01-01

    We use observations and simulations to study the relationship between star-forming galaxies and the IGM at z~3. We use redshift data taken from the VLT LBG Redshift Survey (VLRS) and Keck surveys in fields centred on bright background QSOs, whilst the simulated data is taken from GIMIC. In the simulations, we find that the dominant peculiar velocities are in the form of large-scale coherent motions of gas and galaxies. Gravitational infall of galaxies towards each other is also seen, consistent with linear theory. Peculiar velocity pairs with separations smaller than 1Mpc have a smaller dispersion and better explain the simulated z-space correlations. Lyman-alpha auto- and cross-correlations in the simulations appear to show smaller infall than implied by the expected beta_Lyman-alpha ~ 1.3. Galaxy-wide outflows implemented in the simulations may contribute to this effect. When velocity errors are taken into account, the LBG correlation function prefers the high clustering amplitude shown by higher mass galax...

  12. The VLT LBG Redshift Survey - V. Characterising the z = 3.1 Lyman Alpha Emitter Population

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

    2016-01-01

    We present a survey of Ly$\\alpha$ emitting galaxies in the fields of the VLT LBG Redshift Survey, incorporating the analysis of narrow band number counts, the rest frame UV luminosity function and the two-point correlation function of Ly$\\alpha$ emitters at $z\\approx3.1$. Our photometric sample consists of 750 LAE candidates, over an area of 1.07 deg$^2$, with estimated equivalent widths of $\\gtrsim65$ \\AA, from 5 fields based on deep Subaru Suprime-Cam imaging data. Added to this we have obtained spectroscopic follow-up observations, which successfully detected Ly$\\alpha$ emission in 35 galaxies. Based on the spectroscopic results, we refined our photometric selection constraints, with the resulting sample having a success rate of $78\\pm18\\%$. We calculate the narrow band number counts for our photometric sample and find these to be consistent with previous studies of LAEs at this redshift. We find the $R$-band continuum luminosity function to be $\\sim10\\times$ lower than the equivalent luminosity function o...

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

    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 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.

  14. On radio-bright Active Galactic Nuclei in a complete Spectroscopic Redshift Survey

    Reviglio, P; Reviglio, Pietro; Helfand, David J.

    2006-01-01

    Analysis of the frequency and physical properties of galaxies with star-formation and AGN activity in different environments in the local universe is a cornerstone for understanding structure formation and galaxy evolution. We have built a new multiwavelength catalog for galaxies in a complete redshift survey (the 15R Survey), gathering information on their H-alpha, R-band, radio, far-infrared, and X-ray emission, as well as their radio and optical morphologies, and have developed a classification scheme to compare different selection methods and to select accurately samples of radio emitting galaxies with AGN and star-forming activity. While alternative classification schemes do not lead to major differences for star-forming galaxies, we show that spectroscopic and photometric classifications of AGN lead to incomplete samples. In particular, a large population of AGN-containing galaxies with absorption-line spectra, and in many cases extended radio structures (jets, lobes), is missed in the standard Baldwin-...

  15. SHOCK BREAKOUT IN TYPE II PLATEAU SUPERNOVAE: PROSPECTS FOR HIGH-REDSHIFT SUPERNOVA SURVEYS

    Shock breakout is the brightest radiative phenomenon in a supernova (SN) but is difficult to be observed owing to the short duration and X-ray/ultraviolet (UV)-peaked spectra. After the first observation from the rising phase reported in 2008, its observability at high redshift is attracting enormous attention. We perform multigroup radiation hydrodynamics calculations of explosions for evolutionary presupernova models with various main-sequence masses M MS, metallicities Z, and explosion energies E. We present multicolor light curves of shock breakouts in Type II plateau SNe, being the most frequent core-collapse SNe, and predict apparent multicolor light curves of shock breakout at various redshifts z. We derive the observable SN rate and reachable redshift as functions of filter x and limiting magnitude m x,lim by taking into account an initial mass function, cosmic star formation history, intergalactic absorption, and host galaxy extinction. We propose a realistic survey strategy optimized for shock breakout. For example, the g'-band observable SN rate for m g',lim = 27.5 mag is 3.3 SNe deg-2 day-1 and half of them are located at z ≥ 1.2. It is clear that the shock breakout is a beneficial clue for probing high-z core-collapse SNe. We also establish ways to identify shock breakout and constrain SN properties from the observations of shock breakout, brightness, timescale, and color. We emphasize that the multicolor observations in blue optical bands with ∼hour intervals, preferably over ≥2 continuous nights, are essential to efficiently detect, identify, and interpret shock breakout.

  16. NEW APPROACHES TO PHOTOMETRIC REDSHIFT PREDICTION VIA GAUSSIAN PROCESS REGRESSION IN THE SLOAN DIGITAL SKY SURVEY

    Expanding upon the work of Way and 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.

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

    Krughoff, K.Simon; 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.

  18. The 2dF Galaxy Redshift Survey: Hierarchical galaxy clustering

    Baugh, C M; Gaztañaga, E; Norberg, P; Colless, M; Baldry, I K; Bland-Hawthorn, J; Bridges, T J; Cannon, R; Cole, S; Collins, C; Couch, W; Dalton, G B; De Propris, R; Driver, S P; Efstathiou, G P; Ellis, Richard 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

    2004-01-01

    We use the two-degree field Galaxy Redshift Survey (2dFGRS) to test the hierarchical scaling hypothesis: namely, that the $p$-point galaxy correlation functions can be written in terms of the two point correlation function or variance. This scaling is expected if an initially Gaussian distribution of density fluctuations evolves under the action of gravitational instability. We measure the volume averaged $p$-point correlation functions using a counts in cells technique applied to a volume limited sample of 44,931 $L_*$ galaxies. We demonstrate that $L_{*}$ galaxies display hierarchical clustering up to order $p=6$ in redshift space. The variance measured for $L_{*}$ galaxies is in excellent agreement with the predictions from a $\\Lambda$-cold dark matter N-body simulation. This applies to all cell radii considered, $0.3<(R/h^{-1}{\\rm Mpc})<30$. However, the higher order correlation functions of $L_*$ galaxies have a significantly smaller amplitude than is predicted for the dark matter for $R<10h^{-1...

  19. The AzTEC/SMA Interferometric Imaging Survey of Submillimeter-Selected High-Redshift Galaxies

    Younger, J D; Huang, J -S; Yun, M S; Wilson, G W; Ashby, M L N; Gurwell, M A; Peck, A B; Petitpas, G R; Wilner, D J; Hughes, D H; Aretxaga, I; Kim, S; Scott, K S; Austermann, J; Perera, T; Lowenthal, J D

    2009-01-01

    We present results from a continuing interferometric survey of high-redshift submillimeter galaxies with the Submillimeter Array, including high-resolution (beam size ~2 arcsec) imaging of eight additional AzTEC 1.1mm selected sources in the COSMOS Field, for which we obtain six reliable (peak 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 followup. With this sample in hand, we (1) empirically confirm the radio-submillimeter association, (2) examine the submillimeter morphology - including the nature of submillimeter galaxies 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 submillimeter galaxies that peaks at higher redshift than previous, radio-selected samples. I...

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

    We identify nine galaxies with dynamical masses of M dyn ∼> 1010 M ☉ 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 e,c e,c = 0.74 kpc) for their velocity dispersion (110 –1; median σ = 178 km s–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

  1. Ultraviolet HST Snapshot Survey of 3CR Radio Source Counterparts at Low Redshift

    Allen, M G; Koekemoer, A M; Martel, A R; O'Dea, C P; Baum, S A; Chiaberge, M; Macchetto, F D; Miley, G K; Allen, Mark G.; Sparks, William B.; Koekemoer, Anton; Martel, Andre R.; O'dea, Christopher P.; Baum, Stefi A.; Chiaberge, Marco; Miley, George K.

    2001-01-01

    We present ultraviolet images of 27 3CR radio galaxies with redshifts z<0.1 that have been imaged with the Space Telescope Imaging Spectrograph (STIS) on board the Hubble Space Telescope (HST). The observations employed the NUV-MAMA and broad-band filters with peak sensitivity at 2200A . We find that the UV luminosities show approximately a factor of 10 to 100 higher dispersion than the optical. We compare the UV morphologies with optical V- and R-band WFPC2 snapshot survey images. We have found dramatic, complex and extended ultraviolet emission from radio galaxies even at zero redshift. We find a diverse range of UV morphologies, some completely divergent from their visual morphology, which are reminiscent of the chaotic high-z radio galaxies structures seen in rest-frame UV. The UV morphologies show regions of star formation, jets, and possible scattered AGN continuum. The UV emission is generally not aligned with the radio structure. We also detect the diffuse UV emission of the host galaxy. We propose...

  2. Massive Structures of Galaxies at High Redshifts in the Great Observatories Origins Deep Survey Fields

    Kang, Eugene

    2016-01-01

    If the Universe is dominated by cold dark matter and dark energy as in the currently popular LCDM cosmology, it is expected that large scale structures form gradually, with galaxy clusters of mass M > ~10^14 Msun appearing at around 6 Gyrs after the Big Bang (z ~ 1). Here, we report the discovery of 59 massive structures of galaxies with masses greater than a few x 10^13 Msun at redshifts between z=0.6 and 4.5 in the Great Observatories Origins Deep Survey fields. The massive structures are identified by running top-hat filters on the two dimensional spatial distribution of magnitude-limited samples of galaxies using a combination of spectroscopic and photometric redshifts. We analyze the Millennium simulation data in a similar way to the analysis of the observational data in order to test the LCDM cosmology. We find that there are too many massive structures (M > 7 x 10^13 Msun) observed at z > 2 in comparison with the simulation predictions by a factor of a few, giving a probability of < 1/2500 of the ob...

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

    We present Keck spectroscopic observations and redshifts for a sample of 767 Herschel-SPIRE selected galaxies (HSGs) at 250, 350, and 500 μm, 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 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 μm flux densities. By probing the dust spectral energy distribution (SED) at its peak, we estimate that the vast majority (72%-83%) of z IR∝(1 + z)–0.30±0.02 at z > 0 and demonstrates the growing importance of dusty starbursts for galaxy evolution studies and the build-up of stellar mass throughout cosmic time.

  4. Critical analysis of the luminosity functions per galaxy type measured from redshift surveys

    De Lapparent, V

    2003-01-01

    [ABRIDGED] I perform a detailed comparison of the shape of the optical luminosity functions as a function of galaxy class and filter, which have been obtained from redshift surveys with an effective depth ranging from z~0.01 to z~0.6. This analysis is based on the M* and alpha Schechter parameters. I provide complete tables of all existing measurements, converted into the UBVRcIc Johnson-Cousins system wherever necessary. By using as reference the intrinsic luminosity functions per morphological type measured from local galaxy concentrations (Jerjen et al 1997), I establish that the variations in the luminosity functions from survey to survey and among the galaxy classes are related to the criteria for galaxy classification used in the surveys, as these determine the amount of mixing of the morphological types within a given class. When using a spectral classification with inaccurate spectrophotometric calibrations, the luminosity functions are biased by type contamination with a smooth variation from type to...

  5. The WiggleZ Dark Energy Survey: Direct constraints on blue galaxy intrinsic alignments at intermediate redshifts

    Mandelbaum, Rachel; Bridle, Sarah; Abdalla, Filipe B; Brough, Sarah; Colless, Matthew; Couch, Warrick; Croom, Scott; Davis, Tamara; Drinkwater, Michael J; Forster, Karl; Glazebrook, Karl; Jelliffe, Ben; Jurek, Russell J; Li, Tornado; Madore, Barry; Martin, Chris; Pimbblet, Kevin; Poole, Gregory B; Pracy, Michael; Sharp, Rob; Wisnioski, Emily; Woods, David; Wyder, Ted

    2009-01-01

    Correlations between the intrinsic shapes of galaxy pairs, and between the intrinsic shapes of galaxies and the large-scale density field, may be induced by tidal fields. These correlations, which have been detected at low redshifts (z<0.35) for bright red galaxies in the Sloan Digital Sky Survey (SDSS), and for which upper limits exist for blue galaxies at z~0.1, provide a window into galaxy formation and evolution, and are also an important contaminant for current and future weak lensing surveys. Measurements of these alignments at intermediate redshifts (z~0.6) that are more relevant for cosmic shear observations are very important for understanding the origin and redshift evolution of these alignments, and for minimising their impact on weak lensing measurements. We present the first such intermediate-redshift measurement for blue galaxies, using galaxy shape measurements from SDSS and spectroscopic redshifts from the WiggleZ Dark Energy Survey. Our null detection allows us to place upper limits on the...

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

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

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

    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 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 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 lower redshift measurements and find that the clustering strength is not inconsistent with that of low-redshift L* spirals for simple 'long-lived' galaxy models. Based on data obtained with the National Optical Astronomy Observatories (NOAO) Mayall 4-m Telescope at Kitt Peak National Observatory, USA (programme ID: 06A-0133), the NOAO Blanco 4-m Telescope at

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

    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.

  9. The Sloan Digital Sky Survey Reverberation Mapping Project: Biases in z>1.46 Redshifts due to Quasar Diversity

    Denney, K D; Brandt, W N; Grier, C J; Ho, Luis C; Peterson, B M; Trump, J R; Ge, J

    2016-01-01

    We use the coadded spectra of 32 epochs of Sloan Digital Sky Survey (SDSS) Reverberation Mapping Project observations of 482 quasars with z>1.46 to highlight systematic biases in the SDSS- and BOSS-pipeline redshifts due to the natural diversity of quasar properties. We investigate the characteristics of this bias by comparing the BOSS-pipeline redshifts to an estimate from the centroid of HeII 1640. HeII has a low equivalent width but is often well-defined in high-S/N spectra, does not suffer from self-absorption, and has a narrow component that, when present (the case for about half of our sources), produces a redshift estimate that, on average, is consistent with that determined from [OII] to within 1-sigma of the quadrature sum of the HeII and [OII] centroid measurement uncertainties. The large redshift differences of ~1000 km/s, on average, between the BOSS-pipeline and HeII-centroid redshifts suggest there are significant biases in a portion of BOSS quasar redshift measurements. Adopting the HeII-based ...

  10. The VIMOS Public Extragalactic Redshift Survey (VIPERS). The coevolution of galaxy morphology and colour to z~1

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

    2016-01-01

    We explore the evolution of the statistical distribution of galaxy morphological properties and colours over the redshift range $0.5Survey with the large number of redshifts and extended photometry from the VIPERS survey. Galaxy structural parameters are measured by fitting S\\'ersic profiles to $i$-band images and then combined with absolute magnitudes, colours and redshifts, to trace the evolution in a multi-parameter space. We analyse, using a new method, the combination of colours and structural parameters of early- and late-type galaxies in luminosity--redshift space. We found that both the rest-frame colour distributions in the (U-B) vs. (B-V) plane and the S\\'ersic index distributions are well fitted by a sum of two Gaussians, with a remarkable consistency of red-spheroidal and blue-disky galaxy populations, over the explored redshift ($0.5

  11. Bright galaxies at Hubble's redshift detection frontier: Preliminary results and design from the redshift z~9-10 BoRG pure-parallel HST survey

    Calvi, V; 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

    2015-01-01

    We present the first results and design from the redshift z~9-10 Brightest of the Reionizing Galaxies {\\it 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 {\\lambda}=0.35{\\mu}m to {\\lambda}=1.7{\\mu}m. We analyze the initial ~130 arcmin$^2$ of area over 28 independent lines of sight (~25% of the total planned) to search for z>7 galaxies using a combination of Lyman break and photometric redshift selections. From an effective comoving volume of (5-25) $times 10^5$ Mpc$^3$ for magnitudes brighter than $m_{AB}=26.5-24.0$ in the $H_{160}$-band respectively, we find five galaxy candidates at z~8.3-10 detected at high confidence (S/N>8), including a sour...

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

    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 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 zrelate 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 observations collected at the European Southern Observatory, Cerro Paranal, Chile, using the Very Large Telescope under

  13. Analytic Photometric Redshift Estimator for Type Ia Supernovae From the Large Synoptic Survey Telescope

    Wang, Yun; Kuhlmann, S

    2015-01-01

    Accurate and precise photometric redshifts (photo-z's) 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 (2007) and further developed by Wang, Narayan, and Wood-Vasey (2007). 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-z's, \\sigma(z_{phot})/(1+z_{phot}), can be used as filters to produce a set of photo-z's that have high precision, accuracy, and purity. Using SN Ia colors as well as SN Ia peak magnitude in the $i$ band, we obtain a set of photo-z's with 2 percent accuracy (with \\sigma(z_{phot}-z_{spec})/(1+z_{spec}) = 0.02), a bias in z_{phot} (the mean of z_{phot}-z_{spec}) of -9 X 10^{-5}, and an outlier fraction...

  14. The 2dF Galaxy Redshift Survey: higher order galaxy correlation functions

    Croton, D J; Baugh, C M; Norberg, P; Colless, M; 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 P; Ellis, Richard 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; Dziarmaga, Jacek

    2004-01-01

    We measure moments of the galaxy count probability distribution function in the two-degree field galaxy redshift survey (2dFGRS). The survey is divided into volume limited subsamples in order to examine the dependence of the higher order clustering on galaxy luminosity. We demonstrate the hierarchical scaling of the averaged p-point galaxy correlation functions, xibar_p, up to p=6. The hierarchical amplitudes, S_p = xibar_p/xibar_2^{p-1}, are approximately independent of the cell radius used to smooth the galaxy distribution on small to medium scales. On larger scales we find the higher order moments can be strongly affected by the presence of rare, massive superstructures in the galaxy distribution. The skewness S_3 has a weak dependence on luminosity, approximated by a linear dependence on log luminosity. We discuss the implications of our results for simple models of linear and non-linear bias that relate the galaxy distribution to the underlying mass.

  15. The ALHAMBRA Survey: Bayesian Photometric Redshifts with 23 bands for 3 squared degrees

    Molino, A; Moles, M; Fernández-Soto, A; Cristóbal-Hornillos, D; Ascaso, B; Jiménez-Teja, Y; Schoenell, W; Arnalte-Mur, P; Pović, M; Coe, D; López-Sanjuan, C; Díaz-García, L A; Varela, J; Matute, I; Masegosa, J; Márquez, I; Perea, J; Del Olmo, A; Husillos, C; Alfaro, E; Aparicio-Villegas, T; Cerviño, M; Huertas-Company, M; Aguerri, A L; Broadhurst, T; Cabrera-Caño, J; Cepa, J; Delgado, R M González; Infante, L; Martínez, V J; Prada, F; Quintana, J M

    2013-01-01

    The ALHAMBRA (Advance Large Homogeneous Area Medium Band Redshift Astronomical) survey has observed 8 different regions of the sky, including sections of the COSMOS, DEEP2, ELAIS, GOODS-N, SDSS and Groth fields using a new photometric system with 20 contiguous ~ $300\\AA$ filters covering the optical range, combining them with deep $JHKs$ imaging. The observations, carried out with the Calar Alto 3.5m telescope using the wide field (0.25 sq. deg FOV) optical camera LAICA and the NIR instrument Omega-2000, correspond to ~700hrs on-target science images. The photometric system was designed to maximize the effective depth of the survey in terms of accurate spectral-type and photo-zs estimation along with the capability of identification of relatively faint emission lines. Here we present multicolor photometry and photo-zs for ~438k galaxies, detected in synthetic F814W images, complete down to I~24.5 AB, taking into account realistic noise estimates, and correcting by PSF and aperture effects with the ColorPro so...

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

    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.

  17. A Study of Selection Methods for H alpha Emitting Galaxies at z~1.3 for the Subaru/FMOS Galaxy Redshift Survey for Cosmology (FastSound)

    Tonegawa, Motonari; Totani, Tomonori; Akiyama, Masayuki; Dalton, Gavin; Glazebrook, Karl; Iwamuro, Fumihide; Sumiyoshi, Masanao; Tamura, Naoyuki; Yabe, Kiyoto; Coupon, Jean; Goto, Tomotsugu; Spitler, Lee R.

    2013-01-01

    The efficient selection of high-redshift emission galaxies is important for future large galaxy redshift surveys for cosmology. Here we describe the target selection methods for the FastSound project, a redshift survey for H alpha emitting galaxies at z=1.2-1.5 using Subaru/FMOS to measure the linear growth rate f\\sigma 8 via Redshift Space Distortion (RSD) and constrain the theory of gravity. To select ~400 target galaxies in the 0.2 deg^2 FMOS field-of-view from photometric data of CFHTLS-W...

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

    This is the second paper in a series aimed at finding high-redshift quasars from five-color (u' g' r' i' z') 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 ∼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* B 0 =0.5). Several of the quasars show unusual emission and absorption features in their spectra, including an object at z=4.62 without detectable emission lines, and a broad absorption line (BAL) quasar at z=4.92. (c) (c) 2000. The American Astronomical Society

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

    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. The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey : mock galaxy catalogues for the low-redshift sample

    Manera, Marc; Samushia, Lado; Tojeiro, Rita; Howlett, Cullan; Ross, Ashley J.; Percival, Will J.; Gil-Marín, Hector; Brownstein, Joel R.; Burden, Angela; Montesano, Francesco

    2015-01-01

    MM and WJP acknowledge support from European Research Council, through grant ‘MDEPUGS’. We present 1000 mock galaxy catalogues (mocks) for the analysis of the low-redshift sample (LOWZ; effective redshift z ˜ 0.32) of the Baryon Oscillation Spectroscopic Survey (BOSS) Data Releases 10 and 11. These mocks have been created following the PTHalos method revised to include new developments. The main improvement is the introduction of a redshift dependence in the halo occupation distribution in...

  1. The zCOSMOS Redshift Survey: How group environment alters global downsizing trends

    Iovino, A; Scodeggio, M; Knobel, C; Kovac, 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; Pérez-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

    2009-01-01

    We took advantage of the wealth of information provided by the first ~10000 galaxies of the zCOSMOS-bright survey and its group catalogue to study the complex interplay between group environment and galaxy properties. The classical indicator F_blue (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. Using rest-frame B-band selected samples, the groups galaxy population exhibits significant blueing as redshift increases, but maintains a lower F_blue with respect both to the global and 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 focusing the analysis on narrow mass bins such that mass segregation becomes negligible we find th...

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

    Tiley, Alfred L; 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

    2016-01-01

    We present the stellar mass ($M_{*}$), and K-corrected $K$-band absolute magnitude ($M_{K}$) Tully-Fisher relations (TFRs) for sub-samples of the 584 galaxies spatially resolved in H$\\alpha$ 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, $V_{80}$ at a radius equal to the major axis of an ellipse containing 80% of the total integrated H$\\alpha$ 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 $V_{80}/\\sigma > 3$, where $\\sigma$ is the flux weighted average velocity dispersion. We find the $M_{K}$ and $M_{*}$ TFRs for this sub-sample to be $M_{K} / \\rm{mag}= (-7.3 \\pm 0.9) \\times [(\\log(V_{80}/\\rm{km\\ s^{-1}})-2.25]- 23.4 \\pm 0.2$ , and $\\log(M_{*} / M_{\\odot})= (4.7 \\pm 0.4) \\times [(\\log(V_{80}/\\rm{km\\ s^{-1}}) - 2.25] + 10.0 \\pm 0.3$,...

  3. The 2dF Galaxy Redshift Survey: Clustering properties of radio galaxies

    Magliocchetti, M; Hawkins, E; Peacock, J A; Bland-Hawthorn, J; Bridges, T J; Cannon, R; Cole, S; Colless, M; Collins, C; Couch, W; Dalton, G B; De Propris, R; Driver, S P; Efstathiou, G P; Ellis, Richard S; Frenk, C S; Glazebrook, K; Jackson, C A; Jones, B; Lahav, O; Lewis, I; Lumsden, S; Norberg, P; Peterson, B A; Sutherland, W; Taylor, K; Magliocchetti, Manuela; Maddox, Steve J.; Hawkins, Ed; Peacock, John A.; Bland-Hawthorn, Joss; Bridges, Terry; Cannon, Russell; Cole, Shaun; Colless, Matthew; Collins, Chris; Couch, Warrick; Dalton, Gavin; Propris, Roberto de; Driver, Simon P.; Efstathiou, George; Ellis, Richard S.; Frenk, Carlos S.; Glazebrook, Karl; Jackson, Carole A.; Jones, Bryn; Lahav, Ofer; Lewis, Ian; Lumsden, Stuart; Norberg, Peder; Peterson, Bruce A.; Sutherland, Will; Taylor, Keith

    2004-01-01

    The clustering properties of local, S_{1.4 GHz} > 1 mJy, radio sources are investigated for a sample of 820 objects drawn from the joint use of the FIRST and 2dF Galaxy Redshift surveys. To this aim, we present 271 new bj < 19.45 spectroscopic counterparts of FIRST radio sources to be added to those already introduced in Magliocchetti et al. (2002). The two-point correlation function for the local radio population is found to be entirely consistent with estimates obtained for the whole sample of 2dFGRS galaxies. We estimate the parameters of the real-space correlation function xi(r)=(r/r_0)^{-\\gamma}, r_0=6.7^{+0.9}_{-1.1} Mpc and \\gamma=1.6\\pm 0.1, where h=0.7 is assumed. Different results are instead obtained if we only consider sources that present signatures of AGN activity in their spectra. These objects are shown to be very strongly correlated, with r_0=10.9^{+1.0}_{-1.2} Mpc and \\gamma=2\\pm 0.1, a steeper slope than has been claimed in other recent works. No difference is found in the clustering pro...

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

    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. zCOSMOS: A Large VLT/VIMOS redshift survey covering 0 < z < 3 in the COSMOS field

    Lilly, S. J.; Fevre, O. Le; Renzini, A.; Zamorani, G.; Scodeggio, M.; Contini, T.; Carollo, C. M.; G. Hasinger(JHU); Kneib, J. -P.; Iovino, A.; Brun, V. Le; Maier, C.; Mainieri, V.; Mignoli, M.; Silverman, J.

    2006-01-01

    zCOSMOS is a large redshift survey that is being undertaken in the COSMOS field using 600 hours of observation with the VIMOS spectrograph on the 8-m VLT. The survey is designed to characterise the environments of COSMOS galaxies from the 100 kpc scales of galaxy groups up to the 100 Mpc scale of the cosmic web and to produce diagnostic information on galaxies and active galactic nuclei. The zCOSMOS survey consists of two parts: (a) zCOSMOS-bright, a magnitude-limited I-band IAB < 22.5 sample...

  6. zCOSMOS: A large VLT/VIMOS redshift survey covering 0 < z < 3 in the COSMOS field

    Lilly, S. J.; Capak, P.; Scoville, N.; Shopbell, P.; THOMPSON, D

    2007-01-01

    zCOSMOS is a large-redshift survey that is being undertaken in the COSMOS field using 600 hr of observation with the VIMOS spectrograph on the 8 m VLT. The survey is designed to characterize the environments of COSMOS galaxies from the 100 kpc scales of galaxy groups up to the 100 Mpc scale of the cosmic web and to produce diagnostic information on galaxies and active galactic nuclei. The zCOSMOS survey consists of two parts: (1) zCOSMOSbright, a magnitude-limited I-band I_(AB) < ...

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

    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.

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

    Sutter, P. M.; Wandelt, Benjamin D. [Department of Physics, University of Illinois at Urbana-Champaign, Urbana, IL 61801 (United States); Lavaux, Guilhem [Department of Physics and Astronomy, University of Waterloo, Waterloo, ON N2L 3G1 (Canada); Weinberg, David H. [Center for Cosmology and Astro-Particle Physics, Ohio State University, Columbus, OH 43210 (United States)

    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.

  9. A survey of luminous high-redshift quasars with SDSS and WISE. I. target selection and optical spectroscopy

    Wang, Feige; Fan, Xiaohui; Yang, Jinyi; Yi, Weimin; Bian, Fuyan; McGreer, Ian D; Yang, Qian; Ai, Yanli; Dong, Xiaoyi; Zuo, Wenwen; Jiang, Linhua; Green, Richard; Wang, Shu; Cai, Zheng; Wang, Ran; Yue, Minghao

    2016-01-01

    High-redshift quasars are important tracers of structure and evolution in the early universe. However, they are very rare and difficult to find when using color selection because of contamination from late-type dwarfs. High-redshift quasar surveys based on only optical colors suffer from incompleteness and low identification efficiency, especially at $z\\gtrsim4.5$. We have developed a new method to select $4.7\\lesssim z \\lesssim 5.4$ quasars with both high efficiency and completeness by combining optical and mid-IR Wide-field Infrared Survey Explorer (WISE) photometric data, and are conducting a luminous $z\\sim5$ quasar survey in the whole Sloan Digital Sky Survey (SDSS) footprint. We have spectroscopically observed 99 out of 110 candidates with $z$-band magnitudes brighter than 19.5 and 64 (64.6\\%) of them are quasars with redshifts of $4.4\\lesssim z \\lesssim 5.5$ and absolute magnitudes of $-29\\lesssim M_{1450} \\lesssim -26.4$. In addition, we also observed 14 fainter candidates selected with the same crite...

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

    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 effectively separate under-dense from over-dense regions by considering cells in the 1st and 5th quintiles of the probability distribution of the observed counts. Conclusions: We show that despite systematic uncertainties, it is possible to reconstruct the lowest and highest density environments on scales of 5 h-1 Mpc at moderate redshifts 0.5 ≲ z ≲ 1.1, over a large volume such as the one covered by the VIPERS survey. This is vital for characterising cosmic variance and rare populations (e.g, brightest galaxies) in environmental studies at these redshifts. Based on observations collected at the European Southern Observatory, Cerro Paranal, Chile, using the Very Large Telescope under programs 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 website is http://www.vipers.inaf.it/Appendix A is available in electronic form at http://www.aanda.org

  11. The Northern Sky Optical Cluster Survey IV: An Intermediate Redshift Galaxy Cluster Catalog and the Comparison of Two Detection Algorithms

    Lopes, P A A

    2004-01-01

    We present an optically selected galaxy cluster catalog from ~ 2,700 square degrees of the Digitized Second Palomar Observatory Sky Survey (DPOSS), spanning the redshift range 0.1 50), where stellar contamination is modest and nearly uniform. We also present a performance comparison of two different detection methods applied to this data, the Adaptive Kernel and Voronoi Tessellation techniques. In the regime where both catalogs are expected to be complete, we find excellent agreement, as well as with the most recent surveys in the literature. Extensive simulations are performed and applied to the two different methods, indicating a contamination rate of ~ 5%. These simulations are also used to optimize the algorithms and evaluate the selection function for the final cluster catalog. Redshift and richness estimates are also provided, making possible the selection of subsamples for future studies.

  12. Clustering of Low-Redshift (z <= 2.2) Quasars from the Sloan Digital Sky Survey

    Ross, Nicholas P; Strauss, Michael A; Berk, Daniel E Vanden; Connolly, Andrew J; Richards, Gordon T; Schneider, Donald P; Weinberg, David H; Hall, Patrick B; Bahcall, Neta A; Brunner, Robert J

    2009-01-01

    We present measurements of the quasar two-point correlation function, \\xi_{Q}, over the redshift range z=0.3-2.2 based upon data from the SDSS. Using a homogeneous sample of 30,239 quasars with spectroscopic redshifts from the DR5 Quasar Catalogue, our study represents the largest sample used for this type of investigation to date. With this redshift range and an areal coverage of approx 4,000 deg^2, we sample over 25 h^-3 Gpc^3 (comoving) assuming the current LCDM cosmology. Over this redshift range, we find that the redshift-space correlation function, xi(s), is adequately fit by a single power-law, with s_{0}=5.95+/-0.45 h^-1 Mpc and \\gamma_{s}=1.16+0.11-0.16 when fit over s=1-25 h^-1 Mpc. Using the projected correlation function we calculate the real-space correlation length, r_{0}=5.45+0.35-0.45 h^-1 Mpc and \\gamma=1.90+0.04-0.03, over scales of rp=1-130 h^-1 Mpc. Dividing the sample into redshift slices, we find very little, if any, evidence for the evolution of quasar clustering, with the redshift-spac...

  13. QSO Photometric Redshift estimation for the XMM-Newton/2dF Survey

    Kitsionas, S; Georgantopoulos, I; Georgakakis, A; Giannakis, O

    2003-01-01

    The technique of estimating redshifts using photometric rather than spectroscopic observations has recently received great attention due to its simplicity and the accuracy of the results obtained. In this work, we estimate photometric redshifts for an X-ray selected QSO sample. This is the first time this technique is applied on such a sample. We first calculate the accuracy of the results obtained by comparing photometric to spectroscopic redshifts for a sub-sample of our QSO sample: for the majority (~67%) of the objects in this sub-sample, photometric redshift estimates are correct within Dz<0.3. We then derive the photometric redshift distribution for the whole QSO sample. In the future, we expect to use the photometric redshift distribution in order to derive the distributions of properties such as the Hardness Ratio and hence the hydrogen column density, the luminosity function etc. As an example, we estimate here the dependence of the Hardness Ratio of the QSO sample on photometric redshift.

  14. The VIMOS Ultra-Deep Survey: ~10,000 galaxies with spectroscopic redshifts to study galaxy assembly at early epochs 2

    Fevre, O Le; Cassata, P; Garilli, B; Brun, V Le; Maccagni, D; Pentericci, L; Thomas, R; Vanzella, E; Zamorani, G; Zucca, E; Amorin, R; Bardelli, S; Capak, P; Cassara, 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; Fotopoulo, S; Lopez-Sanjuan, C; Mellier, Y; Scoville, N

    2014-01-01

    We present the VIMOS Ultra Deep Survey (VUDS), a spectroscopic redshift survey of ~10.000 very faint galaxies to study the major phase of galaxy assembly 2survey covers 1 deg^2 in 3 separate fields: COSMOS, ECDFS and VVDS-02h, with targets selection based on an inclusive combination of photometric redshifts and color properties. Spectra covering 3650survey strategy, the target selection, the data processing, as well as the redshift measurement process, emphasizing the specific methods adapted to this high redshift range. The spectra quality and redshift reliability are discussed, and we derive a completeness in redshift measurement of 91%, or 74% for the most reliable measurements, down to i_AB=25, and measurements are performed all the way down to i_AB=27. The redshift distribution of the main sample peaks at z=3-4 and extends over a large redshift range mainly in 2 < z < 6. A...

  15. H{alpha} EQUIVALENT WIDTHS FROM THE 3D-HST SURVEY: EVOLUTION WITH REDSHIFT AND DEPENDENCE ON STELLAR MASS

    Fumagalli, Mattia; Patel, Shannon G.; Franx, Marijn; Labbe, Ivo [Leiden Observatory, Leiden University, P.O. Box 9513, 2300-RA Leiden (Netherlands); Brammer, Gabriel [European Southern Observatory, Alonso de Cordova 3107, Casilla 19001, Vitacura, Santiago (Chile); Van Dokkum, Pieter; Lundgren, Britt; Momcheva, Ivelina; Skelton, Rosalind E.; Whitaker, Katherine E.; Nelson, Erica [Department of Astronomy, Yale University, New Haven, CT 06511 (United States); Da Cunha, Elisabete; Rix, Hans-Walter; Schmidt, Kasper B. [Max Planck Institute for Astronomy (MPIA), Koenigstuhl 17, D-69117 Heidelberg (Germany); Kriek, Mariska [Department of Astronomy, University of California, Berkeley, CA 94720 (United States)

    2012-10-01

    We investigate the evolution of the H{alpha} equivalent width, EW(H{alpha}), with redshift and its dependence on stellar mass, using the first data from the 3D-HST survey, a large spectroscopic Treasury program with the Hubble Space Telescope Wide Field Camera 3. Combining our H{alpha} measurements of 854 galaxies at 0.8 < z < 1.5 with those of ground-based surveys at lower and higher redshift, we can consistently determine the evolution of the EW(H{alpha}) distribution from z = 0 to z = 2.2. We find that at all masses the characteristic EW(H{alpha}) is decreasing toward the present epoch, and that at each redshift the EW(H{alpha}) is lower for high-mass galaxies. We find EW(H{alpha}) {approx}(1 + z){sup 1.8} with little mass dependence. Qualitatively, this measurement is a model-independent confirmation of the evolution of star-forming galaxies with redshift. A quantitative conversion of EW(H{alpha}) to specific star formation rate (sSFR) is model dependent because of differential reddening corrections between the continuum and the Balmer lines. The observed EW(H{alpha}) can be reproduced with the characteristic evolutionary history for galaxies, whose star formation rises with cosmic time to z {approx} 2.5 and then decreases to z = 0. This implies that EW(H{alpha}) rises to 400 A at z = 8. The sSFR evolves faster than EW(H{alpha}), as the mass-to-light ratio also evolves with redshift. We find that the sSFR evolves as (1 + z){sup 3.2}, nearly independent of mass, consistent with previous reddening insensitive estimates. We confirm previous results that the observed slope of the sSFR-z relation is steeper than the one predicted by models, but models and observations agree in finding little mass dependence.

  16. Monster Redshift Surveys through Dispersive Slitless Imaging: The Baryon Oscillation Probe

    Glazebrook, Karl; Baldry, Ivan; Moos, Warren; Kruk, Jeff; McCandliss, Stephan

    2004-01-01

    Wide-field imaging from space should not forget the dispersive dimension. We consider the capability of space-based imaging with a slitless grism: because of the low near-infrared background in space and the high sky-density of high redshift emission line galaxies this makes for a very powerful redshift machine with no moving parts. A small 1m space telescope with a 0.5 degree field of view could measure redshifts for 10^7 galaxies at 0.5

  17. The 2dF Galaxy Redshift Survey: Power-spectrum analysis of the final dataset and cosmological implications

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

    2005-01-01

    We present a power spectrum analysis of the final 2dF Galaxy Redshift Survey, employing a direct Fourier method. The sample used comprises 221,414 galaxies with measured redshifts. We investigate in detail the modelling of the sample selection. A new angular mask is derived, based on revisions to the photometric calibration. The redshift selection function is determined by dividing the survey according to rest-frame colour, and deducing a self-consistent treatment of k-corrections and evolution for each population. The covariance matrix for the power-spectrum estimates is determined using two different approaches to the construction of mock surveys which are used to demonstrate that the input cosmological model can be correctly recovered. We are confident that the 2dFGRS power spectrum can be used to infer the matter content of the universe. On large scales, our estimated power spectrum shows evidence for the `baryon oscillations' that are predicted in CDM models. Fitting to a CDM model, assuming a primordial...

  18. Coherent Combination of Baryon Acoustic Oscillation Statistics and Peculiar Velocity Measurements from Redshift Survey

    Song, Yong-Seon

    2010-01-01

    New statistical method is proposed to coherently combine Baryon Acoustic Oscillation statistics (BAO) and peculiar velocity measurements exploiting decomposed density-density and velocity-velocity spectra in real space from the observed redshift distortions in redshift space, 1) to achieve stronger dark energy constraints, \\sigma(w)=0.06 and \\sigma(w_a)=0.20, which are enhanced from BAO or velocity measurements alone, and 2) to cross-check consistency of dark energy constraints from two diffe...

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

    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_{{*}} / 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.

  20. The SCUBA HAlf Degree Extragalactic Survey (SHADES) - IV: Radio-mm-FIR photometric redshifts

    Aretxaga, I; Coppin, K; Mortier, A M J; Wagg, J; Dunlop, J S; Chapin, E L; Eales, S A; Gaztañaga, E; Halpern, M; Ivison, R J; van Kampen1, E; Scott, D; Serjeant, S; Smail, I; Babbedge, T; Benson, A J; Chapman, S; Clements, D L; Dunne, L; Dye, S; Farrah, D; Jarvis, M J; Mann, R G; Pope, A; Priddey, R; Rawlings, S; Seigar, M; Silva, L; Simpson, C; Vaccari, M; Aretxaga, Itziar; Hughes, David H.; Coppin, Kristen; Mortier, Angela M.J.; Wagg, Jeff; Dunlop, James S.; Chapin, Edward L.; Eales, Stephen A.; Gaztanaga, Enrique; Halpern, Mark; Ivison, Rob J.; Kampen1, Eelco van; Scott, Douglas; Serjeant, Stephen; Smail, Ian; Babbedge, Thomas; Benson, Andrew J.; Chapman, Scott; Clements, David L.; Dunne, Loretta; Dye, Simon; Farrah, Duncan; Jarvis, Matthew J.; Mann, Robert G.; Pope, Alexandra; Priddey, Robert; Rawlings, Steve; Seigar, Marc; Silva, Laura; Simpson, Chris; Vaccari, Mattia

    2007-01-01

    We present the redshift distribution of the SHADES galaxy population based on the rest-frame radio-mm-FIR colours of 120 robustly detected 850um sources in the Lockman Hole East (LH) and Subaru XMM-Newton Deep Field (SXDF). The redshift distribution derived from the full SED information is shown to be narrower than that determined from the radio-submm spectral index, as more photometric bands contribute to higher redshift accuracies. The redshift of sources derived from at least two photometric bands peaks at z ~ 2.4 and has a near-Gaussian distribution, with 50 per cent (interquartile) of sources at z=1.8-3.1. We find a statistically-significant difference between the measured redshift distributions in the two fields; the SXDF peaking at a slightly lower redshift (median z ~ 2.2) than the LH (median z ~ 2.7), which we attribute to the noise-properties of the photometric observations. We demonstrate however that there could also be field-to-field variations that are consistent with the measured differences in...

  1. The Subaru FMOS Galaxy Redshift Survey (FastSound). I. Overview of the Survey Targeting on H$\\alpha$ Emitters at $z \\sim 1.4$

    Tonegawa, Motonari; Okada, Hiroyuki; Akiyama, Masayuki; Dalton, Gavin; Glazebrook, Karl; Iwamuro, Fumihide; Maihara, Toshinori; Ohta, Kouji; Shimizu, Ikkoh; Takato, Naruhisa; Tamura, Naoyuki; Yabe, Kiyoto; Bunker, Andrew J; Coupon, Jean; Ferreira, Pedro G; Frenk, Carlos S; Goto, Tomotsugu; Hikage, Chiaki; Ishikawa, Takashi; Matsubara, Takahiko; More, Surhud; Okumura, Teppei; Percival, Will J; Spitler, Lee R; Szapudi, Istvan

    2015-01-01

    FastSound is a galaxy redshift survey using the near-infrared Fiber Multi-Object Spectrograph (FMOS) mounted on the Subaru Telescope, targeting H$\\alpha$ emitters at $z \\sim 1.18$--$1.54$ down to the sensitivity limit of H$\\alpha$ flux $\\sim 2 \\times 10^{-16} \\ \\rm erg \\ cm^{-2} s^{-1}$. The primary goal of the survey is to detect redshift space distortions (RSD), to test General Relativity by measuring the growth rate of large scale structure and to constrain modified gravity models for the origin of the accelerated expansion of the universe. The target galaxies were selected based on photometric redshifts and H$\\alpha$ flux estimates calculated by fitting spectral energy distribution (SED) models to the five optical magnitudes of the Canada France Hawaii Telescope Legacy Survey (CFHTLS) Wide catalog. The survey started in March 2012, and all the observations were completed in July 2014. In total, we achieved $121$ pointings of FMOS (each pointing has a $30$ arcmin diameter circular footprint) covering $20.6...

  2. The LABOCA survey of the Extended Chandra Deep Field South: A photometric redshift survey of submillimetre galaxies

    Wardlow, J L; Coppin, K E K; Alexander, D M; Brandt, W N; Danielson, A L R; Luo, B; Swinbank, A M; Walter, F; Weiss, A; Xue, Y Q; Zibetti, S; Bertoldi, F; Biggs, A D; Chapman, S C; Dannerbauer, H; Dunlop, J S; Gawiser, E; Ivison, R J; Knudsen, K K; Kovacs, A; Lacey, C G; Menten, K M; Padilla, N; Rix, H -W; van der Werf, P P

    2010-01-01

    [abridged] We derive photometric redshifts from 17-band optical to mid-IR photometry of 74 robust counterparts to 68 of the 126 submillimetre galaxies (SMGs) selected at 870um by LABOCA observations in the ECDFS. The median photometric redshift of identified SMGs is z=2.2\\pm0.1, the interquartile range is z=1.8-2.7 and we identify 10 (~15%) high-redshift (z>3) SMGs. We derive a simple redshift estimator for SMGs based on the 3.6 and 8um fluxes, which is accurate to Delta_z~0.4 for SMGs at z3 and hence ~30% of all SMGs have z>3. We estimate that the full S_870um>4mJy SMG population has a median redshift of 2.5\\pm0.6. In contrast to previous suggestions we find no significant correlation between S_870um and redshift. The median stellar mass of the SMGs derived from SED fitting is (9.2\\pm0.9)x10^10Msun and the interquartile range is (4.7-14)x10^10Msun, although we caution that uncertainty in the star-formation histories results in a factor of ~5 uncertainty in these stellar masses. The median characteristic dust...

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

    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.

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

    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

  5. The optically unbiased GRB host (TOUGH) survey. V. VLT/X-shooter emission-line redshifts for Swift GRBs at z~2

    Krühler, Thomas; Milvang-Jensen, Bo; Fynbo, Johan P U; Hjorth, Jens; Jakobsson, Páll; Levan, Andrew J; Sparre, Martin; Tanvir, Nial R; Watson, Darach J

    2012-01-01

    We present simultaneous optical and near-infrared (NIR) spectroscopy of 19 Swift GRB host galaxies with VLT/X-shooter with the aim of measuring their redshifts. Galaxies were selected from The Optically Unbiased GRB Host (TOUGH) survey (15 of the 19 galaxies) or because they hosted GRBs without a bright optical afterglow. Here, we provide emission-line redshifts for 13 of the observed galaxies with brightnesses between F606W > 27 mag and R=22.9 mag (median R=24.6 mag). The median redshift is z=2.1 for all, and z=2.3 for the TOUGH hosts. Our new data significantly improve the redshift completeness of the TOUGH survey, which now stands at 77% (53 out of 69 GRBs). They furthermore provide accurate redshifts for eight prototype-dark GRBs (e.g., GRBs 071021 at z=2.452 and 080207 at z=2.086), which are exemplary of GRBs where redshifts are challenging to obtain via afterglow spectroscopy. This establishes X-shooter spectroscopy as an efficient tool for redshift determination of faint, star-forming, high-redshift ga...

  6. A public void catalog from the SDSS DR7 Galaxy Redshift Surveys based on the watershed transform

    Sutter, P M; Wandelt, Benjamin D; Weinberg, David H

    2012-01-01

    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^-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 void...

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

    Roseboom, I G; 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; Dunlop, J S; Dwek, E; Eales, S; Elbaz, D; Farrah, D; Franceschini, A; Glenn, J; Griffin, M; Halpern, M; Hatziminaoglou, E; Ibar, E; Isaak, K; Lagache, G; Levenson, L; Lu, N; Madden, S; Maffei, B; Mainetti, G; Marchetti, L; Marsden, G; Morrison, G; Mortier, A M J; Nguyen, H T; O'Halloran, B; Oliver, S J; Omont, A; Page, M J; Panuzzo, P; Papageorgiou, A; Pearson, C P; Perez-Fournon, I; Pohlen, M; Rawlings, J I; Raymond, G; Rigopoulou, D; Rizzo, D; Rodighiero, G; Rowan-Robinson, M; Schulz, B; Scott, Douglas; Seymour, N; Shupe, D L; Smith, A J; Stevens, J A; Symeonidis, M; Trichas, M; Tugwell, K E; Vaccari, M; Valtchanov, I; Vieira, J D; Viero, M P; Vigroux, L; Wardlow, J; Wang, L; Wright, G; Xu, C K; Zemcov, M

    2011-01-01

    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 {\\mu}m 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} = ({\

  8. Spectral Classification of Quasars in the Sloan Digital Sky Survey: Eigenspectra; Redshift and Luminosity Effects

    Yip, C W; Vanden Berk, Daniel E; Ma, Z; Frieman, J A; Subba-Rao, M; Szalay, A S; Richards, G T; Hall, P B; Schneider, D P; Hopkins, A M; Trump, J; Brinkmann, J

    2004-01-01

    We study 16,707 quasar spectra from the SDSS using the Karhunen-Lo\\`eve (KL) transform (or Principal Component Analysis, PCA). The quasar eigenspectra of the full catalog reveal the following: 1st order - the mean spectrum; 2nd order - a host-galaxy component; 3rd order - the UV-optical continuum slope; 4th order - the correlations of Balmer emission lines. We find that the spectral classification of quasars is redshift and luminosity dependent, as such there does not exist a compact set ( 95%) of the entire catalog. We therefore construct several sets of eigenspectra in different redshift and luminosity bins. From these eigenspectra we find that quasar spectra can be classified (by the first two eigenspectra) into a sequence that is defined by a simple progression in the steepness of the slope of the continuum. We also find a dependence on redshift and luminosity in the eigencoefficients. The dominant redshift effect is a result of the evolution of the blended FeII emission (optical) and the Balmer continuum...

  9. The BOSS Emission-Line Lens Survey (BELLS). I. A large spectroscopically selected sample of Lens Galaxies at redshift ~ 0.5

    Brownstein, Joel R; 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; 10.1088/0004-637X/744/1/41

    2011-01-01

    We present a catalog of 25 definite and 11 probable strong galaxy-galaxy gravitational lens systems with redshifts 0.4 \\lesssim z \\lesssim 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 ACS Survey (SLACS: Bolton et al. 2006; 2008) to higher redshift. We describe the details of the BOSS spectroscopic candidate detections, our HST Adanced Camera for Surveys (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...

  10. Clustering of High Redshift ($z\\ge 2.9$) Quasars from the Sloan Digital Sky Survey

    Shen, Y; Oguri, M; Hennawi, J F; Fan, X; Richards, G T; Hall, P B; Gunn, J E; Schneider, D P; Szalay, A S; Thakar, A R; Vanden Berk, D E; Anderson, S F; Bahcall, N A; Connolly, A J; Knapp, G R; Shen, Yue; Strauss, Michael A.; Oguri, Masamune; Hennawi, Joseph F.; Fan, Xiaohui; Richards, Gordon T.; Hall, Patrick B.; Gunn, James E.; Schneider, Donald P.; Szalay, Alexander S.; Thakar, Anirudda R.; Berk, Daniel E. Vanden; Anderson, Scott F.; Bahcall, Neta A.; Connolly, Andrew J.; Knapp, Gillian R.

    2007-01-01

    (Abridged) We study the two-point correlation function of a uniformly selected sample of 4,426 luminous optical quasars with redshift $2.9 \\le z\\le 5.4$ selected over 4041 deg$^2$ from the Fifth Data Release of the Sloan Digital Sky Survey. For a real-space correlation function of the form $\\xi(r)=(r/r_0)^{-\\gamma}$, the fitted parameters in comoving coordinates are $r_0 = 15.2 \\pm 2.7 h^{-1}$ Mpc and $\\gamma = 2.0 \\pm 0.3$, over a scale range $4\\le r_p\\le 150 h^{-1}$ Mpc. Thus high-redshift quasars are appreciably more strongly clustered than their $z \\approx 1.5$ counterparts, which have a comoving clustering length $r_0 \\approx 6.5 h^{-1}$ 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 $r_0 = 16.9 \\pm 1.7 h^{-1}$ Mpc for the former, and $r_0 = 24.3 \\pm 2.4 h^{-1}$ Mpc for the latter. Following Martini & Weinberg, we relate the clustering strength and quasar number density to the quasar lifet...

  11. Hα EQUIVALENT WIDTHS FROM THE 3D-HST SURVEY: EVOLUTION WITH REDSHIFT AND DEPENDENCE ON STELLAR MASS

    We investigate the evolution of the Hα equivalent width, EW(Hα), with redshift and its dependence on stellar mass, using the first data from the 3D-HST survey, a large spectroscopic Treasury program with the Hubble Space Telescope Wide Field Camera 3. Combining our Hα measurements of 854 galaxies at 0.8 1.8 with little mass dependence. Qualitatively, this measurement is a model-independent confirmation of the evolution of star-forming galaxies with redshift. A quantitative conversion of EW(Hα) to specific star formation rate (sSFR) is model dependent because of differential reddening corrections between the continuum and the Balmer lines. The observed EW(Hα) can be reproduced with the characteristic evolutionary history for galaxies, whose star formation rises with cosmic time to z ∼ 2.5 and then decreases to z = 0. This implies that EW(Hα) rises to 400 Å at z = 8. The sSFR evolves faster than EW(Hα), as the mass-to-light ratio also evolves with redshift. We find that the sSFR evolves as (1 + z)3.2, nearly independent of mass, consistent with previous reddening insensitive estimates. We confirm previous results that the observed slope of the sSFR-z relation is steeper than the one predicted by models, but models and observations agree in finding little mass dependence.

  12. [Redshift estimation of galaxy spectra based on similarity measure].

    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

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

    Conroy, C; White, M; Newman, J; Yan, R; Cooper, M; Gerke, B; Davis, M; Koo, D

    2005-01-01

    We present measurements of the void probability function (VPF) at z~1 using data from the DEEP2 Redshift Survey and its evolution to z~0 using data from the Sloan Digital Sky Survey. 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, \\xi; 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, \\bar{\\xi}. This implies that differences in the VPF across different galaxy populations are consistent with being due entire...

  14. The Deep SPIRE HerMES Survey: Spectral Energy Distributions and their Astrophysical Indications at High Redshift

    Brisbin, D; Altieri, B; Amblard, A; Arumugam, V; Aussel, H; Babbedge, T; Blain, A; Bock, J; Boselli, A; Buat, V; Castro-Rodríguez, N; Cava, A; Chanial, P; Clements, D L; Conley, A; Conversi, L; Cooray, A; Dowell, C D; Dwek, E; Eales, S; Elbaz, D; Fox, M; Franceschini, A; Gear, W; Glenn, J; Griffin, M; Halpern, M; Hatziminaoglou, E; Ibar, E; Isaak, K; Ivison, R J; Lagache, G; Levenson, L; Lonsdale, Carol J; Lu, N; Madden, S; Maffei, B; Mainetti, G; Marchetti, L; Morrison, G E; Nguyen, H T; O’Halloran, B; Oliver, S J; Omont, A; Owen, F N; Pannella, M; Panuzzo, P; Papageorgiou, A; Pearson, C P; Pérez-Fournon, I; Pohlen, M; Rizzo, D; Roseboom, I G; Rowan-Robinson, M; Portal, M Sánchez; Schulz, B; Seymour, N; Shupe, D L; Smith, A J; Stevens, J A; Strazzullo, V; Symeonidis, M; Trichas, M; Tugwell, K E; Vaccari, M; Valtchanov, I; Vigroux, L; Wang, L; Ward, R; Wright, G; Xu, C K; Zemcov, M

    2010-01-01

    The Spectral and Photometric Imaging Receiver (SPIRE) on Herschel has been carrying out deep extragalactic surveys, one of whose aims is to establish spectral energy distributions (SED)s of individual galaxies spanning the infrared/submillimeter (IR/SMM) wavelength region. We report observations of the (IR/SMM) emission from the Lockman North field (LN) and Great Observatories Origins Deep Survey field North (GOODS-N). Because galaxy images in the wavelength range covered by Herschel generally represent a blend with contributions from neighboring galaxies, we present sets of galaxies in each field especially free of blending at 250, 350, and 500 microns. We identify the cumulative emission of these galaxies and the fraction of the far infrared cosmic background radiation they contribute. Our surveys reveal a number of highly luminous galaxies at redshift z ∼< 3 and a novel relationship between infrared and visible emission that shows a dependence on luminosity and redshift.

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

    Lupu, R. E.; Scott, K. S.; Aguirre, J. E. [Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104 (United States); Aretxaga, I. [Instituto Nacional de Astrofisica, Optica y Electronica, Aptdo. Postal 51 y 216, 72000 Puebla (Mexico); Auld, R.; Dariush, A. [School of Physics and Astronomy, Cardiff University, The Parade, Cardiff CF24 3AA (United Kingdom); Barton, E.; Cooke, J.; Cooray, A. [Department of Physics and Astronomy, University of California, Irvine, CA 92697 (United States); Beelen, A. [Institut d' Astrophysique spatiale bat 121-Universite Paris-Sud, F-91405 Orsay Cedex (France); Bertoldi, F. [Argelander Institute for Astronomy, Bonn University, Auf dem Huegel 71, D-53121 Bonn (Germany); Bock, J. J.; Bradford, C. M. [Jet Propulsion Laboratory, Pasadena, CA 91109 (United States); Bonfield, D. [Centre for Astrophysics Research, Science and Technology Research Centre, University of Hertfordshire, Herts AL10 9AB (United Kingdom); Buttiglione, S.; De Zotti, G. [INAF, Osservatorio Astronomico di Padova, Vicolo Osservatorio 5, I-35122 Padova (Italy); Cava, A. [Instituto de Astrofisica de Canarias, C/Via Lactea s/n, E-38200 La Laguna (Spain); Clements, D. L. [Astrophysics Group, Physics Department, Blackett Laboratory, Imperial College London, Prince Consort Road, London SW7 2AZ (United Kingdom); Dannerbauer, H. [Laboratoire AIM, CEA/DSM-CNRS-Universite Paris Diderot, DAPNIA/Service d' Astrophysique, CEA Saclay, Orme des Merisiers, F-91191 Gif-sur-Yvette Cedex (France); Dunne, L., E-mail: Roxana.E.Lupu@nasa.gov [School of Physics and Astronomy, University of Nottingham, University Park, Nottingham NG7 2RD (United Kingdom); and others

    2012-10-01

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

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

    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 operated by the Association of Universities for Research in Astronomy, Inc. under NASA contract NAS5-26555.

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

    Song, J; 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; Suhada, 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

    2012-01-01

    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 deg^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_{med}=0.57. Approximately 18% of the sample with measured redshifts lies at z>0.8. We estimate ...

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

    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.

  19. A Far-Infrared Spectroscopic Survey of Intermediate Redshift (Ultra) Luminous Infrared Galaxies

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

    2014-01-01

    We present Herschel far-IR photometry and spectroscopy as well as ground based CO observations of an intermediate redshift (0.21 10^11.5L_sun). With these measurements we trace the dust continuum, far-IR atomic line emission, in particular [CII]\\,157.7microns, as well as the molecular gas of z~0.3 (U)LIRGs 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_CII/L_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 [CII] observations, we find that the majority of galaxies at all redshifts and all luminosities follow a L_CII-L_FIR relation with a slope of unity, from which local ULIRGs and high-z AGN dominated sources are clear outliers. We also confirm that the strong anti-correlation between the L_CII/L_FIR ratio and the far-IR color L_60/L_100 observed in...

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

    Davidzon, I; 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; Brun, V Le; Fevre, O Le; 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

    2016-01-01

    We exploit the first public data release of VIPERS to investigate environmental effects in galaxy evolution between $z\\sim0.5$ and $0.9$. The large number of spectroscopic redshifts over an area of about $10\\,\\mathrm{deg}^2$ provides a galaxy sample with high statistical power. The accurate redshift measurements, with $\\sigma_z = 0.00047(1+z_\\mathrm{spec})$, allow us to robustly isolate galaxies living in the lowest- and highest-density environments, as defined in terms of spatial 3D density contrast. We estimate the stellar mass function (SMF) of galaxies residing in these two environments, and constrain its high-mass end with unprecedented precision. We find that the galaxy SMF in the densest regions has a different shape than that 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 SMF to the comoving volume occupied by the corresponding environment, and relate estimates from different redshift bins. We observe an...

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

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

    2016-01-01

    The KMOS Redshift One Spectroscopic Survey (KROSS) is an ESO-guaranteed time survey of 795 typical star-forming galaxies in the redshift range z = 0.8–1.0 with the KMOS instrument on the Very Large Telescope. In this paper, we present resolved kinematics and star formation rates for 584 z ∼ 1 galaxies. This constitutes the largest near-infrared Integral Field Unit survey of galaxies at z ∼ 1 to date. We demonstrate the success of our selection criteria with 90 per cent of our targets found to...

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

    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/

  3. Galaxies at Redshifts z > 5

    Lanzetta, Kenneth M.; Chen, Hsiao-Wen; Pascarelle, Sebastian; Yahata, Noriaki

    1998-01-01

    Here we describe our attempts to establish statistically complete samples of very high redshift galaxies by obtaining photometric redshifts of galaxies in Medium Deep Survey (MDS) fields and photometric and spectroscopic redshifts of galaxies in very deep STIS slitless spectroscopy fields. On the basis of this analysis, we have identified galaxies of redshift z = 4.92 in an MDS field and of redshift z = 6.68 in a very deep STIS field.

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

    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 IR > 1011.5 L ☉). 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 C II/L 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 C II–L 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 C II/L FIR ratio and the far-IR color L 60/L 100 observed in the local universe holds over a broad range of redshifts and luminosities, in the sense that warmer sources exhibit lower L C II/L 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 C II/L FIR ratios, the moderate star formation efficiencies (L IR/LCO′ or L IR/MH2), 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 present day and z > 1 is already significant by z ∼ 0.3.

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

    Magdis, Georgios E.; Rigopoulou, D. [Department of Physics, University of Oxford, Keble Road, Oxford OX1 3RH (United Kingdom); Hopwood, R.; Clements, D. [Physics Department, Imperial College London, South Kensington Campus, London SW7 2AZ (United Kingdom); Huang, J.-S. [National Astronomical Observatories of China, Chinese Academy of Sciences, Beijing 100012 (China); Farrah, D. [Department of Physics, Virginia Tech, Blacksburg, VA 24061 (United States); Pearson, C. [RAL Space, Science, and Technology Facilities Council, Rutherford Appleton Laboratory, Didcot OX11 0QX (United Kingdom); Alonso-Herrero, Almudena [Instituto de Fisica de Cantabria, CSIC-UC, E-39006 Santander (Spain); Bock, J. J. [California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125 (United States); Cooray, A. [Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States); Griffin, M. J. [School of Physics and Astronomy, Cardiff University, Queens Buildings, The Parade, Cardiff CF24 3AA (United Kingdom); Oliver, S. [Astronomy Centre, Department of Physics and Astronomy, University of Sussex, Brighton BN1 9QH (United Kingdom); Perez Fournon, I. [Instituto de Astrofsica de Canarias (IAC), 38200, La Laguna, Tenerife (Spain); Riechers, D. [Department of Astronomy, Cornell University, 220 Space Sciences Building, Ithaca, NY 14853 (United States); Swinyard, B. M.; Thatte, N. [Institute for Astronomy, Astrophysics, Space Applications and Remote Sensing, National Observatory of Athens, GR-15236 Athens (Greece); Scott, D. [Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, BC V6T1Z1 (Canada); Valtchanov, I. [Herschel Science Centre, European Space Astronomy Centre, Villanueva de la Canada, E-28691 Madrid (Spain); Vaccari, M., E-mail: ipf@iac.es [Astrophysics Group, Physics Department, University of the Western Cape, Private Bag X17, 7535 Bellville, Cape Town (South Africa)

    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

  6. Galaxy Clustering and Large-Scale Structure from z = 0.2 to z = 0.5 in Two Norris Redshift Surveys

    Small, T A; Sargent, W; Hamilton, D; Small, Todd; Ma, Chung-Pei; Sargent, Wallace; Hamilton, Donald

    1999-01-01

    (abridged) We present a study of the nature and evolution of large-scale structure based on two independent redshift surveys of faint field galaxies conducted with the 176-fiber Norris Spectrograph on the Palomar 200-inch telescope. The two surveys together sparsely cover ~20 sq. degrees and contain 835 r 90% of all galaxies at z 5.

  7. ALMA Spectroscopic Survey in the Hubble Ultra Deep Field: Molecular gas reservoirs in high-redshift galaxies

    Decarli, Roberto; Aravena, Manuel; Carilli, Chris; Bouwens, Rychard; da Cunha, Elisabete; Daddi, Emanuele; Elbaz, David; Riechers, Dominik; Smail, Ian; Swinbank, Mark; Weiss, Axel; Bacon, Roland; Bauer, Franz; Bell, Eric F; Bertoldi, Frank; Chapman, Scott; Colina, Luis; Cortes, Paulo C; Cox, Pierre; Gónzalez-López, Jorge; Inami, Hanae; Ivison, Rob; Hodge, Jacqueline; Karim, Alex; Magnelli, Benjamin; Ota, Kazuaki; Popping, Gergö; Rix, Hans-Walter; Sargent, Mark; van der Wel, Arjen; van der Werf, Paul

    2016-01-01

    We study the molecular gas properties of high-$z$ galaxies observed in the ALMA Spectroscopic Survey (ASPECS) that targets a $\\sim1$ arcmin$^2$ region in the Hubble Ultra Deep Field (UDF), a blind survey of CO emission (tracing molecular gas) in the 3mm and 1mm bands. Of a total of 1302 galaxies in the field, 56 have spectroscopic redshifts and correspondingly well-defined physical properties. Among these, 11 have infrared luminosities $L_{\\rm{}IR}>10^{11}$ L$_\\odot$, i.e. a detection in CO emission was expected. Out these, 7 are detected at various significance in CO, and 4 are undetected in CO emission. In the CO-detected sources, we find CO excitation conditions that are lower than typically found in starburst/SMG/QSO environments. We use the CO luminosities (including limits for non-detections) to derive molecular gas masses. We discuss our findings in context of previous molecular gas observations at high redshift (star-formation law, gas depletion times, gas fractions): The CO-detected galaxies in the U...

  8. Precise photometric redshifts with a narrow-band filter set: The PAU Survey at the William Herschel Telescope

    Martí, Pol; Castander, Francisco J; Gaztañaga, Enrique; Eriksen, Martin; Sánchez, Carles

    2014-01-01

    The Physics of the Accelerating Universe (PAU) survey at the William Herschel Telescope (WHT) 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 \\sigma(z)/(1 + z) ~ 0.0035 and map the large-scale structure of the universe in three dimensions up to i_AB < 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 (FWHM) filters with a ~25% overlap and spanning the wavelength range from 450 nm to 850 nm, together with a ugrizY broad-band filter system. We then present the migration matrix r_ij, 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...

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

    Geach, James E

    2011-01-01

    We present an application of unsupervised machine learning - the self-organised map (SOM) - as a tool for visualising, exploring and mining the catalogues of large astronomical surveys. Self-organisation 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 the example of galaxies with active galactic nuclei as a demonstration, and (ii) photometric redshift estimation, illustrating how SOMs can be used as totally empirical predictive tools. With a training set of ~3800 galaxies with z_spec<1, we achieve photometric redshift accuracies competitive with other (mainly template fitting) techniques that use a similar number of photometric bands (sigma(Dz)=0.03 with a ~2% outlier rate when using u*-band to 8um photometry). We also test the SOM as a p...

  10. The ALMA Redshift 4 Survey (AR4S): I. The massive end of the z=4 main sequence of galaxies

    Schreiber, C; Leiton, R; Elbaz, D; Wang, T; Okumura, K; Labbé, I

    2016-01-01

    We introduce the ALMA Redshift 4 Survey (AR4S), a systematic ALMA survey of all the known galaxies with stellar mass (M*) larger than 5e10 Msun at 3.5redshifts, which is proof that the main ...

  11. The VIMOS Ultra Deep Survey First Data Release: spectra and spectroscopic redshifts of 698 objects up to z~6 in CANDELS

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

    2016-01-01

    This paper describes the first data release (DR1) of the VIMOS Ultra Deep Survey (VUDS). The DR1 includes all low-resolution spectroscopic data obtained in 276.9 arcmin2 of the CANDELS-COSMOS and CANDELS-ECFDS survey areas, including accurate spectroscopic redshifts z_spec and individual spectra obtained with VIMOS on the ESO-VLT. A total of 698 objects have a measured redshift, with 677 galaxies, two type-I AGN and a small number of 19 contaminating stars. The targets of the spectroscopic survey are selected primarily on the basis of their photometric redshifts to ensure a broad population coverage. About 500 galaxies have z_spec>2, 48 with z_spec>4, and the highest reliable redshifts reach beyond z_spec=6. This dataset approximately doubles the number of galaxies with spectroscopic redshifts at z>3 in these fields. We discuss the general properties of the sample in terms of the spectroscopic redshift distribution, the distribution of Lyman-alpha equivalent widths, and physical properties including stellar m...

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

    Brownstein, Joel R.; Bolton, Adam S.; Pandey, Parul [Department of Physics and Astronomy, University of Utah, Salt Lake City, UT 84112 (United States); Schlegel, David J. [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Eisenstein, Daniel J. [Harvard College Observatory, 60 Garden Street, MS 20, Cambridge, MA 02138 (United States); Kochanek, Christopher S. [Department of Astronomy and Center for Cosmology and Astroparticle Physics, Ohio State University, Columbus, OH 43210 (United States); Connolly, Natalia [Department of Physics, Hamilton College, Clinton, NY 13323 (United States); Maraston, Claudia [Institute of Cosmology and Gravitation, University of Portsmouth, Portsmouth PO1 3FX (United Kingdom); Seitz, Stella [University Observatory Munich, Scheinstrasse 1, 81679 Muenchen (Germany); Wake, David A. [Department of Astronomy, Yale University, New Haven, CT 06520 (United States); Wood-Vasey, W. Michael [Pittsburgh Center for Particle Physics, Astrophysics, and Cosmology (PITT-PACC), Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA 15260 (United States); Brinkmann, Jon [Apache Point Observatory, P.O. Box 59, Sunspot, NM 88349 (United States); Schneider, Donald P. [Department of Astronomy and Astrophysics and Institute for Gravitation and the Cosmos, Pennsylvania State University, University Park, PA 16802 (United States); Weaver, Benjamin A. [Center for Cosmology and Particle Physics, New York University, New York, NY 10003 (United States)

    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.

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

    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

  14. Star formation trends in high-redshift galaxy surveys: the elephant or the tail?

    Stringer, Martin; Frenk, Carlos S; Stark, Daniel P

    2010-01-01

    Star formation rate and accummulated stellar mass are two fundamental physical quantities that describe the evolutionary state of a forming galaxy. Two recent attempts to determine the relationship between these quantities, by interpreting a sample of star-forming galaxies at redshift of z~4, have led to opposite conclusions. We use a model galaxy population to investigate possible causes for this discrepancy and conclude that minor errors in the conversion from observables to physical quantities can lead to major misrepresentation when applied without awareness of sample selection. We also investigate, in a general way, the physical origin of the correlation between star formation rate and stellar mass within hierarchical galaxy formation theory.

  15. An integral field spectroscopic survey for high redshift damped Lyman-alpha galaxies

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

    2007-01-01

    We search for galaxy counterparts to damped Lyman-alpha absorbers (DLAs) at z>2 towards nine quasars, which have 14 DLAs and 8 sub-DLAs in their spectra. We use integral field spectroscopy to search for Ly-alpha emission line objects at the redshifts of the absorption systems. Besides recovering two previously confirmed objects, we find six statistically significant candidate Ly-alpha emission line objects. The candidates are identified as having wavelengths close to the DLA line where the ba...

  16. Stellar populations and star formation in AGN hosts at intermediate redshift in the SHARDS survey

    Hernán-Caballero, Antonio; Alonso-Herrero, Almudena; Pérez-González, Pablo G.; Cava, Antonio; Cardiel, Nicolás; team, the SHARDS

    2013-01-01

    SHARDS is an ongoing ESO/GTC large program that is obtaining ultra-deep photometry of the GOODS-North field in 24 medium-band filters (reaching m=26.5 AB in all bands) in the 500-950 nm range with GTC/OSIRIS. It is designed to study the properties of high-z massive galaxies, but it can also provide very valuable information about the population of AGN at intermediate redshifts (z~0.5-2). Here we present preliminary results on a study of the stellar populations and star formation activity in t...

  17. The Redshift One LDSS-3 Emission line Survey (ROLES) II: Survey method and z~1 mass-dependent star-formation rate density

    Gilbank, David G; Glazebrook, Karl; Bower, Richard G; Baldry, I K; Davies, G T; Hau, G K T; Li, I H; McCarthy, P

    2010-01-01

    Motivated by suggestions of 'cosmic downsizing', in which the dominant contribution to the cosmic star formation rate density (SFRD) proceeds from higher to lower mass galaxies with increasing cosmic time, we describe the design and implementation of the Redshift One LDSS3 Emission line Survey (ROLES). ROLES is a K-selected (22.5 < K_AB < 24.0) survey for dwarf galaxies [8.5redshifts and star-formation rates (SFRs) for star-forming galaxies down to a limit of ~0.3 Msun/yr. We present the [OII] luminosity function measured in ROLES and find a faint end slope of alpha_faint ~ -1.5, similar to that measured at z~0.1 in the SDSS. By combining ROLES with higher mass surveys, we measure the SFRD as a function of stellar mass using [OII] (with and without various empirical corrections), and using SED-fitting to obtain the SFR from the rest-frame UV lum...

  18. Accuracy of photometric redshifts for future weak lensing surveys from space

    Bellagamba, Fabio; Moscardini, Lauro; Bolzonella, Micol

    2012-01-01

    Photometric redshifts are a key tool to extract as much information as possible from planned cosmic shear experiments. In this work we aim to test the performances that can be achieved with observations in the near-infrared from space and in the optical from the ground. This is done by performing realistic simulations of multi-band observations of a patch of the sky, and submitting these mock images to software usually applied to real images to extract the photometry and then a redshift estimate for each galaxy. In this way we mimic the most relevant sources of uncertainty present in real data analysis, including blending and light pollution between galaxies. As an example we adopt the infrared setup of the ESA-proposed Euclid mission, while we simulate different observations in the optical, modifying filters, exposure times and seeing values. Finally, we consider directly some future ground-based experiments, such as LSST, Pan-Starrs and DES. The results highlight the importance of u-band observations, espec...

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

    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

  20. An integral field spectroscopic survey for high redshift damped Lyman-alpha galaxies

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

    2007-01-01

    We search for galaxy counterparts to damped Lyman-alpha absorbers (DLAs) at z>2 towards nine quasars, which have 14 DLAs and 8 sub-DLAs in their spectra. We use integral field spectroscopy to search for Ly-alpha emission line objects at the redshifts of the absorption systems. Besides recovering two previously confirmed objects, we find six statistically significant candidate Ly-alpha 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 Ly-alpha 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. 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 ...

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

    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.

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

    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 −1.00−0.06(0.10)+0.06(0.09) (statistical)−0.08+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.

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

    Choi, Ami; Blake, Chris; Hildebrandt, Hendrik; Duncan, Christopher A J; Erben, Thomas; Nakajima, Reiko; Van Waerbeke, Ludovic; Viola, Massimo

    2015-01-01

    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 \

  4. The zCOSMOS redshift survey : Influence of luminosity, mass and environment on the galaxy merger rate

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

    2011-01-01

    The contribution of major mergers to galaxy mass assembly along cosmic time is an important ingredient to the galaxy evolution scenario. We aim to measure the evolution of the merger rate for both luminosity/mass selected galaxy samples and investigate its dependence with the local environment. We use a sample of 10644 spectroscopically observed galaxies from the zCOSMOS redshift survey to identify pairs of galaxies destined to merge, using only pairs for which the velocity difference and projected separation of both components with a confirmed spectroscopic redshift indicate a high probability of merging. We have identified 263 spectroscopically confirmed pairs with r_p^{max} = 100 h^{-1} kpc. We find that the density of mergers depends on luminosity/mass, being higher for fainter/less massive galaxies, while the number of mergers a galaxy will experience does not depends significantly on its intrinsic luminosity but rather on its stellar mass. We find that the pair fraction and merger rate increase with loc...

  5. The zCOSMOS Redshift Survey: evolution of the light in bulges and discs since z~0.8

    Tasca, L A M; Fevre, O Le; Ilbert, O; Lilly, S J; Zamorani, G; Lopez-Sanjuan, C; Ho, L C; Bardelli, S; Cattaneo, A; Cucciati, O; Farrah, D; Iovino, A; Koekemoer, A M; Liu, C T; Massey, R; Renzini, A; Taniguchi, Y; Welikala, N; Zucca, E; Carollo, C M; Contini, T; Kneib, J P; Mainieri, V; Scodeggio, M; Bolzonella, M; Bongiorno, A; Caputi, K; de la Torre, S; Franzetti, P; Garilli, B; Guzzo, L; Kampczyk, P; Knobel, C; Kovavc, K; Lamareille, F; Borgne, J -F Le; Brun, V Le; Maier, C; Mignoli, M; Pello, R; Peng, Y; Montero, E Perez; Rich, R M; Tanaka, M; Vergani, D; Bordoloi, R; Cappi, A; Cimatti, A; Coppa, G; McCracken, H J; Moresco, M; Pozzetti, L; Sanders, D; Sheth, K

    2014-01-01

    We studied the chronology of galactic bulge and disc formation by analysing the relative contributions of these components to the B-band rest-frame luminosity density at different epochs. We present the first estimate of the evolution of the fraction of rest-frame B-band light in galactic bulges and discs since redshift z~0.8. We performed a bulge-to-disc decomposition of HST/ACS images of 3266 galaxies in the zCOSMOS-bright survey with spectroscopic redshifts in the range 0.7 < z < 0.9. We find that the fraction of B-band light in bulges and discs is $(26 \\pm 4)%$ and $(74 \\pm 4)%$, respectively. When compared with rest-frame B-band measurements of galaxies in the local Universe in the same mass range ($10^{9} M_{\\odot}\\lessapprox M \\lessapprox 10^{11.5} M_{\\odot}$), we find that the B-band light in discs decreases by ~30% from z~0.7-0.9 to z~0, while the light from the bulge increases by ~30% over the same period of time. We interpret this evolution as the consequence of star formation and mass assemb...

  6. The 2dF Galaxy Redshift Survey The environmental dependence of galaxy star formation rates near clusters

    Lewis, I; De Propris, R; Couch, W; Bower, R; Offer, A R; Lewis, Ian; Balogh, Michael; Propris, Roberto De; Couch, Warrick; Bower, Richard; Offer, Alison

    2002-01-01

    We have measured the equivalent width of the H-alpha emission line for 11006 galaxies brighter than M_b=-19 (LCDM) at 0.052dF Galaxy Redshift Survey (2dF), in the fields of seventeen known galaxy clusters. The limited redshift range ensures that our results are insensitive to aperture bias, and to residuals from night sky emission lines. We use these measurements to trace mustar, the star formation rate normalized to Lstar, as a function of distance from the cluster centre, and local projected galaxy density. We find that the distribution of mustar steadily skews toward larger values with increasing distance from the cluster centre, converging to the field distribution at distances greater than ~3 times the virial radius. A correlation between star formation rate and local projected density is also found, which is independent of cluster velocity dispersion and disappears at projected densities below ~1 galaxy (brighter than M_b=-19) per Mpc^2. This characteristic scale corresponds approxim...

  7. The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey: the low redshift sample

    Parejko, John K; Padmanabhan, Nikhil; Wake, David A; Berlind, Andreas A; Bizyaev, Dmitry; Blanton, Michael; Bolton, Adam S; Bosch, Frank van den; Brinkmann, Jon; Brownstein, Joel R; da Costa, Luiz Alberto Nicolaci; Eisenstein, Daniel J; Guo, Hong; Kazin, Eyal; Maia, Marcio; Malanushenko, Elena; Maraston, Claudia; McBride, Cameron K; Nichol, Robert C; Oravetz, Daniel J; Pan, Kaike; Percival, Will J; Prada, Francisco; Ross, Ashley J; Ross, Nicholas P; Schlegel, David J; Schneider, Don; Simmons, Audrey E; Skibba, Ramin; Tinker, Jeremy; Tojeiro, Rita; Weaver, Benjamin A; Wetzel, Andrew; White, Martin; Weinberg, David H; Thomas, Daniel; Zehavi, Idit; Zheng, Zheng

    2012-01-01

    We report on the small scale (0.5Survey (BOSS), to be released as part of SDSS Data Release 9 (DR9). We describe the sample selection, basic properties of the galaxies, and caveats for working with the data. We calculate the real- and redshift-space two-point correlation functions of these galaxies, fit these measurements using Halo Occupation Distribution (HOD) modeling within dark matter cosmological simulations, and estimate the errors using mock catalogs. These galaxies lie in massive halos, with a mean halo mass of 5.2x10^13 h^-1 M_sun, a large scale bias of ~2.0, and a satellite fraction of 12+/-2%. Thus, these galaxies occupy halos with average masses in between those of the higher redshift BOSS CMASS sample and the original SDSS I/II LRG sample.

  8. A GBT Survey for HI 21 cm Absorption in the Disks and Halos of Low-Redshift Galaxies

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

    2010-01-01

    We present an HI 21 cm absorption survey with the Green Bank Telescope (GBT) of galaxy-quasar pairs selected by combining data from the Sloan Digital Sky Survey (SDSS) and the Faint Images of the Radio Sky at Twenty-Centimeters (FIRST) survey. Our sample consists of 23 sightlines through 15 low-redshift foreground galaxy - background quasar pairs with impact parameters ranging from 1.7 kpc up to 86.7 kpc. We also present follow-up Very Large Array (VLA) imaging of the foreground galaxy UGC 7408. We detected one absorber in the GBT survey from the foreground dwarf galaxy at an impact parameter of 1.7 kpc and another possible absorber in the VLA imaging of the nearby dwarf galaxy, UGC 7408. Both of the absorbers are narrow (FWHM of 3.6 and 4.8 km/s), have sub Damped Lyman alpha column densities, and are most likely originating from the disk gas of the foreground galaxies. We also detected HI emission from three galaxies including UGC 7408. Although our sample contains both blue and red galaxies, the two HI abso...

  9. THE OPTICALLY UNBIASED GRB HOST (TOUGH) SURVEY. V. VLT/X-SHOOTER EMISSION-LINE REDSHIFTS FOR SWIFT GRBs AT z {approx} 2

    Kruehler, Thomas; Malesani, Daniele; Milvang-Jensen, Bo; Fynbo, Johan P. U.; Hjorth, Jens; Sparre, Martin; Watson, Darach J. [Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, DK-2100 Copenhagen (Denmark); Jakobsson, Pall [Centre for Astrophysics and Cosmology, Science Institute, University of Iceland, Dunhagi 5, 107 Reykjavik (Iceland); Levan, Andrew J. [Department of Physics, University of Warwick, Coventry, CV4 7AL (United Kingdom); Tanvir, Nial R. [Department of Physics and Astronomy, University of Leicester, University Road, Leicester, LE1 7RH (United Kingdom)

    2012-10-10

    We present simultaneous optical and near-infrared (NIR) spectroscopy of 19 Swift {gamma}-ray burst (GRB) host galaxies observed with the VLT/X-shooter with the aim of measuring their redshifts. Galaxies were selected from The Optically Unbiased GRB Host (TOUGH) survey (15 of the 19 galaxies) or because they hosted GRBs without a bright optical afterglow. Here we provide emission-line redshifts for 13 of the observed galaxies with brightnesses between F606W > 27 mag and R = 22.9 mag (median R-tilde =24.6 mag). The median redshift is z-tilde =2.1 for all hosts and z-tilde =2.3 for the TOUGH hosts. Our new data significantly improve the redshift completeness of the TOUGH survey, which now stands at 77% (53 out of 69 GRBs). They furthermore provide accurate redshifts for nine prototype dark GRBs (e.g., GRB 071021 at z = 2.452 and GRB 080207 at z = 2.086), which are exemplary of GRBs where redshifts are challenging to obtain via afterglow spectroscopy. This establishes X-shooter spectroscopy as an efficient tool for redshift determination of faint, star-forming, high-redshift galaxies such as GRB hosts. It is hence a further step toward removing the bias in GRB samples that is caused by optically dark events, and provides the basis for a better understanding of the conditions in which GRBs form. The distribution of column densities as measured from X-ray data (N{sub H,X}), for example, is closely related to the darkness of the afterglow and skewed toward low N{sub H,X} values in samples that are dominated by bursts with bright optical afterglows.

  10. THE NEWFIRM MEDIUM-BAND SURVEY: PHOTOMETRIC CATALOGS, REDSHIFTS, AND THE BIMODAL COLOR DISTRIBUTION OF GALAXIES OUT TO z ∼ 3

    We present deep near-IR (NIR) medium-bandwidth photometry over the wavelength range 1-1.8 μm 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 σz/(1 + z) ∼ 1%-2% for ∼4000 galaxies at z = 0-3. The NMBS catalogs contain ∼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 ∼ 3, a higher redshift than has been probed so far.