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Sample records for redshift space distortions

  1. Redshift-space distortions in massive neutrino and evolving dark...

    Office of Scientific and Technical Information (OSTI)

    Redshift-space distortions in massive neutrino and evolving dark energy cosmologies ... This content will become publicly available on March 16, 2017 Title: Redshift-space ...

  2. Nonlinear stochastic growth rates and redshift space distortions

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Jennings, Elise; Jennings, David

    2015-04-09

    The linear growth rate is commonly defined through a simple deterministic relation between the velocity divergence and the matter overdensity in the linear regime. We introduce a formalism that extends this to a nonlinear, stochastic relation between ? ? ?(x,t)/aH and ?. This provides a new phenomenological approach that examines the conditional mean (???), together with the fluctuations of ? around this mean. We measure these stochastic components using N-body simulations and find they are non-negative and increase with decreasing scale from ~10% at kmorerelation and nonlinearity are more pronounced for halos, M ? 5 x 10Mh?, compared to the dark matter at z 0 and 1. Nonlinear growth effects manifest themselves as a rotation of the mean (???) away from the linear theory prediction fLT?, where fLT is the linear growth rate. This rotation increases with wavenumber, k, and we show that it can be well-described by second order Lagrangian perturbation theory (2LPT) for k LT from two point statistics in redshift space. Given that the relationship between ? and ? is stochastic and nonlinear, this will have implications for the interpretation and precision of fLT extracted using models which assume a linear, deterministic expression.less

  3. Nonlinear stochastic growth rates and redshift space distortions

    SciTech Connect (OSTI)

    Jennings, Elise; Jennings, David

    2015-04-09

    The linear growth rate is commonly defined through a simple deterministic relation between the velocity divergence and the matter overdensity in the linear regime. We introduce a formalism that extends this to a nonlinear, stochastic relation between ? ? ?(x,t)/aH and ?. This provides a new phenomenological approach that examines the conditional mean (???), together with the fluctuations of ? around this mean. We measure these stochastic components using N-body simulations and find they are non-negative and increase with decreasing scale from ~10% at k<0.2hMpc? to 25% at k ~ 0.45hMpc? at z 0. Both the stochastic relation and nonlinearity are more pronounced for halos, M ? 5 x 10Mh?, compared to the dark matter at z 0 and 1. Nonlinear growth effects manifest themselves as a rotation of the mean (???) away from the linear theory prediction fLT?, where fLT is the linear growth rate. This rotation increases with wavenumber, k, and we show that it can be well-described by second order Lagrangian perturbation theory (2LPT) for k < 0.1 hMpc?. The stochasticity in the ? ? relation is not so simply described by 2LPT, and we discuss its impact on measurements of fLT from two point statistics in redshift space. Given that the relationship between ? and ? is stochastic and nonlinear, this will have implications for the interpretation and precision of fLT extracted using models which assume a linear, deterministic expression.

  4. Non-linear stochastic growth rates and redshift space distortions

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Jennings, Elise; Jennings, David

    2015-04-09

    The linear growth rate is commonly defined through a simple deterministic relation between the velocity divergence and the matter overdensity in the linear regime. We introduce a formalism that extends this to a non-linear, stochastic relation between θ = ∇ ∙ v(x,t)/aH and δ. This provides a new phenomenological approach that examines the conditional mean <θ|δ>, together with the fluctuations of θ around this mean. We also measure these stochastic components using N-body simulations and find they are non-negative and increase with decreasing scale from ~10 per cent at k < 0.2 h Mpc-1 to 25 per cent at kmore » ~ 0.45 h Mpc-1 at z = 0. Both the stochastic relation and non-linearity are more pronounced for haloes, M ≤ 5 × 1012 M⊙ h-1, compared to the dark matter at z = 0 and 1. Non-linear growth effects manifest themselves as a rotation of the mean <θ|δ> away from the linear theory prediction -fLTδ, where fLT is the linear growth rate. This rotation increases with wavenumber, k, and we show that it can be well-described by second-order Lagrangian perturbation theory (2LPT) fork < 0.1 h Mpc-1. Furthermore, the stochasticity in the θ – δ relation is not so simply described by 2LPT, and we discuss its impact on measurements of fLT from two-point statistics in redshift space. Furthermore, given that the relationship between δ and θ is stochastic and non-linear, this will have implications for the interpretation and precision of fLT extracted using models which assume a linear, deterministic expression.« less

  5. Disentangling Redshift-Space Distortions and Nonlinear Bias using the 2D Power Spectrum

    SciTech Connect (OSTI)

    Jennings, Elise; Wechsler, Risa H.

    2015-08-07

    We present the nonlinear 2D galaxy power spectrum, P(k, µ), in redshift space, measured from the Dark Sky simulations, using galaxy catalogs constructed with both halo occupation distribution and subhalo abundance matching methods, chosen to represent an intermediate redshift sample of luminous red galaxies. We find that the information content in individual µ (cosine of the angle to the line of sight) bins is substantially richer then multipole moments, and show that this can be used to isolate the impact of nonlinear growth and redshift space distortion (RSD) effects. Using the µ < 0.2 simulation data, which we show is not impacted by RSD effects, we can successfully measure the nonlinear bias to an accuracy of ~ 5% at k < 0.6hMpc-1 . This use of individual µ bins to extract the nonlinear bias successfully removes a large parameter degeneracy when constraining the linear growth rate of structure. We carry out a joint parameter estimation, using the low µ simulation data to constrain the nonlinear bias, and µ > 0.2 to constrain the growth rate and show that f can be constrained to ~ 26(22)% to a kmax < 0.4(0.6)hMpc-1 from clustering alone using a simple dispersion model, for a range of galaxy models. Our analysis of individual µ bins also reveals interesting physical effects which arise simply from different methods of populating halos with galaxies. We also find a prominent turnaround scale, at which RSD damping effects are greater then the nonlinear growth, which differs not only for each µ bin but also for each galaxy model. These features may provide unique signatures which could be used to shed light on the galaxy–dark matter connection. Furthermore, the idea of separating nonlinear growth and RSD effects making use of the full information in the 2D galaxy power spectrum yields significant improvements in constraining cosmological parameters and may be a promising probe of galaxy formation models.

  6. Disentangling Redshift-Space Distortions and Nonlinear Bias using the 2D Power Spectrum

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Jennings, Elise; Wechsler, Risa H.

    2015-08-07

    We present the nonlinear 2D galaxy power spectrum, P(k, µ), in redshift space, measured from the Dark Sky simulations, using galaxy catalogs constructed with both halo occupation distribution and subhalo abundance matching methods, chosen to represent an intermediate redshift sample of luminous red galaxies. We find that the information content in individual µ (cosine of the angle to the line of sight) bins is substantially richer then multipole moments, and show that this can be used to isolate the impact of nonlinear growth and redshift space distortion (RSD) effects. Using the µ < 0.2 simulation data, which we show ismore » not impacted by RSD effects, we can successfully measure the nonlinear bias to an accuracy of ~ 5% at k < 0.6hMpc-1 . This use of individual µ bins to extract the nonlinear bias successfully removes a large parameter degeneracy when constraining the linear growth rate of structure. We carry out a joint parameter estimation, using the low µ simulation data to constrain the nonlinear bias, and µ > 0.2 to constrain the growth rate and show that f can be constrained to ~ 26(22)% to a kmax < 0.4(0.6)hMpc-1 from clustering alone using a simple dispersion model, for a range of galaxy models. Our analysis of individual µ bins also reveals interesting physical effects which arise simply from different methods of populating halos with galaxies. We also find a prominent turnaround scale, at which RSD damping effects are greater then the nonlinear growth, which differs not only for each µ bin but also for each galaxy model. These features may provide unique signatures which could be used to shed light on the galaxy–dark matter connection. Furthermore, the idea of separating nonlinear growth and RSD effects making use of the full information in the 2D galaxy power spectrum yields significant improvements in constraining cosmological parameters and may be a promising probe of galaxy formation models.« less

  7. Redshift distortions of galaxy correlation functions

    SciTech Connect (OSTI)

    Fry, J.N. Florida Univ., Gainesville, FL . Dept. of Physics); Gaztanaga, E. Oxford Univ. . Dept. of Physics)

    1993-05-12

    To examine how peculiar velocities can affect the 2-, 3-, and 4-point correlation functions, we evaluate volume-average correlations for configurations that emphasize and minimize distortions for four different volume-limited samples from each of the CfA, SSRS, and IRAS redshift catalogs. We present the results as the correlation length r[sub 0] and power index [gamma] of the 2-point correlation, [anti [Xi

  8. Galaxy power spectrum in redshift space: Combining perturbation theory with the halo model

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Okumura, Teppei; Hand, Nick; Seljak, Uros; Vlah, Zvonimir; Desjacques, Vincent

    2015-11-19

    Theoretical modeling of the redshift-space power spectrum of galaxies is crucially important to correctly extract cosmological information from galaxy redshift surveys. The task is complicated by the nonlinear biasing and redshift space distortion (RSD) effects, which change with halo mass, and by the wide distribution of halo masses and their occupations by galaxies. One of the main modeling challenges is the existence of satellite galaxies that have both radial distribution inside the halos and large virial velocities inside halos, a phenomenon known as the Finger-of-God (FoG) effect. We present a model for the redshift-space power spectrum of galaxies in whichmore » we decompose a given galaxy sample into central and satellite galaxies and relate different contributions to the power spectrum to 1-halo and 2-halo terms in a halo model. Our primary goal is to ensure that any parameters that we introduce have physically meaningful values, and are not just fitting parameters. For the lowest order 2-halo terms we use the previously developed RSD modeling of halos in the context of distribution function and perturbation theory approach. This term needs to be multiplied by the effect of radial distances and velocities of satellites inside the halo. To this one needs to add the 1-halo terms, which are nonperturbative. We show that the real space 1-halo terms can be modeled as almost constant, with the finite extent of the satellites inside the halo inducing a small k2R2 term over the range of scales of interest, where R is related to the size of the halo given by its halo mass. Furthermore, we adopt a similar model for FoG in redshift space, ensuring that FoG velocity dispersion is related to the halo mass. For FoG k2 type expansions do not work over the range of scales of interest and FoG resummation must be used instead. We test several simple damping functions to model the velocity dispersion FoG effect. Applying the formalism to mock galaxies modeled after the

  9. Peculiar velocities in redshift space: formalism, N-body simulations and perturbation theory

    SciTech Connect (OSTI)

    Okumura, Teppei; Seljak, Uroš; Vlah, Zvonimir; Desjacques, Vincent E-mail: useljak@berkeley.edu E-mail: Vincent.Desjacques@unige.ch

    2014-05-01

    Direct measurements of peculiar velocities of galaxies and clusters of galaxies can in principle provide explicit information on the three dimensional mass distribution, but this information is modulated by the fact that velocity field is sampled at galaxy positions, and is thus probing galaxy momentum. We derive expressions for the cross power spectrum between the density and momentum field and the auto spectrum of the momentum field in redshift space, by extending the distribution function method to these statistics. The resulting momentum cross and auto power spectra in redshift space are expressed as infinite sums over velocity moment correlators in real space, as is the case for the density power spectrum in redshift space. We compute each correlator using Eulerian perturbation theory (PT) and halo biasing model and compare the resulting redshift-space velocity statistics to those measured from N-body simulations for both dark matter and halos. We find that in redshift space linear theory predictions for the density-momentum cross power spectrum as well as for the momentum auto spectrum fail to predict the N-body results at very large scales. On the other hand, our nonlinear PT prediction for these velocity statistics, together with real-space power spectrum for dark matter from simulations, improves the accuracy for both dark matter and halos. We also present the same analysis in configuration space, computing the redshift-space pairwise mean infall velocities and velocity correlation function and compare to nonlinear PT.

  10. Dark matter and halo bispectrum in redshift space: theory and applications

    SciTech Connect (OSTI)

    Gil-Marn, Hctor; Percival, Will [Institute of Cosmology and Gravitation, University of Portsmouth, Dennis Sciama Building, Portsmouth PO1 3FX (United Kingdom); Wagner, Christian [Max-Planck-Institut fr Astrophysik, Karl-Schwarzschild Str. 1, 85741 Garching (Germany); Norea, Jorge [Department of Theoretical Physics and Center for Astroparticle Physics (CAP), 24 quai E. Ansermet, CH-1211 Geneva 4 (Switzerland); Verde, Licia, E-mail: hector.gil@port.ac.uk, E-mail: cwagner@mpa-garching.mpg.de, E-mail: jorge.norena@unige.ch, E-mail: liciaverde@icc.ub.edu, E-mail: will.percival@port.ac.uk [ICREA Instituci Catalana de Recerca i Estudis Avanats, Passeig Llus Companys 23, E-08010 Barcelona (Spain)

    2014-12-01

    We present a phenomenological modification of the standard perturbation theory prediction for the bispectrum in redshift space that allows us to extend the model to mildly non-linear scales over a wide range of redshifts, z?1.5. Our model require 18 free parameters that are fitted to N-body simulations using the shapes k{sub 2}/k{sub 1}=1,1.5,2.0,2.5. We find that we can describe the bispectrum of dark matter particles with ?5% accuracy for k{sub i}?<0.10h/Mpc at z=0, for k{sub i}?<0.15h/Mpc at z=0.5, for k{sub i}?<0.17h/Mpc at z=1.0 and for k{sub i}?<0.20h/Mpc at z=1.5. For very squeezed triangles with k{sub 1}=k{sub 2}?>0.1hMpc{sup -1} and k{sub 3}?0.02hMpc{sup -1}, however, neither SPT nor the proposed fitting formula are able to describe the measured dark matter bispectrum with this accuracy. We show that the fitting formula is sufficiently general that can be applied to other intermediate shapes such as k{sub 2}/k{sub 1}=1.25,1.75,and2.25. We also test that the fitting formula is able to describe with similar accuracy the bispectrum of cosmologies with different ?{sub m}, in the range 0.2?redshift space power spectrum monopole and quadrupole with the bispectrum monopole for both dark matter particles and haloes. We find that the combination of these three statistics can break the degeneracy between b{sub 1}, f and ?{sub 8}. For dark matter particles the new model can be used to recover f and ?{sub 8} with ?1% accuracy. For dark matter haloes we find that f and ?{sub 8} present larger systematic shifts, ?10%. The systematic offsets arise because of limitations in the modelling of the interplay between bias and redshift space distortions, and represent a limitation as the statistical errors of forthcoming surveys reach this level. Conveniently

  11. Early-type galaxies at intermediate redshift observed with Hubble space telescope WFC3: perspectives on recent star formation

    SciTech Connect (OSTI)

    Rutkowski, Michael J.; Jeong, Hyunjin; Yi, Sukyoung K.; Cohen, Seth H.; Windhorst, Rogier A.; Kaviraj, Sugata; Ryan, Russell E. Jr.; Koekemoer, Anton; Hathi, Nimish P.; Dopita, Michael A.

    2014-12-01

    We present an analysis of the stellar populations of 102 visually selected early-type galaxies (ETGs) with spectroscopic redshifts (0.35 ? z ? 1.5) from observations in the Early Release Science program with the Wide Field Camera 3 (WFC3) on the Hubble Space Telescope (HST). We fit one- and two-component synthetic stellar models to the ETGs UV-optical-near-IR spectral energy distributions and find that a large fraction (?40%) are likely to have experienced a minor (f{sub YC} ? 10% of stellar mass) burst of recent (t{sub YC} ? 1 Gyr) star formation. The measured age and mass fraction of the young stellar populations do not strongly trend with measurements of galaxy morphology. We note that massive (M > 10{sup 10.5} M {sub ?}) recent star-forming ETGs appear to have larger sizes. Furthermore, high-mass, quiescent ETGs identified with likely companions populate a distinct region in the size-mass parameter space, in comparison with the distribution of massive ETGs with evidence of recent star formation (RSF). We conclude that both mechanisms of quenching star formation in disk-like ETGs and (gas-rich, minor) merger activity contribute to the formation of young stars and the size-mass evolution of intermediate redshift ETGs. The number of ETGs for which we have both HST WFC3 panchromatic (especially UV) imaging and spectroscopically confirmed redshifts is relatively small, therefore, a conclusion about the relative roles of both of these mechanisms remains an open question.

  12. Testing cosmic geometry without dynamic distortions using voids

    SciTech Connect (OSTI)

    Hamaus, Nico; Sutter, P.M.; Lavaux, Guilhem; Wandelt, Benjamin D. E-mail: sutter@iap.fr E-mail: wandelt@iap.fr

    2014-12-01

    We propose a novel technique to probe the expansion history of the Universe based on the clustering statistics of cosmic voids. In particular, we compute their two-point statistics in redshift space on the basis of realistic mock galaxy catalogs and apply the Alcock-Paczynski test. In contrast to galaxies, we find void auto-correlations to be marginally affected by peculiar motions, providing a model-independent measure of cosmological parameters without systematics from redshift-space distortions. Because only galaxy-galaxy and void-galaxy correlations have been considered in these types of studies before, the presented method improves both statistical and systematic uncertainties on the product of angular diameter distance and Hubble rate, furnishing the potentially cleanest probe of cosmic geometry available to date.

  13. Cosmological constraints from the redshift dependence of the Alcock-Paczynski test: galaxy density gradient field

    SciTech Connect (OSTI)

    Li, Xiao-Dong; Park, Changbom; Forero-Romero, J. E.; Kim, Juhan E-mail: cbp@kias.re.kr E-mail: kjhan@kias.re.kr

    2014-12-01

    We propose a method based on the redshift dependence of the Alcock-Paczynski (AP) test to measure the expansion history of the universe. It uses the isotropy of the galaxy density gradient field to constrain cosmological parameters. If the density parameter ? {sub m} or the dark energy equation of state w are incorrectly chosen, the gradient field appears to be anisotropic with the degree of anisotropy varying with redshift. We use this effect to constrain the cosmological parameters governing the expansion history of the universe. Although redshift-space distortions (RSD) induced by galaxy peculiar velocities also produce anisotropies in the gradient field, these effects are close to uniform in magnitude over a large range of redshift. This makes the redshift variation of the gradient field anisotropy relatively insensitive to the RSD. By testing the method on mock surveys drawn from the Horizon Run 3 cosmological N-body simulations, we demonstrate that the cosmological parameters can be estimated without bias. Our method is complementary to the baryon acoustic oscillation or topology methods as it depends on D{sub AH} , the product of the angular diameter distance and the Hubble parameter.

  14. Combining weak-lensing tomography and spectroscopic redshift surveys

    SciTech Connect (OSTI)

    Cai, Yan -Chuan; Bernstein, Gary

    2012-05-11

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

  15. Combining weak-lensing tomography and spectroscopic redshift surveys

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Cai, Yan -Chuan; Bernstein, Gary

    2012-05-11

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

  16. A faint galaxy redshift survey behind massive clusters

    SciTech Connect (OSTI)

    Frye, Brenda

    1999-12-01

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

  17. Probabilistic Photometric Redshifts in the Era of Petascale Astronomy

    SciTech Connect (OSTI)

    Carrasco Kind, Matias

    2014-01-01

    With the growth of large photometric surveys, accurately estimating photometric redshifts, preferably as a probability density function (PDF), and fully understanding the implicit systematic uncertainties in this process has become increasingly important. These surveys are expected to obtain images of billions of distinct galaxies. As a result, storing and analyzing all of these photometric redshift PDFs will be non-trivial, and this challenge becomes even more severe if a survey plans to compute and store multiple different PDFs. In this thesis, we have developed an end-to-end framework that will compute accurate and robust photometric redshift PDFs for massive data sets by using two new, state-of-the-art machine learning techniques that are based on a random forest and a random atlas, respectively. By using data from several photometric surveys, we demonstrate the applicability of these new techniques, and we demonstrate that our new approach is among the best techniques currently available. We also show how different techniques can be combined by using novel Bayesian techniques to improve the photometric redshift precision to unprecedented levels while also presenting new approaches to better identify outliers. In addition, our framework provides supplementary information regarding the data being analyzed, including unbiased estimates of the accuracy of the technique without resorting to a validation data set, identification of poor photometric redshift areas within the parameter space occupied by the spectroscopic training data, and a quantification of the relative importance of the variables used during the estimation process. Furthermore, we present a new approach to represent and store photometric redshift PDFs by using a sparse representation with outstanding compression and reconstruction capabilities. We also demonstrate how this framework can also be directly incorporated into cosmological analyses. The new techniques presented in this thesis are crucial

  18. A large-scale structure at redshift 1.71 in the Lockman Hole

    SciTech Connect (OSTI)

    Henry, J. Patrick; Hasinger, Günther; Suh, Hyewon; Aoki, Kentaro; Finoguenov, Alexis; Fotopoulou, Sotiria; Salvato, Mara; Tanaka, Masayuki

    2014-01-01

    We previously identified LH146, a diffuse X-ray source in the Lockman Hole, as a galaxy cluster at redshift 1.753. The redshift was based on one spectroscopic value, buttressed by seven additional photometric redshifts. We confirm here the previous spectroscopic redshift and present concordant spectroscopic redshifts for an additional eight galaxies. The average of these nine redshifts is 1.714 ± 0.012 (error on the mean). Scrutiny of the galaxy distribution in redshift space and the plane of the sky shows that there are two concentrations of galaxies near the X-ray source. In addition, there are three diffuse X-ray sources spread along the axis connecting the galaxy concentrations. LH146 is one of these three and lies approximately at the center of the two galaxy concentrations and the outer two diffuse X-ray sources. We thus conclude that LH146 is at the redshift initially reported but it is not a single virialized galaxy cluster, as previously assumed. Rather, it appears to mark the approximate center of a larger region containing more objects. For brevity, we refer to all these objects and their alignments as a large-scale structure. The exact nature of LH146 itself remains unclear.

  19. Probing correlations of early magnetic fields using μ-distortion

    SciTech Connect (OSTI)

    Ganc, Jonathan; Sloth, Martin S. E-mail: sloth@cp3.dias.sdu.dk

    2014-08-01

    The damping of a non-uniform magnetic field between the redshifts of about 10{sup 4} and 10{sup 6} injects energy into the photon-baryon plasma and causes the CMB to deviate from a perfect blackbody spectrum, producing a so-called μ-distortion. We can calculate the correlation (μ T) of this distortion with the temperature anisotropy T of the CMB to search for a correlation ( B{sup 2}ζ) between the magnetic field B and the curvature perturbation ζ; knowing the ( B{sup 2}ζ) correlation would help us distinguish between different models of magnetogenesis. Since the perturbations which produce the μ-distortion will be much smaller scale than the relevant density perturbations, the observation of this correlation is sensitive to the squeezed limit of ( B{sup 2}ζ), which is naturally parameterized by b{sub NL} (a parameter defined analogously to f{sub NL}). We find that a PIXIE-like CMB experiments has a signal to noise S/N≈ 1.0 × b{sub NL} ( B-tilde {sub μ}/10nG){sup 2}, where B-tilde {sub μ} is the magnetic field's strength on μ-distortion scales normalized to today's redshift; thus, a 10 nG field would be detectable with b{sub NL}=O(1). However, if the field is of inflationary origin, we generically expect it to be accompanied by a curvature bispectrum (ζ{sup 3}) induced by the magnetic field. For sufficiently small magnetic fields, the signal ( B{sup 2} ζ) will dominate, but for B-tilde {sub μ}∼> 1 nG, one would have to consider the specifics of the inflationary magnetogenesis model. We also discuss the potential post-magnetogenesis sources of a ( B{sup 2}ζ) correlation and explain why there will be no contribution from the evolution of the magnetic field in response to the curvature perturbation.

  20. PULSAR PAIR CASCADES IN A DISTORTED MAGNETIC DIPOLE FIELD

    SciTech Connect (OSTI)

    Harding, Alice K.; Muslimov, Alex G.

    2011-01-01

    We investigate the effect of a distorted neutron star dipole magnetic field on pulsar pair cascade multiplicity and pair death lines. Using a simple model for a distorted dipole field that produces an offset polar cap (PC), we derive the accelerating electric field above the PC in space-charge-limited flow. We find that even a modest azimuthally asymmetric distortion can significantly increase the accelerating electric field on one side of the PC and, combined with a smaller field line radius of curvature, leads to larger pair multiplicity. The death line for producing pairs by curvature radiation moves downward in the P- P-dot diagram, allowing high pair multiplicities in a larger percentage of the radio pulsar population. These results could have important implications for the radio pulsar population, high energy pulsed emission, and the pulsar contribution to cosmic ray positrons.

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  2. SPECTROSCOPIC REDSHIFTS OF GALAXIES WITHIN THE FRONTIER FIELDS

    SciTech Connect (OSTI)

    Ebeling, Harald; Ma, Cheng-Jiun; Barrett, Elizabeth

    2014-04-01

    We present a catalog of 1921 spectroscopic redshifts measured in the fields of the massive galaxy clusters MACSJ0416.12403 (z = 0.397), MACSJ0717.5+3745 (z = 0.546), and MACSJ1149.5+2223 (z = 0.544), i.e., three of the four clusters selected by Space Telescope Science Institute as the targets of the Frontier Fields (FFs) initiative for studies of the distant Universe via gravitational lensing. Compiled in the course of the Massive Cluster Survey project (MACS) that detected the FF clusters, this catalog is provided to the community for three purposes: (1) to allow the identification of cluster members for studies of the galaxy population of these extreme systems, (2) to facilitate the removal of unlensed galaxies and thus reduce shear dilution in weak-lensing analyses, and (3) to improve the calibration of photometric redshifts based on both ground- and spacebased observations of the FF clusters.

  3. Superconductivity Distorted by the Coexisting Pseudogap in the...

    Office of Scientific and Technical Information (OSTI)

    Superconductivity Distorted by the Coexisting Pseudogap in the Antinodal Region of ... Citation Details In-Document Search Title: Superconductivity Distorted by the Coexisting ...

  4. ACCOUNTING FOR COSMIC VARIANCE IN STUDIES OF GRAVITATIONALLY LENSED HIGH-REDSHIFT GALAXIES IN THE HUBBLE FRONTIER FIELD CLUSTERS

    SciTech Connect (OSTI)

    Robertson, Brant E.; Stark, Dan P.; Ellis, Richard S.; Dunlop, James S.; McLure, Ross J.; McLeod, Derek

    2014-12-01

    Strong gravitational lensing provides a powerful means for studying faint galaxies in the distant universe. By magnifying the apparent brightness of background sources, massive clusters enable the detection of galaxies fainter than the usual sensitivity limit for blank fields. However, this gain in effective sensitivity comes at the cost of a reduced survey volume and, in this Letter, we demonstrate that there is an associated increase in the cosmic variance uncertainty. As an example, we show that the cosmic variance uncertainty of the high-redshift population viewed through the Hubble Space Telescope Frontier Field cluster Abell 2744 increases from ?35% at redshift z ? 7 to ? 65% at z ? 10. Previous studies of high-redshift galaxies identified in the Frontier Fields have underestimated the cosmic variance uncertainty that will affect the ultimate constraints on both the faint-end slope of the high-redshift luminosity function and the cosmic star formation rate density, key goals of the Frontier Field program.

  5. REDSHIFT CATALOG FOR SWIFT LONG GAMMA-RAY BURSTS

    SciTech Connect (OSTI)

    Xiao Limin; Schaefer, Bradley E., E-mail: lxiao1@lsu.edu [Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70803 (United States)

    2011-04-20

    We present a catalog of the redshifts for most long-duration gamma-ray bursts (GRBs) by Swift from 2004 December 20 to 2008 July 23 (258 bursts in total). All available information is collected, including spectroscopic redshifts, photometric redshift limits, and redshifts calculated from various luminosity relations. Error bars for the redshifts derived from the luminosity relations are asymmetric, with tails extended to the high-redshift end, and this effect is evaluated by looking at the 30% of Swift bursts with spectroscopic redshifts. A simulation is performed to eliminate this asymmetric effect, and the resultant redshift distribution is deconvolved. We test and confirm this simulation on the sample of bursts with known spectroscopic redshifts and then apply it to the 70% of Swift bursts that do not have spectroscopic measures. A final intrinsic redshift distribution is then made for almost all Swift bursts, and the efficiency of the spectroscopic detections is evaluated. The efficiency of spectroscopic redshifts varies from near unity at low redshift to 0.5 at z = 1, to near 0.3 at z = 4, and to 0.1 at z = 6. We also find that the fraction of GRBs with z>5 is {approx}10%, and this fraction is compared with simulations from a cosmological model.

  6. Reflective optical imaging system with balanced distortion

    DOE Patents [OSTI]

    Chapman, Henry N.; Hudyma, Russell M.; Shafer, David R.; Sweeney, Donald W.

    1999-01-01

    An optical system compatible with short wavelength (extreme ultraviolet) An optical system compatible with short wavelength (extreme ultraviolet) radiation comprising four reflective elements for projecting a mask image onto a substrate. The four optical elements comprise, in order from object to image, convex, concave, convex and concave mirrors. The optical system is particularly suited for step and scan lithography methods. The invention enables the use of larger slit dimensions associated with ring field scanning optics, improves wafer throughput and allows higher semiconductor device density. The inventive optical system is characterized by reduced dynamic distortion because the static distortion is balanced across the slit width.

  7. Zigzag laser with reduced optical distortion

    DOE Patents [OSTI]

    Albrecht, Georg F.; Comaskey, Brian; Sutton, Steven B.

    1994-01-01

    The architecture of the present invention has been driven by the need to solve the beam quality problems inherent in Brewster's angle tipped slab lasers. The entrance and exit faces of a solid state slab laser are cut perpendicular with respect to the pump face, thus intrinsically eliminating distortion caused by the unpumped Brewster's angled faces. For a given zigzag angle, the residual distortions inherent in the remaining unpumped or lightly pumped ends may be reduced further by tailoring the pump intensity at these ends.

  8. Zigzag laser with reduced optical distortion

    DOE Patents [OSTI]

    Albrecht, G.F.; Comaskey, B.; Sutton, S.B.

    1994-04-19

    The architecture of the present invention has been driven by the need to solve the beam quality problems inherent in Brewster's angle tipped slab lasers. The entrance and exit faces of a solid state slab laser are cut perpendicular with respect to the pump face, thus intrinsically eliminating distortion caused by the unpumped Brewster's angled faces. For a given zigzag angle, the residual distortions inherent in the remaining unpumped or lightly pumped ends may be reduced further by tailoring the pump intensity at these ends. 11 figures.

  9. Reflective optical imaging systems with balanced distortion

    DOE Patents [OSTI]

    Hudyma, Russell M.

    2001-01-01

    Optical systems compatible with extreme ultraviolet radiation comprising four reflective elements for projecting a mask image onto a substrate are described. The four optical elements comprise, in order from object to image, convex, concave, convex and concave mirrors. The optical systems are particularly suited for step and scan lithography methods. The invention enables the use of larger slit dimensions associated with ring field scanning optics, improves wafer throughput, and allows higher semiconductor device density. The inventive optical systems are characterized by reduced dynamic distortion because the static distortion is balanced across the slit width.

  10. Relativistic redshifts in quasar broad lines

    SciTech Connect (OSTI)

    Tremaine, Scott; Shen, Yue; Liu, Xin; Loeb, Abraham E-mail: yshen@obs.carnegiescience.edu E-mail: aloeb@cfa.harvard.edu

    2014-10-10

    The broad emission lines commonly seen in quasar spectra have velocity widths of a few percent of the speed of light, so special- and general-relativistic effects have a significant influence on the line profile. We have determined the redshift of the broad Hβ line in the quasar rest frame (determined from the core component of the [O III] line) for over 20,000 quasars from the Sloan Digital Sky Survey Data Release 7 quasar catalog. The mean redshift as a function of line width is approximately consistent with the relativistic redshift that is expected if the line originates in a randomly oriented Keplerian disk that is obscured when the inclination of the disk to the line of sight exceeds ∼30°-45°, consistent with simple active galactic nucleus unification schemes. This result also implies that the net line-of-sight inflow/outflow velocities in the broad-line region are much less than the Keplerian velocity when averaged over a large sample of quasars with a given line width.

  11. Machine-z: Rapid machine-learned redshift indicator for Swift gamma-ray bursts

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Ukwatta, T. N.; Wozniak, P. R.; Gehrels, N.

    2016-03-08

    Studies of high-redshift gamma-ray bursts (GRBs) provide important information about the early Universe such as the rates of stellar collapsars and mergers, the metallicity content, constraints on the re-ionization period, and probes of the Hubble expansion. Rapid selection of high-z candidates from GRB samples reported in real time by dedicated space missions such as Swift is the key to identifying the most distant bursts before the optical afterglow becomes too dim to warrant a good spectrum. Here, we introduce ‘machine-z’, a redshift prediction algorithm and a ‘high-z’ classifier for Swift GRBs based on machine learning. Our method relies exclusively onmore » canonical data commonly available within the first few hours after the GRB trigger. Using a sample of 284 bursts with measured redshifts, we trained a randomized ensemble of decision trees (random forest) to perform both regression and classification. Cross-validated performance studies show that the correlation coefficient between machine-z predictions and the true redshift is nearly 0.6. At the same time, our high-z classifier can achieve 80 per cent recall of true high-redshift bursts, while incurring a false positive rate of 20 per cent. With 40 per cent false positive rate the classifier can achieve ~100 per cent recall. As a result, the most reliable selection of high-redshift GRBs is obtained by combining predictions from both the high-z classifier and the machine-z regressor.« less

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

    SciTech Connect (OSTI)

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

    2014-06-20

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

  13. Space Videos

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Space Videos Space

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

    SciTech Connect (OSTI)

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

    2013-10-01

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

  15. ON THE REDSHIFT OF THE VERY HIGH ENERGY BLAZAR 3C 66A

    SciTech Connect (OSTI)

    Furniss, A.; Williams, D. A. [Santa Cruz Institute of Particle Physics and Department of Physics, University of California Santa Cruz, 1156 High Street, Santa Cruz, CA 95064 (United States)] [Santa Cruz Institute of Particle Physics and Department of Physics, University of California Santa Cruz, 1156 High Street, Santa Cruz, CA 95064 (United States); Fumagalli, M. [Carnegie Observatories, 813 Santa Barbara Street, Pasadena, CA 91101 (United States)] [Carnegie Observatories, 813 Santa Barbara Street, Pasadena, CA 91101 (United States); Danforth, C. [CASA, Department of Astrophysical and Planetary Sciences, University of Colorado, 389-UCB, Boulder, CO 80309 (United States)] [CASA, Department of Astrophysical and Planetary Sciences, University of Colorado, 389-UCB, Boulder, CO 80309 (United States); Prochaska, J. X. [Department of Astronomy and Astrophysics, UCO/Lick Observatory, University of California, 1156 High Street, Santa Cruz, CA 95064 (United States)] [Department of Astronomy and Astrophysics, UCO/Lick Observatory, University of California, 1156 High Street, Santa Cruz, CA 95064 (United States)

    2013-03-20

    As a bright gamma-ray source, 3C 66A is of great interest to the high-energy astrophysics community, having a potential for placing cosmological constraints on models for the extragalactic background light (EBL) and the processes which contribute to this photon field. No firm spectroscopic redshift measurement has been possible for this blazar due to a lack of intrinsic emission and absorption features in optical spectra. We present new far-ultraviolet spectra from the Hubble Space Telescope/Cosmic Origins Spectrograph (HST/COS) of the BL Lac object 3C 66A covering the wavelength range 1132-1800 A. The data show a smooth continuum with intergalactic medium absorption features which can be used to place a firm lower limit on the blazar redshift of z {>=} 0.3347. An upper limit is set by statistically treating the non-detection of additional absorbers beyond z = 0.3347, indicating a redshift of less than 0.41 at 99% confidence and ruling out z {>=} 0.444 at 99.9% confidence. We conclude by showing how the redshift limits derived from the COS spectra remove the potential for this gamma-ray emitting blazar to place an upper limit on the flux of the EBL using high energy data from a flare in 2009 October.

  16. Metal-induced charge transfer, structural distortion, and orbital...

    Office of Scientific and Technical Information (OSTI)

    Metal-induced charge transfer, structural distortion, and orbital order in SrTiO3 thin films Prev Next Title: Metal-induced charge transfer, structural distortion, and ...

  17. Photometric Redshifts for the Dark Energy Survey and VISTA and...

    Office of Scientific and Technical Information (OSTI)

    We conduct a detailed analysis of the photometric redshift requirements for the proposed Dark Energy Survey (DES) using two sets of mock galaxy simulations and an artificial neural ...

  18. The Efficacy of Galaxy Shape Parameters in Photometric Redshift...

    Office of Scientific and Technical Information (OSTI)

    Journal Article: The Efficacy of Galaxy Shape Parameters in Photometric Redshift Estimation: A Neural Network Approach Citation Details In-Document Search Title: The Efficacy of ...

  19. Potential-well distortion in barrier Rf

    SciTech Connect (OSTI)

    King Ng

    2004-04-29

    Head-tail asymmetry has been observed in the longitudinal beam profiles in the Fermilab Recycler Ring where protons or antiprotons are stored in rf barrier buckets. The asymmetry is caused by the distortion of the rf potential well in the presence of resistive impedance. Gaussian energy distribution can fit the observed asymmetric beam profile but not without discrepancy. It can also fit the measured energy distribution. On the other hand, generalized elliptic distribution gives a better fit to the beam profile. However, it fails to reproduce the observed energy distribution.

  20. Prediction of Part Distortion in Die Casting

    SciTech Connect (OSTI)

    R. Allen Miller

    2005-03-30

    The die casting process is one of the net shape manufacturing techniques and is widely used to produce high production castings with tight tolerances for many industries. An understanding of the stress distribution and the deformation pattern of parts produced by die casting will result in less deviation from the part design specification, a better die design and eventually more productivity and cost savings. This report presents methods that can be used to simulate the die casting process in order to predict the deformation and stresses in the produced part and assesses the degree to which distortion modeling is practical for die casting at the current time. A coupled thermal-mechanical finite elements model was used to simulate the die casting process. The simulation models the effect of thermal and mechanical interaction between the casting and the die. It also includes the temperature dependant material properties of the casting. Based on a designed experiment, a sensitivity analysis was conducted on the model to investigate the effect of key factors. These factors include the casting material model, material properties and thermal interaction between casting and dies. To verify the casting distortion predictions, it was compared against the measured dimensions of produced parts. The comparison included dimensions along and across the parting plane and the flatness of one surface.

  1. DISCOVERY OF A QUADRUPLE LENS IN CANDELS WITH A RECORD LENS REDSHIFT z = 1.53

    SciTech Connect (OSTI)

    Van der Wel, A.; Van de Ven, G.; Maseda, M.; Rix, H. W.; Rudnick, G. H.; Grazian, A.; Finkelstein, S. L.; Koo, D. C.; Faber, S. M.; Kocevski, D. D.

    2013-11-01

    Using spectroscopy from the Large Binocular Telescope and imaging from the Hubble Space Telescope we discovered the first strong galaxy lens at z {sub lens} > 1. The lens has a secure photometric redshift of z = 1.53 ± 0.09 and the source is spectroscopically confirmed at z = 3.417. The Einstein radius (0.''35; 3.0 kpc) encloses 7.6 × 10{sup 10} M {sub ☉}, with an upper limit on the dark matter fraction of 60%. The highly magnified (40×) source galaxy has a very small stellar mass (∼10{sup 8} M {sub ☉}) and shows an extremely strong [O III]{sub 5007Å} emission line (EW{sub 0} ∼ 1000 Å) bolstering the evidence that intense starbursts among very low-mass galaxies are common at high redshift.

  2. Compact quiescent galaxies at intermediate redshifts {sup ,}

    SciTech Connect (OSTI)

    Hsu, Li-Yen; Stockton, Alan; Shih, Hsin-Yi

    2014-12-01

    From several searches of the area common to the Sloan Digital Sky Survey and the United Kingdom Infrared Telescope Infrared Deep Sky Survey, we have selected 22 luminous galaxies between z ? 0.4 and z ? 0.9 that have colors and sizes similar to those of the compact quiescent galaxies at z > 2. By exploring structural parameters and stellar populations, we found that most of these galaxies actually formed most of their stars at z < 2 and are generally less compact than those found at z > 2. Several of these young objects are disk-like or possibly prolate. This lines up with several previous studies that found that massive quiescent galaxies at high redshifts often have disk-like morphologies. If these galaxies were to be confirmed to be disk-like, their formation mechanism must be able to account for both compactness and disks. On the other hand, if these galaxies were to be confirmed to be prolate, the fact that prolate galaxies do not exist in the local universe would indicate that galaxy formation mechanisms have evolved over cosmic time. We also found five galaxies forming over 80% of their stellar masses at z > 2. Three of these galaxies appear to have been modified to have spheroid-like morphologies, in agreement with the scenario of 'inside-out' buildup of massive galaxies. The remaining galaxies, SDSS J014355.21+133451.4 and SDSS J115836.93+021535.1, have truly old stellar populations and disk-like morphologies. These two objects would be good candidates for nearly unmodified compact quiescent galaxies from high redshifts that are worth future study.

  3. Rotating stall control in a high-speed stage with inlet distortion. Part 2: Circumferential distortion

    SciTech Connect (OSTI)

    Spakovszky, Z.S.; Weigl, H.J.; Paduano, J.D.; Schalkwyk, C.M. van; Suder, K.L.; Bright, M.M.

    1999-07-01

    This paper presents the first attempt to stabilize rotating stall in a single-stage transonic axial flow compressor with inlet distortion using active feedback control. The experiments were conducted at the NASA Lewis Research Center on a single-stage transonic core compressor inlet stage. An array of 12 jet injectors located upstream of the compressor was used for forced response testing and feedback stabilization. Results for a circumferential total pressure distortion of about one dynamic head and a 120 deg extent (DC(60){equals}0.61) are reported in this paper. Part 1 (Spaskovszky et al., 1999) reports results for radial distortion. Control laws were designed using empirical transfer function estimates determined from forced response results. Distortion introduces coupling between the harmonics of circumferential pressure perturbations, requiring multivariable identification and control design techniques. The compressor response displayed a strong first spatial harmonic, dominated by the well-known incompressible Moore-Greitzer mode. Steady axisymmetric injection of 4 percent of the compressor mass flow resulted in a 6.2 percent reduction of stalling mass flow. Constant gain feedback, using unsteady asymmetric injection, yielded a further range extension of 9 percent. A more sophisticated robust H{sub {infinity}} controller allowed a reduction in stalling mass flow of 10.2 percent relative to steady injection, yielding a total reduction in stalling mass flow of 16.4 percent.

  4. Galaxy clustering with photometric surveys using PDF redshift information

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

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

    2016-03-28

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

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

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Bernstein, Gary; Huterer, Dragan

    2010-01-11

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

  6. Overcoming residual stresses and machining distortion in the...

    Office of Scientific and Technical Information (OSTI)

    in the production of aluminum alloy satellite boxes. Citation Details In-Document Search Title: Overcoming residual stresses and machining distortion in the production of ...

  7. Simulation of Distortion and Residual Stress Development During...

    Office of Scientific and Technical Information (OSTI)

    Simulation of Distortion and Residual Stress Development During Heat Treatment of Steel ... Available experimental steel casting heat treatment data was determined to be of ...

  8. Harmonic and interharmonic distortion modeling in multiconverter systems

    SciTech Connect (OSTI)

    Carbone, R.; Morrison, R.E.; Testa, A.; Menniti, D.

    1995-07-01

    The problem of modeling multiconverter systems in presence of harmonic and interharmonic distortion is considered. Specifically, current source rectifiers are considered as distortion sources some supply d.c. motors and the remaining supplying inverters feeding a.c. machines. The classical analogue, frequency domain and time domain models proposed in the literature to study harmonic distortion in a multiconverter system are considered and for each model suitable extension to include the interharmonic distortion are presented and critically analyzed. The results of several experiments are reported to show the usefulness and to compare the accuracy of the different extensions considered.

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

    SciTech Connect (OSTI)

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

    2014-12-20

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

  10. Photometric Redshifts for the Dark Energy Survey and VISTA and...

    Office of Scientific and Technical Information (OSTI)

    the photometric redshift estimate by a factor of two at z > 1. We draw attention to the ... By removing all galaxies with a 1sigma photo-z scatter greater than 0.1 from our DES+VHS ...

  11. THE REDSHIFT EVOLUTION OF THE RELATION BETWEEN STELLAR MASS,...

    Office of Scientific and Technical Information (OSTI)

    so-called fundamental metallicity relation, in the galaxy sample of the Sloan Digital Sky Survey Data Release 7. We separate the galaxies into narrow redshift bins and compare ...

  12. Bulgeless galaxies at intermediate redshift: Sample selection, color properties, and the existence of powerful active galactic nuclei

    SciTech Connect (OSTI)

    Bizzocchi, Luca; Leonardo, Elvira; Grossi, Marco; Afonso, Jos; Fernandes, Cristina; Retr, Joo; Filho, Mercedes E.; Lobo, Catarina; Griffith, Roger L.; Anton, Sonia; Bell, Eric F.; Brinchmann, Jarle; Henriques, Bruno; Messias, Hugo

    2014-02-10

    We present a catalog of bulgeless galaxies, which includes 19,225 objects selected in four of the deepest, largest multi-wavelength data sets availableCOSMOS, AEGIS, GEMS, and GOODSat intermediate redshift (0.4 ? z ? 1.0). The morphological classification was provided by the Advanced Camera for Surveys General Catalog (ACS-GC), which used publicly available data obtained with the ACS instrument on the Hubble Space Telescope. Rest-frame photometric quantities were derived using kcorrect. We analyze the properties of the sample and the evolution of pure-disk systems with redshift. Very massive [log (M {sub *}/M {sub ?}) > 10.5] bulgeless galaxies contribute to ?30% of the total galaxy population number density at z ? 0.7, but their number density drops substantially with decreasing redshift. We show that only a negligible fraction of pure disks appear to be quiescent systems, and red sequence bulgeless galaxies show indications of dust-obscured star formation. X-ray catalogs were used to search for X-ray emission within our sample. After visual inspection and detailed parametric morphological fitting we identify 30 active galactic nuclei (AGNs) that reside in galaxies without a classical bulge. The finding of such peculiar objects at intermediate redshift shows that while AGN growth in merger-free systems is a rare event (0.2% AGN hosts in this sample of bulgeless galaxies), it can indeed happen relatively early in the history of the universe.

  13. Constraining the minimum luminosity of high redshift galaxies through gravitational lensing

    SciTech Connect (OSTI)

    Mashian, Natalie; Loeb, Abraham E-mail: aloeb@cfa.harvard.edu

    2013-12-01

    We simulate the effects of gravitational lensing on the source count of high redshift galaxies as projected to be observed by the Hubble Frontier Fields program and the James Webb Space Telescope (JWST) in the near future. Taking the mass density profile of the lensing object to be the singular isothermal sphere (SIS) or the Navarro-Frenk-White (NFW) profile, we model a lens residing at a redshift of z{sub L} = 0.5 and explore the radial dependence of the resulting magnification bias and its variability with the velocity dispersion of the lens, the photometric sensitivity of the instrument, the redshift of the background source population, and the intrinsic maximum absolute magnitude (M{sub max}) of the sources. We find that gravitational lensing enhances the number of galaxies with redshifts z∼> 13 detected in the angular region θ{sub E}/2 ≤ θ ≤ 2θ{sub E} (where θ{sub E} is the Einstein angle) by a factor of ∼ 3 and 1.5 in the HUDF (df/dν{sub 0} ∼ 9 nJy) and medium-deep JWST surveys (df/dν{sub 0} ∼ 6 nJy). Furthermore, we find that even in cases where a negative magnification bias reduces the observed number count of background sources, the lensing effect improves the sensitivity of the count to the intrinsic faint-magnitude cut-off of the Schechter luminosity function. In a field centered on a strong lensing cluster, observations of z∼> 6 and z∼> 13 galaxies with JWST can be used to infer this cut-off magnitude for values as faint as M{sub max} ∼ -14.4 and -16.1 mag (L{sub min} ≈ 2.5 × 10{sup 26} and 1.2 × 10{sup 27} erg s{sup −1} Hz{sup −1}) respectively, within the range bracketed by existing theoretical models. Gravitational lensing may therefore offer an effective way of constraining the low-luminosity cut-off of high-redshift galaxies.

  14. Impact of Distortions on Fiber Position Location in the dark...

    Office of Scientific and Technical Information (OSTI)

    The mapping of the sky to the focal plane, needed to position the fibers accurately, is described in detail. A major challenge is dealing with the large amount of distortion ...

  15. HERSCHEL OBSERVATIONS OF FAR-INFRARED COOLING LINES IN INTERMEDIATE REDSHIFT (ULTRA)-LUMINOUS INFRARED GALAXIES

    SciTech Connect (OSTI)

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

    2014-01-20

    We report the first results from a spectroscopic survey of the [C II] 158?m line from a sample of intermediate redshift (0.2 10{sup 11.5} L {sub ?}), using the Spectral and Photometric Imaging REceiver-Fourier Transform Spectrometer on board the Herschel Space Observatory. This is the first survey of [C II] emission, an important tracer of star formation, at a redshift range where the star formation rate density of the universe increases rapidly. We detect strong [C II] 158?m line emission from over 80% of the sample. We find that the [C II] line is luminous, in the range (0.8-4) 10{sup 3} of the far-infrared continuum luminosity of our sources, and appears to arise from photodissociation regions on the surface of molecular clouds. The L{sub [C} {sub II]}/L {sub IR} ratio in our intermediate redshift (U)LIRGs is on average ?10times larger than that of local ULIRGs. Furthermore, we find that the L{sub [C} {sub II]}/L {sub IR} and L{sub [CII]}/L{sub CO(1-0)} ratios in our sample are similar to those of local normal galaxies and high-z star-forming galaxies. ULIRGs at z ? 0.5 show many similarities to the properties of local normal and high-z star-forming galaxies. Our findings strongly suggest that rapid evolution in the properties of the star-forming regions of (U)LIRGs is likely to have occurred in the last 5 billion years.

  16. THE SPITZER HIGH-REDSHIFT RADIO GALAXY SURVEY

    SciTech Connect (OSTI)

    De Breuck, Carlos; Galametz, Audrey; Vernet, Joel; Seymour, Nick; Stern, Daniel; Eisenhardt, P. R. M.; Willner, S. P.; Fazio, G. G.; Lacy, Mark; Rettura, Alessandro; Rocca-Volmerange, Brigitte

    2010-12-10

    We present results from a comprehensive imaging survey of 70 radio galaxies at redshifts 1 < z < 5.2 using all three cameras on board the Spitzer Space Telescope. The resulting spectral energy distributions unambiguously show a stellar population in 46 sources and hot dust emission associated with the active nucleus in 59. Using a new rest-frame S{sub 3{sub {mu}m}}/S{sub 1.6{sub {mu}m}} versus S{sub 5{sub {mu}m}}/S{sub 3{sub {mu}m}} criterion, we identify 42 sources where the rest-frame 1.6 {mu}m emission from the stellar population can be measured. For these radio galaxies, the median stellar mass is high, 2 x 10{sup 11} M{sub sun}, and remarkably constant within the range 1 < z < 3. At z>3, there is tentative evidence for a factor of two decrease in stellar mass. This suggests that radio galaxies have assembled the bulk of their stellar mass by z {approx} 3, but confirmation by more detailed decomposition of stellar and active galactic nucleus (AGN) emission is needed. The rest-frame 500 MHz radio luminosities are only marginally correlated with stellar mass but are strongly correlated with the rest-frame 5 {mu}m hot dust luminosity. This suggests that the radio galaxies have a large range of Eddington ratios. We also present new Very Large Array 4.86 and 8.46 GHz imaging of 14 radio galaxies and find that radio core dominance-an indicator of jet orientation-is strongly correlated with hot dust luminosity. While all of our targets were selected as narrow-lined, type 2 AGNs, this result can be understood in the context of orientation-dependent models if there is a continuous distribution of orientations from obscured type 2 to unobscured type 1 AGNs rather than a clear dichotomy. Finally, four radio galaxies have nearby (<6'') companions whose mid-IR colors are suggestive of their being AGNs. This may indicate an association between radio galaxy activity and major mergers.

  17. Identifying high-redshift gamma-ray bursts with RATIR

    SciTech Connect (OSTI)

    Littlejohns, O. M.; Butler, N. R. [School of Earth and Space Exploration, Arizona State University, AZ 85287 (United States); Cucchiara, A. [Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Watson, A. M.; Lee, W. H.; Richer, M. G.; De Diego, J. A.; Georgiev, L.; Gonzlez, J.; Romn-Ziga, C. G. [Instituto de Astronoma, Universidad Nacional Autnoma de Mxico, Apartado Postal 70-264, 04510 Mxico, D. F. (Mexico); Kutyrev, A. S.; Troja, E.; Gehrels, N.; Moseley, H. [NASA, Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Klein, C. R.; Fox, O. D.; Bloom, J. S. [Astronomy Department, University of California, Berkeley, CA 94720-7450 (United States); Prochaska, J. X.; Ramirez-Ruiz, E. [Department of Astronomy and Astrophysics, UCO/Lick Observatory, University of California, 1156 High Street, Santa Cruz, CA 95064 (United States)

    2014-07-01

    We present a template-fitting algorithm for determining photometric redshifts, z {sub phot}, of candidate high-redshift gamma-ray bursts (GRBs). Using afterglow photometry, obtained by the Reionization and Transients InfraRed (RATIR) camera, this algorithm accounts for the intrinsic GRB afterglow spectral energy distribution, host dust extinction, and the effect of neutral hydrogen (local and cosmological) along the line of sight. We present the results obtained by this algorithm and the RATIR photometry of GRB 130606A, finding a range of best-fit solutions, 5.6 < z {sub phot} < 6.0, for models of several host dust extinction laws (none, the Milky Way, Large Magellanic Clouds, and Small Magellanic Clouds), consistent with spectroscopic measurements of the redshift of this GRB. Using simulated RATIR photometry, we find that our algorithm provides precise measures of z {sub phot} in the ranges of 4 < z {sub phot} ? 8 and 9 < z {sub phot} < 10 and can robustly determine when z {sub phot} > 4. Further testing highlights the required caution in cases of highly dust-extincted host galaxies. These tests also show that our algorithm does not erroneously find z {sub phot} < 4 when z {sub sim} > 4, thereby minimizing false negatives and allowing us to rapidly identify all potential high-redshift events.

  18. Type Ia supernova rate measurements to redshift 2.5 from CANDELS: Searching for prompt explosions in the early universe

    SciTech Connect (OSTI)

    Rodney, Steven A.; Riess, Adam G.; Graur, Or; Jones, David O. [Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, MD 21218 (United States); Strolger, Louis-Gregory; Dahlen, Tomas; Casertano, Stefano; Ferguson, Henry C.; Koekemoer, Anton M. [Space Telescope Science Institute, Baltimore, MD 21218 (United States); Dickinson, Mark E. [National Optical Astronomy Observatory, 950 North Cherry Avenue, Tucson, AZ 85719 (United States); Garnavich, Peter [Department of Physics, University of Notre Dame, Notre Dame, IN 46556 (United States); Hayden, Brian [E.O. Lawrence Berkeley National Lab, 1 Cyclotron Road, Berkeley, CA 94720 (United States); Jha, Saurabh W.; McCully, Curtis; Patel, Brandon [Department of Physics and Astronomy, Rutgers, The State University of New Jersey, Piscataway, NJ 08854 (United States); Kirshner, Robert P. [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States); Mobasher, Bahram [Department of Physics and Astronomy, University of California, Riverside, CA 92521 (United States); Weiner, Benjamin J. [Department of Astronomy, University of Arizona, Tucson, AZ 85721 (United States); Cenko, S. Bradley [Astrophysics Science Division, NASA Goddard Space Flight Center, Mail Code 661, Greenbelt, MD 20771 (United States); Clubb, Kelsey I. [Department of Astronomy, University of California, Berkeley, CA 94720 (United States); and others

    2014-07-01

    The Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS) was a multi-cycle treasury program on the Hubble Space Telescope (HST) that surveyed a total area of ?0.25 deg{sup 2} with ?900 HST orbits spread across five fields over three years. Within these survey images we discovered 65 supernovae (SNe) of all types, out to z ? 2.5. We classify ?24 of these as Type Ia SNe (SNe Ia) based on host galaxy redshifts and SN photometry (supplemented by grism spectroscopy of six SNe). Here we present a measurement of the volumetric SN Ia rate as a function of redshift, reaching for the first time beyond z = 2 and putting new constraints on SN Ia progenitor models. Our highest redshift bin includes detections of SNe that exploded when the universe was only ?3 Gyr old and near the peak of the cosmic star formation history. This gives the CANDELS high redshift sample unique leverage for evaluating the fraction of SNe Ia that explode promptly after formation (<500 Myr). Combining the CANDELS rates with all available SN Ia rate measurements in the literature we find that this prompt SN Ia fraction is f{sub P} = 0.53{sub stat0.10}{sup 0.09}{sub sys0.26}{sup 0.10}, consistent with a delay time distribution that follows a simple t {sup 1} power law for all times t > 40 Myr. However, mild tension is apparent between ground-based low-z surveys and space-based high-z surveys. In both CANDELS and the sister HST program CLASH (Cluster Lensing And Supernova Survey with Hubble), we find a low rate of SNe Ia at z > 1. This could be a hint that prompt progenitors are in fact relatively rare, accounting for only 20% of all SN Ia explosionsthough further analysis and larger samples will be needed to examine that suggestion.

  19. ULTRAVIOLET SPECTROSCOPY OF RAPIDLY ROTATING SOLAR-MASS STARS: EMISSION-LINE REDSHIFTS AS A TEST OF THE SOLAR-STELLAR CONNECTION

    SciTech Connect (OSTI)

    Linsky, Jeffrey L.; Bushinsky, Rachel; Ayres, Tom; France, Kevin

    2012-07-20

    We compare high-resolution ultraviolet spectra of the Sun and thirteen solar-mass main-sequence stars with different rotational periods that serve as proxies for their different ages and magnetic field structures. In this, the second paper in the series, we study the dependence of ultraviolet emission-line centroid velocities on stellar rotation period, as rotation rates decrease from that of the Pleiades star HII314 (P{sub rot} = 1.47 days) to {alpha} Cen A (P{sub rot} = 28 days). Our stellar sample of F9 V to G5 V stars consists of six stars observed with the Cosmic Origins Spectrograph on the Hubble Space Telescope (HST) and eight stars observed with the Space Telescope Imaging Spectrograph on HST. We find a systematic trend of increasing redshift with more rapid rotation (decreasing rotation period) that is similar to the increase in line redshift between quiet and plage regions on the Sun. The fastest-rotating solar-mass star in our study, HII314, shows significantly enhanced redshifts at all temperatures above log T = 4.6, including the corona, which is very different from the redshift pattern observed in the more slowly rotating stars. This difference in the redshift pattern suggests that a qualitative change in the magnetic-heating process occurs near P{sub rot} = 2 days. We propose that HII314 is an example of a solar-mass star with a magnetic heating rate too large for the physical processes responsible for the redshift pattern to operate in the same way as for the more slowly rotating stars. HII314 may therefore lie above the high activity end of the set of solar-like phenomena that is often called the 'solar-stellar connection'.

  20. EVOLUTION OF GALAXY LUMINOSITY FUNCTION USING PHOTOMETRIC REDSHIFTS

    SciTech Connect (OSTI)

    Ramos, B. H. F.; Pellegrini, P. S.; Da Costa, L. N.; Maia, M. A. G.; Ogando, R. L. C.; De Simoni, F.; Benoist, C.; Makler, M.; Mesquita, A. A. E-mail: pssp@linea.gov.br E-mail: maia@linea.gov.br E-mail: fsimoni@linea.gov.br E-mail: martin@cbpf.br

    2011-08-15

    We examine the impact of using photometric redshifts for studying the evolution of both the global galaxy luminosity function (LF) and that for different galaxy types. To this end, we compare the LFs obtained using photometric redshifts from the Canada-France-Hawaii Telescope Legacy Survey (CFHTLS) D1 field with those from the spectroscopic survey VIMOS VLT Deep Survey (VVDS) comprising {approx}4800 galaxies. We find that for z {<=} 2.0, in the interval of magnitudes considered by this survey, the LFs obtained using photometric and spectroscopic redshifts show a remarkable agreement. This good agreement led us to use all four Deep fields of the CFHTLS comprising {approx}386,000 galaxies to compute the LF of the combined fields and directly estimate the error in the parameters based on the field-to-field variation. We find that the characteristic absolute magnitude M* of Schechter fits fades by {approx}0.7 mag from z {approx} 1.8 to z {approx} 0.3, while the characteristic density {phi}* increases by a factor of {approx}4 in the same redshift interval. We use the galaxy classification provided by the template fitting program used to compute photometric redshifts and split the sample into galaxy types. We find that these Schechter parameters evolve differently for each galaxy type, an indication that their evolution is a combination of several effects: galaxy merging, star formation quenching, and mass assembly. All these results are compatible with those obtained by different spectroscopic surveys such as VVDS, DEEP2, and zCosmos, which reinforces the fact that photometric redshifts can be used to study galaxy evolution, at least for the redshift bins adopted so far. This is of great interest since future very large imaging surveys containing hundreds of millions of galaxies will allow us to obtain important precise measurements to constrain the evolution of the LF and to explore the dependence of this evolution on morphology and/or color helping constrain the

  1. MEASURING BARYON ACOUSTIC OSCILLATIONS ON 21 cm INTENSITY FLUCTUATIONS AT MODERATE REDSHIFTS

    SciTech Connect (OSTI)

    Mao Xiaochun

    2012-06-20

    After reionization, emission in the 21 cm hyperfine transition provides a direct probe of neutral hydrogen distributed in galaxies. Different from galaxy redshift surveys, observation of baryon acoustic oscillations in the cumulative 21 cm emission may offer an attractive method for constraining dark energy properties at moderate redshifts. Keys to this program are techniques to extract the faint cosmological signal from various contaminants, such as detector noise and continuum foregrounds. In this paper, we investigate the possible systematic and statistical errors in the acoustic scale estimates using ground-based radio interferometers. Based on the simulated 21 cm interferometric measurements, we analyze the performance of a Fourier-space, light-of-sight algorithm in subtracting foregrounds, and further study the observing strategy as a function of instrumental configurations. Measurement uncertainties are presented from a suite of simulations with a variety of parameters, in order to have an estimate of what behaviors will be accessible in the future generation of hydrogen surveys. We find that 10 separate interferometers, each of which contains {approx}300 dishes, observing an independent patch of the sky and producing an instantaneous field of view (FOV) of {approx}100 deg{sup 2}, can be used to make a significant detection of acoustic features over a period of a few years. Compared to optical surveys, the broad bandwidth, wide FOV, and multi-beam observation are all unprecedented capabilities of low-frequency radio experiments.

  2. A hydrodynamical approach to CMB ?-distortion from primordial perturbations

    SciTech Connect (OSTI)

    Pajer, Enrico; Zaldarriaga, Matias E-mail: matiasz@ias.edu

    2013-02-01

    Spectral distortion of the cosmic microwave background provides a unique opportunity to probe primordial perturbations on very small scales by performing large-scale measurements. We discuss in a systematic and pedagogic way all the relevant physical phenomena involved in the production and evolution of the ?-type spectral distortion. Our main results agree with previous estimates (in particular we show that a recently found factor of 3/4 arises from relativistic corrections to the wave energy). We also discuss several subleading corrections such as adiabatic cooling and the effects of bulk viscosity, baryon loading and photon heat conduction. Finally we provide formulae for the spatial dependence of ?-distortions and its transfer function between the end of the ?-era and now.

  3. Low thermal distortion extreme-UV lithography reticle

    DOE Patents [OSTI]

    Gianoulakis, Steven E.; Ray-Chaudhuri, Avijit K.

    2001-01-01

    Thermal distortion of reticles or masks can be significantly reduced by emissivity engineering, i.e., the selective placement or omission of coatings on the reticle. Reflective reticles so fabricated exhibit enhanced heat transfer thereby reducing the level of thermal distortion and ultimately improving the quality of the transcription of the reticle pattern onto the wafer. Reflective reticles include a substrate having an active region that defines the mask pattern and non-active region(s) that are characterized by a surface that has a higher emissivity than that of the active region. The non-active regions are not coated with the radiation reflective material.

  4. Low thermal distortion extreme-UV lithography reticle

    DOE Patents [OSTI]

    Gianoulakis, Steven E.; Ray-Chaudhuri, Avijit K.

    2002-01-01

    Thermal distortion of reticles or masks can be significantly reduced by emissivity engineering, i.e., the selective placement or omission of coatings on the reticle. Reflective reticles so fabricated exhibit enhanced heat transfer thereby reducing the level of thermal distortion and ultimately improving the quality of the transcription of the reticle pattern onto the wafer. Reflective reticles include a substrate having an active region that defines the mask pattern and non-active region(s) that are characterized by a surface that has a higher emissivity than that of the active region. The non-active regions are not coated with the radiation reflective material.

  5. Low thermal distortion Extreme-UV lithography reticle and method

    DOE Patents [OSTI]

    Gianoulakis, Steven E.; Ray-Chaudhuri, Avijit K.

    2002-01-01

    Thermal distortion of reticles or masks can be significantly reduced by emissivity engineering, i.e., the selective placement or omission of coatings on the reticle. Reflective reticles so fabricated exhibit enhanced heat transfer thereby reducing the level of thermal distortion and ultimately improving the quality of the transcription of the reticle pattern onto the wafer. Reflective reticles include a substrate having an active region that defines the mask pattern and non-active region(s) that are characterized by a surface that has a higher emissivity than that of the active region. The non-active regions are not coated with the radiation reflective material.

  6. System for interferometric distortion measurements that define an optical path

    DOE Patents [OSTI]

    Bokor, Jeffrey; Naulleau, Patrick

    2003-05-06

    An improved phase-shifting point diffraction interferometer can measure both distortion and wavefront aberration. In the preferred embodiment, the interferometer employs an object-plane pinhole array comprising a plurality of object pinholes located between the test optic and the source of electromagnetic radiation and an image-plane mask array that is positioned in the image plane of the test optic. The image-plane mask array comprises a plurality of test windows and corresponding reference pinholes, wherein the positions of the plurality of pinholes in the object-plane pinhole array register with those of the plurality of test windows in image-plane mask array. Electromagnetic radiation that is directed into a first pinhole of object-plane pinhole array thereby creating a first corresponding test beam image on the image-plane mask array. Where distortion is relatively small, it can be directly measured interferometrically by measuring the separation distance between and the orientation of the test beam and reference-beam pinhole and repeating this process for at least one other pinhole of the plurality of pinholes of the object-plane pinhole array. Where the distortion is relative large, it can be measured by using interferometry to direct the stage motion, of a stage supporting the image-plane mask array, and then use the final stage motion as a measure of the distortion.

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

    SciTech Connect (OSTI)

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

    2014-07-01

    One of the main problems of observational cosmology is to determine the range in which a reliable measurement of galaxy correlations is possible. This corresponds to determining the shape of the correlation function, its possible evolution with redshift and the size and amplitude of large scale structures. Different selection effects, inevitably entering in any observation, introduce important constraints in the measurement of correlations. In the context of galaxy redshift surveys selection effects can be caused by observational techniques and strategies and by implicit assumptions used in the data analysis. Generally all these effects are taken into account by using pair-counting algorithms to measure two-point correlations. We review these methods stressing that they are based on the a-priori assumption that galaxy distribution is spatially homogeneous inside a given sample. We show that, when this assumption is not satisfied by the data, results of the correlation analysis are affected by finite size effects. In order to quantify these effects, we introduce a new method based on the computation of the gradient of galaxy counts along tiny cylinders. We show, by using artificial homogeneous and inhomogeneous point distributions, that this method identifies redshift dependent selection effects and disentangles them from the presence of large scale density fluctuations. We then apply this new method to several redshift catalogs and we find evidence that galaxy distribution, in those samples where selection effects are small enough, is characterized by power-law correlations with exponent ?=0.9 up to 20 Mpc/h followed by a change of slope that, in the range 20100 Mpc/h, corresponds to a power-law exponent ?=0.25. Whether a crossover to spatial uniformity occurs at ?100 Mpc/h or larger scales cannot be clarified by the present data.

  8. GALAXY EVOLUTION IN OVERDENSE ENVIRONMENTS AT HIGH REDSHIFT: PASSIVE EARLY-TYPE GALAXIES IN A CLUSTER AT z {approx} 2

    SciTech Connect (OSTI)

    Strazzullo, V.; Gobat, R.; Daddi, E.; Onodera, M.; Carollo, M.; Dickinson, M.; Renzini, A.; Arimoto, N.; Cimatti, A.; Finoguenov, A.; Chary, R.-R.

    2013-08-01

    We present a study of galaxy populations in the central region of the IRAC-selected, X-ray-detected galaxy cluster Cl J1449+0856 at z = 2. Based on a sample of spectroscopic and photometric cluster members, we investigate stellar populations and the morphological structure of cluster galaxies over an area of {approx}0.7 Mpc{sup 2} around the cluster core. The cluster stands out as a clear overdensity both in redshift space and in the spatial distribution of galaxies close to the center of the extended X-ray emission. The cluster core region (r < 200 kpc) shows a clearly enhanced passive fraction with respect to field levels. However, together with a population of massive, passive galaxies mostly with early-type morphologies, the cluster core also hosts massive, actively star-forming, often highly dust reddened sources. Close to the cluster center, a multi-component system of passive and star-forming galaxies could represent the future brightest cluster galaxy still forming. We observe a clear correlation between passive stellar populations and an early-type morphology, in agreement with field studies at similar redshift. Passive early-type galaxies in this cluster are typically a factor of 2-3 smaller than similarly massive early types at z {approx} 0. On the other hand, these same objects are on average larger by a factor of {approx}2 than field early-types at similar redshift, lending support to recent claims of an accelerated structural evolution in high-redshift dense environments. These results point toward the early formation of a population of massive galaxies, already evolved both in their structure and stellar populations, coexisting with still actively forming massive galaxies in the central regions of young clusters 10 billion years ago.

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

    SciTech Connect (OSTI)

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

    2005-02-01

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

  10. Confronting X-Ray Emission Models with theHighest-Redshift Kiloparsec-Scale Jets: The z = 3.89 Jet in Quasar 1745+624

    SciTech Connect (OSTI)

    Cheung, C.C.; Stawarz, L.; Siemiginowska, A.; /Harvard-Smithsonian Ctr. Astrophys.

    2006-06-28

    A newly identified kiloparsec-scale X-ray jet in the high-redshift z=3.89 quasar 1745+624 is studied with multi-frequency Very Large Array, Hubble Space Telescope, and Chandra X-ray imaging data. This is only the third large-scale X-ray jet beyond z > 3 known and is further distinguished as being the most luminous relativistic jet observed at any redshift, exceeding 10{sup 45} erg/s in both the radio and X-ray bands. Apart from the jet's extreme redshift, luminosity, and high inferred equipartition magnetic field (in comparison to local analogues), its basic properties such as X-ray/radio morphology and radio polarization are similar to lower-redshift examples. Its resolved linear structure and the convex broad-band spectral energy distributions of three distinct knots are also a common feature among known powerful X-ray jets at lower-redshift. Relativistically beamed inverse Compton and ''non-standard'' synchrotron models have been considered to account for such excess X-ray emission in other jets; both models are applicable to this high-redshift example but with differing requirements for the underlying jet physical properties, such as velocity, energetics, and electron acceleration processes. One potentially very important distinguishing characteristic between the two models is their strongly diverging predictions for the X-ray/radio emission with increasing redshift. This is considered, though with the limited sample of three z > 3 jets it is apparent that future studies targeted at very high-redshift jets are required for further elucidation of this issue. Finally, from the broad-band jet emission we estimate the jet kinetic power to be no less than 10{sup 46} erg/s, which is about 10% of the Eddington luminosity corresponding to this galaxy's central supermassive black hole mass M{sub BH} {approx}> 10{sup 9} M{sub {circle_dot}} estimated here via the virial relation. The optical luminosity of the quasar core is about ten times over Eddington, hence the

  11. Welding Induced Alignment Distortion in Dual-in-Line LD Packages

    SciTech Connect (OSTI)

    Liu, Wenning N.; Sun, Xin; Khaleel, Mohammad A.; Shi, Frank G.

    2007-11-11

    The tolerance for the movement of a single mode fiber relative to the laser is extremely tight, a submicron movement can often lead to a significant misalignment and thus the reduction in the power coupled into the fiber. Among various fiber pigtailing assembly technologies, pulsed laser welding is the method with submicron accuracy and is most conducive to automation. However, the melting-solidification process during laser welding can often distort the pre-achieved fiber-optic alignment. This Welding-Induced-Alignment-Distortion (WIAD) is a serious concern and significantly affects the yield for single mode fiber pigtailing to a semiconductor laser. In this paper, effect of laser welding sequence on WIAD in a dual-in-line packager is numerically investigated by means of Finite Element Method (FEM). Optimal welding sequence may minimize WIAD in dual-in-line package. Additionally, unsymmetrical space between fiber and U-channel induced by laser welding of U-channelto-plate in DIP LD packages is found to have obvious effect on WIAD.

  12. Breast tissue decomposition with spectral distortion correction: A postmortem study

    SciTech Connect (OSTI)

    Ding, Huanjun; Zhao, Bo; Baturin, Pavlo; Behroozi, Farnaz; Molloi, Sabee

    2014-10-15

    Purpose: To investigate the feasibility of an accurate measurement of water, lipid, and protein composition of breast tissue using a photon-counting spectral computed tomography (CT) with spectral distortion corrections. Methods: Thirty-eight postmortem breasts were imaged with a cadmium-zinc-telluride-based photon-counting spectral CT system at 100 kV. The energy-resolving capability of the photon-counting detector was used to separate photons into low and high energy bins with a splitting energy of 42 keV. The estimated mean glandular dose for each breast ranged from 1.8 to 2.2 mGy. Two spectral distortion correction techniques were implemented, respectively, on the raw images to correct the nonlinear detector response due to pulse pileup and charge-sharing artifacts. Dual energy decomposition was then used to characterize each breast in terms of water, lipid, and protein content. In the meantime, the breasts were chemically decomposed into their respective water, lipid, and protein components to provide a gold standard for comparison with dual energy decomposition results. Results: The accuracy of the tissue compositional measurement with spectral CT was determined by comparing to the reference standard from chemical analysis. The averaged root-mean-square error in percentage composition was reduced from 15.5% to 2.8% after spectral distortion corrections. Conclusions: The results indicate that spectral CT can be used to quantify the water, lipid, and protein content in breast tissue. The accuracy of the compositional analysis depends on the applied spectral distortion correction technique.

  13. THE FIRST HIGH-REDSHIFT QUASAR FROM Pan-STARRS

    SciTech Connect (OSTI)

    Morganson, Eric; De Rosa, Gisella; Decarli, Roberto; Walter, Fabian; Rix, Hans-Walter; Chambers, Ken; Burgett, William; Flewelling, Heather; Hodapp, Klaus; Kaiser, Nick; Magnier, Eugene; Sweeney, Bill; Waters, Christopher; McGreer, Ian; Fan, Xiaohui; Greiner, Jochen; Price, Paul

    2012-06-15

    We present the discovery of the first high-redshift (z > 5.7) quasar from the Panoramic Survey Telescope and Rapid Response System 1 (Pan-STARRS1 or PS1). This quasar was initially detected as an i{sub P1} dropout in PS1, confirmed photometrically with the SAO Wide-field InfraRed Camera at Arizona's Multiple Mirror Telescope (MMT) and the Gamma-Ray Burst Optical/Near-Infrared Detector at the MPG 2.2 m telescope in La Silla. The quasar was verified spectroscopically with the MMT Spectrograph, Red Channel and the Cassegrain Twin Spectrograph at the Calar Alto 3.5 m telescope. Its near-infrared spectrum was taken at the Large Binocular Telescope Observatory (LBT) with the LBT Near-Infrared Spectroscopic Utility with Camera and Integral Field Unit for Extragalactic Research. It has a redshift of 5.73, an AB z{sub P1} magnitude of 19.4, a luminosity of 3.8 Multiplication-Sign 10{sup 47} erg s{sup -1}, and a black hole mass of 6.9 Multiplication-Sign 10{sup 9} M{sub Sun }. It is a broad absorption line quasar with a prominent Ly{beta} peak and a very blue continuum spectrum. This quasar is the first result from the PS1 high-redshift quasar search that is projected to discover more than 100 i{sub P1} dropout quasars and could potentially find more than 10 z{sub P1} dropout (z > 6.8) quasars.

  14. Beyond the Lone-Pair Model for Structurally Distorted Metal Oxides

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Beyond the Lone-Pair Model for Structurally Distorted Metal Oxides Beyond the Lone-Pair Model for Structurally Distorted Metal Oxides Print Wednesday, 28 February 2007 00:00 "Ferroelectricity," by analogy to ferromagnetism, is defined as the presence of spontaneous electrical polarization in a material, often arising from distortions in the material's crystal structure. In oxides of the metals lead and bismuth, such distortions were for many years attributed to the existence of

  15. The SDSS Coadd: A Galaxy Photometric Redshift Catalog

    SciTech Connect (OSTI)

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

    2011-11-01

    We present and describe a catalog of galaxy photometric redshifts (photo-z's) for the Sloan Digital Sky Survey (SDSS) Coadd Data. We use the Artificial Neural Network (ANN) technique to calculate photo-z's and the Nearest Neighbor Error (NNE) method to estimate photo-z errors for {approx} 13 million objects classified as galaxies in the coadd with r < 24.5. The photo-z and photo-z error estimators are trained and validated on a sample of {approx} 89, 000 galaxies that have SDSS photometry and spectroscopic redshifts measured by the SDSS Data Release 7 (DR7), the Canadian Network for Observational Cosmology Field Galaxy Survey (CNOC2), the Deep Extragalactic Evolutionary Probe Data Release 3(DEEP2 DR3), the SDSS-III's Baryon Oscillation Spectroscopic Survey (BOSS), the Visible imaging Multi-Object Spectrograph - Very Large Telescope Deep Survey (VVDS) and the WiggleZ Dark Energy Survey. For the best ANN methods we have tried, we find that 68% of the galaxies in the validation set have a photo-z error smaller than {sigma}{sub 68} = 0.036. After presenting our results and quality tests, we provide a short guide for users accessing the public data.

  16. DETERMINING THE LUMINOSITY FUNCTION OF SWIFT LONG GAMMA-RAY BURSTS WITH PSEUDO-REDSHIFTS

    SciTech Connect (OSTI)

    Tan Weiwei; Yu Yunwei [Institute of Astrophysics, Central China Normal University, Wuhan (China); Cao Xiaofeng, E-mail: yuyw@phy.ccnu.edu.cn [School of Physics, Huazhong University of Science and Technology, Wuhan (China)

    2013-07-20

    The determination of the luminosity function (LF) of gamma-ray bursts (GRBs) is an important role for the cosmological applications of the GRBs, which, however, is seriously hindered by some selection effects due to redshift measurements. In order to avoid these selection effects, we suggest calculating pseudo-redshifts for Swift GRBs according to the empirical L-E{sub p} relationship. Here, such a L-E{sub p} relationship is determined by reconciling the distributions of pseudo- and real redshifts of redshift-known GRBs. The values of E{sub p} taken from Butler's GRB catalog are estimated with Bayesian statistics rather than observed. Using the GRB sample with pseudo-redshifts of a relatively large number, we fit the redshift-resolved luminosity distributions of the GRBs with a broken-power-law LF. The fitting results suggest that the LF could evolve with redshift by a redshift-dependent break luminosity, e.g., L{sub b} = 1.2 Multiplication-Sign 10{sup 51}(1 + z){sup 2} erg s{sup -1}. The low- and high-luminosity indices are constrained to 0.8 and 2.0, respectively. It is found that the proportional coefficient between the GRB event rate and the star formation rate should correspondingly decrease with increasing redshifts.

  17. A search for moderate-redshift survivors from the population of luminous compact passive galaxies at high redshift

    SciTech Connect (OSTI)

    Stockton, Alan; Shih, Hsin-Yi; Larson, Kirsten; Mann, Andrew W. E-mail: hsshih@ifa.hawaii.edu E-mail: amann@ifa.hawaii.edu

    2014-01-10

    From a search of a ∼2400 deg{sup 2} region covered by both the Sloan Digital Sky Survey and UKIRT Infrared Deep Sky Survey databases, we have attempted to identify galaxies at z ∼ 0.5 that are consistent with their being essentially unmodified examples of the luminous passive compact galaxies found at z ∼ 2.5. After isolating good candidates via deeper imaging, we further refine the sample with Keck moderate-resolution spectroscopy and laser guide star adaptive-optics imaging. For four of the five galaxies that so far remain after passing through this sieve, we analyze plausible star-formation histories based on our spectra in order to identify galaxies that may have survived with little modification from the population formed at high redshift. We find two galaxies that are consistent with having formed ≳ 95% of their mass at z > 5. We attempt to estimate masses both from our stellar population determinations and from velocity dispersions. Given the high frequency of small axial ratios, both in our small sample and among samples found at high redshifts, we tentatively suggest that some of the more extreme examples of passive compact galaxies may have prolate morphologies.

  18. One dimensional wavefront distortion sensor comprising a lens array system

    DOE Patents [OSTI]

    Neal, Daniel R.; Michie, Robert B.

    1996-01-01

    A 1-dimensional sensor for measuring wavefront distortion of a light beam as a function of time and spatial position includes a lens system which incorporates a linear array of lenses, and a detector system which incorporates a linear array of light detectors positioned from the lens system so that light passing through any of the lenses is focused on at least one of the light detectors. The 1-dimensional sensor determines the slope of the wavefront by location of the detectors illuminated by the light. The 1 dimensional sensor has much greater bandwidth that 2 dimensional systems.

  19. One dimensional wavefront distortion sensor comprising a lens array system

    DOE Patents [OSTI]

    Neal, D.R.; Michie, R.B.

    1996-02-20

    A 1-dimensional sensor for measuring wavefront distortion of a light beam as a function of time and spatial position includes a lens system which incorporates a linear array of lenses, and a detector system which incorporates a linear array of light detectors positioned from the lens system so that light passing through any of the lenses is focused on at least one of the light detectors. The 1-dimensional sensor determines the slope of the wavefront by location of the detectors illuminated by the light. The 1 dimensional sensor has much greater bandwidth that 2 dimensional systems. 8 figs.

  20. Photometric redshifts and clustering of emission line galaxies selected jointly by DES and eBOSS

    SciTech Connect (OSTI)

    Jouvel, S.; et al.

    2015-09-23

    We present the results of the first test plates of the extended Baryon Oscillation Spectroscopic Survey. This paper focuses on the emission line galaxies (ELG) population targetted from the Dark Energy Survey (DES) photometry. We analyse the success rate, efficiency, redshift distribution, and clustering properties of the targets. From the 9000 spectroscopic redshifts targetted, 4600 have been selected from the DES photometry. The total success rate for redshifts between 0.6 and 1.2 is 71\\% and 68\\% respectively for a bright and faint, on average more distant, samples including redshifts measured from a single strong emission line. We find a mean redshift of 0.8 and 0.87, with 15 and 13\\% of unknown redshifts respectively for the bright and faint samples. In the redshift range 0.6redshifts, the mean redshift for the bright and faint sample is 0.85 and 0.9 respectively. Star contamination is lower than 2\\%. We measure a galaxy bias averaged on scales of 1 and 10~Mpc/h of 1.72 \\pm 0.1 for the bright sample and of 1.78 \\pm 0.12 for the faint sample. The error on the galaxy bias have been obtained propagating the errors in the correlation function to the fitted parameters. This redshift evolution for the galaxy bias is in agreement with theoretical expectations for a galaxy population with MB-5\\log h < -21.0. We note that biasing is derived from the galaxy clustering relative to a model for the mass fluctuations. We investigate the quality of the DES photometric redshifts and find that the outlier fraction can be reduced using a comparison between template fitting and neural network, or using a random forest algorithm.

  1. Voltage distortion in distribution feeders with nonlinear loads

    SciTech Connect (OSTI)

    Emanuel, A.E.; Janczak, J. ); Pileggi, D.J.; Gulachenski, E.M.; Root, C.E.; Breen, M. ); Gentile, T.J. )

    1994-01-01

    The voltage of three real-life 13.8kV feeders supplying customers with non-linear loads was analyzed by means of computer simulations. Three classes of non-linear loads were considered. Each class is characteristic for different types of ac to dc converters such as the input dc supply used for adjustable-speed-drives, battery chargers, PC's, TV's and electronically ballasted lights. The analysis is based on the determination of the most harmonic susceptible busses and their response to each harmonic frequency. A new expeditive method that takes into account the background harmonic voltage phasor, and an equivalent bus impedance was developed and used to compute the maximum non-linear loads that yields VTHD = 5%, (Voltage Total Harmonic Distortion). The main conclusion of this work is that when mitigation methods are not used, for a 15kV class feeder with a maximum 10MVA installed load, the total non-linear residential load should not exceed 300kW if the ITHD <30% (Current Total Harmonic Distortion), and 100kW if ITHD >100%.

  2. Distance-redshift relations in an anisotropic cosmological model

    SciTech Connect (OSTI)

    Menezes, R. S. Jr.; Pigozzo, C.; Carneiro, S. E-mail: cpigozzo@ufba.br

    2013-03-01

    In this paper we study an anisotropic model generated from a particular Bianchi type-III metric, which is a generalization of Gdel's metric and an exact solution of Einstein's field equations. We analyse type Ia supernova data, namely the SDSS sample calibrated with the MLCS2k2 fitter, and we verify in which ranges of distances and redshifts the anisotropy could be observed. We also consider, in a joint analysis, the position of the first peak in the CMB anisotropy spectrum, as well as current observational constraints on the Hubble constant. We conclude that a small anisotropy is permitted by the data, and that more accurate measurements of supernova distances above z = 2 might indicate the existence of such anisotropy in the universe.

  3. AN X-RAY-SELECTED GALAXY CLUSTER IN THE LOCKMAN HOLE AT REDSHIFT 1.753

    SciTech Connect (OSTI)

    Patrick Henry, J.; Salvato, Mara; Hasinger, Guenther; Finoguenov, Alexis; Brunner, Hermann; Burwitz, Vadim; Buschkamp, Peter; Foerster-Schreiber, Natasha; Genzel, Reinhard; Rovilos, Manolis; Szokoly, Gyula; Bouche, Nicolas; Egami, Eiichi; Fotopoulou, Sotiria; Mainieri, Vincenzo

    2010-12-10

    We have discovered an X-ray-selected galaxy cluster with a spectroscopic redshift of 1.753. The redshift is of the brightest cluster galaxy (BCG), which is coincident with the peak of the X-ray surface brightness. We also have concordant photometric redshifts for seven additional candidate cluster members. The X-ray luminosity of the cluster is (3.68 {+-} 0.70) x 10{sup 43} erg s{sup -1} in the 0.1-2.4 keV band. The optical/IR properties of the BCG imply that its formation redshift was {approx}5 if its stars formed in a short burst. This result continues the trend from lower redshift in which the observed properties of BCGs are most simply explained by a single monolithic collapse at very high redshift instead of the theoretically preferred gradual hierarchical assembly at later times. However, the models corresponding to different formation redshifts are more clearly separated as our observation epoch approaches the galaxy formation epoch. Although our infrared photometry is not deep enough to define a red sequence, we do identify a few galaxies at the cluster redshift that have the expected red sequence photometric properties.

  4. RECONSTRUCTING REDSHIFT DISTRIBUTIONS WITH CROSS-CORRELATIONS: TESTS AND AN OPTIMIZED RECIPE

    SciTech Connect (OSTI)

    Matthews, Daniel J.; Newman, Jeffrey A., E-mail: djm70@pitt.ed, E-mail: janewman@pitt.ed [Department of Physics and Astronomy, University of Pittsburgh, 3941 O'Hara Street, Pittsburgh, PA 15260 (United States)

    2010-09-20

    Many of the cosmological tests to be performed by planned dark energy experiments will require extremely well-characterized photometric redshift measurements. Current estimates for cosmic shear are that the true mean redshift of the objects in each photo-z bin must be known to better than 0.002(1 + z), and the width of the bin must be known to {approx}0.003(1 + z) if errors in cosmological measurements are not to be degraded significantly. A conventional approach is to calibrate these photometric redshifts with large sets of spectroscopic redshifts. However, at the depths probed by Stage III surveys (such as DES), let alone Stage IV (LSST, JDEM, and Euclid), existing large redshift samples have all been highly (25%-60%) incomplete, with a strong dependence of success rate on both redshift and galaxy properties. A powerful alternative approach is to exploit the clustering of galaxies to perform photometric redshift calibrations. Measuring the two-point angular cross-correlation between objects in some photometric redshift bin and objects with known spectroscopic redshift, as a function of the spectroscopic z, allows the true redshift distribution of a photometric sample to be reconstructed in detail, even if it includes objects too faint for spectroscopy or if spectroscopic samples are highly incomplete. We test this technique using mock DEEP2 Galaxy Redshift survey light cones constructed from the Millennium Simulation semi-analytic galaxy catalogs. From this realistic test, which incorporates the effects of galaxy bias evolution and cosmic variance, we find that the true redshift distribution of a photometric sample can, in fact, be determined accurately with cross-correlation techniques. We also compare the empirical error in the reconstruction of redshift distributions to previous analytic predictions, finding that additional components must be included in error budgets to match the simulation results. This extra error contribution is small for surveys that

  5. LOW-METALLICITY STAR FORMATION IN HIGH-REDSHIFT GALAXIES AT z {approx} 8

    SciTech Connect (OSTI)

    Taniguchi, Y.; Shioya, Y.; Trump, J. R.

    2010-12-01

    Based on the recent very deep near-infrared imaging of the Hubble Ultra Deep Field with WFC3 on the Hubble Space Telescope, five groups published the most probable samples of galaxies at z {approx} 8, selected by the so-called dropout method or photometric redshift; e.g., Y{sub 105}-dropouts (Y{sub 105} - J{sub 125} > 0.8). These studies are highly useful for investigating both the early star formation history of galaxies and the sources of cosmic re-ionization. In order to better understand these issues, we carefully examine whether there are low-z interlopers in the samples of z {approx} 8 galaxy candidates. We focus on the strong emission-line galaxies at z {approx} 2 in this paper. Such galaxies may be selected as Y{sub 105}-dropouts since the [O III] {lambda}5007 emission line is redshifted into the J{sub 125} band. We have found that the contamination from such low-z interlopers is negligibly small. Therefore, all objects found by the five groups are free from this type of contamination. However, it remains difficult to extract real z {approx} 8 galaxies because all the sources are very faint and the different groups have found different candidates. With this in mind, we construct a robust sample of eight galaxies at z {approx} 8 from the objects found by the five groups: each of these eight objects has been selected by at least two groups. Using this sample, we discuss their UV continuum slope. We also discuss the escape fraction of ionizing photons adopting various metallicities. Our analysis suggests that massive stars forming in low-metallicity gas (Z {approx} 5 x 10{sup -4} Z{sub sun}) can be responsible for the completion of cosmic re-ionization if the escape fraction of the ionizing continuum from galaxies is as large as 0.5, and this is consistent with the observed blue UV continua.

  6. Beyond the Lone-Pair Model for Structurally Distorted Metal Oxides

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Beyond the Lone-Pair Model for Structurally Distorted Metal Oxides Print "Ferroelectricity," by analogy to ferromagnetism, is defined as the presence of spontaneous electrical polarization in a material, often arising from distortions in the material's crystal structure. In oxides of the metals lead and bismuth, such distortions were for many years attributed to the existence of "lone pair" electrons: pairs of chemically inert, nonbonding valence electrons in hybrid orbitals

  7. Beyond the Lone-Pair Model for Structurally Distorted Metal Oxides

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Beyond the Lone-Pair Model for Structurally Distorted Metal Oxides Print "Ferroelectricity," by analogy to ferromagnetism, is defined as the presence of spontaneous electrical polarization in a material, often arising from distortions in the material's crystal structure. In oxides of the metals lead and bismuth, such distortions were for many years attributed to the existence of "lone pair" electrons: pairs of chemically inert, nonbonding valence electrons in hybrid orbitals

  8. Machine-z: Rapid machine-learned redshift indicator for Swift...

    Office of Scientific and Technical Information (OSTI)

    Machine-z: Rapid machine-learned redshift indicator for Swift gamma-ray bursts This content will become publicly available on March 8, 2017 Title: Machine-z: Rapid machine-learned ...

  9. COLOR-MAGNITUDE RELATION AND MORPHOLOGY OF LOW-REDSHIFT ULIRGs...

    Office of Scientific and Technical Information (OSTI)

    IN SLOAN DIGITAL SKY SURVEY Citation Details In-Document Search Title: COLOR-MAGNITUDE RELATION AND MORPHOLOGY OF LOW-REDSHIFT ULIRGs IN SLOAN DIGITAL SKY SURVEY We present ...

  10. Estimating luminosities and stellar masses of galaxies photometrically without determining redshifts

    SciTech Connect (OSTI)

    Hsieh, B. C.; Yee, H. K. C. E-mail: hyee@astro.utoronto.ca

    2014-09-10

    Large direct imaging surveys usually use a template-fitting technique to estimate photometric redshifts for galaxies, which are then applied to derive important galaxy properties such as luminosities and stellar masses. These estimates can be noisy and suffer from systematic biases because of the possible mis-selection of templates and the propagation of the photometric redshift uncertainty. We introduce an algorithm, the Direct Empirical Photometric method (DEmP), that can be used to directly estimate these quantities using training sets, bypassing photometric redshift determination. DEmP also applies two techniques to minimize the effects arising from the non-uniform distribution of training set galaxy redshifts from a flux-limited sample. First, for each input galaxy, fitting is performed using a subset of the training set galaxies with photometry and colors closest to those of the input galaxy. Second, the training set is artificially resampled to produce a flat distribution in redshift or other properties, e.g., luminosity. To test the performance of DEmP, we use a four filter-band mock catalog to examine its ability to recover redshift, luminosity, stellar mass, and luminosity and stellar mass functions. We also compare the results to those from two publicly available template-fitting methods, finding that the DEmP algorithm outperforms both. We find that resampling the training set to have a uniform redshift distribution produces the best results not only in photometric redshift, but also in estimating luminosity and stellar mass. The DEmP method is especially powerful in estimating quantities such as near-IR luminosities and stellar mass using only data from a small number of optical bands.

  11. Modification to the luminosity distance redshift relation in modified gravity theories

    SciTech Connect (OSTI)

    Flanagan, Eanna E.; Rosenthal, Eran; Wasserman, Ira M.

    2009-02-15

    We derive an expression for the luminosity distance as a function of redshift for a flat Robertson-Walker spacetime perturbed by arbitrary scalar perturbations possibly produced by a modified gravity theory with two different scalar perturbation potentials. Measurements of the luminosity distance as function of redshift provide a constraint on a combination of the scalar potentials and so they can complement weak lensing and other measurements in trying to distinguish among the various alternative theories of gravity.

  12. Virtually distortion-free imaging system for large field, high resolution lithography

    DOE Patents [OSTI]

    Hawryluk, A.M.; Ceglio, N.M.

    1993-01-05

    Virtually distortion free large field high resolution imaging is performed using an imaging system which contains large field distortion or field curvature. A reticle is imaged in one direction through the optical system to form an encoded mask. The encoded mask is then imaged back through the imaging system onto a wafer positioned at the reticle position.

  13. Epitaxial growth of NiTiO3 with a distorted ilmenite structure

    SciTech Connect (OSTI)

    Varga, Tamas; Droubay, Timothy C.; Bowden, Mark E.; Nachimuthu, Ponnusamy; Shutthanandan, V.; Bolin, Trudy B.; Shelton, William A.; Chambers, Scott A.

    2012-06-30

    MTiO3 (M = Fe, Mn, Ni) compounds have received recent attention as possible candidates for new multiferroic materials capable of magnetization switching by application of an electric field. Epitaxial Ni1-xTi1-yO3 films of different thickness and composition were deposited on Al2O3(0001) by pulsed laser deposition, and characterized using several techniques. Structural parameters for the metastable LiNbO3-type NiTiO3 structure with the space group R3c were predicted using density functional theory calculations, and compared with the experimental results. Our structural data from x-ray diffraction and x-ray absorption spectroscopy indicate that epitaxial ilmenite-type NiTiO3 films were successfully grown. Furthermore, lattice strain exerted by the sapphire substrate results in a distorted ilmenite structure similar to the LiNbO3-type one. Our results demonstrate the potential of oxide heteroepitaxy to stabilize metastable multiferroic phases that may be difficult to prepare or are inaccessible in the bulk.

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

    SciTech Connect (OSTI)

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

    2013-04-10

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

  15. SHELS: A complete galaxy redshift survey with R ? 20.6

    SciTech Connect (OSTI)

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

    2014-08-01

    The SHELS (Smithsonian Hectospec Lensing Survey) is a complete redshift survey covering two well-separated fields (F1 and F2) of the Deep Lens Survey to a limiting R = 20.6. Here we describe the redshift survey of the F2 field (R.A.{sub 2000} = 09{sup h}19{sup m}32.4 and decl.{sub 2000} = +3000'00''). The survey includes 16,294 new redshifts measured with the Hectospec on the MMT. The resulting survey of the 4deg{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 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.

  16. The progenitors of the compact early-type galaxies at high redshift

    SciTech Connect (OSTI)

    Williams, Christina C.; Giavalisco, Mauro; Lee, Bomee; Cassata, Paolo; Tundo, Elena; Conselice, Christopher J.; Wiklind, Tommy; Guo, Yicheng; Barro, Guillermo; Faber, Sandra M.; Koo, David C.; Bell, Eric F.; Dekel, Avishai; Ferguson, Henry C.; Grogin, Norman; Koekemoer, Anton; Hathi, Nimish; Huang, Kuang-Han; Kocevski, Dale; and others

    2014-01-01

    We use GOODS and CANDELS images to identify progenitors of massive (M > 10{sup 10} M {sub ☉}) compact early-type galaxies (ETGs) at z ∼ 1.6. Because merging and accretion increase the size of the stellar component of galaxies, if the progenitors are among known star-forming galaxies, these must be compact themselves. We select candidate progenitors among compact Lyman-break galaxies at z ∼ 3 on the basis of their mass, star-formation rate (SFR), and central stellar density, and we find that these account for a large fraction of, and possibly all, compact ETGs at z ∼ 1.6. We find that the average far-UV spectral energy distribution (SED) of the candidates is redder than that of the non-candidates, but the optical and mid-IR SED are the same, implying that the redder UV of the candidates is inconsistent with larger dust obscuration and consistent with more evolved (aging) star formation. This is in line with other evidence suggesting that compactness is a sensitive predictor of passivity among high-redshift massive galaxies. We also find that the light distribution of both the compact ETGs and their candidate progenitors does not show any extended 'halos' surrounding the compact 'core,' both in individual images and in stacks. We argue that this is generally inconsistent with the morphology of merger remnants, even if gas rich, as predicted by N-body simulations. This suggests that the compact ETGs formed via highly dissipative, mostly gaseous accretion of units whose stellar components are very small and undetected in the Hubble Space Telescope images, with their stellar mass assembling in situ, and that they have not experienced any major merging until the epoch of observations at z ∼ 1.6.

  17. SEARCHING FOR THE HIGHEST REDSHIFT SOURCES IN 250-500 {mu}m SUBMILLIMETER SURVEYS

    SciTech Connect (OSTI)

    Pope, Alexandra; Chary, Ranga-Ram

    2010-06-01

    We explore a technique for identifying the highest redshift (z>4) sources in Herschel/SPIRE and BLAST submillimeter surveys by localizing the position of the far-infrared dust peak. Just as Spitzer/IRAC was used to identify stellar 'bump' sources, the far-IR peak is also a redshift indicator; although the latter also depends on the average dust temperature. We demonstrate the wide range of allowable redshifts for a reasonable range of dust temperatures and show that it is impossible to constraint the redshift of individual objects using solely the position of the far-IR peak. By fitting spectral energy distribution models to simulated Herschel/SPIRE photometry we show the utility of radio and/or far-infrared data in breaking this degeneracy. With prior knowledge of the dust temperature distribution it is possible to obtain statistical samples of high redshift submillimeter galaxy (SMG) candidates. We apply this technique to the BLAST survey of ECDFS to constrain the number of dusty galaxies at z>4. We find 8 {+-} 2 galaxies with flux density ratios of S {sub 500}>S {sub 350}; this sets an upper limit of 17 {+-} 4 deg{sup -2} if we assume all are at z>4. This is <35 % of all 500 {mu}m-selected galaxies down to S {sub 500}>45 mJy (L {sub IR}>2 x 10{sup 13} L {sub sun} for z>4). Modeling with conventional temperature and redshift distributions estimates the percentage of these 500 {mu}m peak galaxies at z>4 to be between 10% and 85%. Our results are consistent with other estimates of the number density of very high redshift SMGs and follow the decline in the star formation rate density at z>4.

  18. Confined Space Imager (CSI) Software

    SciTech Connect (OSTI)

    Karelilz, David

    2013-07-03

    The software provides real-time image capture, enhancement, and display, and sensor control for the Confined Space Imager (CSI) sensor system The software captures images over a Cameralink connection and provides the following image enhancements: camera pixel to pixel non-uniformity correction, optical distortion correction, image registration and averaging, and illumination non-uniformity correction. The software communicates with the custom CSI hardware over USB to control sensor parameters and is capable of saving enhanced sensor images to an external USB drive. The software provides sensor control, image capture, enhancement, and display for the CSI sensor system. It is designed to work with the custom hardware.

  19. RUNAWAY STARS AND THE ESCAPE OF IONIZING RADIATION FROM HIGH-REDSHIFT GALAXIES

    SciTech Connect (OSTI)

    Conroy, Charlie; Kratter, Kaitlin M.

    2012-08-20

    Approximately 30% of all massive stars in the Galaxy are runaways with velocities exceeding 30 km s{sup -1}. Their high speeds allow them to travel {approx}0.1-1 kpc away from their birthplace before they explode at the end of their several Myr lifetimes. At high redshift, when galaxies were much smaller than in the local universe, runaways could venture far from the dense inner regions of their host galaxies. From these large radii, and therefore low column densities, much of their ionizing radiation is able to escape into the intergalactic medium. Runaways may therefore significantly enhance the overall escape fraction of ionizing radiation, f{sub esc}, from small galaxies at high redshift. We present simple models of the high-redshift runaway population and its impact on f{sub esc} as a function of halo mass, size, and redshift. We find that the inclusion of runaways enhances f{sub esc} by factors of Almost-Equal-To 1.1-8, depending on halo mass, galaxy geometry, and the mechanism of runaway production, implying that runaways may contribute 50%-90% of the total ionizing radiation escaping from high-redshift galaxies. Runaways may therefore play an important role in reionizing the universe.

  20. A restoration model of distorted electron density in wave-cutoff probe measurement

    SciTech Connect (OSTI)

    Jun, Hyun-Su Lee, Yun-Seong

    2014-02-15

    This study investigates the problem of electron density distortion and how the density can be restored in a wave-cutoff probe. Despite recent plasma diagnostics research using a wave-cutoff probe, the problem of electron density distortion caused by plasma conditions has not been resolved. Experimental results indicate that electron density measured using the wave-cutoff method is highly susceptible to variations in the probe tip gap. This electron density distortion is caused by the bulk plasma disturbance between probe tips, and it must be removed for calculating the absolute electron density. To do this, a detailed analytic model was developed using the power balance equation near probe tips. This model demonstrates the characteristics of plasma distortion in wave-cutoff probe measurement and successfully restored the absolute value of electron density with varying probe tip gaps.

  1. Uncertainties in compliance with harmonic current distortion limits in electric power systems

    SciTech Connect (OSTI)

    Gruzs, T.M. )

    1991-07-01

    The harmonic distortion of any repetitive voltage or current waveform is typically described by the quantity total harmonic distortion (THD). With the proliferation of nonlinear loads, such as static power converters, there has been increasing concern over the generation of harmonic currents and the effects of these currents on the power system. Proposals have been made to limit harmonic currents in power systems using the total harmonic distortion of the current as the criterion. This criterion, although it may be necessary, can be ambiguous and lead to compliance uncertainties. In this paper a discussion is presented on several of the practical problems by applying total harmonic current distortion limits to industrial and commercial power systems.

  2. Investigation of redshift- and duration-dependent clustering of gamma-ray bursts

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Ukwatta, T. N.; Woźniak, P. R.

    2015-11-05

    Gamma-ray bursts (GRBs) are detectable out to very large distances and as such are potentially powerful cosmological probes. Historically, the angular distribution of GRBs provided important information about their origin and physical properties. As a general population, GRBs are distributed isotropically across the sky. However, there are published reports that once binned by duration or redshift, GRBs display significant clustering. We have studied the redshift- and duration-dependent clustering of GRBs using proximity measures and kernel density estimation. Utilizing bursts detected by Burst and Transient Source Experiment, Fermi/gamma-ray burst monitor, and Swift/Burst Alert Telescope, we found marginal evidence for clustering inmore » very short duration GRBs lasting less than 100 ms. As a result, our analysis provides little evidence for significant redshift-dependent clustering of GRBs.« less

  3. Investigation of redshift- and duration-dependent clustering of gamma-ray bursts

    SciTech Connect (OSTI)

    Ukwatta, T. N.; Woźniak, P. R.

    2015-11-05

    Gamma-ray bursts (GRBs) are detectable out to very large distances and as such are potentially powerful cosmological probes. Historically, the angular distribution of GRBs provided important information about their origin and physical properties. As a general population, GRBs are distributed isotropically across the sky. However, there are published reports that once binned by duration or redshift, GRBs display significant clustering. We have studied the redshift- and duration-dependent clustering of GRBs using proximity measures and kernel density estimation. Utilizing bursts detected by Burst and Transient Source Experiment, Fermi/gamma-ray burst monitor, and Swift/Burst Alert Telescope, we found marginal evidence for clustering in very short duration GRBs lasting less than 100 ms. As a result, our analysis provides little evidence for significant redshift-dependent clustering of GRBs.

  4. THE FAINT END OF THE CLUSTER-GALAXY LUMINOSITY FUNCTION AT HIGH REDSHIFT

    SciTech Connect (OSTI)

    Mancone, Conor L.; Baker, Troy; Gonzalez, Anthony H.; Ashby, Matthew L. N.; Snyder, Greg; Stanford, Spencer A.; Brodwin, Mark; Eisenhardt, Peter R. M.; Stern, Daniel; Wright, Edward L.

    2012-12-20

    We measure the faint-end slope of the galaxy luminosity function (LF) for cluster galaxies at 1 < z < 1.5 using Spitzer IRAC data. We investigate whether this slope, {alpha}, differs from that of the field LF at these redshifts, and with the cluster LF at low redshifts. The latter is of particular interest as low-luminosity galaxies are expected to undergo significant evolution. We use seven high-redshift spectroscopically confirmed galaxy clusters drawn from the IRAC Shallow Cluster Survey to measure the cluster-galaxy LF down to depths of M* + 3 (3.6 {mu}m) and M* + 2.5 (4.5 {mu}m). The summed LF at our median cluster redshift (z = 1.35) is well fit by a Schechter distribution with {alpha}{sub 3.6{mu}m} = -0.97 {+-} 0.14 and {alpha}{sub 4.5{mu}m} = -0.91 {+-} 0.28, consistent with a flat faint-end slope and is in agreement with measurements of the field LF in similar bands at these redshifts. A comparison to {alpha} in low-redshift clusters finds no statistically significant evidence of evolution. Combined with past studies which show that M* is passively evolving out to z {approx} 1.3, this means that the shape of the cluster LF is largely in place by z {approx} 1.3. This suggests that the processes that govern the buildup of the mass of low-mass cluster galaxies have no net effect on the faint-end slope of the cluster LF at z {approx}< 1.3.

  5. DISSECTING PHOTOMETRIC REDSHIFT FOR ACTIVE GALACTIC NUCLEUS USING XMM- AND CHANDRA-COSMOS SAMPLES

    SciTech Connect (OSTI)

    Salvato, M.; Hasinger, G.; Ilbert, O.; Rau, A.; Brusa, M.; Bongiorno, A.; Civano, F.; Elvis, M.; Zamorani, G.; Vignali, C.; Comastri, A.; Bardelli, S.; Bolzonella, M.; Cappelluti, N.; Aussel, H.; Le Floc'h, E.; Mainieri, V.; Capak, P.; Caputi, K.; and others

    2011-12-01

    In this paper, we release accurate photometric redshifts for 1692 counterparts to Chandra sources in the central square degree of the Cosmic Evolution Survey (COSMOS) field. The availability of a large training set of spectroscopic redshifts that extends to faint magnitudes enabled photometric redshifts comparable to the highest quality results presently available for normal galaxies. We demonstrate that morphologically extended, faint X-ray sources without optical variability are more accurately described by a library of normal galaxies (corrected for emission lines) than by active galactic nucleus (AGN) dominated templates, even if these sources have AGN-like X-ray luminosities. Preselecting the library on the bases of the source properties allowed us to reach an accuracy {sigma}{sub {Delta}z/(1+z{sub s{sub p{sub e{sub c)}}}}}{approx}0.015 with a fraction of outliers of 5.8% for the entire Chandra-COSMOS sample. In addition, we release revised photometric redshifts for the 1735 optical counterparts of the XMM-detected sources over the entire 2 deg{sup 2} of COSMOS. For 248 sources, our updated photometric redshift differs from the previous release by {Delta}z > 0.2. These changes are predominantly due to the inclusion of newly available deep H-band photometry (H{sub AB} = 24 mag). We illustrate once again the importance of a spectroscopic training sample and how an assumption about the nature of a source together, with the number and the depth of the available bands, influences the accuracy of the photometric redshifts determined for AGN. These considerations should be kept in mind when defining the observational strategies of upcoming large surveys targeting AGNs, such as eROSITA at X-ray energies and the Australian Square Kilometre Array Pathfinder Evolutionary Map of the Universe in the radio band.

  6. The fate of high redshift massive compact galaxies in dense environments

    SciTech Connect (OSTI)

    Kaufmann, Tobias; Mayer, Lucio; Carollo, Marcella; Feldmann, Robert; /Fermilab /Chicago U., KICP

    2012-01-01

    Massive compact galaxies seem to be more common at high redshift than in the local universe, especially in denser environments. To investigate the fate of such massive galaxies identified at z {approx} 2 we analyse the evolution of their properties in three cosmological hydrodynamical simulations that form virialized galaxy groups of mass {approx} 10{sup 13} M{sub {circle_dot}} hosting a central massive elliptical/S0 galaxy by redshift zero. We find that at redshift {approx} 2 the population of galaxies with M{sub *} > 2 x 10{sup 10} M{sub {circle_dot}} is diverse in terms of mass, velocity dispersion, star formation and effective radius, containing both very compact and relatively extended objects. In each simulation all the compact satellite galaxies have merged into the central galaxy by redshift 0 (with the exception of one simulation where one of such satellite galaxy survives). Satellites of similar mass at z = 0 are all less compact than their high redshift counterparts. They form later than the galaxies in the z = 2 sample and enter the group potential at z < 1, when dynamical friction times are longer than the Hubble time. Also, by z = 0 the central galaxies have increased substantially their characteristic radius via a combination of in situ star formation and mergers. Hence in a group environment descendants of compact galaxies either evolve towards larger sizes or they disappear before the present time as a result of the environment in which they evolve. Since the group-sized halos that we consider are representative of dense environments in the {Lambda}CDM cosmology, we conclude that the majority of high redshift compact massive galaxies do not survive until today as a result of the environment.

  7. Photon and neutrino redshift in the field of braneworld compact stars

    SciTech Connect (OSTI)

    Hladík, Jan; Stuchlík, Zdeněk E-mail: zdenek.stuchlik@fpf.slu.cz

    2011-07-01

    We study gravitational redshift of photons and neutrinos radiated by the braneworld neutron or quark stars that are considered in the framework of the simple model of the internal spacetime with uniform distribution of energy density, and the external spacetime described by the Reissner-Nordström geometry characterized by the braneworld ''tidal'' charge b. For negative tidal charges, the external spacetime is of the black-hole type, while for positive tidal charges, the external spacetime can be of both black-hole and naked-singularity type. We consider also extremely compact stars allowing existence of trapped null geodesics in their interior. We assume radiation of photons from the surface at radius R, neutrinos from the whole compact star interior, and their motion along radial null geodesics of the spacetime. In dependency on the compact stars parameters b and R, the photon surface redshift is related to the range of the neutrino internal redshift and the signatures of the tidal charge and possible existence of extremely compact stars are discussed. When both surface (photon) and internal (neutrino) redshift are given by observations, both compact star parameters R and b can be determined in the framework of our simple model.

  8. A SIMPLE TECHNIQUE FOR PREDICTING HIGH-REDSHIFT GALAXY EVOLUTION

    SciTech Connect (OSTI)

    Behroozi, Peter S.; Silk, Joseph

    2015-01-20

    We show that the ratio of galaxies' specific star formation rates (SSFRs) to their host halos' specific mass accretion rates (SMARs) strongly constrains how the galaxies' stellar masses, SSFRs, and host halo masses evolve over cosmic time. This evolutionary constraint provides a simple way to probe z > 8 galaxy populations without direct observations. Tests of the method with galaxy properties at z = 4 successfully reproduce the known evolution of the stellar mass-halo mass (SMHM) relation, galaxy SSFRs, and the cosmic star formation rate (CSFR) for 5 < z < 8. We then predict the continued evolution of these properties for 8 < z < 15. In contrast to the nonevolution in the SMHM relation at z < 4, the median galaxy mass at fixed halo mass increases strongly at z > 4. We show that this result is closely linked to the flattening in galaxy SSFRs at z > 2 compared to halo SMARs; we expect that average galaxy SSFRs at fixed stellar mass will continue their mild evolution to z ? 15. The expected CSFR shows no breaks or features at z > 8.5; this constrains both reionization and the possibility of a steep falloff in the CSFR at z = 9-10. Finally, we make predictions for stellar mass and luminosity functions for the James Webb Space Telescope, which should be able to observe one galaxy with M {sub *} ? 10{sup 8} M {sub ?} per 10{sup 3}Mpc{sup 3} at z = 9.6 and one such galaxy per 10{sup 4}Mpc{sup 3} at z = 15.

  9. Impact of the MLC on the MRI field distortion of a prototype MRI-linac

    SciTech Connect (OSTI)

    Kolling, Stefan; Keall, Paul; Oborn, Brad

    2013-12-15

    Purpose: To cope with intrafraction tumor motion, integrated MRI-linac systems for real-time image guidance are currently under development. The multileaf collimator (MLC) is a key component in every state-of-the-art radiotherapy treatment system, allowing for accurate field shaping and tumor tracking. This work quantifies the magnetic impact of a widely used MLC on the MRI field homogeneity for such a modality.Methods: The finite element method was employed to model a MRI-linac assembly comprised of a 1.0?T split-bore MRI magnet and the key ferromagnetic components of a Varian Millennium 120 MLC, namely, the leaves and motors. Full 3D magnetic field maps of the system were generated. From these field maps, the peak-to-peak distortion within the MRI imaging volume was evaluated over a 30?cm diameter sphere volume (DSV) around the isocenter and compared to a maximum preshim inhomogeneity of 300??T. Five parametric studies were performed: (1) The source-to-isocenter distance (SID) was varied from 100 to 200?cm, to span the range of a compact system to that with lower magnetic coupling. (2) The MLC model was changed from leaves only to leaves with motors, to determine the contribution to the total distortion caused by MLC leaves and motors separately. (3) The system was configured in the inline or perpendicular orientation, i.e., the linac treatment beam was oriented parallel or perpendicular to the magnetic field direction. (4) The treatment field size was varied from 0 0 to 2020?cm{sup 2}, to span the range of clinical treatment fields. (5) The coil currents were scaled linearly to produce magnetic field strengths B{sub 0} of 0.5, 1.0, and 1.5?T, to estimate how the MLC impact changes with B{sub 0}.Results: (1) The MLC-induced MRI field distortion fell continuously with increasing SID. (2) MLC leaves and motors were found to contribute to the distortion in approximately equal measure. (3) Due to faster falloff of the fringe field, the field distortion was

  10. Calculation of voltage harmonic distortion caused by small non-linear loads

    SciTech Connect (OSTI)

    Hegazy, Y.G.; Salama, M.M.A.

    1995-10-01

    This paper presents an accurate method to evaluate the harmonic distortion in distribution systems. This method overcomes most of the drawbacks of the traditional methods. The main idea of the proposed method is to represent the harmonic effects of small non-linear loads by an equivalent large load. A case study is presented in the paper to illustrate the proposed method. The total harmonic distortion factor is evaluated at different busses of a distribution system using the proposed method. The results are then compared to those obtained using the traditional methods.

  11. High redshift signatures in the 21 cm forest due to cosmic string wakes

    SciTech Connect (OSTI)

    Tashiro, Hiroyuki; Sekiguchi, Toyokazu; Silk, Joseph E-mail: toyokazu.sekiguchi@nagoya-u.jp

    2014-01-01

    Cosmic strings induce minihalo formation in the early universe. The resultant minihalos cluster in string wakes and create a ''21 cm forest'' against the cosmic microwave background (CMB) spectrum. Such a 21 cm forest can contribute to angular fluctuations of redshifted 21 cm signals integrated along the line of sight. We calculate the root-mean-square amplitude of the 21 cm fluctuations due to strings and show that these fluctuations can dominate signals from minihalos due to primordial density fluctuations at high redshift (z?>10), even if the string tension is below the current upper bound, G? < 1.5 10{sup ?7}. Our results also predict that the Square Kilometre Array (SKA) can potentially detect the 21 cm fluctuations due to strings with G? ? 7.5 10{sup ?8} for the single frequency band case and 4.0 10{sup ?8} for the multi-frequency band case.

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

    SciTech Connect (OSTI)

    Bauermeister, A.; Blitz, L.; Wright, M.; Bolatto, A.; Teuben, P.; Bureau, M.; Leroy, A.; Ostriker, E.; Wong, T.

    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.

  13. GRB 120521C at z ? 6 and the properties of high-redshift ?-ray bursts

    SciTech Connect (OSTI)

    Laskar, Tanmoy; Berger, Edo; Zauderer, B. Ashley; Margutti, Raffaella; Fong, Wen-fai [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Tanvir, Nial; Wiersema, Klaas [Department of Physics and Astronomy, University of Leicester, University Road, Leicester LE1 7RH (United Kingdom); Levan, Andrew [Department of Physics, University of Warwick, Coventry CV4 7AL (United Kingdom); Perley, Daniel [Department of Astronomy, California Institute of Technology, MC 249-17, 1200 East California Boulevard, Pasadena, CA 91125 (United States); Menten, Karl [Max-Planck-Institut fr Radioastronomie, Auf dem Hgel 69, D-53121 Bonn (Germany); Hrudkova, Marie [Isaac Newton Group of Telescopes, Apartado de Correos 321, E-387 00 Santa Cruz de la Palma, Canary Islands (Spain)

    2014-01-20

    We present optical, near-infrared, and radio observations of the afterglow of GRB 120521C. By modeling the multi-wavelength data set, we derive a photometric redshift of z ? 6.0, which we confirm with a low signal-to-noise ratio spectrum of the afterglow. We find that a model with a constant-density environment provides a good fit to the afterglow data, with an inferred density of n ? 0.05 cm{sup 3}. The radio observations reveal the presence of a jet break at t {sub jet} ? 7 d, corresponding to a jet opening angle of ?{sub jet} ? 3. The beaming-corrected ?-ray and kinetic energies are E {sub ?} ? E{sub K} ? 3 10{sup 50} erg. We quantify the uncertainties in our results using a detailed Markov Chain Monte Carlo analysis, which allows us to uncover degeneracies between the physical parameters of the explosion. To compare GRB 120521C to other high-redshift bursts in a uniform manner we re-fit all available afterglow data for the two other bursts at z ? 6 with radio detections (GRBs 050904 and 090423). We find a jet break at t {sub jet} ? 15 d for GRB 090423, in contrast to previous work. Based on these three events, we find that ?-ray bursts (GRBs) at z ? 6 appear to explode in constant-density environments, and exhibit a wide range of energies and densities that span the range inferred for lower redshift bursts. On the other hand, we find a hint for narrower jets in the z ? 6 bursts, potentially indicating a larger true event rate at these redshifts. Overall, our results indicate that long GRBs share a common progenitor population at least to z ? 8.

  14. Redshift Distributions of Galaxies in the DES Science Verification Shear Catalogue and Implications for Weak Lensing

    SciTech Connect (OSTI)

    Bonnett, C.

    2015-07-21

    We present photometric redshift estimates for galaxies used in the weak lensing analysis of the Dark Energy Survey Science Verification (DES SV) data. Four model- or machine learning-based photometric redshift methods { annz2, bpz calibrated against BCC-U fig simulations, skynet, and tpz { are analysed. For training, calibration, and testing of these methods, we also construct a catalogue of spectroscopically confirmed galaxies matched against DES SV data. The performance of the methods is evalu-ated against the matched spectroscopic catalogue, focusing on metrics relevant for weak lensing analyses, with additional validation against COSMOS photo-zs. From the galaxies in the DES SV shear catalogue, which have mean redshift 0.72 0.01 over the range 0:3 < z < 1:3, we construct three tomographic bins with means of z = {0.45; 0.67,1.00g}. These bins each have systematic uncertainties ?z ? 0.05 in the mean of the fiducial skynet photo-z n(z). We propagate the errors in the redshift distributions through to their impact on cosmological parameters estimated with cosmic shear, and find that they cause shifts in the value of ?8 of approx. 3%. This shift is within the one sigma statistical errors on ?8 for the DES SV shear catalog. We also found that further study of the potential impact of systematic differences on the critical surface density, ?crit, contained levels of bias safely less than the statistical power of DES SV data. We recommend a final Gaussian prior for the photo-z bias in the mean of n(z) of width 0:05 for each of the three tomographic bins, and show that this is a sufficient bias model for the corresponding cosmology analysis.

  15. Radar transponder operation with compensation for distortion due to amplitude modulation

    DOE Patents [OSTI]

    Ormesher, Richard C.; Tise, Bertice L.; Axline, Jr., Robert M.

    2011-01-04

    In radar transponder operation, a variably delayed gating signal is used to gate a received radar pulse and thereby produce a corresponding gated radar pulse for transmission back to the source of the received radar pulse. This compensates for signal distortion due to amplitude modulation on the retransmitted pulse.

  16. BRIGHT HOT IMPACTS BY ERUPTED FRAGMENTS FALLING BACK ON THE SUN: UV REDSHIFTS IN STELLAR ACCRETION

    SciTech Connect (OSTI)

    Reale, F.; Orlando, S.; Testa, P.; Landi, E.; Schrijver, C. J.

    2014-12-10

    A solar eruption after a flare on 2011 June 7 produced EUV-bright impacts of fallbacks far from the eruption site, observed with the Solar Dynamics Observatory. These impacts can be taken as a template for the impact of stellar accretion flows. Broad redshifted UV lines have been commonly observed in young accreting stars. Here we study the emission from the impacts in the Atmospheric Imaging Assembly's UV channels and compare the inferred velocity distribution to stellar observations. We model the impacts with two-dimensional hydrodynamic simulations. We find that the localized UV 1600 emission and its timing with respect to the EUV emission can be explained by the impact of a cloud of fragments. The first impacts produce strong initial upflows. The following fragments are hit and shocked by these upflows. The UV emission comes mostly from the shocked front shell of the fragments while they are still falling, and is therefore redshifted when observed from above. The EUV emission instead continues from the hot surface layer that is fed by the impacts. Fragmented accretion can therefore explain broad redshifted UV lines (e.g., C IV 1550 ) to speeds around 400km s{sup 1} observed in accreting young stellar objects.

  17. DUST FORMATION, EVOLUTION, AND OBSCURATION EFFECTS IN THE VERY HIGH-REDSHIFT UNIVERSE

    SciTech Connect (OSTI)

    Dwek, Eli; Benford, Dominic J. [Observational Cosmology Lab., Code 665, NASA at Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Staguhn, Johannes; Su, Ting [Also at Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218, USA. (United States); Arendt, Richard G. [Also at CRESST, University of Maryland Baltimore County, Baltimore, MD 21250, USA. (United States); Kovacks, Attila, E-mail: eli.dwek@nasa.gov [Also at Astronomy Department, CalTech, Pasadena, CA 90025, USA. (United States)

    2014-06-20

    The evolution of dust at redshifts z ? 9, and consequently the dust properties, differs greatly from that in the local universe. In contrast to the local universe, core collapse supernovae (CCSNe) are the only source of thermally condensed dust. Because of the low initial dust-to-gas mass ratio, grain destruction rates are low, so that CCSNe are net producers of interstellar dust. Galaxies with large initial gas mass or high mass infall rate will therefore have a more rapid net rate of dust production compared to galaxies with lower gas mass, even at the same star formation rate. The dust composition is dominated by silicates, which exhibit a strong rise in the UV opacity near the Lyman break. This ''silicate-UV break'' may be confused with the Lyman break, resulting in a misidentification of a galaxy's photometric redshift. In this Letter we demonstrate these effects by analyzing the spectral energy distribution of MACS1149-JD, a lensed galaxy at z = 9.6. A potential 2mm counterpart of MACS1149-JD has been identified with GISMO. While additional observations are required to corroborate this identification, we use this possible association to illustrate the physical processes and the observational effects of dust in the very high-redshift universe.

  18. Simulation of Distortion and Residual Stress Development During Heat Treatment of Steel Castings

    SciTech Connect (OSTI)

    Beckermann, Christoph; Carlson, Kent

    2011-07-22

    Heat treatment and associated processing, such as quenching, are critical during high strength steel casting production. These processes must be managed closely to prevent thermal and residual stresses that may result in distortion, cracking (particularly after machining), re-work, and weld repair. The risk of casting distortion limits aggressive quenching that can be beneficial to the process and yield an improved outcome. As a result of these distortions, adjustments must be made to the casting or pattern design, or tie bars must be added. Straightening castings after heat treatments can be both time-consuming and expensive. Residual stresses may reduce a casting's overall service performance, possibly resulting in catastrophic failure. Stress relieving may help, but expends additional energy in the process. Casting software is very limited in predicting distortions during heat treatment, so corrective measures most often involve a tedious trial-and-error procedure. An extensive review of existing heat treatment residual stress and distortion modeling revealed that it is vital to predict the phase transformations and microstructure of the steel along with the thermal stress development during heat treatment. After reviewing the state-of-the-art in heat treatment residual stress and distortion modeling, an existing commercial code was selected because of its advanced capabilities in predicting phase transformations, the evolving microstructure and related properties along with thermal stress development during heat treatment. However, this software was developed for small parts created from forgings or machined stock, and not for steel castings. Therefore, its predictive capabilities for heat treatment of steel castings were investigated. Available experimental steel casting heat treatment data was determined to be of insufficient detail and breadth, and so new heat treatment experiments were designed and performed, casting and heat treating modified versions of

  19. Galaxy Mergers and Dark Matter Halo Mergers in LCDM: Mass, Redshift, and Mass-Ratio Dependence

    SciTech Connect (OSTI)

    Stewart, Kyle R.; Bullock, James S.; Barton, Elizabeth J.; Wechsler, Risa H.; /KIPAC, Menlo Park /SLAC

    2009-08-03

    We employ a high-resolution LCDM N-body simulation to present merger rate predictions for dark matter halos and investigate how common merger-related observables for galaxies - such as close pair counts, starburst counts, and the morphologically disturbed fraction - likely scale with luminosity, stellar mass, merger mass ratio, and redshift from z = 0 to z = 4. We provide a simple 'universal' fitting formula that describes our derived merger rates for dark matter halos a function of dark halo mass, merger mass ratio, and redshift, and go on to predict galaxy merger rates using number density-matching to associate halos with galaxies. For example, we find that the instantaneous merger rate of m/M > 0.3 mass ratio events into typical L {approx}> fL{sub *} galaxies follows the simple relation dN/dt {approx_equal} 0.03(1+f)Gyr{sup -1} (1+z){sup 2.1}. Despite the rapid increase in merger rate with redshift, only a small fraction of > 0.4L{sub *} high-redshift galaxies ({approx} 3% at z = 2) should have experienced a major merger (m/M > 0.3) in the very recent past (t < 100 Myr). This suggests that short-lived, merger-induced bursts of star formation should not contribute significantly to the global star formation rate at early times, in agreement with observational indications. In contrast, a fairly high fraction ({approx} 20%) of those z = 2 galaxies should have experienced a morphologically transformative merger within a virial dynamical time. We compare our results to observational merger rate estimates from both morphological indicators and pair-fraction based determinations between z = 0-2 and show that they are consistent with our predictions. However, we emphasize that great care must be made in these comparisons because the predicted observables depend very sensitively on galaxy luminosity, redshift, overall mass ratio, and uncertain relaxation timescales for merger remnants. We show that the majority of bright galaxies at z = 3 should have undergone a major

  20. InP quantum dots: Electronic structure, surface effects, and the redshifted emission

    SciTech Connect (OSTI)

    Fu, H.; Zunger, A.

    1997-07-01

    We present pseudopotential plane-wave electronic-structure calculations on InP quantum dots in an effort to understand quantum confinement and surface effects and to identify the origin of the long-lived and redshifted luminescence. We find that (i) unlike the case in small GaAs dots, the lowest unoccupied state of InP dots is the {Gamma}{sub 1c}-derived direct state rather than the X{sub 1c}-derived indirect state and (ii) unlike the prediction of {bold k}{center_dot}{bold p} models, the highest occupied state in InP dots has a 1sd-type envelope function rather than a (dipole-forbidden) 1pf envelope function. Thus explanations (i) and (ii) to the long-lived redshifted emission in terms of an orbitally forbidden character can be excluded. Furthermore, (iii) fully passivated InP dots have no surface states in the gap. However, (iv) removal of the anion-site passivation leads to a P dangling bond (DB) state just above the valence band, which will act as a trap for photogenerated holes. Similarly, (v) removal of the cation-site passivation leads to an In dangling-bond state below the conduction band. While the energy of the In DB state depends only weakly on quantum size, its radiative lifetime increases with quantum size. The calculated {approximately}300-meV redshift and the {approximately}18 times longer radiative lifetime relative to the dot-interior transition for the 26-{Angstrom} dot with an In DB are in good agreement with the observations of full-luminescence experiments for unetched InP dots. Yet, (vi) this type of redshift due to surface defect is inconsistent with that measured in {ital selective} excitation for HF-etched InP dots. (vii) The latter type of ({open_quotes}resonant{close_quotes}) redshift is compatible with the calculated {ital screened} singlet-triplet splitting in InP dots, suggesting that the slow emitting state seen in selective excitation could be a triplet state. {copyright} {ital 1997} {ital The American Physical Society}

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

    SciTech Connect (OSTI)

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

    2014-11-20

    We present Herschel far-IR photometry and spectroscopy as well as ground-based CO observations of an intermediate redshift (0.21 ? z ? 0.88) sample of Herschel-selected (ultra)-luminous infrared galaxies (L {sub IR} > 10{sup 11.5} L {sub ?}). With these measurements, we trace the dust continuum, far-IR atomic line emission, in particular [C II] 157.7 ?m, 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 present day and z

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

    SciTech Connect (OSTI)

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

    2012-12-20

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

  3. Confined Space Imager (CSI) Software

    Energy Science and Technology Software Center (OSTI)

    2013-07-03

    The software provides real-time image capture, enhancement, and display, and sensor control for the Confined Space Imager (CSI) sensor system The software captures images over a Cameralink connection and provides the following image enhancements: camera pixel to pixel non-uniformity correction, optical distortion correction, image registration and averaging, and illumination non-uniformity correction. The software communicates with the custom CSI hardware over USB to control sensor parameters and is capable of saving enhanced sensor images to anmore » external USB drive. The software provides sensor control, image capture, enhancement, and display for the CSI sensor system. It is designed to work with the custom hardware.« less

  4. THE GEOMETRY EFFECTS OF AN EXPANDING UNIVERSE ON THE DETECTION OF COOL NEUTRAL GAS AT HIGH REDSHIFT

    SciTech Connect (OSTI)

    Curran, S. J.

    2012-03-20

    Recent high-redshift surveys for 21 cm absorption in damped Ly{alpha} absorption systems (DLAs) take the number of published searches at z{sub abs} > 2 to 25, the same number as at z{sub abs} < 2, although the detection rate at high redshift remains significantly lower (20% compared to 60%). Using the known properties of the DLAs to estimate the unknown profile widths of the 21 cm non-detections and including the limits via a survival analysis, we show that the mean spin temperature/covering factor degeneracy at high redshift is, on average, double that of the low-redshift sample. This value is significantly lower than the previous factor of eight for the spin temperatures and is about the same factor as in the angular diameter distance ratios between the low- and high-redshift samples. That is, without the need for the several pivotal assumptions, which lead to an evolution in the spin temperature, we show that the observed distribution of 21 cm detections in DLAs can be accounted for by the geometry effects of an expanding universe. That is, as yet there is no evidence of the spin temperature of gas-rich galaxies evolving with redshift.

  5. An Effective Method to Accurately Calculate the Phase Space Factors for β - β - Decay

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Neacsu, Andrei; Horoi, Mihai

    2016-01-01

    Accurate calculations of the electron phase space factors are necessary for reliable predictions of double-beta decay rates and for the analysis of the associated electron angular and energy distributions. We present an effective method to calculate these phase space factors that takes into account the distorted Coulomb field of the daughter nucleus, yet it allows one to easily calculate the phase space factors with good accuracy relative to the most exact methods available in the recent literature.

  6. Non percolative nature of the metal-insulator transition and persistence of local Jahn-Teller distortions in the rhombohedral regime of La1-xCaxMnO3

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Shatnawi, Mouath; Bozin, Emil S.; Mitchell, J. F.; Billinge, Simon J. L.

    2016-04-25

    Evolution of the average and local crystal structure of Ca-doped LaMnO3 has been studied across the metal to insulator (MI) and the orthorhombic to rhombohedral (OR) structural phase transitions over a broad temperature range for two Ca concentrations (x = 0.18,0.22). Combined Rietveld and high real space resolution atomic pair distribution function (PDF) analysis of neutron total scattering data was carried out with aims of exploring the possibility of nanoscale phase separation (PS) in relation to MI transition, and charting the evolution of local Jahn-Teller (JT) distortion of MnO6 octahedra across the OR transition at TS~720 K. The study utilizedmore » explicit two-phase PDF structural modeling, revealing that away from TMI there is no evidence for nanoscale phase coexistence. The local JT distortions disappear abruptly upon crossing into the metallic regime both with doping and temperature, with only a small temperature-independent signature of quenched disorder being observable at low temperature as compared to CaMnO3. The results hence do not support the percolative scenario for the MI transition in La1–xCaxMnO3 based on PS, and question its ubiquity in the manganites. In contrast to LaMnO3 that exhibits long-range orbital correlations and sizable octahedral distortions at low temperature, the doped samples with compositions straddling the MI boundary exhibit correlations (in the insulating regime) limited to only ~1 nm with observably smaller distortions. In the x = 0.22 sample local JT distortions are found to persist across the OR transition and deep into the R phase (up to ~1050 K), where they are crystallographically prohibited. As a result, their magnitude and subnanometer spatial extent remain unchanged.« less

  7. DIFFUSE FAR-UV LINE EMISSION FROM THE LOW-REDSHIFT LYMAN BREAK GALAXY ANALOG KISSR242

    SciTech Connect (OSTI)

    France, Kevin; Nell, Nicholas; Green, James C. [Center for Astrophysics and Space Astronomy, 389 UCB, University of Colorado, Boulder, CO 80309 (United States); Leitherer, Claus, E-mail: kevin.france@colorado.ed [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)

    2010-10-10

    We present new ultraviolet (UV) observations of the luminous compact blue galaxy KISSR242, obtained with the Hubble Space Telescope-Cosmic Origins Spectrograph (HST-COS). We identify multiple resolved sub-arcsecond near-UV sources within the COS aperture. The far-UV spectroscopic data show strong outflow absorption lines, consistent with feedback processes related to an episode of massive star formation. O I, C II, and Si II-Si IV are observed with a mean outflow velocity (v {sub out}) = -60 km s{sup -1}. We also detect faint fine-structure emission lines of singly ionized silicon for the first time in a low-redshift starburst galaxy. These emissions have been seen previously in deep Lyman break galaxy surveys at z {approx} 3. The Si II* lines are at the galaxy rest velocity, and they exhibit a quantitatively different line profile from the absorption features. These lines have a width of {approx}75 km s{sup -1}, too broad for point-like emission sources such as the H II regions surrounding individual star clusters. The size of the Si II* emitting region is estimated to be {approx}250 pc. We discuss the possibility of this emission arising in overlapping super star cluster H II regions, but find this explanation to be unlikely in light of existing far-UV observations of local star-forming galaxies. We suggest that the observed Si II* emission originates in a diffuse warm halo populated by interstellar gas driven out by intense star formation and/or accreted during a recent interaction that may be fueling the present starburst episode in KISSR242.

  8. A new reversal mode in exchange coupled antiferromagnetic/ferromagnetic disks: distorted viscous vortex

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Gilbert, Dustin A.; Ye, Li; Varea, Aïda; Agramunt-Puig, Sebastià; del Valle, Nuria; Navau, Carles; López-Barbera, José Francisco; Buchanan, Kristen S.; Hoffmann, Axel; Sánchez, Alvar; et al

    2015-04-28

    Magnetic vortices have generated intense interest in recent years due to their unique reversal mechanisms, fascinating topological properties, and exciting potential applications. In addition, the exchange coupling of magnetic vortices to antiferromagnets has also been shown to lead to a range of novel phenomena and functionalities. Here we report a new magnetization reversal mode of magnetic vortices in exchange coupled Ir20Mn80/Fe20Ni80 microdots: distorted viscous vortex reversal. In contrast to the previously known or proposed reversal modes, the vortex is distorted close to the interface and viscously dragged due to the uncompensated spins of a thin antiferromagnet, which leads to unexpectedmore » asymmetries in the annihilation and nucleation fields. These results provide a deeper understanding of the physics of exchange coupled vortices and may also have important implications for applications involving exchange coupled nanostructures.« less

  9. dgtoexo2: A Distorted Grid Output File to Exodus II Finite Element Database Conversion Utility

    SciTech Connect (OSTI)

    Moffat, H.K.

    1998-12-01

    This report describes how to obtain publication-quality graphics from distorted grid electronic structure codes using the combination of the conversion utility, dgtoexo2, and mustafa, an AVS Express application. dgtoexo2 converts scalar function results from a format applicable to distorted grid codes into the Exodus II unstructured finite element data representation. nmstafa can read Exodus II files and use the AVS Express engine to visualize data on unix and Windows NT platforms. Though not designed for the purpose, the dgtoexo2/EXOdUS II/mustafa combination is sufficiently versatile to provide for the specialized graphics needs of electronic structure codes. The combination also scales well, producing robust performance for problems involving millions of grid points.

  10. A new reversal mode in exchange coupled antiferromagnetic/ferromagnetic disks: distorted viscous vortex

    SciTech Connect (OSTI)

    Gilbert, Dustin A.; Ye, Li; Varea, Aïda; Agramunt-Puig, Sebastià; del Valle, Nuria; Navau, Carles; López-Barbera, José Francisco; Buchanan, Kristen S.; Hoffmann, Axel; Sánchez, Alvar; Sort, Jordi; Liu, Kai; Nogués, Josep

    2015-04-28

    Magnetic vortices have generated intense interest in recent years due to their unique reversal mechanisms, fascinating topological properties, and exciting potential applications. In addition, the exchange coupling of magnetic vortices to antiferromagnets has also been shown to lead to a range of novel phenomena and functionalities. Here we report a new magnetization reversal mode of magnetic vortices in exchange coupled Ir20Mn80/Fe20Ni80 microdots: distorted viscous vortex reversal. In contrast to the previously known or proposed reversal modes, the vortex is distorted close to the interface and viscously dragged due to the uncompensated spins of a thin antiferromagnet, which leads to unexpected asymmetries in the annihilation and nucleation fields. These results provide a deeper understanding of the physics of exchange coupled vortices and may also have important implications for applications involving exchange coupled nanostructures.

  11. Structural distortions in 5-10 nm silver nanoparticles under high pressure

    SciTech Connect (OSTI)

    Koski, Kristie J.; Kamp, Noelle M.; Kunz, Martin; Knight, Jason K.; Alivisatos, A.P.; Smith, R.K.

    2008-10-13

    We present experimental evidence that silver nanoparticles in the size range of 5-10 nm undergo a reversible structural transformation under hydrostatic pressures up to 10 GPa. We have used x-ray diffraction with a synchrotron light source to investigate pressure-dependent and size-dependent trends in the crystal structure of silver nanoparticles in a hydrostatic medium compressed in a diamond-anvil cell. Results suggest a reversible linear pressure-dependent rhombohedral distortion which has not been previously observed in bulk silver. We propose a mechanism for this transition that considers the bond-length distribution in idealized multiply twinned icosahedral particles. To further support this hypothesis, we also show that similar measurements of single-crystal platinum nanoparticles reveal no such distortions.

  12. Lattice distortions and oxygen vacancies produced in Au+ irradiated nano-crystalline cubic zirconia

    SciTech Connect (OSTI)

    Edmondson, Philip D; Weber, William J; Namavar, Fereydoon; Zhang, Yanwen

    2011-01-01

    The structural impact of oxygen vacancies in nanocrystalline cubic zirconia is investigated. A non-equilibrium number of oxygen vacancies in introduced to the lattice by ion irradiation. The lattice is observed to be initially compressed, undergoes a relaxation at 0.7 displacements per atom (dpa), and experiences a contraction before reaching a temperature dependent steady state value at above 7 dpa. The level of lattice distortion is related to the charge state of the accumulating oxygen vacancies.

  13. Spectroscopic manifestations of local crystal distortions in excited 4f states in crystals of huntite structure

    SciTech Connect (OSTI)

    Malakhovskii, A. V.; Gnatchenko, S. L.; Kachur, I. S.; Piryatinskaya, V. G.; Sukhachev, A. L.; Sokolov, A. E.; Strokova, A. Ya.; Kartashev, A. V.; Temerov, V. L.

    2013-01-15

    Optical absorption spectra of YbAl{sub 3}(BO{sub 3}){sub 4}, TmAl{sub 3}(BO{sub 3}){sub 4} and TbFe{sub 3}(BO{sub 3}){sub 4} trigonal crystals have been studied in temperature range 2-300 K. Temperature behavior of absorption lines parameters has shown, that during some f-f transitions the local environment of rare earth ions undergo distortions, which are absent in the ground state.

  14. A PARAMETRIC STUDY OF POSSIBLE SOLUTIONS TO THE HIGH-REDSHIFT OVERPRODUCTION OF STARS IN MODELED DWARF GALAXIES

    SciTech Connect (OSTI)

    White, Catherine E.; Somerville, Rachel S.; Ferguson, Henry C.

    2015-02-01

    Both numerical hydrodynamic and semi-analytic cosmological models of galaxy formation struggle to match observed star formation histories of galaxies in low-mass halos (M {sub H} ? 10{sup 11} M {sub ?}), predicting more star formation at high redshift and less star formation at low redshift than observed. The fundamental problem is that galaxies' gas accretion and star formation rates are too closely coupled in the models: the accretion rate largely drives the star formation rate. Observations point to gas accretion rates that outpace star formation at high redshift, resulting in a buildup of gas and a delay in star formation until lower redshifts. We present three empirical adjustments of standard recipes in a semi-analytic model motivated by three physical scenarios that could cause this decoupling: (1) the mass-loading factors of outflows driven by stellar feedback may have a steeper dependence on halo mass at earlier times, (2) the efficiency of star formation may be lower in low-mass halos at high redshift, and (3) gas may not be able to accrete efficiently onto the disk in low-mass halos at high redshift. These new recipes, once tuned, better reproduce the evolution of f {sub *}? M {sub *}/M {sub H} as a function of halo mass as derived from abundance matching over redshifts z = 0 to 3, though they have different effects on cold gas fractions, star formation rates, and metallicities. Changes to gas accretion and stellar-driven winds are promising, while direct modification of the star formation timescale requires drastic measures that are not physically well motivated.

  15. Optic for industrial endoscope/borescope with narrow field of view and low distortion

    DOE Patents [OSTI]

    Stone, Gary F.; Trebes, James E.

    2005-08-16

    An optic for the imaging optics on the distal end of a flexible fiberoptic endoscope or rigid borescope inspection tool. The image coverage is over a narrow (<20 degrees) field of view with very low optical distortion (<5% pin cushion or barrel distortion), compared to the typical <20% distortion. The optic will permit non-contact surface roughness measurements using optical techniques. This optic will permit simultaneous collection of selected image plane data, which data can then be subsequently optically processed. The image analysis will yield non-contact surface topology data for inspection where access to the surface does not permit a mechanical styles profilometer verification of surface topology. The optic allows a very broad spectral band or range of optical inspection. It is capable of spectroscopic imaging and fluorescence induced imaging when a scanning illumination source is used. The total viewing angle for this optic is 10 degrees for the full field of view of 10 degrees, compared to 40-70 degrees full angle field of view of the conventional gradient index or GRIN's lens systems.

  16. Galaxy Clustering, Photometric Redshifts and Diagnosis of Systematics in the DES Science Verification Data

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Crocce, M.

    2015-12-09

    We study the clustering of galaxies detected at i < 22.5 in the Science Verification observations of the Dark Energy Survey (DES). Two-point correlation functions are measured using 2.3 × 106 galaxies over a contiguous 116 deg2 region in five bins of photometric redshift width Δz = 0.2 in the range 0.2 < z < 1.2. The impact of photometric redshift errors is assessed by comparing results using a template-based photo-zalgorithm (BPZ) to a machine-learning algorithm (TPZ). A companion paper presents maps of several observational variables (e.g. seeing, sky brightness) which could modulate the galaxy density. Here we characterize andmore » mitigate systematic errors on the measured clustering which arise from these observational variables, in addition to others such as Galactic dust and stellar contamination. After correcting for systematic effects, we then measure galaxy bias over a broad range of linear scales relative to mass clustering predicted from the Planck Λ cold dark matter model, finding agreement with the Canada-France-Hawaii Telescope Legacy Survey (CFHTLS) measurements with χ2 of 4.0 (8.7) with 5 degrees of freedom for the TPZ (BPZ) redshifts. Furthermore, we test a ‘linear bias’ model, in which the galaxy clustering is a fixed multiple of the predicted non-linear dark matter clustering. The precision of the data allows us to determine that the linear bias model describes the observed galaxy clustering to 2.5 percent accuracy down to scales at least 4–10 times smaller than those on which linear theory is expected to be sufficient.« less

  17. Galaxy Clustering, Photometric Redshifts and Diagnosis of Systematics in the DES Science Verification Data

    SciTech Connect (OSTI)

    Crocce, M.

    2015-12-09

    We study the clustering of galaxies detected at i < 22.5 in the Science Verification observations of the Dark Energy Survey (DES). Two-point correlation functions are measured using 2.3 × 106 galaxies over a contiguous 116 deg2 region in five bins of photometric redshift width Δz = 0.2 in the range 0.2 < z < 1.2. The impact of photometric redshift errors is assessed by comparing results using a template-based photo-zalgorithm (BPZ) to a machine-learning algorithm (TPZ). A companion paper presents maps of several observational variables (e.g. seeing, sky brightness) which could modulate the galaxy density. Here we characterize and mitigate systematic errors on the measured clustering which arise from these observational variables, in addition to others such as Galactic dust and stellar contamination. After correcting for systematic effects, we then measure galaxy bias over a broad range of linear scales relative to mass clustering predicted from the Planck Λ cold dark matter model, finding agreement with the Canada-France-Hawaii Telescope Legacy Survey (CFHTLS) measurements with χ2 of 4.0 (8.7) with 5 degrees of freedom for the TPZ (BPZ) redshifts. Furthermore, we test a ‘linear bias’ model, in which the galaxy clustering is a fixed multiple of the predicted non-linear dark matter clustering. The precision of the data allows us to determine that the linear bias model describes the observed galaxy clustering to 2.5 percent accuracy down to scales at least 4–10 times smaller than those on which linear theory is expected to be sufficient.

  18. A K{sub S} AND IRAC SELECTION OF HIGH-REDSHIFT EXTREMELY RED OBJECTS

    SciTech Connect (OSTI)

    Wang, Wei-Hao; Barger, Amy J.; Cowie, Lennox L.

    2012-01-10

    In order to find the most extreme dust-hidden high-redshift galaxies, we select 196 extremely red objects in the K{sub S} and Infrared Array Camera (IRAC) bands (KIEROs, [K{sub s} - 4.5 {mu}m]{sub AB} > 1.6) in the 0.06 deg{sup 2} Great Observatories Origins Deep Surveys-North (GOODS-N) region. This selection avoids the Balmer breaks of galactic spectra at z < 4 and picks up red galaxies with strong dust extinction. The photometric redshifts of KIEROs are between 1.5 and 5, with {approx}70% at z {approx} 2-4. KIEROs are very massive, with M{sub *} {approx} 10{sup 10}-10{sup 12} M{sub Sun }. They are optically faint and usually cannot be picked out by the Lyman break selection. On the other hand, the KIERO selection includes approximately half of the known millimeter and submillimeter galaxies in the GOODS-N. Stacking analyses in the radio, millimeter, and submillimeter all show that KIEROs are much more luminous than average 4.5 {mu}m-selected galaxies. Interestingly, the stacked fluxes for Advanced Camera for Surveys (ACS)-undetected KIEROs in these wave bands are 2.5-5 times larger than those for ACS-detected KIEROs. With the stacked radio fluxes and the local radio-FIR correlation, we derive mean infrared luminosities of (2-7) Multiplication-Sign 10{sup 12} L{sub Sun} and mean star formation rates (SFRs) of 400-1200 M{sub Sun} yr{sup -1} for KIEROs with redshifts. We do not find evidence of a significant subpopulation of passive KIEROs. The large stellar masses and SFRs imply that KIEROs are z > 2 massive galaxies in rapid formation. Our results show that a large sample of dusty ultraluminous sources can be selected in this way and that a large fraction of high-redshift star formation is hidden by dust.

  19. Superluminous supernovae as standardizable candles and high-redshift distance probes

    SciTech Connect (OSTI)

    Inserra, C.; Smartt, S. J.

    2014-12-01

    We investigate the use of type Ic superluminous supernovae (SLSN Ic) as standardizable candles and distance indicators. Their appeal as cosmological probes stems from their remarkable peak luminosities, hot blackbody temperatures, and bright rest-frame ultraviolet emission. We present a sample of 16 published SLSN, from redshifts 0.1 to 1.2, and calculate accurate K corrections to determine uniform magnitudes in 2 synthetic rest-frame filter bandpasses with central wavelengths at 400 nm and 520 nm. At 400 nm, we find an encouragingly low scatter in their uncorrected, raw mean magnitudes with M(400) = –21.86 ± 0.35 mag for the full sample of 16 objects. We investigate the correlation between their decline rates and peak magnitude and find that the brighter events appear to decline more slowly. In a manner similar to the Phillips relation for type Ia SNe (SNe Ia), we define a ΔM {sub 20} decline relation. This correlates peak magnitude and decline over 20 days and can reduce the scatter in standardized peak magnitudes to ±0.22 mag. We further show that M(400) appears to have a strong color dependence. Redder objects are fainter and also become redder faster. Using this peak magnitudecolor evolution relation, a surprisingly low scatter of between ±0.08 mag and ±0.13 mag can be found in peak magnitudes, depending on sample selection. However, we caution that only 8 to 10 objects currently have enough data to test this peak magnitudecolor evolution relation. We conclude that SLSN Ic are promising distance indicators in the high-redshift universe in regimes beyond those possible with SNe Ia. Although the empirical relationships are encouraging, the unknown progenitor systems, how they may evolve with redshift, and the uncertain explosion physics are of some concern. The two major measurement uncertainties are the limited numbers of low-redshift, well-studied objects available to test these relationships and internal dust extinction in the host galaxies.

  20. ON THE KENNICUTT-SCHMIDT RELATION OF LOW-METALLICITY HIGH-REDSHIFT GALAXIES

    SciTech Connect (OSTI)

    Gnedin, Nickolay Y. [Particle Astrophysics Center, Fermi National Accelerator Laboratory, Batavia, IL 60510 (United States); Kravtsov, Andrey V., E-mail: gnedin@fnal.go, E-mail: andrey@oddjob.uchicago.ed [Department of Astronomy and Astrophysics, University of Chicago, Chicago, IL 60637 (United States)

    2010-05-01

    We present results of self-consistent, high-resolution cosmological simulations of galaxy formation at z {approx} 3. The simulations employ a recently developed recipe for star formation based on the local abundance of molecular hydrogen, which is tracked self-consistently during the course of simulation. The phenomenological H{sub 2} formation model accounts for the effects of dissociating UV radiation of stars in each galaxy, as well as self-shielding and shielding of H{sub 2} by dust, and therefore allows us to explore effects of lower metallicities and higher UV fluxes prevalent in high-redshift galaxies on their star formation. We compare stellar masses, metallicities, and star formation rates of the simulated galaxies to available observations of the Lyman break galaxies (LBGs) and find a reasonable agreement. We find that the Kennicutt-Schmidt (KS) relation exhibited by our simulated galaxies at z {approx} 3 is substantially steeper and has a lower amplitude than the z = 0 relation at {Sigma}{sub H} {approx_lt} 100 M{sub o-dot} pc{sup -2}. The predicted relation, however, is consistent with existing observational constraints for the z {approx} 3 damped Ly{alpha} and LBGs. Our tests show that the main reason for the difference from the local KS relation is lower metallicity of the interstellar medium in high-redshift galaxies. We discuss several implications of the metallicity-dependence of the KS relation for galaxy evolution and interpretation of observations. In particular, we show that the observed size of high-redshift exponential disks depends sensitively on their KS relation. Our results also suggest that significantly reduced star formation efficiency at low gas surface densities can lead to strong suppression of star formation in low-mass high-redshift galaxies and long gas consumption time scales over most of the disks in large galaxies. The longer gas consumption time scales could make disks more resilient to major and minor mergers and could help

  1. THE MID-INFRARED ENVIRONMENTS OF HIGH-REDSHIFT RADIO GALAXIES

    SciTech Connect (OSTI)

    Galametz, Audrey; Stern, Daniel; De Breuck, Carlos; Vernet, Joeel; Hatch, Nina; Mayo, Jack; Miley, George; Rettura, Alessandro; Seymour, Nick; Adam Stanford, S.

    2012-04-20

    Taking advantage of the impressive sensitivity of Spitzer to detect massive galaxies at high redshift, we study the mid-infrared environments of powerful, high-redshift radio galaxies at 1.2 < z < 3. Galaxy cluster member candidates were isolated using a single Spitzer/IRAC mid-infrared color criterion, [3.6]-[4.5] > -0.1 (AB), in the fields of 48 radio galaxies at 1.2 < z < 3. Using a counts-in-cell analysis, we identify a field as overdense when 15 or more red IRAC sources are found within 1' (i.e., 0.5 Mpc at 1.2 < z < 3) of the radio galaxy to the 5{sigma} flux density limits of our IRAC data (f{sub 4.5} = 13.4 {mu}Jy). We find that radio galaxies lie preferentially in medium to dense regions, with 73% of the targeted fields denser than average. Our (shallow) 120 s data permit the rediscovery of previously known clusters and protoclusters associated with radio galaxies as well as the discovery of new promising galaxy cluster candidates at z > 1.2.

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

    SciTech Connect (OSTI)

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

    2011-04-10

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

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

    SciTech Connect (OSTI)

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

    2012-03-01

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

  4. Tunable effective nonlinear refractive index of graphene dispersions during the distortion of spatial self-phase modulation

    SciTech Connect (OSTI)

    Wang, Gaozhong; Zhang, Saifeng E-mail: jwang@siom.ac.cn; Cheng, Xin; Dong, Ningning; Zhang, Long; Wang, Jun E-mail: jwang@siom.ac.cn; Umran, Fadhil A.; Coghlan, Darragh; Blau, Werner J.; Cheng, Ya

    2014-04-07

    Spatial self-phase modulation (SSPM) was observed directly when a focused He-Ne laser beam at 633 nm went through liquid-phase-exfoliated graphene dispersions. The diffraction pattern of SSPM was found to be distorted rapidly right after the incident beam horizontally passing through the dispersions, while no distortion for the vertically incident geometry. We show that the distortion is originated mainly from the non-axis-symmetrical thermal convections of the graphene nanosheets induced by laser heating, and the relative change of nonlinear refractive index can be determined by the ratio of the distortion angle to the half-cone angle. Therefore, the effective nonlinear refractive index of graphene dispersions can be tuned by changing the incident intensity and the temperature of the dispersions.

  5. Virtually distortion-free imaging system for large field, high resolution lithography using electrons, ions or other particle beams

    DOE Patents [OSTI]

    Hawryluk, A.M.; Ceglio, N.M.

    1993-01-12

    Virtually distortion free large field high resolution imaging is performed using an imaging system which contains large field distortion or field curvature. A reticle is imaged in one direction through the optical system to form an encoded mask. The encoded mask is then imaged back through the imaging system onto a wafer positioned at the reticle position. Particle beams, including electrons, ions and neutral particles, may be used as well as electromagnetic radiation.

  6. ULTRA STEEP SPECTRUM RADIO SOURCES IN THE LOCKMAN HOLE: SERVS IDENTIFICATIONS AND REDSHIFT DISTRIBUTION AT THE FAINTEST RADIO FLUXES

    SciTech Connect (OSTI)

    Afonso, J.; Bizzocchi, L.; Grossi, M.; Messias, H.; Fernandes, C. A. C.; Ibar, E.; Ivison, R. J.; Simpson, C.; Chapman, S.; Gonzalez-Solares, E.; Jarvis, M. J.; Rottgering, H.; Norris, R. P.; Dunlop, J.; Best, P.; Pforr, J.; Vaccari, M.; Seymour, N.; Farrah, D.; Huang, J.-S.; and others

    2011-12-20

    Ultra steep spectrum (USS) radio sources have been successfully used to select powerful radio sources at high redshifts (z {approx}> 2). Typically restricted to large-sky surveys and relatively bright radio flux densities, it has gradually become possible to extend the USS search to sub-mJy levels, thanks to the recent appearance of sensitive low-frequency radio facilities. Here a first detailed analysis of the nature of the faintest USS sources is presented. By using Giant Metrewave Radio Telescope and Very Large Array radio observations of the Lockman Hole at 610 MHz and 1.4 GHz, a sample of 58 USS sources, with 610 MHz integrated fluxes above 100 {mu}Jy, is assembled. Deep infrared data at 3.6 and 4.5 {mu}m from the Spitzer Extragalactic Representative Volume Survey (SERVS) are used to reliably identify counterparts for 48 (83%) of these sources, showing an average total magnitude of [3.6]{sub AB} = 19.8 mag. Spectroscopic redshifts for 14 USS sources, together with photometric redshift estimates, improved by the use of the deep SERVS data, for a further 19 objects, show redshifts ranging from z = 0.1 to z = 2.8, peaking at z {approx} 0.6 and tailing off at high redshifts. The remaining 25 USS sources, with no redshift estimate, include the faintest [3.6] magnitudes, with 10 sources undetected at 3.6 and 4.5 {mu}m (typically [3.6] {approx}> 22-23 mag from local measurements), which suggests the likely existence of higher redshifts among the sub-mJy USS population. The comparison with the Square Kilometre Array Design Studies Simulated Skies models indicates that Fanaroff-Riley type I radio sources and radio-quiet active galactic nuclei may constitute the bulk of the faintest USS population, and raises the possibility that the high efficiency of the USS technique for the selection of high-redshift sources remains even at the sub-mJy level.

  7. High Average Power Laser Gain Medium With Low Optical Distortion Using A Transverse Flowing Liquid Host

    DOE Patents [OSTI]

    Comaskey, Brian J.; Ault, Earl R.; Kuklo, Thomas C.

    2005-07-05

    A high average power, low optical distortion laser gain media is based on a flowing liquid media. A diode laser pumping device with tailored irradiance excites the laser active atom, ion or molecule within the liquid media. A laser active component of the liquid media exhibits energy storage times longer than or comparable to the thermal optical response time of the liquid. A circulation system that provides a closed loop for mixing and circulating the lasing liquid into and out of the optical cavity includes a pump, a diffuser, and a heat exchanger. A liquid flow gain cell includes flow straighteners and flow channel compression.

  8. Size dependence of cubic to trigonal structural distortion in silver micro- and nanocrystals under high pressure

    SciTech Connect (OSTI)

    Guo, Qixum; Zhao, Yusheng; Zin, Zhijun; Wang, Zhongwu; Skrabalak, Sara E; Xia, Younan

    2008-01-01

    Silver micro- and nanocrystals with sizes of {approx}2--3.5 {mu}m and {approx}50--100 nm were uniaxially compressed under nonhydrostatic pressures (strong deviatoric stress) up to {approx}30 GPa at room temperature in a symmetric diamond-anvil cell and studied in situ using angle-dispersive synchrotron X-ray diffraction. A cubic to trigonal structural distortion along a 3-fold rotational axis was discovered by careful and comprehensive analysis of the apparent lattice parameter and full width at half-maximum, which are strongly dependent upon the Miller index and crystal size.

  9. REDSHIFT DETERMINATION AND CO LINE EXCITATION MODELING FOR THE MULTIPLY LENSED GALAXY HLSW-01

    SciTech Connect (OSTI)

    Scott, K. S.; Lupu, R. E.; Aguirre, J. E.; Auld, R.; Eales, S.; Aussel, H.; Chanial, P.; Beelen, A.; Bock, J.; Bradford, C. M.; Carpenter, J. M.; Cooray, A.; Dowell, C. D.; Brisbin, D.; Burgarella, D.; Chapman, S. C.; Clements, D. L.; Conley, A.; Cox, P.

    2011-05-20

    We report on the redshift measurement and CO line excitation of HERMES J105751.1+573027 (HLSW-01), a strongly lensed submillimeter galaxy discovered in Herschel/SPIRE observations as part of the Herschel Multi-tiered Extragalactic Survey (HerMES). HLSW-01 is an ultra-luminous galaxy with an intrinsic far-infrared luminosity of L{sub FIR} = 1.4 x 10{sup 13} L{sub sun}, and is lensed by a massive group of galaxies into at least four images with a total magnification of {mu} = 10.9 {+-} 0.7. With the 100 GHz instantaneous bandwidth of the Z-Spec instrument on the Caltech Submillimeter Observatory, we robustly identify a redshift of z = 2.958 {+-} 0.007 for this source, using the simultaneous detection of four CO emission lines (J = 7 {yields} 6, J = 8 {yields} 7, J = 9 {yields} 8, and J = 10 {yields} 9). Combining the measured line fluxes for these high-J transitions with the J = 1 {yields} 0, J = 3 {yields} 2, and J = 5 {yields} 4 line fluxes measured with the Green Bank Telescope, the Combined Array for Research in Millimeter Astronomy, and the Plateau de Bure Interferometer, respectively, we model the physical properties of the molecular gas in this galaxy. We find that the full CO spectral line energy distribution is described well by warm, moderate-density gas with T{sub kin} = 86-235 K and n{sub H{sub 2}} = (1.1-3.5) x 10{sup 3} cm{sup -3}. However, it is possible that the highest-J transitions are tracing a small fraction of very dense gas in molecular cloud cores, and two-component models that include a warm/dense molecular gas phase with T{sub kin} {approx} 200 K, n{sub H{sub 2}}{approx}10{sup 5} cm{sup -3} are also consistent with these data. Higher signal-to-noise measurements of the J{sub up} {>=} 7 transitions with high spectral resolution, combined with high spatial resolution CO maps, are needed to improve our understanding of the gas excitation, morphology, and dynamics of this interesting high-redshift galaxy.

  10. BROADBAND STUDY OF GRB 091127: A SUB-ENERGETIC BURST AT HIGHER REDSHIFT?

    SciTech Connect (OSTI)

    Troja, E.; Sakamoto, T.; Brown, J. C.; Gehrels, N.; Marshall, F. E.; Racusin, J. L.; Guidorzi, C.; Norris, J. P.; Panaitescu, A.; Kobayashi, S.; Mawson, N.; Melandri, A.; Mundell, C. G.; Steele, I. A.; Omodei, N.; Burrows, D. N.; Evans, P. A.; Oates, S. R.; Pal'shin, V.; Preece, R. D.; and others

    2012-12-10

    GRB 091127 is a bright gamma-ray burst (GRB) detected by Swift at a redshift z = 0.49 and associated with SN 2009nz. We present the broadband analysis of the GRB prompt and afterglow emission and study its high-energy properties in the context of the GRB/SN association. While the high luminosity of the prompt emission and standard afterglow behavior are typical of cosmological long GRBs, its low-energy release (E{sub {gamma}} < 3 Multiplication-Sign 10{sup 49} erg), soft spectrum, and unusual spectral lag connect this GRB to the class of sub-energetic bursts. We discuss the suppression of high-energy emission in this burst, and investigate whether this behavior could be connected with the sub-energetic nature of the explosion.

  11. AN EXTREME GRAVITATIONALLY REDSHIFTED IRON LINE AT 4.8 KeV IN Mrk 876

    SciTech Connect (OSTI)

    Bottacini, Eugenio; Orlando, Elena; Moskalenko, Igor [W. W. Hansen Experimental Physics Laboratory and Kavli Institute for Particle Astrophysics and Cosmology, Stanford University (United States); Greiner, Jochen [Max-Planck-Institut fr extraterrestrische Physik, Giessenbachstrasse 1, D-85748 Garching (Germany); Ajello, Marco [Department of Physics and Astronomy, Clemson University, Clemson, SC 29634-0978 (United States); Persic, Massimo, E-mail: eugenio.bottacini@stanford.edu [INAF-Trieste, via G.B.Tiepolo 11, I-34143 Trieste (Italy)

    2015-01-01

    X-ray spectral lines at unforeseen energies are important because they can shed light on the extreme physical conditions of the environment around the supermassive black holes of active galactic nuclei (AGNs). Mrk 876 displays such a line at 4.80{sub ?0.04}{sup +0.05} rest-frame energy. A possible interpretation of its origin can be found in the hotspot scenario. In this scenario, the primary radiation from a flare in the hot corona of an AGN illuminates a limited portion of the accretion disk that emits by fluorescence. In this context, the line can represent an extreme gravitationally redshifted Fe line originating on the accretion disk below six gravitational radii from a rotating supermassive black hole. The correct estimate of the line significance requires a dedicated approach. Based on an existing rigorous approach, we have performed extensive Monte Carlo simulations. We determine that the line is a real feature at a ?99% confidence level.

  12. USING THE 1.6 {mu}m BUMP TO STUDY REST-FRAME NEAR-INFRARED-SELECTED GALAXIES AT REDSHIFT 2

    SciTech Connect (OSTI)

    Sorba, Robert; Sawicki, Marcin

    2010-10-01

    We explore the feasibility and limitations of using the 1.6 {mu}m bump as a photometric redshift indicator and selection technique, and use it to study the rest-frame H-band galaxy luminosity and stellar mass functions (SMFs) at redshift z {approx} 2. We use publicly available Spitzer/IRAC images in the GOODS fields and find that color selection in the IRAC bandpasses alone is comparable in completeness and contamination to BzK selection. We find that the shape of the 1.6 {mu}m bump is robust, and photometric redshifts are not greatly affected by choice of model parameters. Comparison with spectroscopic redshifts shows photometric redshifts to be reliable. We create a rest-frame NIR-selected catalog of galaxies at z {approx} 2 and construct a galaxy SMF. Comparisons with other SMFs at approximately the same redshift but determined using shorter wavelengths show good agreement. This agreement suggests that selection at bluer wavelengths does not miss a significant amount of stellar mass in passive galaxies. Comparison with SMFs at other redshifts shows evidence for the downsizing scenario of galaxy evolution. We conclude by pointing out the potential for using the 1.6 {mu}m bump technique to select high-redshift galaxies with the JWST, whose {lambda}>0.6 {mu}m coverage will not be well suited to selecting galaxies using techniques that require imaging at shorter wavelengths.

  13. Lyalpha RADIATIVE TRANSFER WITH DUST: ESCAPE FRACTIONS FROM SIMULATED HIGH-REDSHIFT GALAXIES

    SciTech Connect (OSTI)

    Laursen, Peter; Sommer-Larsen, Jesper; Andersen, Anja C. E-mail: jslarsen@astro.ku.d

    2009-10-20

    The Lyalpha emission line is an essential diagnostic tool for probing galaxy formation and evolution. Not only is it commonly the strongest observable line from high-redshift galaxies, but from its shape detailed information about its host galaxy can be revealed. However, due to the scattering nature of Lyalpha photons increasing their path length in a nontrivial way, if dust is present in the galaxy, the line may be severely suppressed and its shape altered. In order to interpret observations correctly, it is thus of crucial significance to know how much of the emitted light actually escapes the galaxy. In the present work, using a combination of high-resolution cosmological hydrosimulations and an adaptively refinable Monte Carlo Lyalpha radiative transfer code including an environment dependent model of dust, the escape fractions f {sub esc} of Lyalpha radiation from high-redshift (z = 3.6) galaxies are calculated. In addition to the average escape fraction, the variation of f {sub esc} in different directions and from different parts of the galaxies is investigated, as well as the effect on the emergent spectrum. Escape fractions from a sample of simulated galaxies of representative physical properties are found to decrease for increasing galaxy virial mass M {sub vir}, from f {sub esc} approaching unity for M {sub vir} approx 10{sup 9} M {sub sun} to f {sub esc} less than 10% for M {sub vir} approx 10{sup 12} M {sub sun}. In spite of dust being almost gray, it is found that the emergent spectrum is affected nonuniformly, with the escape fraction of photons close to the line center being much higher than of those in the wings, thus effectively narrowing the Lyalpha line.

  14. Atomic chemistry in turbulent astrophysical media II: Effect of the redshift zero metagalactic background

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Gray, William J.; Scannapieco, Evan

    2016-02-22

    Here, we carry out direct numerical simulations of turbulent astrophysical media exposed to the redshift zero metagalactic background. The simulations assume solar composition and explicitly track ionizations, recombinations, and ion-by-ion radiative cooling for hydrogen, helium, carbon, nitrogen, oxygen, neon, sodium, magnesium, silicon, sulfur, calcium, and iron. Each run reaches a global steady state that depends not only on the ionization parameter,more » $U,$ and mass-weighted average temperature, $${T}_{{\\rm{MW}}},$$ but also on the one-dimensional turbulent velocity dispersion, $${\\sigma }_{{\\rm{1D}}}$$. We carry out runs that span a grid of models with U ranging from 0 to 10–1 and $${\\sigma }_{{\\rm{1D}}}$$ ranging from 3.5 to 58 km s–1, and we vary the product of the mean density and the driving scale of the turbulence, $${nL},$$ which determines the average temperature of the medium, from $${nL}={10}^{16}$$ to $${nL}={10}^{20}$$ cm–2. The turbulent Mach numbers of our simulations vary from $$M\\approx 0.5$$ for the lowest velocity dispersion cases to $$M\\approx 20$$ for the largest velocity dispersion cases. When $$M\\lesssim 1,$$ turbulent effects are minimal, and the species abundances are reasonably described as those of a uniform photoionized medium at a fixed temperature. On the other hand, when $$M\\gtrsim 1,$$ dynamical simulations such as the ones carried out here are required to accurately predict the species abundances. We gather our results into a set of tables to allow future redshift zero studies of the intergalactic medium to account for turbulent effects.« less

  15. The highest redshift quasar at z = 7.085: A radio-quiet source

    SciTech Connect (OSTI)

    Momjian, E.; Carilli, C. L.; Walter, F.; Venemans, B. E-mail: ccarilli@nrao.edu E-mail: venemans@mpia.de

    2014-01-01

    We present 1-2 GHz Very Large Array A-configuration continuum observations on the highest redshift quasar known to date, the z = 7.085 quasar ULAS J112001.48+064124.3. The results show no radio continuum emission at the optical position of the quasar or its vicinity at a level of ?3? or 23.1 ?Jy beam{sup 1}. This 3? limit corresponds to a rest-frame 1.4 GHz luminosity density limit of L {sub ?,} {sub 1.4} {sub GHz} < 1.76 10{sup 24} W Hz{sup 1} for a spectral index of ? = 0, and L {sub ?,} {sub 1.4} {sub GHz} < 1.42 10{sup 25} W Hz{sup 1} for a spectral index of ? = 1. The rest-frame 1.4 GHz luminosity limits are L {sub rad} < 6.43 10{sup 6} L {sub ?} and L {sub rad} < 5.20 10{sup 7} L {sub ?} for ? = 0 and ? = 1, respectively. The derived limits for the ratio of the rest-frame 1.4 GHz luminosity density to the B-band optical luminosity density are R{sub 1.4}{sup ?}<0.53 and <4.30 for the above noted spectral indices, respectively. Given our upper limits on the radio continuum emission and the radio-to-optical luminosity ratio, we conclude that this quasar is radio-quiet and located at the low end of the radio-quiet distribution of high-redshift (z ? 6) quasars.

  16. CANDELS/GOODS-S, CDFS, and ECDFS: photometric redshifts for normal and X-ray-detected galaxies

    SciTech Connect (OSTI)

    Hsu, Li-Ting; Salvato, Mara; Nandra, Kirpal; Brusa, Marcella; Bender, Ralf; Buchner, Johannes; Brightman, Murray; Georgakakis, Antonis; Donley, Jennifer L.; Kocevski, Dale D.; Guo, Yicheng; Barro, Guillermo; Faber, Sandra M.; Rangel, Cyprian; Willner, S. P.; Ashby, Matthew L. N.; Budavri, Tams; Szalay, Alexander S.; Dahlen, Tomas; and others

    2014-11-20

    We present photometric redshifts and associated probability distributions for all detected sources in the Extended Chandra Deep Field South (ECDFS). This work makes use of the most up-to-date data from the Cosmic Assembly Near-IR Deep Legacy Survey (CANDELS) and the Taiwan ECDFS Near-Infrared Survey (TENIS) in addition to other data. We also revisit multi-wavelength counterparts for published X-ray sources from the 4 Ms CDFS and 250 ks ECDFS surveys, finding reliable counterparts for 1207 out of 1259 sources (?96%). Data used for photometric redshifts include intermediate-band photometry deblended using the TFIT method, which is used for the first time in this work. Photometric redshifts for X-ray source counterparts are based on a new library of active galactic nuclei/galaxy hybrid templates appropriate for the faint X-ray population in the CDFS. Photometric redshift accuracy for normal galaxies is 0.010 and for X-ray sources is 0.014 and outlier fractions are 4% and 5.2%, respectively. The results within the CANDELS coverage area are even better, as demonstrated both by spectroscopic comparison and by galaxy-pair statistics. Intermediate-band photometry, even if shallow, is valuable when combined with deep broadband photometry. For best accuracy, templates must include emission lines.

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

    SciTech Connect (OSTI)

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

    2013-08-01

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

  18. Monoclinically distorted perovskites, A{sub 2}ZnTiO{sub 6} (A=Pr, Gd): Rietveld refinement, and dielectric studies

    SciTech Connect (OSTI)

    Das, Nibedita; Nath, Masood A.; Thakur, Gohil S.; Thirumal, M.; Ganguli, Ashok K.

    2015-09-15

    Double perovskite related oxide A{sub 2}ZnTiO{sub 6}A=Pr, Gd were synthesized by the solid state reaction method at 1523 K. The structure and microstructure of the compounds were studied by X-ray, SAED and FESEM. Rietveld refinement of the powder X-ray analysis shows that the compounds crystallizes in monoclinic space group P2{sub 1}/n (a{sup +}b{sup −}b{sup −}) with unit cell parameter √2a{sub p}×√2a{sub p}×2a{sub p} (a=5.5026(1) Å, b=5.6305(1) Å, c=7.8149(1) Å, β=90.02(1)° for Pr{sub 2}ZnTiO{sub 6} and a=5.3621(1) Å, b=5.6565(2) Å, c=7.6779(2) Å and β=90.264(2)° for Gd{sub 2}ZnTiO{sub 6}. Electron diffraction study confirms P2{sub 1}/n symmetry of the oxides. The monoclinic distortion is larger in Gd{sub 2}ZnTiO{sub 6} than Pr{sub 2}ZnTiO{sub 6} which is associated with the tolerance factor and the tilting angle of ZnO{sub 6} and TiO{sub 6} octahedra (ϕ=13.64° for Pr{sub 2}ZnTiO{sub 6} and 16.51° for Gd{sub 2}ZnTiO{sub 6}). The compounds are highly ordered. The charge and size difference between B site cations are the driving force for the ordering of the B′O{sub 6} and B″O{sub 6} octahedra. Pr{sub 2}ZnTiO{sub 6} shows a dielectric constant of 27 and dielectric loss of 0.003 while Gd{sub 2}ZnTiO{sub 6} has a dielectric constant of 17 and dielectric loss of 0.005 measured at 1 MHz. - Graphical abstract: Synthesis of new double perovskite dielectric material with very low dielectric loss. - Highlights: • Synthesis of new monoclinically distorted double perovskite (Pr{sub 2}ZnTiO{sub 6}). • Synthesis of monoclinically distorted double perovskite (Gd{sub 2}ZnTiO{sub 6}). • Selected area electron diffraction study of A{sub 2}ZnTiO{sub 6} (A=Pr, Gd). • Study of dielectric properties of A{sub 2}ZnTiO{sub 6} (A=Pr, Gd)

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

    SciTech Connect (OSTI)

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

    2014-03-10

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

  20. RAPID, MACHINE-LEARNED RESOURCE ALLOCATION: APPLICATION TO HIGH-REDSHIFT GAMMA-RAY BURST FOLLOW-UP

    SciTech Connect (OSTI)

    Morgan, A. N.; Richards, Joseph W.; Butler, Nathaniel R.; Bloom, Joshua S. [Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States); Long, James; Broderick, Tamara, E-mail: amorgan@astro.berkeley.edu [Department of Statistics, University of California, Berkeley, CA 94720-3860 (United States)

    2012-02-20

    As the number of observed gamma-ray bursts (GRBs) continues to grow, follow-up resources need to be used more efficiently in order to maximize science output from limited telescope time. As such, it is becoming increasingly important to rapidly identify bursts of interest as soon as possible after the event, before the afterglows fade beyond detectability. Studying the most distant (highest redshift) events, for instance, remains a primary goal for many in the field. Here, we present our Random Forest Automated Triage Estimator for GRB redshifts (RATE GRB-z ) for rapid identification of high-redshift candidates using early-time metrics from the three telescopes onboard Swift. While the basic RATE methodology is generalizable to a number of resource allocation problems, here we demonstrate its utility for telescope-constrained follow-up efforts with the primary goal to identify and study high-z GRBs. For each new GRB, RATE GRB-z provides a recommendation-based on the available telescope time-of whether the event warrants additional follow-up resources. We train RATE GRB-z using a set consisting of 135 Swift bursts with known redshifts, only 18 of which are z > 4. Cross-validated performance metrics on these training data suggest that {approx}56% of high-z bursts can be captured from following up the top 20% of the ranked candidates, and {approx}84% of high-z bursts are identified after following up the top {approx}40% of candidates. We further use the method to rank 200 + Swift bursts with unknown redshifts according to their likelihood of being high-z.

  1. STAR FORMATION AND DUST OBSCURATION IN THE TIDALLY DISTORTED GALAXY NGC 2442

    SciTech Connect (OSTI)

    Pancoast, Anna; Sajina, Anna; Lacy, Mark; Noriega-Crespo, Alberto; Rho, Jeonghee

    2010-11-01

    We present a detailed investigation of the morphological distribution and level of star formation and dust obscuration in the nearby tidally distorted galaxy NGC 2442. Spitzer images in the IR at 3.6, 4.5, 5.8, 8.0, and 24 {mu}m and GALEX images at 1500 A and 2300 A allow us to resolve the galaxy on scales between {approx}240 and 600 pc. We supplement these with archival data in the B, J, H, and K bands. We use the 8 {mu}m, 24 {mu}m, and FUV (1500 A) emission to study the star formation rate (SFR). We find that, globally, these tracers of star formation give a range of results of {approx}6-11 M{sub sun} yr{sup -1}, with the dust-corrected FUV giving the highest value of SFR. We can reconcile the UV- and IR-based estimates by adopting a steeper UV extinction curve that lies in between the starburst (Calzetti) and Small Magellanic Cloud extinction curves. However, the regions of the highest SFR intensity along the spiral arms are consistent with a starburst-like extinction. Overall, the level of star formation we find is higher than previously published for this galaxy, by about a factor of 2, which, contrary to previous conclusions, implies that the interaction that caused the distorted morphology of NGC 2442 likely also triggered increased levels of star formation activity. We also find marked asymmetry in that the north spiral arm has a noticeably higher SFR than the southern arm. The tip of the southern spiral arm shows a likely tidally distorted peculiar morphology. It is UV bright and shows unusual IRAC colors, consistent with other published tidal features IRAC data. Outside of the spiral arms, we discover what appears to be a superbubble, {approx}1.7 kpc across, which is seen most clearly in the IRAC images. Significant H{alpha}, UV, and IR emission in the area also suggest vigorous ongoing star formation. A known, recent supernova (SN 1999ga) is located at the edge of this superbubble. Although speculative at this stage, this area suggests a large star

  2. Giant magnetoelastic distortions of the crystal structure of the weakly anisotropic compound UFe/sub 2/

    SciTech Connect (OSTI)

    Popov, Y.F.; Levitin, R.Z.; Zeleny, M.; Deryagin, A.V.; Andreev, A.V.

    1980-06-01

    We investigate the temperature dependences of the crystal-lattice parameters, of the anisotropy, and of the Young's modulus of the intermetallide compound UFe/sub 2/. The contribution of the uranium ions to the magnetic moment of this compound is negligible (..mu../sub U/=0.06..mu../sub B/), owing to the almoft complete delocalization of the uranium 5f electrons. The measured magnetic anisotropy is relatively small (K/sub 1/approx. =-10/sup 6/ erg/cm/sup 3/ at 0 K). However, the transition to the magnetically ordered state (T/sub c/=170 K) is accompanied by large rhombohedral distortions of the UFe/sub 2/ crystal structure and by a considerable anomaly of the Young's modulus, thus attesting to a large value of the magnetoelastic interaction in this compound (..delta..K/sub 1/ /sup m/eapprox. =-8 x 10/sup 6/ erg/cm/sup 3/).

  3. Photon-axion conversion as a mechanism for supernova dimming: Limits from CMB spectral distortion

    SciTech Connect (OSTI)

    Mirizzi, Alessandro; Raffelt, Georg G.; Serpico, Pasquale D.

    2005-07-15

    Axion-photon conversion induced by intergalactic magnetic fields has been proposed as an explanation for the dimming of distant supernovae of type Ia (SNe Ia) without cosmic acceleration. The effect depends on the intergalactic electron density n{sub e} as well as the B-field strength and domain size. We show that for n{sub e} < or approx. 10{sup -9} cm{sup -3} the same mechanism would cause excessive spectral distortion of the cosmic microwave background (CMB). This small-n{sub e} parameter region had been left open by the most restrictive previous constraints based on the dispersion of quasar (QSO) spectra. The combination of CMB and QSO limits suggests that the photon-axion conversion mechanism can only play a subleading role for SN Ia dimming. A combined analysis of all the observables affected by the photon-axion oscillations would be required to give a final verdict on the viability of this model.

  4. Fermi surface distortion induced by interaction between Rashba and Zeeman effects

    SciTech Connect (OSTI)

    Choi, Won Young; Koo, Hyun Cheol; Chang, Joonyeon; Kim, Hyung-jun; Lee, Kyung-Jin

    2015-05-07

    To evaluate Fermi surface distortion induced by interaction between Rashba and Zeeman effects, the channel resistance in an InAs quantum well layer is investigated with an in-plane magnetic field transverse to the current direction. In the magnetoresistance curve, the critical point occurs at ∼3.5 T, which is approximately half of the independently measured Rashba field. To get an insight into the correlation between the critical point in magnetoresistance curve and the Rashba strength, the channel conductivity is calculated using a two-dimensional free-electron model with relaxation time approximation. The critical point obtained from the model calculation is in agreement with the experiment, suggesting that the observation of critical point can be an alternative method to experimentally determine the Rashba parameter.

  5. Oxygen octahedral distortions in LaMO3/SrTiO3 superlattices

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Sanchez-Santolino, Gabriel; Cabero, Mariona; Varela, Maria; Garcia-Barriocanal, Javier; Leon, Carlos; Pennycook, Stephen J.; Santamaria, Jacobo

    2014-04-24

    Here we study the interfaces between the Mott insulator LaMnO3 (LMO) and the band insulator SrTiO3 (STO) in epitaxially grown superlattices with different thickness ratios and different transport and magnetic behaviors. Using atomic resolution electron energy-loss spectrum imaging, we analyze simultaneously the structural and chemical properties of these interfaces. We find changes in the oxygen octahedral tilts within the LaMnO3 layers when the thickness ratio between the manganite and the titanate layers is varied. Superlattices with thick LMO and ultrathin STO layers present unexpected octahedral tilts in the STO, along with a small amount of oxygen vacancies. On the othermore » hand, thick STO layers exhibit undistorted octahedra while the LMO layers present reduced O octahedral distortions near the interfaces. In conclusion, these findings will be discussed in view of the transport and magnetic differences found in previous studies.« less

  6. Rapid distortion analysis of high speed homogeneous turbulence subject to periodic shear

    SciTech Connect (OSTI)

    Bertsch, Rebecca L. Girimaji, Sharath S.

    2015-12-15

    The effect of unsteady shear forcing on small perturbation growth in compressible flow is investigated. In particular, flow-thermodynamic field interaction and the resulting effect on the phase-lag between applied shear and Reynolds stress are examined. Simplified linear analysis of the perturbation pressure equation reveals crucial differences between steady and unsteady shear effects. The analytical findings are validated with numerical simulations of inviscid rapid distortion theory (RDT) equations. In contrast to steadily sheared compressible flows, perturbations in the unsteady (periodic) forcing case do not experience an asymptotic growth phase. Further, the resonance growth phenomenon found in incompressible unsteady shear turbulence is absent in the compressible case. Overall, the stabilizing influence of both unsteadiness and compressibility is compounded leading to suppression of all small perturbations. The underlying mechanisms are explained.

  7. Experimental and Numerical Analysis on the Distortion of Parts Made of 20MnCr5 by Hot Metal Forming

    SciTech Connect (OSTI)

    Rentsch, Ruediger; Brinksmeier, Ekkard [Stiftung Institut fuer Werkstofftechnik, Badgasteiner Strasse 3, 28359 Bremen (Germany)

    2011-05-04

    For high performance applications, shafts and gears made of 20MnCr5 (AISI 5120) are manufactured in large numbers every year. Inhomogeneities in the material properties, process perturbations and asymmetries in shape and operation setups provide a potential for the distortion of parts, often released by heat treatment. In this contribution experimental results on the distortion of shafts and the dishing of disk-like gear wheel blanks are presented. The numerical analysis of the hot-rolling process allowed to trace a peculiar segregation distribution at the cross-section of the bars back to the casting process, and to identify an asymmetric strain distribution which may be the main cause for shaft distortion. For the dishing of the disks a correlation to the resulting distribution of the material flow was found and, a process perturbation parameter identified which is assumed to be responsible for the observed material flow variation.

  8. HST/COS OBSERVATIONS OF THE QUASAR HE 2347-4342: PROBING THE EPOCH OF He II PATCHY REIONIZATION AT REDSHIFTS z = 2.4-2.9

    SciTech Connect (OSTI)

    Shull, J. Michael; France, Kevin; Danforth, Charles W.; Smith, Britton [CASA, Department of Astrophysical and Planetary Sciences, University of Colorado, 389-UCB, Boulder, CO 80309 (United States); Tumlinson, Jason, E-mail: michael.shull@colorado.ed, E-mail: danforth@casa.colorado.ed, E-mail: kevin.france@colorado.ed, E-mail: britton.smith@colorado.ed, E-mail: tumlinson@stsci.ed [Space Telescope Science Institute, Baltimore, MD 21218 (United States)

    2010-10-20

    We report ultraviolet spectra of the high-redshift (z{sub em} {approx} 2.9) quasar, HE 2347 - 4342, taken by the Cosmic Origins Spectrograph (COS) on the Hubble Space Telescope. Spectra in the G130M (medium resolution, 1135-1440 A) and G140L (low resolution, 1030-2000 A) gratings exhibit patchy Gunn-Peterson absorption in the 303.78 A Ly{alpha} line of He II between z = 2.39-2.87 (G140L) and z = 2.74-2.90 (G130M). With COS, we obtain better spectral resolution, higher signal-to-noise ratio (S/N), and better determined backgrounds than previous studies, with sensitivity to abundance fractions x{sub He{sub II}} {approx} 0.01 in filaments of the cosmic web. The He II optical depths from COS are higher than those with the Far Ultraviolet Spectroscopic Explorer and range from {tau}{sub He{sub II}} {<=} 0.02 to {tau}{sub He{sub II}} {>=} 5, with a slow recovery in mean optical depth to ({tau}{sub He{sub II}}) {<=} 2 at z < 2.7. The He II/H I optical-depth ratio varies ({eta}{approx} 10-100 for 2.4 < z < 2.73 and {eta} = 5-500 for 2.75 < z < 2.89) on scales {Delta}z {approx}< 0.01 (10.8 Mpc in comoving radial distance at z = 2.8), with numerous flux-transmission windows between 1135 and 1186 A. The He II absorption extends to 1186.26 A (z = 2.905), including associated absorbers with z{sub abs} {approx} z{sub QSO} and minimal 'proximity effect' of flux transmission at the He II edge. We propose a QSO systemic redshift z{sub QSO} = 2.904 {+-} 0.002, some {Delta}z = 0.019 higher than that derived from O I {lambda}1302 emission. Three long troughs (4-10 A or 25-60 Mpc comoving distance) of strong He II absorption between z = 2.75and2.90 are uncharacteristic of the intergalactic medium if He II reionized at z{sub r} {approx} 3. Contrary to recent indirect estimates (z{sub r} = 3.2 {+-} 0.2) from H I optical depths, the epoch of He II reionization may extend to z {approx}< 2.7.

  9. PHOTOMETRIC REDSHIFTS IN THE HAWAII-HUBBLE DEEP FIELD-NORTH (H-HDF-N)

    SciTech Connect (OSTI)

    Yang, G.; Xue, Y. Q.; Kong, X.; Wang, J.-X.; Yuan, Y.-F.; Zhou, H. Y.; Luo, B.; Brandt, W. N.; Alexander, D. M.; Bauer, F. E.; Cui, W.; Lehmer, B. D.; Wu, X.-B.; Yuan, F. E-mail: xuey@ustc.edu.cn

    2015-01-01

    We derive photometric redshifts (z {sub phot}) for sources in the entire (∼0.4 deg{sup 2}) Hawaii-Hubble Deep Field-North (H-HDF-N) field with the EAzY code, based on point-spread-function-matched photometry of 15 broad bands from the ultraviolet (U band) to mid-infrared (IRAC 4.5 μm). Our catalog consists of a total of 131,678 sources. We evaluate the z {sub phot} quality by comparing z {sub phot} with spectroscopic redshifts (z {sub spec}) when available, and find a value of normalized median absolute deviation σ{sub NMAD} = 0.029 and an outlier fraction of 5.5% (outliers are defined as sources having |z{sub phot} – z{sub spec} |/(1 + z{sub spec} ) > 0.15) for non-X-ray sources. More specifically, we obtain σ{sub NMAD} = 0.024 with 2.7% outliers for sources brighter than R = 23 mag, σ{sub NMAD} = 0.035 with 7.4% outliers for sources fainter than R = 23 mag, σ{sub NMAD} = 0.026 with 3.9% outliers for sources having z < 1, and σ{sub NMAD} = 0.034 with 9.0% outliers for sources having z > 1. Our z {sub phot} quality shows an overall improvement over an earlier z {sub phot} work that focused only on the central H-HDF-N area. We also classify each object as a star or galaxy through template spectral energy distribution fitting and complementary morphological parameterization, resulting in 4959 stars and 126,719 galaxies. Furthermore, we match our catalog with the 2 Ms Chandra Deep Field-North main X-ray catalog. For the 462 matched non-stellar X-ray sources (281 having z {sub spec}), we improve their z {sub phot} quality by adding three additional active galactic nucleus templates, achieving σ{sub NMAD} = 0.035 and an outlier fraction of 12.5%. We make our catalog publicly available presenting both photometry and z {sub phot}, and provide guidance on how to make use of our catalog.

  10. Star formation relations and CO spectral line energy distributions across the J-ladder and redshift

    SciTech Connect (OSTI)

    Greve, T. R.; Leonidaki, I.; Xilouris, E. M.; Wei, A.; Henkel, C.; Zhang, Z.-Y.; Van der Werf, P.; Meijerink, R.; Aalto, S.; Armus, L.; Daz-Santos, T.; Evans, A. S.; Fischer, J.; Gao, Y.; Gonzlez-Alfonso, E.; Harris, A.; Naylor, D. A.; Smith, H. A.; Spaans, M.; and others

    2014-10-20

    We present FIR [50-300 ?m]CO luminosity relations (i.e., log L{sub FIR}=?log L{sub CO}{sup ?}+?) for the full CO rotational ladder from J = 1-0 up to J = 13-12 for a sample of 62 local (z ? 0.1) (Ultra) Luminous Infrared Galaxies (LIRGs; L {sub IR[8-1000} {sub ?m]} > 10{sup 11} L {sub ?}) using data from Herschel SPIRE-FTS and ground-based telescopes. We extend our sample to high redshifts (z > 1) by including 35 submillimeter selected dusty star forming galaxies from the literature with robust CO observations, and sufficiently well-sampled FIR/submillimeter spectral energy distributions (SEDs), so that accurate FIR luminosities can be determined. The addition of luminous starbursts at high redshifts enlarge the range of the FIRCO luminosity relations toward the high-IR-luminosity end, while also significantly increasing the small amount of mid-J/high-J CO line data (J = 5-4 and higher) that was available prior to Herschel. This new data set (both in terms of IR luminosity and J-ladder) reveals linear FIRCO luminosity relations (i.e., ? ? 1) for J = 1-0 up to J = 5-4, with a nearly constant normalization (? ? 2). In the simplest physical scenario, this is expected from the (also) linear FIR(molecular line) relations recently found for the dense gas tracer lines (HCN and CS), as long as the dense gas mass fraction does not vary strongly within our (merger/starburst)-dominated sample. However, from J = 6-5 and up to the J = 13-12 transition, we find an increasingly sublinear slope and higher normalization constant with increasing J. We argue that these are caused by a warm (?100 K) and dense (>10{sup 4} cm{sup 3}) gas component whose thermal state is unlikely to be maintained by star-formation-powered far-UV radiation fields (and thus is no longer directly tied to the star formation rate). We suggest that mechanical heating (e.g., supernova-driven turbulence and shocks), and not cosmic rays, is the more likely source of energy for this component. The global CO

  11. DUST EXTINCTION BIAS IN THE COLUMN DENSITY DISTRIBUTION OF GAMMA-RAY BURSTS: HIGH COLUMN DENSITY, LOW-REDSHIFT GRBs ARE MORE HEAVILY OBSCURED

    SciTech Connect (OSTI)

    Watson, Darach [Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, DK-2100 Copenhagen O (Denmark); Jakobsson, Pall, E-mail: darach@dark-cosmology.dk, E-mail: pja@raunvis.hi.is [Centre for Astrophysics and Cosmology, Science Institute, University of Iceland, Dunhaga 5, IS-107 Reykjavik (Iceland)

    2012-08-01

    The afterglows of gamma-ray bursts (GRBs) have more soft-X-ray absorption than expected from the foreground gas column in the Galaxy. While the redshift of the absorption can in general not be constrained from current X-ray observations, it has been assumed that the absorption is due to metals in the host galaxy of the GRB. The large sample of X-ray afterglows and redshifts now available allows the construction of statistically meaningful distributions of the metal column densities. We construct such a sample and show, as found in previous studies, that the typical absorbing column density (N{sub H{sub X}}) increases substantially with redshift, with few high column density objects found at low-to-moderate redshifts. We show, however, that when highly extinguished bursts are included in the sample, using redshifts from their host galaxies, high column density sources are also found at low-to-moderate redshift. We infer from individual objects in the sample and from observations of blazars that the increase in column density with redshift is unlikely to be related to metals in the intergalactic medium or intervening absorbers. Instead we show that the origin of the apparent increase with redshift is primarily due to dust extinction bias: GRBs with high X-ray absorption column densities found at z {approx}< 4 typically have very high dust extinction column densities, while those found at the highest redshifts do not. It is unclear how such a strongly evolving N{sub H{sub X}}/A{sub V} ratio would arise, and based on current data, remains a puzzle.

  12. WIDESPREAD AND HIDDEN ACTIVE GALACTIC NUCLEI IN STAR-FORMING GALAXIES AT REDSHIFT >0.3

    SciTech Connect (OSTI)

    Juneau, Stephanie; Bournaud, Frederic; Daddi, Emanuele; Elbaz, David; Alexander, David M.; Mullaney, James R.; Magnelli, Benjamin; Hwang, Ho Seong; Willner, S. P.; Coil, Alison L.; Rosario, David J.; Trump, Jonathan R.; Faber, S. M.; Kocevski, Dale D.; Cooper, Michael C.; Frayer, David T.; and others

    2013-02-20

    We characterize the incidence of active galactic nuclei (AGNs) in 0.3 < z < 1 star-forming galaxies by applying multi-wavelength AGN diagnostics (X-ray, optical, mid-infrared, radio) to a sample of galaxies selected at 70 {mu}m from the Far-Infrared Deep Extragalactic Legacy survey (FIDEL). Given the depth of FIDEL, we detect 'normal' galaxies on the specific star formation rate (sSFR) sequence as well as starbursting systems with elevated sSFR. We find an overall high occurrence of AGN of 37% {+-} 3%, more than twice as high as in previous studies of galaxies with comparable infrared luminosities and redshifts but in good agreement with the AGN fraction of nearby (0.05 < z < 0.1) galaxies of similar infrared luminosities. The more complete census of AGNs comes from using the recently developed Mass-Excitation (MEx) diagnostic diagram. This optical diagnostic is also sensitive to X-ray weak AGNs and X-ray absorbed AGNs, and reveals that absorbed active nuclei reside almost exclusively in infrared-luminous hosts. The fraction of galaxies hosting an AGN appears to be independent of sSFR and remains elevated both on the sSFR sequence and above. In contrast, the fraction of AGNs that are X-ray absorbed increases substantially with increasing sSFR, possibly due to an increased gas fraction and/or gas density in the host galaxies.

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

    SciTech Connect (OSTI)

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

    2014-03-01

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

  14. ON MEASURING THE COSMIC MICROWAVE BACKGROUND TEMPERATURE AT REDSHIFT 0.89

    SciTech Connect (OSTI)

    Sato, M.; Menten, K. M.; Reid, M. J.; Carilli, C. L.

    2013-02-20

    We report on a measurement of the temperature of the cosmic microwave background radiation field, T {sub CMB}, at z = 0.88582 by imaging HC{sub 3}N(3 <- 2) and (5 <- 4) absorption in the foreground galaxy of the gravitationally lens magnified radio source PKS 1830-211 using the Very Long Baseline Array and the phased Very Large Array. Low-resolution imaging of the data yields a value of T {sub rot} = 5.6{sup +2.5} {sub -0.9} K for the rotational temperature, T {sub rot}, which is consistent with the temperature of the cosmic microwave background at the absorber's redshift of 2.73(1 + z) K. However, our high-resolution imaging reveals that the absorption peak position of the foreground gas is offset from the continuum peak position of the synchrotron radiation from PKS 1830-211SW, which indicates that the absorbing cloud is covering only part of the emission from PKS 1830-211, rather than the entire core-jet region. This changes the line-to-continuum ratios, and we find T {sub rot} between 1.1 and 2.5 K, which is lower than the expected value. This shows that previous T {sub rot} measurements could be biased due to unresolved structure.

  15. Testing the (generalized) Chaplygin gas model with the lookback time-redshift data

    SciTech Connect (OSTI)

    Li, Zhengxiang; Wu, Puxun; Yu, Hongwei E-mail: wpx0227@gmail.com

    2009-09-01

    The Chaplygin gas (CG) and the generalized Chaplygin gas (GCG) models, proposed as candidates of the unified dark matter-dark energy (UDME), are tested with the look-back time (LT) redshift data. We find that the LT data only give a very weak constraint on the model parameter. However, by combing the LT with the baryonic acoustic oscillation peak, we obtain, at the 95.4% confidence level, 0.68 ≤ A{sub c} ≤ 0.82 and 0.59 ≤ h ≤ 0.65 for the CG model , and 0.67 ≤ A{sub s} ≤ 0.89 and −0.29 ≤ α ≤ 0.61 for the GCG model. This shows that both the CG and the GCG are viable as a candidate of UDME. Within the GCG model, we also find that the Chaplygin gas model (α = 1) is ruled out by these data at the 99.7% confidence level.

  16. The high-redshift gamma-ray burst GRB 140515A

    SciTech Connect (OSTI)

    Melandri, A.; Bernardini, M. G.; D'Avanzo, P. D.; Sanchez-Ramirez, R.; Nappo, F.; Nava, L.; Japelj, J.; de Ugarte Postigo, A.; Oates, S.; Campana, S.; Covino, S.; D'Elia, V.; Ghirlanda, G.; Gafton, E.; Ghisellini, G.; Gnedin, N.; Goldoni, P.; Gorosabel, J.; Libbrecht, T.; Malesani, D.; Salvaterra, R.; Thone, C. C.; Vergani, S. D.; Xu, D.; Tagliaferri, G.

    2015-09-09

    High-redshift gamma-ray bursts (GRBs) offer several advantages when studying the distant Universe, providing unique information about the structure and properties of the galaxies in which they exploded. Spectroscopic identification with large ground-based telescopes has improved our knowledge of this kind of distant events. We present the multi-wavelength analysis of the high-zSwift GRB GRB 140515A (z = 6.327). The best estimate of the neutral hydrogen fraction of the intergalactic medium towards the burst is xHI ? 0.002. The spectral absorption lines detected for this event are the weakest lines ever observed in GRB afterglows, suggesting that GRB 140515A exploded in a very low-density environment. Its circum-burst medium is characterised by an average extinction (AV ~ 0.1) that seems to be typical of z ? 6 events. The observed multi-band light curves are explained either with a very hard injected spectrum (p = 1.7) or with a multi-component emission (p = 2.1). In the second case a long-lasting central engine activity is needed in order to explain the late time X-ray emission. Furthermore, the possible origin of GRB 140515A in a Pop III (or in a Pop II star with a local environment enriched by Pop III) massive star is unlikely.

  17. Study of redshifted H I from the epoch of reionization with drift scan

    SciTech Connect (OSTI)

    Paul, Sourabh; Sethi, Shiv K.; Subrahmanyan, Ravi; Shankar, N. Udaya; Dwarakanath, K. S.; Deshpande, Avinash A.; Bernardi, Gianni; Bowman, Judd D.; Briggs, Frank; Gaensler, Bryan M.; Cappallo, Roger J.; Corey, Brian E.; Goeke, Robert F.; Emrich, David; Greenhill, Lincoln J.; Kasper, Justin C.; Hazelton, Bryna J.; Hewitt, Jacqueline N.; Johnston-Hollitt, Melanie; Kaplan, David L. E-mail: sethi@rri.res.in; and others

    2014-09-20

    Detection of the epoch of reionization (EoR) in the redshifted 21 cm line is a challenging task. Here, we formulate the detection of the EoR signal using the drift scan strategy. This method potentially has better instrumental stability compared to the case where a single patch of sky is tracked. We demonstrate that the correlation time between measured visibilities could extend up to 1-2 hr for an interferometer array such as the Murchison Widefield Array, which has a wide primary beam. We estimate the EoR power based on a cross-correlation of visibilities over time and show that the drift scan strategy is capable of detecting the EoR signal with a signal to noise that is comparable/better compared to the tracking case. We also estimate the visibility correlation for a set of bright point sources and argue that the statistical inhomogeneity of bright point sources might allow their separation from the EoR signal.

  18. The high-redshift gamma-ray burst GRB 140515A

    SciTech Connect (OSTI)

    Melandri, A.; Bernardini, M. G.; D'Avanzo, P. D.; Sanchez-Ramirez, R.; Nappo, F.; Nava, L.; Japelj, J.; de Ugarte Postigo, A.; Oates, S.; Campana, S.; Covino, S.; D'Elia, V.; Ghirlanda, G.; Gafton, E.; Ghisellini, G.; Gnedin, N.; Goldoni, P.; Gorosabel, J.; Libbrecht, T.; Malesani, D.; Salvaterra, R.; Thone, C. C.; Vergani, S. D.; Xu, D.; Tagliaferri, G.

    2015-09-09

    High-redshift gamma-ray bursts (GRBs) offer several advantages when studying the distant Universe, providing unique information about the structure and properties of the galaxies in which they exploded. Spectroscopic identification with large ground-based telescopes has improved our knowledge of this kind of distant events. We present the multi-wavelength analysis of the high-zSwift GRB GRB 140515A (z = 6.327). The best estimate of the neutral hydrogen fraction of the intergalactic medium towards the burst is xHI ≤ 0.002. The spectral absorption lines detected for this event are the weakest lines ever observed in GRB afterglows, suggesting that GRB 140515A exploded in a very low-density environment. Its circum-burst medium is characterised by an average extinction (AV ~ 0.1) that seems to be typical of z ≥ 6 events. The observed multi-band light curves are explained either with a very hard injected spectrum (p = 1.7) or with a multi-component emission (p = 2.1). In the second case a long-lasting central engine activity is needed in order to explain the late time X-ray emission. Furthermore, the possible origin of GRB 140515A in a Pop III (or in a Pop II star with a local environment enriched by Pop III) massive star is unlikely.

  19. The high-redshift gamma-ray burst GRB 140515A

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Melandri, A.; Bernardini, M. G.; D'Avanzo, P. D.; Sanchez-Ramirez, R.; Nappo, F.; Nava, L.; Japelj, J.; de Ugarte Postigo, A.; Oates, S.; Campana, S.; et al

    2015-09-09

    High-redshift gamma-ray bursts (GRBs) offer several advantages when studying the distant Universe, providing unique information about the structure and properties of the galaxies in which they exploded. Spectroscopic identification with large ground-based telescopes has improved our knowledge of this kind of distant events. We present the multi-wavelength analysis of the high-zSwift GRB GRB 140515A (z = 6.327). The best estimate of the neutral hydrogen fraction of the intergalactic medium towards the burst is xHI ≤ 0.002. The spectral absorption lines detected for this event are the weakest lines ever observed in GRB afterglows, suggesting that GRB 140515A exploded in amore » very low-density environment. Its circum-burst medium is characterised by an average extinction (AV ~ 0.1) that seems to be typical of z ≥ 6 events. The observed multi-band light curves are explained either with a very hard injected spectrum (p = 1.7) or with a multi-component emission (p = 2.1). In the second case a long-lasting central engine activity is needed in order to explain the late time X-ray emission. Furthermore, the possible origin of GRB 140515A in a Pop III (or in a Pop II star with a local environment enriched by Pop III) massive star is unlikely.« less

  20. How robust are the size measurements of high-redshift compact galaxies?

    SciTech Connect (OSTI)

    Davari, Roozbeh; Ho, Luis C.; Peng, Chien Y.; Huang, Song

    2014-05-20

    Massive quiescent galaxies at z ≈ 2 are apparently much more compact than galaxies of comparable mass today. How robust are these size measurements? We perform comprehensive simulations to determine possible biases and uncertainties in fitting single-component light distributions to real galaxies. In particular, we examine the robustness of the measurements of the luminosity, size, and other structural parameters. We devise simulations with increasing realism to systematically disentangle effects due to the technique (specifically using GALFIT) and the intrinsic structures of the galaxies. By accurately capturing the detailed substructures of nearby elliptical galaxies and then rescaling their sizes and signal-to-noise to mimic galaxies at different redshifts, we confirm that the massive quiescent galaxies at z ≈ 2 are significantly more compact intrinsically than their local counterparts. Their observed compactness is not a result of missing faint outer light due to systematic errors in modeling. In fact, we find that fitting multi-component galaxies with a single Sérsic profile, the procedure most commonly adopted in the literature, biases the inferred sizes higher by up to 10%-20%, which accentuates the amount of size evolution required. If the sky estimation has been done robustly and the model for the point-spread function is fairly accurate, GALFIT can retrieve the properties of single-component galaxies over a wide range of signal-to-noise ratios without introducing any systematic errors.

  1. ON THE CORRELATION OF LOW-ENERGY SPECTRAL INDICES AND REDSHIFTS OF GAMMA-RAY BURSTS

    SciTech Connect (OSTI)

    Geng, J. J.; Huang, Y. F., E-mail: hyf@nju.edu.cn [Department of Astronomy, Nanjing University, Nanjing 210093 (China)

    2013-02-10

    It was found by Amati et al. in 2002 that for a small sample of nine gamma-ray bursts (GRBs), more distant events appear to be systematically harder in the soft gamma-ray band. Here, we have collected a larger sample of 65 GRBs, whose time-integrated spectra are well established and can be well fitted with the so-called Band function. It is confirmed that a correlation between the redshifts (z) and the low-energy indices ({alpha}) of the Band function does exist, though it is a bit more scattered than the result of Amati et al. This correlation cannot be simply attributed to the effect of photon reddening. Furthermore, correlations between {alpha} and E {sub peak} (the peak energy in the {nu}F {sub {nu}} spectrum in the rest frame), {alpha} and E {sub iso} (the isotropic energy release), and {alpha} and L {sub iso} (the isotropic luminosity) are also found, which indicate that these parameters are somehow connected. The results may provide useful constraints on the physics of GRBs.

  2. Spatial and kinematic distributions of transition populations in intermediate redshift galaxy clusters

    SciTech Connect (OSTI)

    Crawford, Steven M.; Wirth, Gregory D.; Bershady, Matthew A. E-mail: wirth@keck.hawaii.edu

    2014-05-01

    We analyze the spatial and velocity distributions of confirmed members in five massive clusters of galaxies at intermediate redshift (0.5 < z < 0.9) to investigate the physical processes driving galaxy evolution. Based on spectral classifications derived from broad- and narrow-band photometry, we define four distinct galaxy populations representing different evolutionary stages: red sequence (RS) galaxies, blue cloud (BC) galaxies, green valley (GV) galaxies, and luminous compact blue galaxies (LCBGs). For each galaxy class, we derive the projected spatial and velocity distribution and characterize the degree of subclustering. We find that RS, BC, and GV galaxies in these clusters have similar velocity distributions, but that BC and GV galaxies tend to avoid the core of the two z ? 0.55 clusters. GV galaxies exhibit subclustering properties similar to RS galaxies, but their radial velocity distribution is significantly platykurtic compared to the RS galaxies. The absence of GV galaxies in the cluster cores may explain their somewhat prolonged star-formation history. The LCBGs appear to have recently fallen into the cluster based on their larger velocity dispersion, absence from the cores of the clusters, and different radial velocity distribution than the RS galaxies. Both LCBG and BC galaxies show a high degree of subclustering on the smallest scales, leading us to conclude that star formation is likely triggered by galaxy-galaxy interactions during infall into the cluster.

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

    SciTech Connect (OSTI)

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

    2012-10-01

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

  4. Synchrotron Radiation Wake in Free Space

    SciTech Connect (OSTI)

    Stupakov, G.V.; /SLAC

    2011-08-31

    In this paper, we derive the transverse radiation force of a bunch of ultrarelativistic charged particles coherently radiating in free space assuming that the bending radius is much larger than the beam dimensions. In contrast to a similar recent study, where the authors decompose the total transverse force and find only a part that is responsible for the distortion of the beam orbit, we derive a full expression for the force and leave the issues of the beam dynamics for a separate consideration. Another approach to the calculation of the transverse force has been previously developed. In many cases considered in this paper, the calculations are extremely cumbersome; they were systematically performed with the use of symbolic engine of the computer program MATHEMATICA.

  5. Discovery of Very High Energy Gamma Rays from PKS 1424+240 and Multiwavelength Constraints on its Redshift

    SciTech Connect (OSTI)

    Acciari, V.A.; Aliu, E.; Arlen, T.; Aune, T.; Bautista, M.; Beilicke, M. Benbow, W.; Bottcher, M.; Boltuch, D.; Bradbury, S.M.; Buckley, J.H.; Bugaev, V.; Byrum, K.; Cannon, A.; Cesarini, A.; Chow, Y.C.; Ciupik, L.; Cogan, P.; Cui, W.; Duke, C.; Falcone, A.; /more authors..

    2012-04-05

    We report the first detection of very-high-energy (VHE) gamma-ray emission above 140GeV from PKS 1424+240, a BL Lac object with an unknown redshift. The photon spectrum above 140GeV measured by VERITAS is well described by a power law with a photon index of 3.8 {+-}0.5{sub stat} {+-} 0.3{sub syst} and a flux normalization at 200 GeV of (5.1 {+-} 0.9{sub stat} {+-} 0.5{sub syst}) x 10{sup -11} TeV{sup -1} cm{sup -2} s{sup -1}, where stat and syst denote the statistical and systematical uncertainty, respectively. The VHE flux is steady over the observation period between MJD 54881 and 55003 (2009 February 19 to June 21). Flux variability is also not observed in contemporaneous high energy observations with the Fermi Large Area Telescope (LAT). Contemporaneous X-ray and optical data were also obtained from the Swift XRT and MDM observatory, respectively. The broadband spectral energy distribution (SED) is well described by a one-zone synchrotron self-Compton (SSC) model favoring a redshift of less than 0.1. Using the photon index measured with Fermi in combination with recent extragalactic background light (EBL) absorption models it can be concluded from the VERITAS data that the redshift of PKS 1424+240 is less than 0.66.

  6. THE LOW-REDSHIFT INTERGALACTIC MEDIUM AS SEEN IN ARCHIVAL LEGACY HST/STIS AND FUSE DATA

    SciTech Connect (OSTI)

    Tilton, Evan M.; Danforth, Charles W.; Michael Shull, J. [CASA, Department of Astrophysical and Planetary Sciences, University of Colorado, 389-UCB, Boulder, CO 80309 (United States); Ross, Teresa L., E-mail: evan.tilton@colorado.edu, E-mail: charles.danforth@colorado.edu, E-mail: michael.shull@colorado.edu, E-mail: rosst@nmsu.edu [Department of Astronomy, New Mexico State University, Las Cruces, NM 88003 (United States)

    2012-11-10

    We present a comprehensive catalog of ultraviolet (HST/STIS and FUSE) absorbers in the low-redshift intergalactic medium (IGM) at z < 0.4. The catalog draws from much of the extensive literature on IGM absorption and reconciles discrepancies among several previous catalogs through a critical evaluation of all reported absorption features in light of new HST/COS data. We report on 746 H I absorbers down to a rest-frame equivalent width of 12 mA over a maximum redshift path length {Delta}z = 5.38. We also confirm 111 O VI absorbers, 29 C IV absorbers, and numerous absorption lines due to other metal ions. We characterize the bivariate distribution of absorbers in redshift and column density as a power law, {partial_derivative}{sup 2}N/{partial_derivative}z{partial_derivative}N) {proportional_to} N{sup -{beta}}, where {beta} = 2.08 {+-} 0.12 for O VI and {beta} = 1.68 {+-} 0.03 for H I. Utilizing a more sophisticated accounting technique than past work, our catalog accounts for {approx}43% of the baryons: 24% {+-} 2% in the photoionized Ly{alpha} forest and 19% {+-} 2% in the warm-hot IGM as traced by O VI. We discuss the large systematic effects of various assumed metallicities and ionization states on these calculations, and we implement recent simulation results in our estimates.

  7. SU-E-J-209: Geometric Distortion at 3T in a Commercial 4D MRI-Compatible Phantom

    SciTech Connect (OSTI)

    Fatemi-Ardekani, A; Wronski, M; Kim, A; Stanisz, G; Sarfehnia, A; Keller, B

    2015-06-15

    Purpose: There are very few commercial 4D phantoms that are marketed as MRI compatible. We are evaluating one such commercial phantom, made to be used with an MRI-Linear accelerator. The focus of this work is to characterize the geometric distortions produced in this phantom at 3T using 3 clinical MR pulse sequences. Methods: The CIRS MRI-Linac Dynamic Phantom (CIRSTM) under investigation in this study consists of a softwaredriven moving tumour volume within a thorax phantom body and enables dose accumulation by placing a dosimeter within the tumour volume. Our initial investigation is to evaluate the phantom in static mode prior to examining its 4D capability. The water-filled thorax phantom was scanned using a wide-bore Philips 3T Achieva MRI scanner employing a Thoracic xl coil and clinical 2D T1W FFE, 2D T1W TSE and 3D T1W TFE pulse sequences. Each of the MR image sets was rigidly fused with a reference CT image of the phantom employing a rigid registration with 6 degrees of freedom. Geometric distortions between the MR and CT image sets were measured in 3 dimensions at selected points along the periphery of the distortion grid embedded within the phantom body (11.5, 7.5 and 3 cm laterally, ant/post and sup/inf of magnetic isocenter respectively). Results: The maximal measured geometric distortions between the MR and reference CT points of interest were 0.9, 1.8 and 1.3 mm in the lateral, anteriorposterior and cranio-caudal directions, respectively. For all 3 spatial dimensions, the maximal distortions occurred for the FFE pulse sequence. Maximal distortions for the 2D FFE, 2D TSE and 3D TFE sequences were 1, 0.7 and 1.8 mm, respectively. Conclusion: Our initial static investigation of this phantom shows minimal geometric distortions at 3T along the periphery of the embedded grid. CIRS has provided us with a phantom at no charge for evaluation at 3 Tesla.

  8. Space Solar Power Program

    SciTech Connect (OSTI)

    Arif, H.; Barbosa, H.; Bardet, C.; Baroud, M.; Behar, A.; Berrier, K.; Berthe, P.; Bertrand, R.; Bibyk, I.; Bisson, J.; Bloch, L.; Bobadilla, G.; Bourque, D.; Bush, L.; Carandang, R.; Chiku, T.; Crosby, N.; De Seixas, M.; De Vries, J.; Doll, S.; Dufour, F.; Eckart, P.; Fahey, M.; Fenot, F.; Foeckersperger, S.; Fontaine, J.E.; Fowler, R.; Frey, H.; Fujio, H.; Gasa, J.M.; Gleave, J.; Godoe, J.; Green, I.; Haeberli, R.; Hanada, T.; Ha

    1992-08-01

    Information pertaining to the Space Solar Power Program is presented on energy analysis; markets; overall development plan; organizational plan; environmental and safety issues; power systems; space transportation; space manufacturing, construction, operations; design examples; and finance.

  9. Distorting general relativity: gravity's rainbow and f(R) theories at work

    SciTech Connect (OSTI)

    Garattini, Remo

    2013-06-01

    We compute the Zero Point Energy in a spherically symmetric background combining the high energy distortion of Gravity's Rainbow with the modification induced by a f(R) theory. Here f(R) is a generic analytic function of the Ricci curvature scalar R in 4D and in 3D. The explicit calculation is performed for a Schwarzschild metric. Due to the spherically symmetric property of the Schwarzschild metric we can compare the effects of the modification induced by a f(R) theory in 4D and in 3D. We find that the final effect of the combined theory is to have finite quantities that shift the Zero Point Energy. In this context we setup a Sturm-Liouville problem with the cosmological constant considered as the associated eigenvalue. The eigenvalue equation is a reformulation of the Wheeler-DeWitt equation which is analyzed by means of a variational approach based on gaussian trial functionals. With the help of a canonical decomposition, we find that the relevant contribution to one loop is given by the graviton quantum fluctuations around the given background. A final discussion on the connection of our result with the observed cosmological constant is also reported.

  10. An Insertion Mutation That Distorts Antibody Binding Site Architecture Enhances Function of a Human Antibody

    SciTech Connect (OSTI)

    Krause, Jens C.; Ekiert, Damian C.; Tumpey, Terrence M.; Smith, Patricia B.; Wilson, Ian A.; Crowe, Jr., James E.

    2011-09-02

    The structural and functional significance of somatic insertions and deletions in antibody chains is unclear. Here, we demonstrate that a naturally occurring three-amino-acid insertion within the influenza virus-specific human monoclonal antibody 2D1 heavy-chain variable region reconfigures the antibody-combining site and contributes to its high potency against the 1918 and 2009 pandemic H1N1 influenza viruses. The insertion arose through a series of events, including a somatic point mutation in a predicted hot-spot motif, introduction of a new hot-spot motif, a molecular duplication due to polymerase slippage, a deletion due to misalignment, and additional somatic point mutations. Atomic resolution structures of the wild-type antibody and a variant in which the insertion was removed revealed that the three-amino-acid insertion near the base of heavy-chain complementarity-determining region (CDR) H2 resulted in a bulge in that loop. This enlarged CDR H2 loop impinges on adjacent regions, causing distortion of the CDR H1 architecture and its displacement away from the antigen-combining site. Removal of the insertion restores the canonical structure of CDR H1 and CDR H2, but binding, neutralization activity, and in vivo activity were reduced markedly because of steric conflict of CDR H1 with the hemagglutinin antigen.

  11. Analysis of the orbit distortion by the use of the wavelet transform

    SciTech Connect (OSTI)

    Matsushita, T.; Takao, M.; Aoyagi, H.; Takeuchi, M.; Tanaka, H.; Agui, A.; Yoshigoe, A.; Nakatani, T.

    2004-05-12

    We have adopted matching pursuit algorithm of discrete wavelet transform (DWT) for the analysis of the beam position shift correlated with the motion of insertion device (ID). The beam position data measured by the rf beam position monitors have included high-frequency 'noises' and fluctuation of background level. Precise evaluation of the electron beam position shift correlated with the motion of the ID is required for estimation of the steering magnet currents in order to suppress the closed orbit distortion (COD). The DWT is a powerful tool for frequency analysis and data processing. The analysis of DWT was applied to the beam position shift correlated with the phase motion of APPLE-2 type undulator (ID23) in SPring-8. The result of the analysis indicated that 'noises' are mainly composed of the components of 50 {approx} 6.25Hz and < 0.1Hz. We carried out the data processing to remove the 'noises' by the matching pursuit algorithm. Then we have succeeded in suppressing the COD within 2 {mu}m by the use of the steering magnet currents calculated from the processed data.

  12. Studies of Deteriorated Heat Transfer in Prismatic Cores Stemming from Irradiation-Induced Geometry Distortion

    SciTech Connect (OSTI)

    Williams, Brian G.; Schultz, Richard R.; McEligot, Don M.; McCreery, Glenn

    2015-08-31

    A reference design for the Next Generation Nuclear Plant (NGNP) is to use General Atomics Modular High Temperature Gas-cooled Reactor (MHTGR). For such a configuration in normal operation, the helium coolant flow proceeds from the upper plenum to the lower plenum principally through the core coolant channels and the interstitial gaps (bypass flow) that separate the prismatic blocks from one another. Only the core prismatic blocks have coolant channels. The interstitial gaps are present throughout the core, the inner reflector region, and the out reflector region. The bypass flows in a prismatic gas-cooled reactor (GCR) are of potential concern because they reduce the desired flow rates in the coolant channels and, thereby, can increase outlet gas temperatures and maximum fuel temperatures. Consequently, it is appropriate to account for bypass flows in reactor thermal gas dynamic analyses. The objectives of this project include the following: fundamentally understand bypass flow and heat transfer at scaled, undistorted conditions and with geometry distortions; develop improved estimates of associated loss coefficients, surface friction and heat transfer for systems and network codes; and obtain related data for validation of CFD (computational fluid dynamic) or system (e.g., RELAP5) codes which can be employed in predictions for a GCR for normal power, reduced power, and residual heat removal operations.

  13. A CLOSE-PAIR ANALYSIS OF DAMP MERGERS AT INTERMEDIATE REDSHIFTS

    SciTech Connect (OSTI)

    Chou, Richard C. Y.; Abraham, Roberto G.; Bridge, Carrie R. E-mail: abraham@astro.utoronto.ca

    2012-12-01

    We have studied the kinematics of {approx}2800 candidate close-pair galaxies at 0.1 < z < 1.2 identified from the Canada-France-Hawaii Telescope Legacy Survey fields. Spectra of these systems were obtained using spectrometers on the 6.5 m Magellan and 5 m Hale telescopes. These data allow us to constrain the rate of dry mergers at intermediate redshifts and to test the 'hot halo' model for quenching of star formation. Using virial radii estimated from the correlation between dynamical and stellar masses published by Leauthaud et al., we find that around 1/5 of our candidate pairs are likely to share a common dark matter halo (our metric for close physical association). These pairs are divided into red-red, blue-red, and blue-blue systems using the rest-frame colors classification method introduced in Chou et al.. Galaxies classified as red in our sample have very low star formation rates, but they need not be totally quiescent, and hence we refer to them as 'damp', rather than 'dry', systems. After correcting for known selection effects, the fraction of blue-blue pairs is significantly greater than that of red-red and blue-red pairs. Red-red pairs are almost entirely absent from our sample, suggesting that damp mergers are rare at z {approx} 0.5. Our data support models with a short merging timescale (<0.5 Gyr) in which star formation is enhanced in the early phase of mergers, but quenched in the late phase. Hot halo models may explain this behavior, but only if virial shocks that heat gas are inefficient until major mergers are nearly complete.

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

    SciTech Connect (OSTI)

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

    2010-06-11

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

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

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

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

    2010-06-11

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

  16. HerMES: Candidate high-redshift galaxies discovered with Herschel/Spire

    SciTech Connect (OSTI)

    Dowell, C. Darren; Bock, J.; Bridge, C.; Cooray, A.; Conley, A.; Glenn, J.; Arumugam, V.; Asboth, V.; Aussel, H.; Bthermin, M.; Boselli, A.; Buat, V.; Burgarella, D.; Cabrera-Lavers, A.; Casey, C. M.; Chapman, S. C.; Clements, D. L.; Conversi, L.; Dannerbauer, H.; and others

    2014-01-01

    We present a method for selecting z > 4 dusty, star-forming galaxies (DSFGs) using Herschel/Spectral and Photometric Imaging Receiver 250/350/500 ?m flux densities to search for red sources. We apply this method to 21 deg{sup 2} of data from the HerMES survey to produce a catalog of 38 high-z candidates. Follow-up of the first five of these sources confirms that this method is efficient at selecting high-z DSFGs, with 4/5 at z = 4.3-6.3 (and the remaining source at z = 3.4), and that they are some of the most luminous dusty sources known. Comparison with previous DSFG samples, mostly selected at longer wavelengths (e.g., 850 ?m) and in single-band surveys, shows that our method is much more efficient at selecting high-z DSFGs, in the sense that a much larger fraction are at z > 3. Correcting for the selection completeness and purity, we find that the number of bright (S {sub 500} {sub ?m} ? 30 mJy), red Herschel sources is 3.3 0.8 deg{sup 2}. This is much higher than the number predicted by current models, suggesting that the DSFG population extends to higher redshifts than previously believed. If the shape of the luminosity function for high-z DSFGs is similar to that at z ? 2, rest-frame UV based studies may be missing a significant component of the star formation density at z = 4-6, even after correction for extinction.

  17. 50 Years of Space

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    50 Years of Space science-innovationassetsimagesicon-science.jpg 50 Years of Space Since 1943, some of the world's smartest and most dedicated technical people have ...

  18. Multiple Redox Modes in the Reversible Lithiation of High-Capacity, Peierls-Distorted Vanadium Sulfide

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Britto, Sylvia; Leskes, Michal; Hua, Xiao; Hébert, Claire-Alice; Shin, Hyeon Suk; Clarke, Simon; Borkiewicz, Olaf; Chapman, Karena W.; Seshadri, Ram; Cho, Jaephil; et al

    2015-06-08

    Vanadium sulfide VS4 in the patronite mineral structure, is a linear chain compound comprising vanadium atoms coordinated by disulfide anions [S2]2–. 51V NMR shows that the material, despite having V formally in the d1 configuration, is diamagnetic, suggesting potential dimerization through metal-metal bonding associated with a Peierls distortion of the linear chains. This is supported by density functional calculations, and is also consistent with the observed alternation in V-V distances of 2.8 Å and 3.2 Å along the chains. Partial lithiation results in reduction of the disulfide ions to sulfide S2–, including via an internal redox process whereby an electronmore » from V4+ is transferred to [S2]2– resulting in oxidation of V4+ to V5+ and reduction of the [S2]2– to S2- to form Li3VS4 containing tetrahedral [VS4]3– anions. On further lithiation this is followed by reduction of the V5+ in Li3VS4 to form Li3+xVS4 (x=0.5-1), a mixed valent V4+/V5+ compound. Eventually reduction to Li2S plus elemental V occurs. Despite the complex redox processes involving both the cation and the anion occurring in this material, the system is found to be partially reversible between 0 and 3 V. In conclusion, the unusual redox processes in this system are elucidated using a suite of short range characterization tools including 51V Nuclear Magnetic Resonance spectroscopy (NMR), S Kedge X-ray Absorption Near Edge Spectroscopy (XANES) and Pair Distribution Function (PDF) Analysis of X-ray data.« less

  19. Enhanced hydrogenation and reduced lattice distortion in size selected Pd-Ag and Pd-Cu alloy nanoparticles

    SciTech Connect (OSTI)

    Sengar, Saurabh K.; Mehta, B. R.; Kulriya, P. K.; Khan, S. A.

    2013-10-21

    Important correlation between valence band spectra and hydrogenation properties in Pd alloy nanoparticles is established by studying the properties of size selected and monocrystalline Pd, Ag, Cu, Pd-Ag, and Pd-Cu nanoparticles. The X-ray photoelectron spectroscopy and elastic recoil detection analysis show that size induced Pd4d centroid shift is related to enhanced hydrogenation with H/Pd ratio of 0.57 and 0.49 in Pd-Ag and Pd-Cu nanoparticles in comparison to reported bulk values of 0.2 and 0.1, respectively. Pd-alloy nanoparticles show lower hydrogen induced lattice distortion. The reduced distortion and higher hydrogen reactivity of Pd-alloy nanoparticles is important for numerous hydrogen related applications.

  20. Local structure underlying anomalous tetragonal distortions in BiFeO{sub 3}-PbTiO{sub 3} ferroelectrics

    SciTech Connect (OSTI)

    Levin, I.; Krayzman, V.; Woicik, J. C.; Tucker, M. G.

    2014-06-16

    The local structure of tetragonal BiFeO{sub 3}-PbTiO{sub 3} solid solutions featuring anomalous lattice distortions has been determined using simultaneous fitting of neutron total scattering and extended X-ray absorption fine structure data. On the local scale, the large tetragonal distortion, promoted by the displacements of the A-cations (Bi and Pb), is accommodated primarily by the [FeO{sub 6}] octahedra, even though both Fe and Ti acquire (5+1)-fold coordination. Bi cations exhibit considerably larger displacements than Pb. The combination of the A-cation displacements and the ability of M-cations to adopt 5-fold coordination is suggested as key for stabilizing the large tetragonality in BiMO{sub 3}-PbTiO{sub 3} systems.

  1. Space and Sensors

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Space and Sensors Space and Sensors Create, deliver, support, and exploit innovative sensing systems for space-based, airborne and ground-based applications to address critical national security and scientific challenges. Contact thumbnail of Business Development Executive Michael Erickson Business Development Executive Richard P. Feynman Center for Innovation (505) 667-8087 Email Space Create, deliver, support, and exploit innovative sensing systems for space-based, airborne and ground-based

  2. Lack of a Jahn-Teller Distortion in La1-xSrxCoO3 Determined by EXAFS and

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Neutron PDF Studies Lack of a Jahn-Teller Distortion in La1-xSrxCoO3 Determined by EXAFS and Neutron PDF Studies The transition metal oxides exhibit a wide range of interesting properties, of which superconductivity in the copper oxides and colossal magnetoresistance in the manganese oxides are perhaps the best known. However, the strange magnetic behavior of several cobalt oxides is another example of these unusual properties, although not yet as intensively studied. The cobaltite system

  3. Active galactic nuclei emission line diagnostics and the mass-metallicity relation up to redshift z ∼ 2: The impact of selection effects and evolution

    SciTech Connect (OSTI)

    Juneau, Stéphanie; Bournaud, Frédéric; Daddi, Emanuele; Elbaz, David; Duc, Pierre-Alain; Gobat, Raphael; Jean-Baptiste, Ingrid; Le Floc'h, Émeric; Pannella, Maurilio; Schreiber, Corentin; Trump, Jonathan R.; Dickinson, Mark

    2014-06-10

    Emission line diagnostic diagrams probing the ionization sources in galaxies, such as the Baldwin-Phillips-Terlevich (BPT) diagram, have been used extensively to distinguish active galactic nuclei (AGN) from purely star-forming galaxies. However, they remain poorly understood at higher redshifts. We shed light on this issue with an empirical approach based on a z ∼ 0 reference sample built from ∼300,000 Sloan Digital Sky Survey galaxies, from which we mimic selection effects due to typical emission line detection limits at higher redshift. We combine this low-redshift reference sample with a simple prescription for luminosity evolution of the global galaxy population to predict the loci of high-redshift galaxies on the BPT and Mass-Excitation (MEx) diagnostic diagrams. The predicted bivariate distributions agree remarkably well with direct observations of galaxies out to z ∼ 1.5, including the observed stellar mass-metallicity (MZ) relation evolution. As a result, we infer that high-redshift star-forming galaxies are consistent with having normal interstellar medium (ISM) properties out to z ∼ 1.5, after accounting for selection effects and line luminosity evolution. Namely, their optical line ratios and gas-phase metallicities are comparable to that of low-redshift galaxies with equivalent emission-line luminosities. In contrast, AGN narrow-line regions may show a shift toward lower metallicities at higher redshift. While a physical evolution of the ISM conditions is not ruled out for purely star-forming galaxies and may be more important starting at z ≳ 2, we find that reliably quantifying this evolution is hindered by selections effects. The recipes provided here may serve as a basis for future studies toward this goal. Code to predict the loci of galaxies on the BPT and MEx diagnostic diagrams and the MZ relation as a function of emission line luminosity limits is made publicly available.

  4. The redshift evolution of the mean temperature, pressure, and entropy profiles in 80 SPT-selected galaxy clusters

    SciTech Connect (OSTI)

    McDonald, M.; Bautz, M.; Benson, B. A.; Vikhlinin, A.; Bayliss, M.; Forman, W. R.; Aird, K. A.; Allen, S. W.; Bleem, L. E.; Carlstrom, J. E.; Chang, C. L.; Crawford, T. M.; Crites, A. T.; Bocquet, S.; Brodwin, M.; Cho, H. M.; Clocchiatti, A.; De Haan, T.; Dobbs, M. A.; Foley, R. J.; and others

    2014-10-10

    We present the results of an X-ray analysis of 80 galaxy clusters selected in the 2500 deg{sup 2} South Pole Telescope survey and observed with the Chandra X-ray Observatory. We divide the full sample into subsamples of ?20 clusters based on redshift and central density, performing a joint X-ray spectral fit to all clusters in a subsample simultaneously, assuming self-similarity of the temperature profile. This approach allows us to constrain the shape of the temperature profile over 0 < r < 1.5R {sub 500}, which would be impossible on a per-cluster basis, since the observations of individual clusters have, on average, 2000 X-ray counts. The results presented here represent the first constraints on the evolution of the average temperature profile from z = 0 to z = 1.2. We find that high-z (0.6 < z < 1.2) clusters are slightly (?30%) cooler both in the inner (r < 0.1R {sub 500}) and outer (r > R {sub 500}) regions than their low-z (0.3 < z < 0.6) counterparts. Combining the average temperature profile with measured gas density profiles from our earlier work, we infer the average pressure and entropy profiles for each subsample. Confirming earlier results from this data set, we find an absence of strong cool cores at high z, manifested in this analysis as a significantly lower observed pressure in the central 0.1R {sub 500} of the high-z cool-core subset of clusters compared to the low-z cool-core subset. Overall, our observed pressure profiles agree well with earlier lower-redshift measurements, suggesting minimal redshift evolution in the pressure profile outside of the core. We find no measurable redshift evolution in the entropy profile at r ? 0.7R {sub 500}this may reflect a long-standing balance between cooling and feedback over long timescales and large physical scales. We observe a slight flattening of the entropy profile at r ? R {sub 500} in our high-z subsample. This flattening is consistent with a temperature bias due to the enhanced (?3) rate at which

  5. Multiple Redox Modes in the Reversible Lithiation of High-Capacity, Peierls-Distorted Vanadium Sulfide

    SciTech Connect (OSTI)

    Britto, Sylvia; Leskes, Michal; Hua, Xiao; Hébert, Claire-Alice; Shin, Hyeon Suk; Clarke, Simon; Borkiewicz, Olaf; Chapman, Karena W.; Seshadri, Ram; Cho, Jaephil; Grey, Clare P.

    2015-06-08

    Vanadium sulfide VS4 in the patronite mineral structure, is a linear chain compound comprising vanadium atoms coordinated by disulfide anions [S2]2–. 51V NMR shows that the material, despite having V formally in the d1 configuration, is diamagnetic, suggesting potential dimerization through metal-metal bonding associated with a Peierls distortion of the linear chains. This is supported by density functional calculations, and is also consistent with the observed alternation in V-V distances of 2.8 Å and 3.2 Å along the chains. Partial lithiation results in reduction of the disulfide ions to sulfide S2–, including via an internal redox process whereby an electron from V4+ is transferred to [S2]2– resulting in oxidation of V4+ to V5+ and reduction of the [S2]2– to S2- to form Li3VS4 containing tetrahedral [VS4]3– anions. On further lithiation this is followed by reduction of the V5+ in Li3VS4 to form Li3+xVS4 (x=0.5-1), a mixed valent V4+/V5+ compound. Eventually reduction to Li2S plus elemental V occurs. Despite the complex redox processes involving both the cation and the anion occurring in this material, the system is found to be partially reversible between 0 and 3 V. In conclusion, the unusual redox processes in this system are elucidated using a suite of short range characterization tools including 51V Nuclear Magnetic Resonance spectroscopy (NMR), S Kedge X-ray Absorption Near Edge Spectroscopy (XANES) and Pair Distribution Function (PDF) Analysis of X-ray data.

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

    SciTech Connect (OSTI)

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

    2014-06-10

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

  7. Hunting space rocks

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Hunting space rocks Hunting space rocks Nina Lanza is studying the solar system by spending six weeks on an ice sheet in Antarctica. The 36-year-old staff scientist at the Los ...

  8. Space Science and Applications

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    the first measurements of Earth's space radiation environment and the discovery of gamma-ray bursts. The majority of ISR-1 staff hold PhDs in Space Physics, Nuclear Physics, or...

  9. Local structural distortion and electrical transport properties of Bi(Ni1/2Ti1/2)O3 perovskite under high pressure

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Zhu, Jinlong; Yang, Liuxiang; Wang, Hsiu -Wen; Zhang, Jianzhong; Yang, Wenge; Hong, Xinguo; Jin, Changqing; Zhao, Yusheng

    2015-12-16

    Perovskite-structure materials generally exhibit local structural distortions that are distinct from long-range, average crystal structure. The characterization of such distortion is critical to understanding the structural and physical properties of materials. In this work, we combined Pair Distribution Function (PDF) technique with Raman spectroscopy and electrical resistivity measurement to study Bi(Ni1/2Ti1/2)O3 perovskite under high pressure. PDF analysis reveals strong local structural distortion at ambient conditions. As pressure increases, the local structure distortions are substantially suppressed and eventually vanish around 4 GPa, leading to concurrent changes in the electronic band structure and anomalies in the electrical resistivity. We find, consistent withmore » PDF analysis, Raman spectroscopy data suggest that the local structure changes to a higher ordered state at pressures above 4 GPa.« less

  10. THE FIRST OBSERVATIONS OF LOW-REDSHIFT DAMPED Ly{alpha} SYSTEMS WITH THE COSMIC ORIGINS SPECTROGRAPH: CHEMICAL ABUNDANCES AND AFFILIATED GALAXIES

    SciTech Connect (OSTI)

    Battisti, A. J.; Meiring, J. D.; Tripp, T. M. [Department of Astronomy, University of Massachusetts, Amherst, MA 01003 (United States); Prochaska, J. X.; Werk, J. K. [Department of Astronomy and Astrophysics, University of California Observatories-Lick Observatory, UC Santa Cruz, CA 95064 (United States); Jenkins, E. B. [Department of Astrophysical Sciences, Princeton University Observatory, Princeton, NJ 08544 (United States); Lehner, N. [Department of Physics, University of Notre Dame, Notre Dame, IN 46556 (United States); Tumlinson, J.; Thom, C. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)

    2012-01-10

    We present Cosmic Origins Spectrograph (COS) measurements of metal abundances in eight 0.083 < z{sub abs} < 0.321 damped Ly{alpha} (DLA) and sub-DLA absorption systems serendipitously discovered in the COS-Halos survey. We find that these systems show a large range in metallicities, with -1.10 < [Z/H] < 0.31, similar to the spread found at higher redshifts. These low-redshift systems on average have subsolar metallicities, but do show a rise in metallicity over cosmic time when compared to higher-redshift systems. We find that the average sub-DLA metallicity is higher than the average DLA metallicity at all redshifts. Nitrogen is underabundant with respect to {alpha}-group elements in all but perhaps one of the absorbers. In some cases, [N/{alpha}] is significantly below the lowest nitrogen measurements in nearby galaxies. Systems for which depletion patterns can be studied show little, if any, depletion, which is characteristic of Milky Way halo-type gas. We also identify affiliated galaxies for three of the sub-DLAs using spectra obtained from a Keck/Low Resolution Imaging Spectrometer (LRIS). None of these sub-DLAs arise in the stellar disks of luminous galaxies; instead, these absorbers may exist in galaxy halos at impact parameters ranging from 38 to 92 kpc. Multiple galaxies are present near two of the sub-DLAs, and galaxy interactions may play a role in the dispersal of the gas. Many of these low-redshift absorbers exhibit simple kinematics, but one sub-DLA has a complicated mix of at least 13 components spread over 150 km s{sup -1}. We find three galaxies near this sub-DLA, which also suggests that galaxy interactions roil the gas. This study reinforces the view that DLAs have a variety of origins, and low-redshift studies are crucial for understanding absorber-galaxy connections.

  11. National Aeronautical and Space Administration (NASA) Johnson Space Flight

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Center | Department of Energy Aeronautical and Space Administration (NASA) Johnson Space Flight Center National Aeronautical and Space Administration (NASA) Johnson Space Flight Center Space Shuttle Endeavour, 2002 The NASA Johnson Space Flight Center in Houston is well known for its achievements in the U.S. space program (this 2002 photo shows the Space Shuttle Endeavour on its way to the International Space Station). Overview NASA will save approximately $43 million in facility operations

  12. National Aeronautical and Space Administration (NASA) Johnson Space Flight

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Center | Department of Energy National Aeronautical and Space Administration (NASA) Johnson Space Flight Center National Aeronautical and Space Administration (NASA) Johnson Space Flight Center Space Shuttle Endeavour, 2002 The NASA Johnson Space Flight Center in Houston is well known for its achievements in the U.S. space program (this 2002 photo shows the Space Shuttle Endeavour on its way to the International Space Station). Overview NASA will save approximately $43 million in facility

  13. TANK SPACE OPTIONS REPORT

    SciTech Connect (OSTI)

    WILLIS WL; AHRENDT MR

    2009-08-11

    Since this report was originally issued in 2001, several options proposed for increasing double-shell tank (DST) storage space were implemented or are in the process of implementation. Changes to the single-shell tank (SST) waste retrieval schedule, completion of DST space saving options, and the DST space saving options in progress have delayed the projected shortfall of DST storage space from the 2007-2011 to the 2018-2025 timeframe (ORP-11242, River Protection Project System Plan). This report reevaluates options from Rev. 0 and includes evaluations of new options for alleviating projected restrictions on SST waste retrieval beginning in 2018 because of the lack of DST storage space.

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

    SciTech Connect (OSTI)

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

    2010-01-01

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

  15. A 15 MHz bandwidth, 60 V{sub pp}, low distortion power amplifier for driving high power piezoelectric transducers

    SciTech Connect (OSTI)

    Capineri, Lorenzo

    2014-10-01

    This paper presents the design and the realization of a linear power amplifier with large bandwidth (15 MHz) capable of driving low impedance ultrasonic transducers. The output current driving capability (up to 5 A) and low distortion makes it suitable for new research applications using high power ultrasound in the medical and industrial fields. The electronic design approach is modular so that the characteristics can be scaled according to specific applications and implementation details for the circuit layout are reported. Finally the characterization of the power amplifier module is presented.

  16. CRITICAL STAR FORMATION RATES FOR REIONIZATION: FULL REIONIZATION OCCURS AT REDSHIFT z Almost-Equal-To 7

    SciTech Connect (OSTI)

    Michael Shull, J.; Harness, Anthony; Trenti, Michele; Smith, Britton D. E-mail: trenti@colorado.edu E-mail: smit1685@msu.edu

    2012-03-10

    We assess the probable redshift (z{sub rei} Almost-Equal-To 7) for full reionization of the intergalactic medium (IGM) using a prescription for the comoving star formation rate (SFR) density ({rho}-dot{sub SFR}) required to maintain photoionization against recombination. Our newly developed online reionization simulator allows users to assess the required SFR and ionization histories, using a variety of assumptions for galactic and stellar populations, IGM clumping factor and temperature, and Lyman continuum (LyC) escape fraction. The decline in high-redshift galaxy candidates and Ly{alpha} emitters at z = 6-8 suggests a rising neutral fraction, with reionization at z {approx}> 7 increasingly difficult owing to increased recombination rates and constraints from the ionizing background and LyC mean free path. The required rate is {rho}-dot{sub SFR}{approx}(.018 M{sub sun}yr{sup -1}Mpc{sup -3})[(1+z)/8]{sup 3}(C{sub H}/3)(0.2/f{sub esc})T{sub 4}{sup -0.845} scaled to fiducial values of clumping factor C{sub H} = 3, escape fraction f{sub esc} = 0.2, electron temperature T{sub e} = 10{sup 4} K, and low-metallicity initial mass functions (IMFs) and stellar atmospheres. Our hydrodynamical + N-body simulations find a mean clumping factor C{sub H} Almost-Equal-To (2.9)[(1 + z)/6]{sup -1.1} in the photoionized, photoheated filaments at z = 5-9. The critical SFR could be reduced by increasing the minimum stellar mass, invoking a top-heavy IMF, or systematically increasing f{sub esc} at high z. The cosmic microwave background optical depth, {tau}{sub e} = 0.088 {+-} 0.015, could be explained by full reionization, producing {tau}{sub e} = 0.050 back to z{sub rei} Almost-Equal-To 7, augmented by {Delta}{tau}{sub e} Almost-Equal-To 0.01-0.04 in a partially ionized IGM at z > 7. In this scenario, the strongest 21 cm signal should occur at redshifted frequencies 124-167 MHz owing to IGM heating over an interval {Delta}z Almost-Equal-To 3 in the range z Almost-Equal-To 7.5-10.5.

  17. HERSCHEL-ATLAS GALAXY COUNTS AND HIGH-REDSHIFT LUMINOSITY FUNCTIONS: THE FORMATION OF MASSIVE EARLY-TYPE GALAXIES

    SciTech Connect (OSTI)

    Lapi, A.; Gonzalez-Nuevo, J.; Fan, L.; Bressan, A.; De Zotti, G.; Danese, L.; Negrello, M.; Dunne, L.; Maddox, S.; Eales, S.; Auld, R.; Dariush, A.; Dye, S.; Baes, M.; Fritz, J.; Bonfield, D. G.; Buttiglione, S.; Cava, A.; Clements, D. L.; Cooray, A.

    2011-11-20

    Exploiting the Herschel Astrophysical Terahertz Large Area Survey Science Demonstration Phase survey data, we have determined the luminosity functions (LFs) at rest-frame wavelengths of 100 and 250 {mu}m and at several redshifts z {approx}> 1, for bright submillimeter galaxies with star formation rates (SFRs) {approx}> 100 M{sub Sun} yr{sup -1}. We find that the evolution of the comoving LF is strong up to z Almost-Equal-To 2.5, and slows down at higher redshifts. From the LFs and the information on halo masses inferred from clustering analysis, we derived an average relation between SFR and halo mass (and its scatter). We also infer that the timescale of the main episode of dust-enshrouded star formation in massive halos (M{sub H} {approx}> 3 Multiplication-Sign 10{sup 12} M{sub Sun }) amounts to {approx}7 Multiplication-Sign 10{sup 8} yr. Given the SFRs, which are in the range of 10{sup 2}-10{sup 3} M{sub Sun} yr{sup -1}, this timescale implies final stellar masses of the order of 10{sup 11}-10{sup 12} M{sub Sun }. The corresponding stellar mass function matches the observed mass function of passively evolving galaxies at z {approx}> 1. The comparison of the statistics for submillimeter and UV-selected galaxies suggests that the dust-free, UV bright phase is {approx}> 10{sup 2} times shorter than the submillimeter bright phase, implying that the dust must form soon after the onset of star formation. Using a single reference spectral energy distribution (SED; the one of the z Almost-Equal-To 2.3 galaxy SMM J2135-0102), our simple physical model is able to reproduce not only the LFs at different redshifts >1 but also the counts at wavelengths ranging from 250 {mu}m to Almost-Equal-To 1 mm. Owing to the steepness of the counts and their relatively broad frequency range, this result suggests that the dispersion of submillimeter SEDs of z > 1 galaxies around the reference one is rather small.

  18. UNDERSTANDING PHYSICAL CONDITIONS IN HIGH-REDSHIFT GALAXIES THROUGH C I FINE STRUCTURE LINES: DATA AND METHODOLOGY

    SciTech Connect (OSTI)

    Jorgenson, Regina A.; Wolfe, Arthur M.; Prochaska, J. Xavier

    2010-10-10

    We probe the physical conditions in high-redshift galaxies, specifically, the damped Ly{alpha} systems (DLAs) using neutral carbon (C I) fine structure lines and molecular hydrogen (H{sub 2}). We report five new detections of C I and analyze the C I in an additional two DLAs with previously published data. We also present one new detection of H{sub 2} in a DLA. We present a new method of analysis that simultaneously constrains both the volume density and the temperature of the gas, as opposed to previous studies that a priori assumed a gas temperature. We use only the column density of C I measured in the fine structure states and the assumption of ionization equilibrium in order to constrain the physical conditions in the gas. We present a sample of 11 C I velocity components in six DLAs and compare their properties to those derived by the global C II* technique. The resulting median values for this sample are (n(H I)) = 69 cm{sup -3}, (T) = 50 K, and (log(P/k)) = 3.86 cm{sup -3} K, with standard deviations, {sigma}{sub n(H{sub i})} = 134 cm{sup -3}, {sigma}{sub T} = 52 K, and {sigma}{sub log(P/k)} = 3.68 cm{sup -3} K. This can be compared with the integrated median values for the same DLAs: (n(H I)) = 2.8 cm{sup -3}, (T) = 139 K, and (log(P/k)) = 2.57 cm{sup -3} K, with standard deviations {sigma}{sub n(H{sub i})} = 3.0 cm{sup -3}, {sigma}{sub T} = 43 K, and {sigma}{sub log(P/k)} = 0.22 cm{sup -3} K. Interestingly, the pressures measured in these high-redshift C I clouds are similar to those found in the Milky Way. We conclude that the C I gas is tracing a higher-density, higher-pressure region, possibly indicative of post-shock gas or a photodissociation region on the edge of a molecular cloud. We speculate that these clouds may be direct probes of the precursor sites of star formation in normal galaxies at high redshift.

  19. The effect of large amplitude motions on the transition frequency redshift in hydrogen bonded complexes: A physical picture

    SciTech Connect (OSTI)

    Mackeprang, Kasper; Kjaergaard, Henrik G.; Salmi, Teemu; Hnninen, Vesa; Halonen, Lauri

    2014-05-14

    We describe the vibrational transitions of the donor unit in water dimer with an approach that is based on a three-dimensional local mode model. We perform a perturbative treatment of the intermolecular vibrational modes to improve the transition wavenumber of the hydrogen bonded OH-stretching transition. The model accurately predicts the transition wavenumbers of the vibrations in water dimer compared to experimental values and provides a physical picture that explains the redshift of the hydrogen bonded OH-oscillator. We find that it is unnecessary to include all six intermolecular modes in the vibrational model and that their effect can, to a good approximation, be computed using a potential energy surface calculated at a lower level electronic structure method than that used for the unperturbed model.

  20. DEEP SPITZER OBSERVATIONS OF INFRARED-FAINT RADIO SOURCES: HIGH-REDSHIFT RADIO-LOUD ACTIVE GALACTIC NUCLEI?

    SciTech Connect (OSTI)

    Norris, Ray P.; Mao, Minnie; Afonso, Jose; Cava, Antonio; Farrah, Duncan; Oliver, Seb; Huynh, Minh T.; Mauduit, Jean-Christophe; Surace, Jason; Ivison, R. J.; Jarvis, Matt; Lacy, Mark; Maraston, Claudia; Middelberg, Enno; Seymour, Nick

    2011-07-20

    Infrared-faint radio sources (IFRSs) are a rare class of objects which are relatively bright at radio wavelengths but very faint at infrared and optical wavelengths. Here we present sensitive near-infrared observations of a sample of these sources taken as part of the Spitzer Extragalactic Representative Volume Survey. Nearly all the IFRSs are undetected at a level of {approx}1 {mu}Jy in these new deep observations, and even the detections are consistent with confusion with unrelated galaxies. A stacked image implies that the median flux density is S{sub 3.6{mu}m} {approx} 0.2 {mu}Jy or less, giving extreme values of the radio-infrared flux density ratio. Comparison of these objects with known classes of object suggests that the majority are probably high-redshift radio-loud galaxies, possibly suffering from significant dust extinction.

  1. Tidally distorted exoplanets: Density corrections for short-period hot-Jupiters based solely on observable parameters

    SciTech Connect (OSTI)

    Burton, J. R.; Watson, C. A.; Fitzsimmons, A.; Moulds, V.; Pollacco, D.; Wheatley, P. J.; Littlefair, S. P.

    2014-07-10

    The close proximity of short-period hot-Jupiters to their parent star means they are subject to extreme tidal forces. This has a profound effect on their structure and, as a result, density measurements that assume that the planet is spherical can be incorrect. We have simulated the tidally distorted surface for 34 known short-period hot-Jupiters, assuming surfaces of constant gravitational equipotential for the planet, and the resulting densities have been calculated based only on observed parameters of the exoplanet systems. Comparing these results to the density values, assuming the planets are spherical, shows that there is an appreciable change in the measured density for planets with very short periods (typically less than two days). For one of the shortest-period systems, WASP-19b, we determine a decrease in bulk density of 12% from the spherical case and, for the majority of systems in this study, this value is in the range of 1%-5%. On the other hand, we also find cases where the distortion is negligible (relative to the measurement errors on the planetary parameters) even in the cases of some very short period systems, depending on the mass ratio and planetary radius. For high-density gas planets requiring apparently anomalously large core masses, density corrections due to tidal deformation could become important for the shortest-period systems.

  2. The 'virtual density' principle of neutronics: Toward rapid computation of reactivity effects in practical core distortion scenarios

    SciTech Connect (OSTI)

    Reed, M.; Smith, K.; Forget, B.

    2013-07-01

    Fast reactor core reactivities are sensitive to geometric distortions arising from three distinct phenomena: (1) irradiation swelling of fuel throughout core lifetime, (2) thermal expansion of fuel during transients, and (3) mechanical oscillations during seismic events. Performing comprehensive reactivity analysis of these distortions requires methods for rapidly computing a multitude of minute reactivity changes. Thus, we introduce the 'virtual density' principle of neutronics as a new perturbation technique to achieve this rapid computation. This new method obviates many of the most challenging aspects of conventional geometric perturbation theory. Essentially, this 'virtual density' principle converts geometric perturbations into equivalent material density perturbations (either isotropic or anisotropic), which are highly accurate and comparatively simple to evaluate. While traditional boundary perturbation theory employs surface integrals, the 'virtual density' principle employs equivalent volume integrals. We introduce and validate this method in three subsequent stages: (1) isotropic 'virtual density', (2) anisotropic 'virtual density' for whole cores, and (3) anisotropic 'virtual density' for interior zones within cores. We numerically demonstrate its accuracy for 2-D core flowering scenarios. (authors)

  3. MEASURING THE ULTIMATE HALO MASS OF GALAXY CLUSTERS: REDSHIFTS AND MASS PROFILES FROM THE HECTOSPEC CLUSTER SURVEY (HeCS)

    SciTech Connect (OSTI)

    Rines, Kenneth; Geller, Margaret J.; Kurtz, Michael J.; Diaferio, Antonaldo E-mail: diaferio@ph.unito.it

    2013-04-10

    The infall regions of galaxy clusters represent the largest gravitationally bound structures in a {Lambda}CDM universe. Measuring cluster mass profiles into the infall regions provides an estimate of the ultimate mass of these halos. We use the caustic technique to measure cluster mass profiles from galaxy redshifts obtained with the Hectospec Cluster Survey (HeCS), an extensive spectroscopic survey of galaxy clusters with MMT/Hectospec. We survey 58 clusters selected by X-ray flux at 0.1 < z < 0.3. The survey includes 22,680 unique MMT/Hectospec redshifts for individual galaxies; 10,145 of these galaxies are cluster members. For each cluster, we acquired high signal-to-noise spectra for {approx}200 cluster members and a comparable number of foreground/background galaxies. The cluster members trace out infall patterns around the clusters. The members define a very narrow red sequence. We demonstrate that the determination of velocity dispersion is insensitive to the inclusion of bluer members (a small fraction of the cluster population). We apply the caustic technique to define membership and estimate the mass profiles to large radii. The ultimate halo mass of clusters (the mass that remains bound in the far future of a {Lambda}CDM universe) is on average (1.99 {+-} 0.11)M{sub 200}, a new observational cosmological test in essential agreement with simulations. Summed profiles binned in M{sub 200} and in L{sub X} demonstrate that the predicted Navarro-Frenk-White form of the density profile is a remarkably good representation of the data in agreement with weak lensing results extending to large radius. The concentration of these summed profiles is also consistent with theoretical predictions.

  4. THERMAL AND RADIATIVE ACTIVE GALACTIC NUCLEUS FEEDBACK HAVE A LIMITED IMPACT ON STAR FORMATION IN HIGH-REDSHIFT GALAXIES

    SciTech Connect (OSTI)

    Roos, Orianne; Juneau, Stéphanie; Bournaud, Frédéric; Gabor, Jared M.

    2015-02-10

    The effects of active galactic nuclei (AGNs) on their host galaxies depend on the coupling between the injected energy and the interstellar medium (ISM). Here, we model and quantify the impact of long-range AGN ionizing radiation—in addition to the often considered small-scale energy deposition—on the physical state of the multi-phase ISM of the host galaxy and on its total star formation rate (SFR). We formulate an AGN spectral energy distribution matched with observations, which we use with the radiative transfer (RT) code Cloudy to compute AGN ionization in a simulated high-redshift disk galaxy. We use a high-resolution (∼6 pc) simulation including standard thermal AGN feedback and calculate RT in post-processing. Surprisingly, while these models produce significant AGN-driven outflows, we find that AGN ionizing radiation and heating reduce the SFR by a few percent at most for a quasar luminosity (L {sub bol} = 10{sup 46.5} erg s{sup –1}). Although the circumgalactic gaseous halo can be kept almost entirely ionized by the AGN, most star-forming clouds (n ≳ 10{sup 2} {sup –} {sup 3} cm{sup –3}) and even the reservoirs of cool atomic gas (n ∼ 0.3-10 cm{sup –3})—which are the sites of future star formation (SF; 100-200 Myr), are generally too dense to be significantly affected. Our analysis ignores any absorption from a putative torus, making our results upper limits on the effects of ionizing radiation. Therefore, while the AGN-driven outflows can remove substantial amounts of gas in the long term, the impact of AGN feedback on the SF efficiency in the interstellar gas in high-redshift galaxies is marginal, even when long-range radiative effects are accounted for.

  5. Earth, Space Sciences

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Earth, Space Sciences Earth, Space Sciences National security depends on science and technology. The United States relies on Los Alamos National Laboratory for the best of both. No place on Earth pursues a broader array of world-class scientific endeavors. Climate, Ocean and Sea Ice Modeling (COSIM)» Earth and Environmental Sciences Division» Intelligence and Space Research» Earth Read caption + A team of scientists is working to understand how local changes in hydrology might bring about

  6. Berkeley Lab Space

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Space Committee Charter Articles Presentations Feedback Contact Us ANNOUNCEMENTS Feb. 13, 2014 Courtesy Salvage Pickup Factsheet To assist the community in disposing of "no longer...

  7. Total Space Heat-

    Gasoline and Diesel Fuel Update (EIA)

    Commercial Buildings Energy Consumption Survey: Energy End-Use Consumption Tables Total Space Heat- ing Cool- ing Venti- lation Water Heat- ing Light- ing Cook- ing Refrig- eration...

  8. Total Space Heat-

    Gasoline and Diesel Fuel Update (EIA)

    Revised: December, 2008 Total Space Heat- ing Cool- ing Venti- lation Water Heat- ing Light- ing Cook- ing Refrig- eration Office Equip- ment Com- puters Other All Buildings...

  9. Total Space Heat-

    Gasoline and Diesel Fuel Update (EIA)

    Released: September, 2008 Total Space Heat- ing Cool- ing Venti- lation Water Heat- ing Light- ing Cook- ing Refrig- eration Office Equip- ment Com- puters Other All Buildings*...

  10. Strong focus space charge

    DOE Patents [OSTI]

    Booth, Rex

    1981-01-01

    Strong focus space charge lens wherein a combination of current-carrying coils and charged electrodes form crossed magnetic and electric fields to focus charged particle beams.

  11. Passive solar space heating

    SciTech Connect (OSTI)

    Balcomb, J.D.

    1980-01-01

    An overview of passive solar space heating is presented indicating trends in design, new developments, performance measures, analytical design aids, and monitored building results.

  12. Multimegawatt space power reactors

    SciTech Connect (OSTI)

    Dearien, J.A.; Whitbeck, J.F.

    1989-01-01

    In response to the need of the Strategic Defense Initiative (SDI) and long range space exploration and extra-terrestrial basing by the National Air and Space Administration (NASA), concepts for nuclear power systems in the multi-megawatt levels are being designed and evaluated. The requirements for these power systems are being driven primarily by the need to minimize weight and maximize safety and reliability. This paper will discuss the present requirements for space based advanced power systems, technological issues associated with the development of these advanced nuclear power systems, and some of the concepts proposed for generating large amounts of power in space. 31 figs.

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

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

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

    2015-07-08

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

  14. Mass calibration of galaxy clusters at redshift 0.11.0 using weak lensing in the Sloan Digital Sky Survey Stripe 82 co-add

    SciTech Connect (OSTI)

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

    2015-07-08

    We present galaxy cluster massrichness relations found in the Sloan Digital Sky Survey Stripe 82 co-add using clusters found using a Voronoi tessellation cluster finder. These relations were found using stacked weak lensing shear observed in a large sample of galaxy clusters. These massrichness relations are presented for four redshift bins, 0.1 < z ? 0.4, 0.4 < z ? 0.7, 0.7 < z ? 1.0 and 0.1 < z ? 1.0. We describe the sample of galaxy clusters and explain how these clusters were found using a Voronoi tessellation cluster finder. We fit a Navarro-Frenk-White profile to the stacked weak lensing shear signal in redshift and richness bins in order to measure virial mass (M200). We describe several effects that can bias weak lensing measurements, including photometric redshift bias, the effect of the central BCG, halo miscentering, photometric redshift uncertainty and foreground galaxy contamination. We present massrichness relations using richness measure NVT with each of these effects considered separately as well as considered altogether. We also examine redshift evolution of the massrichness relation. As a result, we present measurements of the mass coefficient (M200|20) and the power-law slope (?) for power-law fits to the mass and richness values in each of the redshift bins. We find values of the mass coefficient of 8.49 0.526, 14.1 1.78, 30.2 8.74 and 9.23 0.525 1013 h1 M? for each of the four redshift bins, respectively. As a result, we find values of the power-law slope of 0.905 0.0585, 0.948 0.100, 1.33 0.260 and 0.883 0.0500, respectively.

  15. Progress in Studies of Electron-Cloud-Induced Optics Distortions at CesrTA

    SciTech Connect (OSTI)

    Crittenden, James; Calvey, Joseph; Dugan, Gerald; Kreinick, David; Leong, Zhidong; Livezey, Jesse; Palmer, Mark; Rubin, David; Sagan, David; Furman, Miguel; Penn, Gregory; Venturini, Marco; Harkay, Katherine; Holtzapple, Robert; Pivi, Mauro; Wang, Lanfa; /SLAC

    2012-06-25

    The Cornell Electron Storage Ring Test Accelerator (CesrTA) program has included extensive measurements of coherent betatron tune shifts for a variety of electron and positron beam energies, bunch population levels, and bunch train configurations. The tune shifts have been shown to result primarily from the interaction of the beam with the space-charge field of the beam-induced low-energy electron cloud in the vacuum chamber. Comparison to several advanced electron cloud simulation codes has allowed determination of the sensitivity of these measurements to physical parameters characterizing the synchrotron radiation flux, the production of photo-electrons on the vacuum chamber wall, the beam emittance, lattice optics, and the secondary-electron yield model. We report on progress in understanding the cloud buildup and decay mechanisms in magnetic fields and in field-free regions, addressing quantitatively the precise determination of the physical parameters of the modeling. Validation of these models will serve as essential input in the design of damping rings for future high-energy linear colliders.

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

    SciTech Connect (OSTI)

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

    2010-08-01

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

  17. Anti-hierarchical evolution of the active galactic nucleus space density in a hierarchical universe

    SciTech Connect (OSTI)

    Enoki, Motohiro; Ishiyama, Tomoaki; Kobayashi, Masakazu A. R.; Nagashima, Masahiro

    2014-10-10

    Recent observations show that the space density of luminous active galactic nuclei (AGNs) peaks at higher redshifts than that of faint AGNs. This downsizing trend in the AGN evolution seems to be contradictory to the hierarchical structure formation scenario. In this study, we present the AGN space density evolution predicted by a semi-analytic model of galaxy and AGN formation based on the hierarchical structure formation scenario. We demonstrate that our model can reproduce the downsizing trend of the AGN space density evolution. The reason for the downsizing trend in our model is a combination of the cold gas depletion as a consequence of star formation, the gas cooling suppression in massive halos, and the AGN lifetime scaling with the dynamical timescale. We assume that a major merger of galaxies causes a starburst, spheroid formation, and cold gas accretion onto a supermassive black hole (SMBH). We also assume that this cold gas accretion triggers AGN activity. Since the cold gas is mainly depleted by star formation and gas cooling is suppressed in massive dark halos, the amount of cold gas accreted onto SMBHs decreases with cosmic time. Moreover, AGN lifetime increases with cosmic time. Thus, at low redshifts, major mergers do not always lead to luminous AGNs. Because the luminosity of AGNs is correlated with the mass of accreted gas onto SMBHs, the space density of luminous AGNs decreases more quickly than that of faint AGNs. We conclude that the anti-hierarchical evolution of the AGN space density is not contradictory to the hierarchical structure formation scenario.

  18. Atoms for space

    SciTech Connect (OSTI)

    Buden, D.

    1990-10-01

    Nuclear technology offers many advantages in an expanded solar system space exploration program. These cover a range of possible applications such as power for spacecraft, lunar and planetary surfaces, and electric propulsion; rocket propulsion for lunar and Mars vehicles; space radiation protection; water and sewage treatment; space mining; process heat; medical isotopes; and self-luminous systems. In addition, space offers opportunities to perform scientific research and develop systems that can solve problems here on Earth. These might include fusion and antimatter research, using the Moon as a source of helium-3 fusion fuel, and manufacturing perfect fusion targets. In addition, nuclear technologies can be used to reduce risk and costs of the Space Exploration Initiative. 1 fig.

  19. Radiation Effects In Space

    SciTech Connect (OSTI)

    Tripathi, Ram K.

    2011-06-01

    Protecting space missions from severe exposures from radiation, in general, and long duration/deep space human missions, in particular, is a critical design driver, and could be a limiting factor. The space radiation environment consists of galactic cosmic rays (GCR), solar particle events (SPE), trapped radiation, and includes ions of all the known elements over a very broad energy range. These ions penetrate spacecraft materials producing nuclear fragments and secondary particles that damage biological tissues and microelectronic devices. One is required to know how every element (and all isotopes of each element) in the periodic table interacts and fragments on every other element in the same table as a function of kinetic energy ranging over many decades. In addition, the accuracy of the input information and database, in general and nuclear data in particular, impacts radiation exposure health assessments and payload penalty. After a brief review of effects of space radiation on materials and electronics, human space missions to Mars is discussed.

  20. A study of astrometric distortions due to “tree rings” in CCD sensors using LSST Photon Simulator

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Beamer, Benjamin; Nomerotski, Andrei; Tsybychev, Dmitri

    2015-05-22

    Imperfections in the production process of thick CCDs lead to circularly symmetric dopant concentration variations, which in turn produce electric fields transverse to the surface of the fully depleted CCD that displace the photogenerated charges. We use PhoSim, a Monte Carlo photon simulator, to explore and examine the likely impacts these dopant concentration variations will have on astrometric measurements in LSST. The scale and behavior of both the astrometric shifts imparted to point sources and the intensity variations in flat field images that result from these doping imperfections are similar to those previously observed in Dark Energy Camera CCDs, givingmore » initial confirmation of PhoSim's model for these effects. In addition, the organized shape distortions were observed as a result of the symmetric nature of these dopant variations, causing nominally round sources to be imparted with a measurable ellipticity either aligned with or transverse to the radial direction of this dopant variation pattern.« less

  1. National Aeronautical and Space Administration (NASA) Johnson...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    National Aeronautical and Space Administration (NASA) Johnson Space Flight Center National Aeronautical and Space Administration (NASA) Johnson Space Flight Center Space Shuttle ...

  2. National Aeronautical and Space Administration (NASA) Johnson...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Aeronautical and Space Administration (NASA) Johnson Space Flight Center National Aeronautical and Space Administration (NASA) Johnson Space Flight Center Space Shuttle Endeavour, ...

  3. Improved Life of Die Casting Dies of H13 Steel by Attaining Improved Mechanical Properties and Distortion Control During Heat Treatment

    SciTech Connect (OSTI)

    J. F. Wallace; D. Schwam

    1998-10-01

    The ultimate goal of this project is to increase die casting die life by using fast enough quenching rates to obtain good toughness and fatigue resistance in premium grade H-13 steel dies. The main tasks of the project were to compile a database on physical and mechanical properties of H-13; conduct gas quenching experiments to determine cooling rates of dies in difference vacuum furnaces; measure the as-quenched distortion of dies and the residual stresses; generate finite element analysis models to predict cooling rates, distortion, and residual stress of gas quenched dies; and establish rules and create PC-based expert system for prediction of cooling rates, distortion, and residual stress in vacuum/gas quenched H-13 dies. Cooling curves during gas quenching of H-13 blocks and die shapes have been measured under a variety of gas pressure. Dimensional changes caused by the gas quenching processes have been determined by accurate mapping of all surfaces with coordinate measuring machines before and after the quench. Residual stresses were determined by the ASTM E837 hole-drilling strain gage method. To facilitate the computer modeling work, a comprehensive database of H-13 mechanical and physical properties has been compiled. Finite element analysis of the heat treated shapes has been conducted using the TRAST/ABAQUS codes. There is a good fit between the predicted and measured distortion contours. However, the magnitude of the predicted distortion and residual stresses does not match well the measured values. Further fine tuning of the model is required before it can be used to predict distortion and residual stress in a quantitative manner. This last step is a prerequisite to generating rules for a reliable expert system.

  4. Influence of static Jahn-Teller distortion on the magnetic excitation spectrum of PrO{sub 2}: A synchrotron x-ray and neutron inelastic scattering study

    SciTech Connect (OSTI)

    Webster, C. H.; Helme, L. M.; Boothroyd, A. T.; McMorrow, D. F.; Wilkins, S. B.; Detlefs, C.; Detlefs, B.; Bewley, R. I.; McKelvy, M. J.

    2007-10-01

    A synchrotron x-ray diffraction study of the crystallographic structure of PrO{sub 2} in the Jahn-Teller distorted phase is reported. The distortion of the oxygen sublattice, which was previously ambiguous, is shown to be a chiral structure in which neighboring oxygen chains have opposite chiralities. A temperature dependent study of the magnetic excitation spectrum, probed by neutron inelastic scattering, is also reported. Changes in the energies and relative intensities of the crystal field transitions provide an insight into the interplay between the static and dynamic Jahn-Teller effects.

  5. Total Space Heat-

    Gasoline and Diesel Fuel Update (EIA)

    Survey: Energy End-Use Consumption Tables Total Space Heat- ing Cool- ing Venti- lation Water Heat- ing Light- ing Cook- ing Refrig- eration Office Equip- ment Com- puters Other...

  6. Nearest Alignment Space Termination

    Energy Science and Technology Software Center (OSTI)

    2006-07-13

    Near Alignment Space Termination (NAST) is the Greengenes algorithm that matches up submitted sequences with the Greengenes database to look for similarities and align the submitted sequences based on those similarities.

  7. Space Nuclear MIssion History

    Office of Energy Efficiency and Renewable Energy (EERE)

    For over fifty years, the Department of Energy has enabled space exploration on 27 missions by providing safe reliable radioistope power systems and radioisotope heater units for NASA, Navy, Air...

  8. space booklet_DOE

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    U C L E A R E N E R G Y DOE/NE-0071 U . S . D e p a r t m e n t o f E n e r g y O f f i c e o f N u c l e a r E n e r g y , S c i e n c e a n d T e c h n o l o g y N UCLEAR Power in Space 2 On the cover: Launch of the Atlantis Space Shuttle carrying Galileo into space (October 1989). 1 Nuclear Power in Space Table of Contents Introduction 3 Contemplating the Heavens 4 The Pioneer Missions 7 The Voyager Missions 8 The Ulysses Mission 8 The Galileo Mission 11 The Missions - An Overview 16 Power in

  9. Space Science and Applications

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    programs sponsored by the Department of Energy (DOE), the Department of Defense (DoD), the National Aeronautics and Space Administration (NASA), and other U.S. government agencies. ...

  10. Intelligence and Space Research

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    ISR Intelligence and Space Research Create, deliver, support, and exploit innovative sensing systems for space-based, airborne and ground-based applications to address critical national security and scientific challenges Leadership Division Leader Kevin Saeger Deputy Division Leader Angela Mielke Contacts Chief of Staff Aimee Blanchard Email Executive Office Administrator Mary T. Wubbena Email Create, deliver, support and exploit innovative sensing systems Innovative sensing systems for