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in subjects: "Red Shift"

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Searches for high redshift radio galaxies

We have started a search for High Redshift Radio Galaxies (HzRGs) in an area covering 7 sr by selecting a sample of Ultra Steep Spectrum (USS) sources with a low flux density cut-off S{sub 1400} > 10 mJy and a steep spectral index {alpha} < -1 3 (S {alpha} {nu}{sup {alpha}}) using the WENSS, NVSS and TEXAS radio suveys. Preliminary results for 25 sources shows that we are almost twice as effective in finding HzRGs than previous searches using brighter radio sources and less steep radio spectra … more

Date: January 23, 1998

Creator: De Breuck, C., LLNL

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Very high redshift radio galaxies

High redshift radio galaxies (HzRGs) provide unique targets for the study of the formation and evolution of massive galaxies and galaxy clusters at very high redshifts. We discuss how efficient HzRG samples ae selected, the evidence for strong morphological evolution at near-infracd wavelengths, and for jet-induced star formation in the z = 3 800 HzRG 4C41 17

Date: December 1, 1997

Creator: van Breugel, W. J. M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Scheduled discoveries of 7+ high-Redshift supernovae: First cosmology results and bounds on q{sub 0}

Our search for high-redshift Type Ia supernovae discovered, in its first years, a sample of seven supernovae. Using a ``batch`` search strategy, almost all were discovered before maximum light and were observed over the peak of their light curves. The spectra and light curves indicate that almost all were Type Ia supernovae at redshifts z = 0.35 - 0.5. These high-redshift supernovae can provide a distance indicator and ``standard clock`` to study the cosmological parameters q{sub 0} , {Lambda},… more

Date: September 1, 1998

Creator: Perlmutter, S., FNAL

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Observation of cosmological time dilation using type Ia supernovae as clocks

This work is based on the first results from a systematic search for high redshift Type Ia supernovae. Using filters in the R-band we discovered seven such SNe, with redshift z = 0.3-0.5, before or at maximum light. Type Ia SNe are known to be a homogeneous group of SNe, to first order, with very similar light curves, spectra and peak luminosities. In this talk we report that the light curves we observe are all broadened (time dilated) as expected from the expanding universe hypothesis. Small v… more

Date: September 1, 1998

Creator: Goldhaber, G., FNAL

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Highest redshift radio galaxy known in the Southern Hemisphere

We present the discovery of a z = 4 13 galaxy TN J1338-1942, the most distant radio galaxy in the southern hemisphere known to date The source was selected from a sample of Ultra Steep Spectrum (USS; {alpha}<-1 3; S {proportional_to} {nu}{sup {alpha}}) radio sauces using the Texas and NVSS catalogs The discovery spectrum, obtained with the ES0 3 6m telescope, shows bright extended Ly-{alpha} emission The radio source has a very asymmetric morphology, suggesting a strong interaction with an inho… more

Date: December 1, 1997

Creator: De Breuck, C., LLNL

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Comment on "Indication from Pioneer 10/11, Galileo, and Ulysses Data, of an Apparent Anomalous, Weak, Long-Range Acceleration"

In a recent Letter Anderson et al. report some very intriguing radio observations flom various interplanetary spaceprobes over the past 18 years. They interpret this data as an anomalous deceleration of the spaceprobes. Here I offer a different interpretation: that the anomaly is related to the cosmological red shift.

Date: October 27, 1998

Creator: Humphreys, D.R.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Models for high -- Redshift Ly{alpha} emitters

We present models for dusty high{redshift Ly {alpha} emitting galaxies by com- bining the Press{Schechter formalism with a treatment of inhomogeneous dust distri- bution inside galaxies. These models reproduce the surface density of emitters inferred from recent observations, and also agree with previous non{detections. Although a detailed determination of the individual model parameters is precluded by uncertain- ties, we #12;nd that (i) the dust content of primordial galaxies builds up in no … more

Date: December 1, 1998

Creator: Spaans, Zoltan Haiman and Marco

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Empirical constraints on the first stars and quasars

Empirical studies of the first generation of stars and quasars in the Universe will likely become feasible over the next decade. The Next Generation Space Telescope will provide direct imaging and photometry of sub-galactic objects at z approximately greater than 10, while microwave anisotropy experiments, such as MAP or Planck, will set constraints on the ionization history of the intergalactic medium due to these sources. We describe the expected signals that will be detectable with these fut… more

Date: December 1, 1998

Creator: Loeb, Zoltan Haiman and Avi

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Constraining omega and bias from the Stromlo-APM survey

Galaxy redshift surveys provide a distorted picture of the universe due to the non-Hubble component of galaxy motions. By measuring such distortions in the linear regime one can constrain the quantity {beta} = {Omega}{sup 0.6} where {Omega} is the cosmological density parameter and b is the (linear) bias factor for optically-selected galaxies. In this paper we estimate {beta} from the Stromlo-APM redshift survey by comparing the amplitude of the direction-averaged redshift space correlation fun… more

Date: May 1, 1995

Creator: Loveday, J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Induced star formation and morphological evolution in very high redshift radio galaxies

Near-infrared, sub-arcsecond seeing images obtained with the W M Keck I Telescope of show strong evolution at rest-frame optical wavelengths in the morphologies of high redshift radio galaxies (HzRGs) with 1 9 < z < 4 4 The structures change from large-scale low surface brightness regions surrounding bright, multiple component and often radio-aligned features at z > 3, to much more compact and symmetrical shapes at z < 3 The linear sizes ({approximately} 10 kpc) and luminosities (M{sub B} {appr… more

Date: October 1, 1997

Creator: van Breugel, W. J. M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Searches for high redshift radio galaxies

We have started a search for High Redshift Radio Galaxies (HZRGS) in an area covering 7 sr by selecting a sample of Ultra Steep Spectrum (USS) sources with a low flux density cut-off S1400 > 10 mJy and a steep spectral index cut-off of a < -1.3 (S of about nu-alpha) from the WENSS, NVSS and TEXAS surveys. Our first results for 27 sources show that we are almost twice as effective in finding HZRGs than than surveys of relatively bright radio sources with a spectral index cut-off of a < - 1.0. Th… more

Date: May 5, 1997

Creator: De Breuck, C.; Van Breugel, W.; Rottgering, H. & Miley, G.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Cosmic shear with next generation redshift surveys as a cosmological probe

No Description Available.

Date: December 13, 2002

Creator: Linder, Eric V.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

The Wolf effect and the redshift of quasars

We consider a simple model, based on currently accepted models for active galactic nuclei, for a quasi-stellar object (QSO or "quasar") and examine the influence that correlation-induced spectral changes ("The Wolf Effect") may have upon the redshifts of the optical emission lines.

Date: January 23, 1998

Creator: James, Daniel F.V.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

The Mass Of The Coma Cluster From Weak Lensing In The Sloan Digital Sky Survey

We present a weak lensing analysis of the Coma Cluster using the Sloan Digital Sky Survey (SDSS) Data Release Five. Complete imaging of a {approx} 200 square degree region is used to measure the tangential shear of this cluster. The shear is fit to an NFW model and we find a virial radius of r{sub 200} = 1.99{sup +0.21}{sub -0.22}h{sup -1}Mpc which corresponds to a virial mass of M{sub 200} = 1.88{sup +0.65}{sub -0.56} x 10{sup 15}h{sup -1}M{circle_dot}. We additionally compare our weak lensing… more

Date: September 1, 2007

Creator: Kubo, Jeffrey M.; Stebbins, Albert; Annis, James; Dell'Antonio, Ian P.; Lin, Huan; Khiabanian, Hossein et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

The discovery of high-redshift supernovae and their cosmological implications

In this thesis the author discusses the methodology for doing photometry: from procedure of extracting supernova counts from images that contain combined supernova plus galaxy flux, to standard star calibration, to additional instrumental corrections that arise due to the multiple telescopes used for observations. He discusses the different sources of photometric error and their correlations, and the construction of the covariance matrix for all the points in the light curve. He then describes … more

Date: September 1, 1997

Creator: Kim, A.G.

Item Type: Thesis or Dissertation

Partner: UNT Libraries Government Documents Department

open access

Broadband dielectric function of non-equilibrium warm dense gold

We report on the first single-state measurement of the broadband (450-800 nm) dielectric function of gold isochorically heated by a femtosecond laser pulse to energy densities of 10{sup 6}-10{sup 7} J/kg. A Drude and an inter-band component are clearly seen in the imaginary part of the dielectric function. The Drude component increases with energy density while the inter-band component shows both enhancement and red shift. This is in strong disagreement with predictions of a recent calculation … more

Date: April 25, 2006

Creator: Ping, Y.; Hanson, D.; Koslow, I.; Ogitsu, T.; Prendergast, D.; Schwegler, E. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Calcium-Dependent Conformation of a Heme and Fingerprint Peptide of the Di-Heme Cytochrome c Peroxidase from Paracoccus Pantotrophus

The structural changes in the heme macrocycle and substituents caused by binding of Ca{sup 2+} to the diheme cytochrome c peroxidase from Paracoccuspantotrophus were clarified by resonance Raman spectroscopy of the inactive filly oxidized form of the enzyme. The changes in the macrocycle vibrational modes are consistent with a Ca{sup 2+}-dependent increase in the out-of-plane distortion of the low-potential heme, the proposed peroxidatic heme. Most of the increase in out-of-plane distortion occ… more

Date: December 18, 2000

Creator: Pauleta, Sofia R.; Lu, Yi; Goodhew, Celia F.; Moura, Isabel; Pettigrew, Graham W. & Shelnutt, John A.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

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

The greatest challenge in the interpretation of galaxy clustering data from any surveys is galaxy bias. Using a simple Fisher matrix analysis, we show that the bispectrum provides an excellent determination of linear and non-linear bias parameters of intermediate and high-z galaxies, when all measurable triangle configurations down to mildly non-linear scales, where perturbation theory is still valid, are included. The bispectrum is also a powerful probe of primordial non-Gaussianity. The plann… more

Date: May 1, 2007

Creator: Sefusatti, Emiliano; /Fermilab; Komatsu, Eiichiro & /Texas U., Astron. Dept.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Reionization: Characteristic Scales, Topology And Observability

Recently the numerical simulations of the process of reionization of the universe at z > 6 have made a qualitative leap forward, reaching sufficient sizes and dynamic range to determine the characteristic scales of this process. This allowed making the first realistic predictions for a variety of observational signatures. We discuss recent results from large-scale radiative transfer and structure formation simulations on the observability of high-redshift Ly-{alpha} sources. We also briefly … more

Date: November 2, 2007

Creator: Iliev, Ilian T.; U., /Canadian Inst. Theor. Astrophys. /Zurich; Shapiro, Paul R.; /Texas U., Astron. Dept.; Mellema, Garrelt; Observ., /Stockholm et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Optical properties of silicon nanoparticles in the presence of water: A first principles theoretical analysis

We investigate the impact of water, a polar solvent, on the optical absorption of prototypical silicon clusters with oxygen passivation. We approach this complex problem by assessing the contributions of three factors: chemical reactivity; thermal equilibration and dielectric screening. We find that the silanone (Si=O) functional group is not chemically stable in the presence of water and exclude this as a source of significant red shift in absorption in aqueous environments. We perform first p… more

Date: April 8, 2004

Creator: Prendergast, D; Grossman, J; Williamson, A; Fattebert, J & Galli, G

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Elliptical galaxies in high-z clusters: how old are they?

I review recent research on the evolution of elliptical galaxies in high redshift galaxy clusters. Significant progress is being made on many fronts using the powerful tools of e.g. HST and 10 m class telescopes. But determining the actual age of composite stellar populations in distant galaxies is still beyond our capabilities.

Date: June 1, 1998

Creator: Stanford, S.A.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Stirring the Embers: High-Sensitivity VLBI Observations of GRB 030329

We present high-sensitivity Very Long Baseline Interferometry (VLBI) observations 806 days after the {gamma}-ray burst of 2003 March 29 (GRB 030329). The angular diameter of the radio afterglow is measured to be 0:347 {+-} 0:09 mas, corresponding to 0:99 {+-} 0:26 pc at the redshift of GRB 030329 (z = 0:1685). The evolution of the image size favors a uniform external density over an R{sup -2} windlike density profile (at distances of R {approx}> 10{sup 18} cm from the source), although the l… more

Date: September 24, 2007

Creator: Pihlstrom, Y. M.; Taylor, G. B.; U., /New Mexico; Granot, J.; /KIPAC, Menlo Park; Doeleman, S. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

The distributed development environment for SDSS software

The authors present an integrated science software development environment, code maintenance and support system for the Sloan Digital Sky Survey (SDSS) now being actively used throughout the collaboration.

Date: April 1, 1994

Creator: Berman, E.; Gurbani, V.; Mackinnon, B.; Newberg, H.; Nicinski, T.; Petravick, D. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

A Bayesian Analysis of Regularised Source Inversions in Gravitational Lensing

Strong gravitational lens systems with extended sources are of special interest because they provide additional constraints on the models of the lens systems. To use a gravitational lens system for measuring the Hubble constant, one would need to determine the lens potential and the source intensity distribution simultaneously. A linear inversion method to reconstruct a pixellated source distribution of a given lens potential model was introduced by Warren and Dye. In the inversion process, a r… more

Date: January 25, 2006

Creator: Suyu, Sherry H.; Marshall, P. J.; Hobson, M. P. & Blandford, R. D.

Item Type: Report

Partner: UNT Libraries Government Documents Department