Large-scale Peculiar Velocity Research Articles

COBE ‐DMR–normalized Open Cold Dark Matter Cosmogonies

Cut-sky orthogonal mode analyses of the COBE-DMR 53 and 90 GHz sky maps are used to determine the normalization of a variety of open cosmogonical models based on the cold dark matter scenario. To constrain the allowed cosmological parameter range for these open cosmogonies, the predictions of the DMR-normalized models are compared to various observational measures of cosmography and large-scale structure, viz., the age of the universe; small-scale dynamical estimates of the clustered-mass density parameter ?0; constraints on the Hubble parameter h, the X-ray cluster baryonic-mass fraction ?B/?0, and the matter power spectrum shape parameter; estimates of the mass perturbation amplitude; and constraints on the large-scale peculiar velocity field. The open-bubble inflation model (Ratra & Peebles; Bucher, Goldhaber, & Turok; Yamamoto, Sasaki, & Tanaka) is consistent with current determinations of the 95% confidence level (c.l.) range of these observational constraints, provided 0.3 < ?0 0.6 (~95% c.l.). More specifically, for a range of h, the model is reasonably consistent with recent high-redshift estimates of the deuterium abundance that suggest ?Bh2 ~ 0.007, provided ?0 ~ 0.35; recent high-redshift estimates of the deuterium abundance that suggest ?Bh2 ~ 0.02 favor ?0 ~ 0.5, while the old nucleosynthesis value ?Bh2 = 0.0125 requires ?0 ~ 0.4. Small shifts in the inferred COBE-DMR normalization amplitudes due to (1) the small differences between the galactic- and ecliptic-coordinate sky maps, (2) the inclusion or exclusion of the quadrupole moment in the analysis, (3) the faint high-latitude Galactic emission treatment, and (4) the dependence of the theoretical cosmic microwave background anisotropy angular spectral shape on the value of h and ?B are explicitly quantified. Corresponding variations in the likelihood fits of models to the DMR data then imply that the DMR data alone do not possess sufficient discriminative power to prefer any values for ?0, h, or ?B at the 95% c.l. for the models considered. At a lower c.l., and when the quadrupole moment is included in the analysis, the DMR data are most consistent with either ?0 0.1 or ?0 ~ 0.7 (depending on the model considered). However, when the quadrupole moment is excluded from the analysis, the DMR data are most consistent with ?0 ~ 0.35-0.5 in all open models considered (with 0.1 ? ?0 ? 1), including the open-bubble inflation model. Earlier claims (Yamamoto & Bunn; Bunn & White) that the DMR data require a 95% c.l. lower bound on ?0 (~0.3) are not supported by our (complete) analysis of the 4 year data: the DMR data alone cannot be used to constrain ?0 meaningfully.

The Peculiar Motions of Early-Type Galaxies in Two Distant Regions. I. Cluster and Galaxy Selection

The EFAR project is a study of 736 candidate elliptical galaxies in 84 clusters lying in two regions towards Hercules-Corona Borealis and Perseus-Pisces-Cetus at distances cz = 6000-15000 km/s. In this paper (the first of a series) we present an introduction to the EFAR project and describe in detail the selection of the clusters and galaxies in our sample. Fundamental data for the galaxies and clusters are given, including accurate new positions for each galaxy and redshifts for each cluster. The galaxy selection functions are determined using diameters measured from Schmidt sky survey images for 2185 galaxies in the cluster fields. Future papers in this series will present the spectroscopic and photometric observations of this sample, investigate the properties of the fundamental plane for ellipticals, and determine the large-scale peculiar velocity fields in these two regions of the universe.

The cosmic microwave background anisotropy and very large structures in the universe: The problem of agreement

Abstract The general formula for correlation function of CMB temperature fluctuations, measured in the real experiments on angular scale ≳x 1°5, is obtained. Predictions by the CDM model with different slope of the primordial spectrum and of the hybrid HDM+CDM (HC) one for COBE, ULISSE and SP93 experiments are calculated. It is shown that the SP93 upper limit on δT/T does not agree with large scale peculiar velocities of galaxies and with existence of very scale structures even in preferable models of the flat University without reionization. A reconstructed spectrum explaining the COBE and ULISSE results, large scale peculiar velocities, two point correlation functions, concentrations of bright galaxies and rich clusters are proposed.

COMPARING LARGE-SCALE COSMOLOGICAL DENSITY FLUCTUATIONS

Abstract Two methods for looking at cosmological density on large scales are briefly described. The first takes galaxies observed in infrared, by the IRAS satellite. The second method, called POTENT by its inventors (Dekel and Bertschinger), uses the observed peculiar motions of galaxies to find the large scale peculiar velocity field. These two methods can be combined to test various theories of structure formation. First, though, we need to make sure that the velocity field derived from POTENT is consistent with the fractional overdensity field derived from IRAS. One way to compare them employs the non-parametric Wilcoxon-Mann-Whitney test.

CLUSTERING AND LARGE-SCALE STRUCTURE WITH THE SLOAN DIGITAL SKY SURVEY

ABSTRACT The Sloan Digital Sky Survey (SDSS) will provide a complete imaging and spectroscopic survey of the high-latitude northern sky. The 2D survey will image the sky in five colors and will contain nearly 5 x 107 galaxies to g ~23m. The spectroscopic survey will obtain spectra of the brightest 106 galaxies, 105 quasars, and 1035 rich clusters of galaxies (to g ~18.3-19.3m, respectively). I summarize some of the science opportunities that will be made possible by this survey for studying the clustering and large-scale structure of the universe. The survey will identify a complete sample of several thousand rich clusters of galaxies, both in 2D and 3D--the largest automated sample yet available. The extensive cluster sample can be used to determine critical clustering properties such as the luminoisty-function, velocity-function, and mass-function of clusters of galaxies (a critical test for cosmological models), detailed cluster dynamics and Omegadyn, the cluster correlation function and its dependence on richness, cluster evolution, superclustering and voids to the largest scales yet observed, the motions of clusters and their large-scale peculiar velocity field, as well as detailed correlations between x-ray and optical properties of clusters, the density-morphology relation, and cluster-quasar associations. The large redshift survey, reaching to a depth of >~600h-1 Mpc, will accurately map the largest scales yet observed, determine the power-spectrum and correlation function on these large scales for different type galaxies, and study the clustering of quasars to high redshifts (z >~ 4). The implications of the survey for cosmological models, the dark matter, and Omega are also discussed.

Large-scale motions in the universe: Using clusters of galaxies as tracers

Can clusters of galaxies be used to trace the large-scale peculiar velocity field of the universe? We answer this question by using large-scale cosmological simulations to compare the motions of rich clusters of galaxies with the motion of the underlying matter distribution. Three models are investigated: Omega = 1 and Omega = 0.3 cold dark matter (CDM), and Omega = 0.3 primeval baryonic isocurvature (PBI) models, all normalized to the Cosmic Background Explorer (COBE) background fluctuations. We compare the cluster and mass distribution of peculiar velocities, bulk motions, velocity dispersions, and Mach numbers as a function of scale for R greater than or = 50/h Mpc. We also present the large-scale velocity and potential maps of clusters and of the matter. We find that clusters of galaxies trace well the large-scale velocity field and can serve as an efficient tool to constrain cosmological models. The recently reported bulk motion of clusters 689 +/- 178 km/s on approximately 150/h Mpc scale (Lauer & Postman 1994) is larger than expected in any of the models studied (less than or = 190 +/- 78 km/s).

Comparison of double-inflationary models with observations.

We consider double-inflationary models with two noninteracting scalar fields: a ``light'' scalar field ${\mathrm{\ensuremath{\varphi}}}_{\mathit{l}}$ with the potential 1/2${\mathit{m}}_{\mathit{l}}^{2}$${\mathrm{\ensuremath{\varphi}}}_{\mathit{l}}^{2}$ and a ``heavy'' scalar field ${\mathrm{\ensuremath{\varphi}}}_{\mathit{h}}$ with the potential \ensuremath{\lambda}/n${\mathrm{\ensuremath{\varphi}}}_{\mathit{h}}^{\mathit{n}}$, n=2,4, whose effective mass is larger than ${\mathit{m}}_{\mathit{l}}$ during inflation with ${\mathrm{\ensuremath{\varphi}}}_{\mathit{h}}$&gt;${\mathit{M}}_{\mathit{P}}$. Cold dark matter (CDM) with the initial spectrum of adiabatic perturbations produced in these models is compared with observations. These models contain two more free parameters than the standard CDM model with an initial scale-invariant spectrum. We normalize our spectra to the COBE DMR and compare the predictions with observations on the biasing factor, large-scale peculiar velocities, quasar and galaxy formation, and the Stromlo-APM counts-in-cells analysis. The model with n=4 is excluded by the data while for the n=2 model, taking cosmic variance into account, a small window of parameters compatible with observations is found.

Large-Scale Peculiar Velocity Field Due to Infinitely Long Cosmic Strings

view Abstract Citations (9) References (26) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Large-Scale Peculiar Velocity Field Due to Infinitely Long Cosmic Strings Hara, Tetsuya ; Maehoenen, Petri ; Miyoshi, Shigeru Abstract We investigate the large-scale peculiar velocity field of dark matter due to the wakes formed by infinitely long cosmic strings. The peculiar velocity due to such strings, which passed through at the stage 1 + ζi is solved analytically for one-dimensional case, including the contribution of the background radiation density. The three dimensional large-scale peculiar velocities will be the vector sum of such velocities, and the root mean square (rms) peculiar velocities can be estimated. The large peculiar velocity of the Local Group (≃600 km s-1) and the distribution of peculiar velocities for nearby 20 clusters of galaxies can be explained by adopting the parameter Gμβγ(n)1/2 (4 ± 1) × 10-6, where μ and β are the line density and the velocity of a cosmic string in units of c = 1 and γ = (1 - β2)-1/2. The parameter n denotes the number of infinitely long cosmic strings per horizon passed through in each e-time expansion of the universe. Publication: The Astrophysical Journal Pub Date: October 1993 DOI: 10.1086/173176 Bibcode: 1993ApJ...415..445H Keywords: COSMOLOGY: THEORY; COSMOLOGY: DARK MATTER; COSMIC STRINGS; GALAXIES: DISTANCES AND REDSHIFTS; COSMOLOGY: LARGE-SCALE STRUCTURE OF UNIVERSE full text sources ADS | data products SIMBAD (1)

On the agreement between COBE anisotropy results and specific predictions from clusters of galaxies

The recent results from the first year of data from the COBE DMR experiment (Smoot et al. 1992) detect a large angle anisotropy in the Cosmic Microwave Background [CMB]. This first set of data seems to indicate that the scale-invariant (n = 1) spec­ trum is preferred, with an amplitude at the horizon crossing of 'H = (5.4 ± 1.6) .10- 6 (Wright et al. 1992). This level is in remarkable agreement with the value of 'H ~ (1.5/b) (6 ± 2.5) . 10- 6 , which was predicted to be the relevant one from a study of the distribution of Abell clusters which sampled large scales which correspond to angles up to twice the COBE FWHM (Scaramella 1992), where the value b - 1.5 was suggested by agreement with the observed large scale peculiar velocities. This observational agreement indicates that on the very large scales the peculiar gravitational potential has kept nearly constant from the epoch of last scattering to the present. This fact, together with the presence of large scale flows, suggests that we live in a spatially flat Universe of critical density, where optical galaxies are mildly biased with respect to the matter distribution, and with a power spectrum which, depending on the spectral index on small scales, has a turnover to n =1 in the 100 - 200 h-1 Mpc scale range. We also considered a tilted (n < 1) CDM model, and find that this model would need a small spectral index (n - 0.3) to match the cluster normalization. However, such an index would yield a too large CMB anisotropy, even without the the possible additional anisotropy due teJ the presence of a significant background of primordial gravitational waves.

Structure formation in a universe with cold plus hot dark matter

view Abstract Citations (87) References (40) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Structure Formation in a Universe with Cold Plus Hot Dark Matter van Dalen, Anthony ; Schaefer, Robert K. Abstract We examine the effect of a small admixture of hot dark matter (HDM) to the "standard" cold dark matter (CDM) model for galaxy formation. With equal amounts of HDM and CDM the growth of galactic scale density peaks in the CDM component is highly damped and galaxy formation is problematic, as has been discussed elsewhere. However, if the HDM contribution is <~ 30% then the damping is not so severe and galaxies can still form by a reasonable redshift. Further, with this amount of HDM agreement with large-scale structure observations are greatly improved over that of pure CDM. In this paper we demonstrate this by comparing the predictions of CDM and cold plus hot dark matter (CPHDM) models with the most recent observations. We will consider galactic cluster correlations, large-scale peculiar velocity flows, observationally derived power spectra, and the likelihood of finding a Great Attractor-sized object. Galaxy formation is still a computationally subtle issue, but we make some preliminary observations concerning two-point correlations and formation times. Publication: The Astrophysical Journal Pub Date: October 1992 DOI: 10.1086/171832 Bibcode: 1992ApJ...398...33V Keywords: Dark Matter; Galactic Evolution; Universe; Astronomical Models; Power Spectra; Red Shift; Transfer Functions; Astrophysics; COSMOLOGY: DARK MATTER; GALAXIES: CLUSTERING; COSMOLOGY: LARGE-SCALE STRUCTURE OF UNIVERSE full text sources ADS |

String-induced density perturbations in hot dark matter

view Abstract Citations (9) References (16) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS String-induced Density Perturbations in Hot Dark Matter Vollick, Dan N. Abstract The density and velocity perturbations produced by cosmic strings in hot dark matter are examined using the Gilbert equation. We use the results from recent numerical simulations which show that the strings have significant small-scale structure. It is shown that the string network can produce structure whose size is comparable to the size of the observed large-scale structure. It is also shown that the large-scale peculiar velocities produced by the string network are coherent over distances which are too small to account for the observed large-scale streaming motions. The role of the small-scale structure in fragmenting the wakes produced by the strings is examined. It is found that small- scale structure below a critical size cannot fragment the wakes, whereas small-scale structure larger than this critical size may be able to fragment the wakes. Publication: The Astrophysical Journal Pub Date: September 1992 DOI: 10.1086/171760 Bibcode: 1992ApJ...397...14V Keywords: Cosmology; Dark Matter; Galactic Clusters; Galactic Evolution; String Theory; Equations Of Motion; Fourier Transformation; Hubble Constant; Neutrinos; Perturbation Theory; Astrophysics; COSMIC STRINGS; COSMOLOGY: DARK MATTER; COSMOLOGY: THEORY; GALAXIES: CLUSTERING; GALAXIES: FORMATION full text sources ADS |

The large-scale velocity field beyond the local supercluster

view Abstract Citations (19) References (55) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The Large-Scale Velocity Field beyond the Local Supercluster Han, Mingsheng Abstract Relative distances of 16 clusters of galaxies in the redshift range from 3000 to 11,000 km s^-1^ are measured using the I-band Tully-Fisher relation. Different techniques of deriving distances of clusters using a distance indicator are discussed and compared in regard to the sample selection bias. The large-scale peculiar velocity field as traced by our sample clusters is found to be highly nonrandom, and appears to be a coherent flow, in the cosmic microwave background (CMB) frame; the flow is towards the general direction of the "Great Attractor," with an amplitude of some 400-600 km s^-1^ at the position of the Local Group (LG). Publication: The Astrophysical Journal Pub Date: August 1992 DOI: 10.1086/171631 Bibcode: 1992ApJ...395...75H Keywords: Astrometry; Galactic Clusters; Local Group (Astronomy); Red Shift; Galactic Evolution; Relic Radiation; Velocity Distribution; Astrophysics; GALAXIES: CLUSTERING; GALAXIES: DISTANCES AND REDSHIFTS full text sources ADS | data products SIMBAD (17) NED (15)

Tracing large-scale fluctuations back in time

view Abstract Citations (101) References (14) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Tracing Large-Scale Fluctuations Back in Time Nusser, Adi ; Dekel, Avishai Abstract A quasi-linear method for recovering the growing mode of the initial fluctuations of a cosmological gravitating system from the present large-scale peculiar velocity of density field is presented and tested. A velocity-potential field is extracted from the observed velocities as in the POTENT procedure, or from the density as in the analysis of IRAS redshift surveys, assuming that the velocity field, smoothed on a scale of a few megaparsecs, is irrotational. Assuming the Zel'dovich approximation with no orbit crossing, the potential is traced back in time by integrating a simple differential equation in Eulerian space - the Zel'dovich-Bernoulli equation. The linear velocity and density fields are computed from the linear potential by differentiation. The method is demonstrated to reconstruct the initial conditions of an N-body simulation, recovering in particular the initial Gaussian distribution of densities; the initial hills are lower and the valleys are deeper than predicted by linear theory. Maps of the initial density field in the local cosmological neighborhood based on the POTENT and IRAS analysis are presented as an illustration of a possible application. Publication: The Astrophysical Journal Pub Date: June 1992 DOI: 10.1086/171360 Bibcode: 1992ApJ...391..443N Keywords: Cosmology; Dark Matter; Galactic Clusters; Gravitation; Distribution Functions; Potential Flow; Power Spectra; Spatial Distribution; Velocity Distribution; Astrophysics; COSMOLOGY: DARK MATTER; COSMOLOGY: LARGE-SCALE STRUCTURE OF UNIVERSE; COSMOLOGY: THEORY; GALAXIES: CLUSTERING; GRAVITATION; METHODS: NUMERICAL full text sources ADS |

Small-scale structure on cosmic strings and galaxy formation.

The density perturbations produced by cosmic strings in cold dark matter are examined using the Zel'dovich approximation. We use the results from recent numerical simulations which show that the strings have significant small-scale structure. It is shown that the string network produces wakelike overdensities which may be able to account for the observed large-scale structure of the Universe. In the process of producing wakes the strings also produce large-scale peculiar velocity fields. It is shown that these velocities are coherent over distances which are too small to account for the observed large-scale streaming motions. It is also shown that the small-scale structure on the strings can fragment the wakes into pieces which have the mass of a galaxy.

Large-scale peculiar velocity fields in superclusters of galaxies

view Abstract Citations (15) References (33) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Large-Scale Peculiar Velocity Fields in Superclusters of Galaxies Gavazzi, G. ; Scodeggio, M. ; Boselli, A. ; Trinchieri, G. Abstract The Tully-Fisher relation is used to derive distances of 262 galaxies in seven clusters. Care is taken to reduce possible causes of error in the distance determination and to evaluate sources of scatter in the distance-velocity relation. The scatter in Virgo, A262 (and possibly in the Coma and Hercules superclusters) is real and is evidence of large- scale (50 Mpc) peculiar velocity fields. In the Virgo region we confirm the existence of background galaxies infalling toward the cluster (see work by Pierce and Tully) and we find evidence for infalling foreground objects. The Cancer cluster is confirmed to be an unbound collection of groups (see work by Bothun et al.). The Hubble relation is linear from 0 to 13,000 km s^-1^ with H_0_= 90+/-17 km s^-1^ Mpc. Publication: The Astrophysical Journal Pub Date: November 1991 DOI: 10.1086/170688 Bibcode: 1991ApJ...382...19G Keywords: Galactic Clusters; H Lines; Velocity Distribution; Astronomical Catalogs; Calibrating; Charge Coupled Devices; Error Analysis; Astrophysics; COSMOLOGY; GALAXIES: CLUSTERING; GALAXIES: REDSHIFTS full text sources ADS | data products SIMBAD (22) NED (7)

Large scale peculiar velocities of galaxies

We have calculated in detail the distribution of large scale peculiar velocities on assuming gaussian primordial mass perturbation and spherical symmetry, instead of the linear perturbaton approximation and window function used in usual fluid models. Calculation was made for several model universes dominated by various kinds of matter. The expected values of the peculiar velocities was found to decrease with increasing distance scale, in agreement with the conventional fluid and cosmic string models. For all acceptable parameter values our model is unable to explain the observed high peculiar velocity on a scale of 60 h −1 Mpc (Dressler et al. 1987). A reasonable explanation for the discrepancy is that there may be a region of huge mass concentration at a distance above 60 h −1 Mpc away from the Local Group.

On the coherence length of large-scale peculiar velocities and gravitational clustering

If the large-scale structure in the universe is formed by gravitational clustering of less than 0 density fluctuations, the correlation function of massive objects/clusters of the clustering hierarchy would be increased over the underlying mass autocorrelation function. This means that if light traces mass, the peculiar gravitational field on the average would be stronger when measured by galaxies associated with such clusters. This in turn would lead to larger rms peculiar velocities deduced from the motions of such samples. Ellipticals are known to populate preferentially dense regions/(rich) clusters, and it is, therefore, suggested that this mechanism is responsible for the large peculiar motions observed recently by the Seven Samurai in a sample of elliptical galaxies. On the assumption that light traces mass, these and the cluster-cluster correlation function results are consistent with gravitational clustering of n of about -1 fluctuations in Omega of about 0.2 universe. It is further shown that according to the gravitational clustering theory, galaxies selected preferentially from poor groups should exhibit small rms peculiar velocities. 21 refs.

Gauge Invariant Cosmological Perturbations with Cold Dark Matter

In the gauge-invariant formalism, the evolution of adiabatic and baryonic isocurvature density perturbations in a universe dominated by cold dark matter (CDM) is thoroughly investigated. We evaluate anisotropies in the cosmic microwave background (CMB) and large scale peculiar velocities. From the recent observations of CMB fluctuations, we find new and stringent constraint is obtained for adiabatic CDM models as S20h>0.3. As for baryonic isocurvature perturbations, though the constraint is required as .G!hI :<:;0.6, we find these baryonic isocurvature models are more viable than axion isocurvature models. However it is difficult for both adiabatic and baryonic isocurvature CDM models to explain the observed large scale velocity field at :<:; 50 hI Mpc while being consistent with the observations of CMB anisotropies.

Cosmic microwave anisotropies and large-scale velocity fields in isocurvature hot dark matter models

view Abstract Citations (15) References (17) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Cosmic Microwave Anisotropies and Large-Scale Velocity Fields in Isocurvature Hot Dark Matter Models Sugiyama, Naoshi ; Sasaki, Misao ; Tomita, Kenji Abstract We investigate the evolution of isocurvature density perturbations in a universe dominated by hot dark matter (HDM) and evaluate anisotropies in the cosmic microwave background and large-scale peculiar velocity fields. We find isocurvature HDM models are more viable than adiabatic HDM models in that the former can account for relatively large velocity fields on large scales while keeping the cosmic microwave background anisotropies below the observational upper limits as compared to the latter. However, isocurvature HDM models would still have difficulties if the actual velocity fields on scales >~ 50h^-1^ Mpc were confirmed to be substantially greater than ~400 km s^-1^. Publication: The Astrophysical Journal Pub Date: March 1989 DOI: 10.1086/185397 Bibcode: 1989ApJ...338L..45S Keywords: Astronomical Models; Background Radiation; Cosmology; Dark Matter; Microwaves; Perturbation Theory; Universe; Velocity Distribution; Astrophysics; COSMIC BACKGROUND RADIATION; COSMOLOGY; EARLY UNIVERSE full text sources ADS |

Searching for the great attractor

view Abstract Citations (60) References (20) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Searching for the Great Attractor Bertschinger, Edmund ; Juszkiewicz, Roman Abstract We test several scenarios for the growth of cosmic structure against recent observations of large-scale peculiar velocities, the velocity field being represented as (1) a dipole flow; (2) a spherical flow toward a great attractor; and (3) a minimal cylindrical model proposed by Faber and Burstein. We show that if the observationally derived flow models are correct, then all the theoretical scenarios we consider have difficulties. For the standard {OMEGA} = 1 biased cold dark matter (CDM) scenario, we confirm earlier conclusions based on the dipole flow model that the CDM predictions fail by a large margin. A drastic revision of the existing fits to the observational data would be required to save this scenario. The isocurvature baryon models (with {OMEGA} = 0.4) fare much better: they naturally lead to large-scale flows. However, these models have difficulty reproducing the observed velocity gradients. The cylindrical flow model constrains theories less than the spherical Great Attractor model does, illustrating the importance of extending present surveys to greater redshift. Publication: The Astrophysical Journal Pub Date: November 1988 DOI: 10.1086/185312 Bibcode: 1988ApJ...334L..59B Keywords: Astronomical Models; Big Bang Cosmology; Dark Matter; Galactic Clusters; Probability Density Functions; Baryons; Normal Density Functions; Statistical Tests; Velocity Distribution; Astrophysics; COSMOLOGY; GALAXIES: CLUSTERING full text sources ADS |