COSMOLOGY FROM GALAXY SURVEYS

2011 ◽  
Vol 20 (10) ◽  
pp. 2115-2119
Author(s):  
WILL J. PERCIVAL
Keyword(s):  
Power Spectrum ◽  
Three Dimensional ◽  
Density Fluctuations ◽  
Microwave Background ◽  
Peculiar Galaxy ◽  
Galaxy Surveys ◽  
Redshift Surveys ◽  
Galaxy Redshift ◽  
The Universe ◽  
Statistical Clustering

Galaxy Redshift surveys provide a three-dimensional map of the Universe. Three distinct processes that encode cosmological information in these maps, are commonly used to constrain models: (i) the comoving power spectrum shape depends on the physical properties of the early Universe, including the physical matter, baryon and neutrino densities, the inflation power spectrum and the degree of Gaussianity of density fluctuations; (ii) we can use the statistical clustering of galaxies as a standard ruler by matching it, or parts of it at different redshifts, and to the Cosmic Microwave Background (CMB); (iii) redshift-space distortions, anisotropic patterns caused by peculiar galaxy velocities, reveal structure growth. Following the design of my talk at the 1st Galileo–Xu Guangqi Meeting, I will use these proceedings to briefly review these experiments.

scholarly journals Mapping the Cosmic Web with the largest all-sky surveys

2014 ◽  
Vol 11 (S308) ◽  
pp. 143-148
Author(s):  
Maciej Bilicki ◽  
John A. Peacock ◽  
Thomas H. Jarrett ◽  
Michelle E. Cluver ◽  
Louise Steward
Keyword(s):  
Three Dimensional ◽  
Optical Data ◽  
Microwave Background ◽  
Sky Surveys ◽  
Photometric Redshift ◽  
Redshift Surveys ◽  
Cross Correlations ◽  
Galaxy Redshift ◽  
Celestial Sphere ◽  
The Universe

AbstractOur view of the low-redshift Cosmic Web has been revolutionized by galaxy redshift surveys such as 6dFGS, SDSS and 2MRS. However, the trade-off between depth and angular coverage limits a systematic three-dimensional account of the entire sky beyond the Local Volume (z< 0.05). In order to reliably map the Universe to cosmologically significant depths over the full celestial sphere, one must draw on multiwavelength datasets and state-of-the-art photometric redshift techniques. We have undertaken a dedicated program of cross-matching the largest photometric all-sky surveys – 2MASS, WISE and SuperCOSMOS – to obtain accurate redshift estimates of millions of galaxies. The first outcome of these efforts – the 2MASS Photometric Redshift catalog (2MPZ, Bilickiet al. 2014a) – has been publicly released and includes almost 1 million galaxies with a mean redshift ofz=0.08. Here we summarize how this catalog was constructed and how using the WISE mid-infrared sample together with SuperCOSMOS optical data allows us to push to redshift shells ofz∼ 0.2 –0.3 on unprecedented angular scales. Our catalogs, with ∼ 20 million sources in total, provide access to cosmological volumes crucial for studies of local galaxy flows (clustering dipole, bulk flow) and cross-correlations with the cosmic microwave background such as the integrated Sachs-Wolfe effect or lensing studies.

scholarly journals BARYONIC ACOUSTIC OSCILLATIONS VIA THE RENORMALIZATION GROUP

2008 ◽  
Vol 23 (01) ◽  
pp. 25-32 ◽  
Author(s):  
SABINO MATARRESE ◽  
MASSIMO PIETRONI
Keyword(s):  
Renormalization Group ◽  
Power Spectrum ◽  
Statistical Physics ◽  
Density Fluctuations ◽  
Quantum Field ◽  
Acoustic Oscillations ◽  
Galaxy Surveys ◽  
Energy Models ◽  
Baryonic Acoustic Oscillations ◽  
The Universe

Renormalization Group techniques, successfully employed in quantum field theory and statistical physics, are applied to study the dynamics of structure formation in the Universe. A semi-analytic approach to the computation of the nonlinear power-spectrum of dark matter density fluctuations is proposed. The method can be applied down to zero redshift and to length scales where perturbation theory fails. Our predictions accurately fit the results of numerical simulations in reproducing the "acoustic oscillations" features of the power spectrum, which will be accurately measured in future galaxy surveys and will provide a probe to distinguish among different dark energy models.

The experience of employment of the mathematical cartography methods in cosmology

2017 ◽  
Vol 923 (5) ◽  
pp. 7-16
Author(s):  
A.V. Kavrayskiy
Keyword(s):  
Background Radiation ◽  
Three Dimensional ◽  
Spherical Coordinates ◽  
Linear Element ◽  
Microwave Background ◽  
Euclidian Space ◽  
Microwave Background Radiation ◽  
Rectangular Coordinates ◽  
The Universe ◽  
Length Distortion

The experience of mathematical modeling of the 3D-sphere in the 4D-space and projecting it by mathematical cartography methods in the 3D-Euclidian space is presented. The problem is solved by introduction of spherical coordinates for the 3D-sphere and their transformation into the rectangular coordinates, using the mathematical cartography methods. The mathematical relationship for calculating the length distortion mp(s) of the ds linear element when projecting the 3D-sphere from the 4-dimensional Euclidian space into three-dimensional Euclidian space is derived. Numerical examples, containing the modeling of the ds small linear element by spherical coordinates of 3D-sphere, projecting this sphere into the 3D-Euclidian space and length of ds calculating by means of its projection dL and size of distortion mp(s) are solved. Based on the model of the Universe known in cosmology as the 3D-sphere, the hypothesis of connection between distortion mp(s) and the known observed effects Redshift and Microwave Background Radiation is considered.

scholarly journals Power-spectrum analysis of three-dimensional redshift surveys

1994 ◽  
Vol 426 ◽  
pp. 23 ◽  
Author(s):  
Hume A. Feldman ◽  
Nick Kaiser ◽  
John A. Peacock
Keyword(s):  
Power Spectrum ◽  
Spectrum Analysis ◽  
Three Dimensional ◽  
Power Spectrum Analysis ◽  
Redshift Surveys

scholarly journals Inflation, Microwave Background Anisotropy, and Open Universe Models

1996 ◽  
Vol 168 ◽  
pp. 321-327
Author(s):  
J.A. Frieman
Keyword(s):  
Early Universe ◽  
Large Scale ◽  
Large Scale Structure ◽  
Density Fluctuations ◽  
Inhomogeneous Distribution ◽  
Microwave Background ◽  
Inflationary Scenario ◽  
Open Universe ◽  
The Universe ◽  
Universe Models

The inflationary scenario for the very early universe has proven very attractive, because it can simultaneously solve a number of cosmological puzzles, such as the homogeneity of the Universe on scales exceeding the particle horizon at early times, the flatness or entropy problem, and the origin of density fluctuations for large-scale structure [1]. In this scenario, the observed Universe (roughly, the present Hubble volume) represents part of a homogeneous inflated region embedded in an inhomogeneous space-time. On scales beyond the size of this homogeneous patch, the initially inhomogeneous distribution of energy-momentum that existed prior to inflation is preserved, the scale of the inhomogeneities merely being stretched by the expansion.

scholarly journals Distribution of IRAS Galaxies

1987 ◽  
Vol 124 ◽  
pp. 229-245
Author(s):  
Michael Rowan-Robinson
Keyword(s):  
Interstellar Dust ◽  
Local Group ◽  
Big Bang ◽  
Galactic Latitude ◽  
Gravitational Acceleration ◽  
Microwave Background ◽  
High Galactic Latitude ◽  
Galaxy Surveys ◽  
Infrared Wavelengths ◽  
The Universe

Infrared wavelengths are free of several of the problems that plague optical galaxy surveys. At high galactic latitude ≥99% of 60μ sources in the IRAS Point Source Catalog, after deletion of obvious stars, are galaxies. At lower latitudes care has to be taken to avoid confusion with emission from interstellar dust (the ‘cirrus’). IRAS galaxies have been used to determined the direction of the gravitational acceleration acting on the Local Group due to galaxies and clusters within about 200 Mpc. This agrees well with the direction of the microwave background dipole. The density of matter in the universe, distributed like IRAS galaxies, needed to account for the observed velocity of the Local Group, corresponds to Ωo = 1.0 ± 0.2. In the standard hot Big Bang model, 90–95% of this matter would have to be non-baryonic.IRAS galaxies are significantly less clustered than optically selected galaxy samples.

scholarly journals CMB: Anisotropies Due to Non-Linear Clustering

1996 ◽  
Vol 168 ◽  
pp. 445-446
Author(s):  
E. Martínez-González ◽  
J. L. Sanz
Keyword(s):  
Linear Density ◽  
Gravitational Effect ◽  
Density Fluctuations ◽  
Microwave Background ◽  
Gravitational Fields ◽  
Hot Gas ◽  
Peculiar Velocities ◽  
Non Linear ◽  
Density Perturbations ◽  
The Universe

Most of the studies on the anisotropy expected in the temperature of the cosmic microwave background (CMB) have been based on linear density perturbations. The anisotropies at angular scales ≥ 1o(horizon at recombination) are preserved during the evolution of the universe, whereas for smaller scales new effects can appear, generated during the non-linear phase of matter clustering evolution: i) the Sunyaev-Zeldovich effect due to hot gas in clusters (Scaramella et al. 1993), ii) the Vishniac effect (Vishniac 1987) due to the coupling between density fluctuations and bulk motions of gas and iii) the integrated gravitational effect (Martínez–González et al. 1994) due to time-varyng gravitational potentials. A single potential φ(t, x), satisfying the Poisson equation, is enouph to describe weak gravitational fields associated to non-linear density fluctuations when one considers scales smaller than the horizon and non-relativistic peculiar velocities. The temperature anisotropies, in a flat universe, are given by the expression (Martínez–González et al. 1990)

scholarly journals Probing Density Fluctuations in the Universe with the FIRST Radio Survey

1999 ◽  
Vol 183 ◽  
pp. 244-244
Author(s):  
C.M. Cress
Keyword(s):  
Correlation Function ◽  
Power Spectrum ◽  
Angular Correlation ◽  
Density Fluctuations ◽  
Linear Evolution ◽  
Angle Measurements ◽  
Model Predictions ◽  
Non Linear ◽  
Angular Correlation Function ◽  
The Universe

We compare the angular correlation function measured for FIRST sources (Becker et al., Cress et al.) with COBE-normalized CDM-model predictions (Cress & Kamionkowski). We note that uncertainties in the z-distribution do not affect the predictions dramatically and that the effects of non-linear evolution of the power spectrum are significant for θ<∼20′. We find the CF at larger angles to be sensitive to clustering of nearby sources. The smaller angle measurements, when combined with results from other surveys (Loan et al., Rengelink et al.) indicate that the bias required for the data to fit CDM models increases as the surveys probe deeper. We also point the reader to Refregier et al. for information on the use of weak lensing of FIRST sources in probing foreground mass.

scholarly journals Photometric Calibration and Large-Scale Clustering in the Universe

1994 ◽  
Vol 161 ◽  
pp. 295-300
Author(s):  
R. Fong ◽  
N. Metcalfe ◽  
T. Shanks
Keyword(s):  
Correlation Function ◽  
Large Scale ◽  
Three Dimensional ◽  
High Signal ◽  
Galaxy Surveys ◽  
Photometric Calibration ◽  
Peculiar Velocities ◽  
Redshift Surveys ◽  
Point Correlation ◽  
Point Correlation Function

The machine measurements of UK Schmidt plates have produced two very large galaxy surveys, the APM survey and the Edinburgh-Durham Southern Galaxy Catalogue (or COSMOS survey). These surveys can constrain the power on large scales of ≳ 10h −1 Mpc better than current redshift surveys, simply because such large numbers, ≳ 2 million galaxies to bJ ≤ 20.5, provide very high signal/noise in the estimated two-point correlation function for galaxies. Furthermore, the results for the three-dimensional galaxy two point correlation function, ξ(r), obtained from the measured projected function, ω(θ), should be quite robust for reasonable model number-redshift distributions, N(z), for these magnitude limits (see, e.g., Roche et al. 1993). Another clear advantage of measuring ω(θ) is that it is unaffected by the peculiar velocities of the galaxies, whereas they have an important effect on the corresponding ξ,(s) using galaxy redshift surveys.

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