TYPICAL SCALES IN THE CLUSTERING OF THE UNIVERSE

1995 ◽  
Vol 04 (04) ◽  
pp. 417-428
Author(s):  
LI-ZHI FANG ◽  
ZU-GAN DENG ◽  
XIAO-YANG XIA
Keyword(s):  
Correlation Function ◽  
Clusters Of Galaxies ◽  
High Confidence ◽  
Scale Free ◽  
Density Perturbations ◽  
Point Correlation ◽  
Point Correlation Function ◽  
Periodic Components ◽  
The Universe ◽  
Characteristic Scales

The cosmic density perturbations are not completely scale-free, i.e. preferential scales should exist in the clustering of the universe. Observations do show the existence of the typical scales, namely, the distribution of various objects cannot be described by a simple fractal law. However, the standard two-point correlation function statistic is ineffective in detecting the typical scales. A better method based on identifying the periodic components in two-point correlation functions was developed. Using this method, the typical scales have been systematically searched for in samples of galaxies, clusters of galaxies, quasars and absorption lines of quasars. It showed the existence of typical scales in the range of 20–130 h−1 Mpc with high confidence. In particular, two typical scales, 60−1 Mpc and 130−1 Mpc, have been detected in all the samples being analysed. Such “universal” scales are probably the characteristic scales in the primordial fluctuations of the universe. Other theoretical implications of the detected typical scales have also been reviewed.

scholarly journals The Anglo-Australian Redshift Survey

1983 ◽  
Vol 104 ◽  
pp. 175-175
Author(s):  
J. Bean ◽  
G. Efstathiou ◽  
R. S. Ellis ◽  
B. A. Peterson ◽  
T. Shanks ◽  
...  
Keyword(s):  
Correlation Function ◽  
Luminosity Function ◽  
Large Scale ◽  
Peculiar Velocities ◽  
Point Correlation ◽  
Point Correlation Function ◽  
Redshift Survey ◽  
Density Inhomogeneities ◽  
The Universe

The aim of the survey is to sample a relatively large, randomly chosen volume of the Universe in order to study the large-scale distribution of galaxies using the two-point correlation function, the peculiar velocities between galaxy pairs and to provide an estimate of the galaxian luminosity function that is unaffected by density inhomogeneities and Virgo infall.

scholarly journals Studying the morphology of reionization with the triangle correlation function of phases

2019 ◽  
Vol 489 (1) ◽  
pp. 1321-1337 ◽  
Author(s):  
Adélie Gorce ◽  
Jonathan R Pritchard
Keyword(s):  
Correlation Function ◽  
Angular Resolution ◽  
Bubble Size Distribution ◽  
Statistical Estimator ◽  
Statistical Tool ◽  
Point Correlation ◽  
Point Correlation Function ◽  
Distribution Algorithms ◽  
The Fourier Transform ◽  
Characteristic Scales

ABSTRACT We present a new statistical tool, called the triangle correlation function (TCF), inspired by the earlier work of Obreschkow et al. It is derived from the three-point correlation function and aims to probe the characteristic scale of ionized regions during the epoch of reionization from 21cm interferometric observations. Unlike most works, which focus on power spectrum, i.e. amplitude information, our statistic is based on the information we can extract from the phases of the Fourier transform of the ionization field. In this perspective, it may benefit from the well-known interferometric concept of closure phases. We find that this statistical estimator performs very well on simple ionization fields. For example, with well-defined fully ionized discs, there is a peaking scale, which we can relate to the radius of the ionized bubbles. We explore the robustness of the TCF when observational effects such as angular resolution and noise are considered. We also get interesting results on fields generated by more elaborate simulations such as 21CMFAST. Although the variety of sources and ionized morphologies in the early stages of the process make its interpretation more challenging, the nature of the signal can tell us about the stage of reionization. Finally, and in contrast to other bubble size distribution algorithms, we show that the TCF can resolve two different characteristic scales in a given map.

scholarly journals Filamentary pattern in the cosmic web: galaxy filaments as pearl necklaces

2014 ◽  
Vol 11 (S308) ◽  
pp. 236-241
Author(s):  
Elmo Tempel ◽  
Maarja Bussov
Keyword(s):  
Correlation Function ◽  
Characteristic Length ◽  
Striking Feature ◽  
Characteristic Scale ◽  
Clusters Of Galaxies ◽  
Regular Pattern ◽  
Galaxy Groups ◽  
Point Correlation ◽  
Point Correlation Function

AbstractGalaxies form chains (filaments) that connect groups and clusters of galaxies. The filamentary network includes nearly half of the galaxies and is visually the most striking feature in cosmological maps. We study the distribution of galaxies along such a filamentary network, trying to find specific patterns. Our galaxy filaments are defined using the Bisous process. We use the two-point correlation function and the Rayleigh $Z$-squared statistic to study how the galaxies are distributed along the filaments. We show that galaxies and galaxy groups are not uniformly distributed along filaments, but tend to form a regular pattern. The characteristic length of the pattern is 7~$h^{-1}$Mpc. A slightly smaller characteristic length 4~$h^{-1}$Mpc can also be found, using the $Z$-squared statistic. One can say that galaxy filaments are like pearl necklaces, where the pearls are galaxy groups distributed more or less regularly along the filaments. We propose that this well defined characteristic scale could be used as a cosmological test.

scholarly journals Trans-Planckian quantum corrections and inflationary vacuum fluctuations of non-minimally coupled scalar fields

2019 ◽  
Vol 34 (33) ◽  
pp. 1950275
Author(s):  
Hiroki Matsui
Keyword(s):  
Correlation Function ◽  
Effective Potential ◽  
Density Perturbation ◽  
Scalar Fields ◽  
New Physics ◽  
Quantum Corrections ◽  
Vacuum Fluctuations ◽  
Density Perturbations ◽  
Point Correlation ◽  
Point Correlation Function

In this paper, we discuss how trans-Planckian physics affects inflationary vacuum fluctuations and primordial density perturbations. The trans-Planckian problem during inflation has been widely discussed in the literature, but it is still under debate. We reconsider this problem by using the two-point correlation function of the non-minimally coupled scalar fields and constructing the effective potential with the adiabatic (WKB) regularization or approximation. First, we clearly show that the cut-off divergence of the quantum fluctuations does not drastically change during inflation under reasonable assumptions and the corrections can be embedded in standard effective potential. Thus, the UV effects on the primordial density perturbation are well translated into the effective potential. Then, we find out the modified effective potential from the inflationary fluctuations and show how the trans-Planckian or UV corrections change the potential during inflation. We clearly show that the new physics strongly affects the inflation potential during inflation and we obtain an inflationary constraint [Formula: see text], where [Formula: see text] is the interaction coupling at the UV scale [Formula: see text].

scholarly journals Spatial correlations of extended cosmological structures

2020 ◽  
Vol 494 (3) ◽  
pp. 3227-3234
Author(s):  
V Santucho ◽  
H E Luparello ◽  
M Lares ◽  
D G Lambas ◽  
A N Ruiz ◽  
...  
Keyword(s):  
Correlation Function ◽  
Large Scale ◽  
Relative Distribution ◽  
Spatial Correlations ◽  
Large Scale Structures ◽  
Large Structures ◽  
Point Correlation ◽  
Point Correlation Function ◽  
Cosmic Voids ◽  
The Universe

ABSTRACT Studies of large-scale structures in the Universe, such as superstructures or cosmic voids, have been widely used to characterize the properties of the cosmic web through statistical analyses. On the other hand, the two-point correlation function of large-scale tracers such as galaxies or haloes provides a reliable statistical measure. However, this function applies to the spatial distribution of point-like objects, and therefore it is not appropriate for extended large structures that strongly depart from spherical symmetry. Here we present an analysis based on the standard correlation function formalism that can be applied to extended objects exhibiting arbitrary shapes. Following this approach, we compute the probability excess Ξ of having spheres sharing parts of cosmic structures with respect to a realization corresponding to a distribution of the same structures in random positions. For this aim, we identify superstructures defined as future virialized structures (FVSs) in semi-analytic galaxies in the MPDL2 MultiDark simulation. We have also identified cosmic voids to provide a joint study of their relative distribution with respect to the superstructures. Our analysis suggests that Ξ provides useful characterizations of the large-scale distribution, as suggested from an analysis of subsets of the simulation. Even when superstructure properties may exhibit negligible variations across the subsets, Ξ has the sensitivity to statistically distinguish sub-boxes that depart from the mean at larger scales. Thus, our methods can be applied in analysis of future surveys to provide characterizations of large-scale structure suitable to distinguish different theoretical scenarios.

scholarly journals The two-point correlation function of rich clusters of galaxies: results from an extended APM cluster redshift survey

1994 ◽  
Vol 271 (1) ◽  
pp. L47-L51 ◽  
Author(s):  
G. B. Dalton ◽  
R. A. C. Croft ◽  
G. Efstathiou ◽  
W. J. Sutherland ◽  
S. J. Maddox ◽  
...  
Keyword(s):  
Correlation Function ◽  
Clusters Of Galaxies ◽  
Point Correlation ◽  
Point Correlation Function ◽  
Redshift Survey

scholarly journals Results from a faint QSO redshift survey

1986 ◽  
Vol 119 ◽  
pp. 37-43
Author(s):  
T. Shanks ◽  
R. Fong ◽  
B.J. Boyle ◽  
B.A. Peterson
Keyword(s):  
Correlation Function ◽  
Luminosity Function ◽  
Ultraviolet Excess ◽  
Fibre Optic ◽  
Complete Sample ◽  
Point Correlation ◽  
Point Correlation Function ◽  
Redshift Survey ◽  
The Universe ◽  
Optic Coupler

We have used the FOCAP fibre optic coupler at the Anglo-Australian Telescope (AAT) to measure redshifts for a complete sample of ∼ 170 B ≤ 21m QSO's selected using the ultraviolet excess (UVX) criterion. We present preliminary estimates of the QSO luminosity function in discrete redshift ranges and show how these observations differentiate between models of QSO evolution. We have also investigated the clustering of QSOs in this complete sample by estimating the QSO 2-point correlation function and we use this to derive direct constraints on the homogeneity of the Universe at large scales.

HIERARCHIES IN THE LARGE-SCALE STRUCTURES OF THE UNIVERSE

2006 ◽  
Vol 15 (08) ◽  
pp. 1199-1215
Author(s):  
T. GOLDMAN ◽  
JUAN PÉREZ-MERCADER
Keyword(s):  
Correlation Function ◽  
Large Scale ◽  
Matter Density ◽  
Density Fluctuations ◽  
Mass Hierarchy ◽  
Maximal Correlation ◽  
Order Of Magnitude ◽  
Point Correlation ◽  
Point Correlation Function ◽  
The Universe

We study the common relationships that exist between the various structures in the Universe, and show that a unifying description appears when these are considered as emerging from dynamical critical phenomena characterized by complex exponents in the two-point correlation function of matter density fluctuations. Since gravity drives their formation, structures are more likely to form where there is maximal correlation in the matter density. Applying this simple principle of maximal correlation to the two-point correlation function in a scaling regime with complex exponents leads to a hierarchy of structures where: (1) the structures can be classified according to an integer and (2) there is a common real exponent for the two-point correlation function across the range of structures. This in turn implies the existence of both universal size and mass hierarchy-order relationships. We show that these relationships are in good agreement with observations, and that sizes and masses for the known structures, from Globules in the Interstellar Medium to Clusters of Galaxies, can be classified (essentially to within one order of magnitude out of more than 10 orders of magnitude) in terms of just three constants.

scholarly journals Large-Scale Structure in the Durham/Ukst Galaxy Redshift Survey

1994 ◽  
Vol 161 ◽  
pp. 693-697
Author(s):  
A. Broadbent ◽  
T. Shanks ◽  
F.G. Watson ◽  
Q.A. Parker ◽  
R. Fong ◽  
...  
Keyword(s):  
Correlation Function ◽  
Statistical Analysis ◽  
Large Scale ◽  
Large Scale Structure ◽  
Scale Structure ◽  
Point Correlation ◽  
Point Correlation Function ◽  
Redshift Survey ◽  
Galaxy Redshift ◽  
The Universe

We report on the progress of the compilation and analysis of the Durham/UKST galaxy redshift survey. This survey will probe a large contiguous volume of space within a 1500 sq. deg. area of sky around the SGP. It will contain redshifts of ∼ 4000 galaxies of bJ < 17m providing detailed information about the structure of the Universe on large scales. Large features on scales of ∼ 100h−1 Mpc are clearly visible on examination of the completed section of the survey, although a statistical analysis of the survey by means of the two-point correlation function is close to zero on scales of r > 10h−1 Mpc.

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