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 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 Probing Large Scale Structures in HI with GMRT

2002 ◽  
Vol 199 ◽  
pp. 108-109 ◽  
Author(s):  
S. Bharadwaj ◽  
B.B. Nath ◽  
S.K. Sethi
Keyword(s):  
Correlation Function ◽  
Brightness Temperature ◽  
Large Scale ◽  
Background Radiation ◽  
Low Frequency ◽  
Large Scale Structure ◽  
Large Scale Structures ◽  
Point Correlation ◽  
Point Correlation Function ◽  
Scale Structures

The redshifted 1420 MHz emission from the HI in unresolved Lyman-α clouds (DLA) at high z will appear as a background radiation in low frequency radio observations. We calculate the brightness temperature and the angular two-point correlation function of the fluctuations of this radiation. This can be an important probe of the large-scale structure at high z.

FRACTAL LARGE-SCALE STRUCTURE FROM A STOCHASTIC SCALING LAW MODEL

2009 ◽  
Vol 24 (22) ◽  
pp. 1743-1748 ◽  
Author(s):  
SALVATORE CAPOZZIELLO ◽  
SCOTT FUNKHOUSER
Keyword(s):  
Correlation Function ◽  
Stochastic Model ◽  
Large Scale ◽  
Scaling Law ◽  
Mass Function ◽  
Large Scale Structures ◽  
Fractal Distribution ◽  
Point Correlation ◽  
Point Correlation Function ◽  
Scale Structures

A stochastic model relating the parameters of astrophysical structures to the parameters of their granular components is applied to the formation of hierarchical, large-scale structures from galaxies assumed as point-like objects. If the density profile of galaxies on a given scale is described by a power law, then the stochastic model leads naturally to a mass function that is proportional to the square of the distance from an occupied point, which corresponds to a two-point correlation function that is inversely proportional to the distance. This result is consistent with observations indicating that galaxies are, on the largest scales, characterized by a fractal distribution with a dimension of order 2 and well-fit with transition to homogeneity at cosmological scales.

scholarly journals The Two-Point Correlation Function of Ringed Galaxies

1996 ◽  
Vol 157 ◽  
pp. 492-494
Author(s):  
Wentao Wu ◽  
Renato A. Dupke ◽  
Carlos R. Rabaça
Keyword(s):  
Correlation Function ◽  
Large Scale ◽  
Large Scale Structures ◽  
General Field ◽  
Point Correlation ◽  
Point Correlation Function ◽  
Scale Structures

AbstractWe calculate the two-point correlation function for a sample of ringed galaxies. Results are similar to that of general field galaxies. We also find evidence that these galaxies form very large scale structures.

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.

scholarly journals One- and two-point source statistics from the LOFAR Two-metre Sky Survey first data release

2020 ◽  
Vol 643 ◽  
pp. A100
Author(s):  
T. M. Siewert ◽  
C. Hale ◽  
N. Bhardwaj ◽  
M. Biermann ◽  
D. J. Bacon ◽  
...  
Keyword(s):  
Point Source ◽  
Flux Density ◽  
Large Scale ◽  
Value Added ◽  
Radio Sources ◽  
Sky Survey ◽  
Point Correlation ◽  
Point Correlation Function ◽  
The Universe ◽  
Density Threshold

Context. The LOFAR Two-metre Sky Survey (LoTSS) will eventually map the complete Northern sky and provide an excellent opportunity to study the distribution and evolution of the large-scale structure of the Universe. Aims. We test the quality of LoTSS observations through a statistical comparison of the LoTSS first data release (DR1) catalogues to expectations from the established cosmological model of a statistically isotropic and homogeneous Universe. Methods. We study the point-source completeness and define several quality cuts, in order to determine the count-in-cell statistics and differential source count statistics, and measure the angular two-point correlation function. We use the photometric redshift estimates, which are available for about half of the LoTSS-DR1 radio sources, to compare the clustering throughout the history of the Universe. Results. For the masked LoTSS-DR1 value-added source catalogue, we find a point-source completeness of 99% above flux densities of 0.8 mJy. The counts-in-cell statistic reveals that the distribution of radio sources cannot be described by a spatial Poisson process. Instead, a good fit is provided by a compound Poisson distribution. The differential source counts are in good agreement with previous findings in deep fields at low radio frequencies and with simulated catalogues from the SKA Design Study and the Tiered Radio Extragalactic Continuum Simulation. Restricting the value added source catalogue to low-noise regions and applying a flux density threshold of 2 mJy provides our most reliable estimate of the angular two-point correlation. Based on the distribution of photometric redshifts and the Planck 2018 best-fit cosmological model, the theoretically predicted angular two-point correlation between 0.1 deg and 6 deg agrees reasonably well with the measured clustering for the sub-sample of radio sources with redshift information. Conclusions. The deviation from a Poissonian distribution might be a consequence of the multi-component nature of a large number of resolved radio sources and/or of uncertainties on the flux density calibration. The angular two-point correlation function is < 10−2 at angular scales > 1 deg and up to the largest scales probed. At a 2 mJy flux density threshold and at a pivot angle of 1 deg, we find a clustering amplitude of A = (5.1 ± 0.6) × 10−3 with a slope parameter of γ = 0.74 ± 0.16. For smaller flux density thresholds, systematic issues are identified, which are most likely related to the flux density calibration of the individual pointings. We conclude that we find agreement with the expectation of large-scale statistical isotropy of the radio sky at the per cent level. The angular two-point correlation agrees well with the expectation of the cosmological standard model.

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