An approximately 300 MPC void of rich clusters of galaxies

Bahcall, Neta A.; Soneira, R. M.

doi:10.1086/160436

Cited by 31 publications

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“…• affected strongly by the galactic obscuration (Abell 1958;Bahcall & Soneira 1982b). The inclusion of clusters with estimated redshifts (Figs.…”

Section: The Cluster Samplesmentioning

confidence: 99%

“…To do this we have composed a compilation of voids in the NGH, hereafter referred to as VC, containing 39 voids of clusters of galaxies from the following sources: (1) Bahcall & Soneira (1982b) -one void of R ≥ 1 Abell clusters; (2) Batuski & Burns (1985) -22 voids of Abell clusters; (3) Einasto et al (1994) -16 voids of A/ACO clusters. We shall use the abbreviations BS, BB, and E for sources 1-3, respectively.…”

Section: Automated Comparison Of the Void Cataloguesmentioning

confidence: 99%

“…The voids in the spatial distribution of galaxies and clusters of galaxies, discovered more than two decades ago (Tifft & Gregory 1976;Gregory & Thompson 1978;Jõeveer & Einasto 1978;Kirshner et al 1981;Bahcall & Soneira 1982a, 1982b, are a dominant feature of the largescale structure (LSS) of the Universe. The observational Send offprint requests to: K.Y.…”

Section: Introductionmentioning

confidence: 99%

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A study of the large voids in the spatial distribution of galaxy clusters in the Northern Galactic Hemisphere

Stavrev¹

2000

Astron. Astrophys. Suppl. Ser.

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Abstract. We present a mapping of the large voids (D ≥ 50 h −1 Mpc) in the spatial distribution of clusters of galaxies in the Northern Galactic Hemisphere in a volume defined by galactic latitude b ≥ +30• and redshift z ≤ 0.14. Rich clusters with spectroscopically measured or photometrically estimated redshifts are used as tracers of the large-scale structure of the Universe. An automated void-search and analysis procedure which identifies a void as a system of intersecting empty spheres is applied, allowing for a description of the void dimensions, volumes and shapes more complete than in previous investigations. A number of void catalogues corresponding to different tracer types, different sources of redshift data, and different versions of the search method have been generated and analysed. Visualizations of the 2-D and 3-D distributions of voids are presented. The estimated mean dimensions of the voids of R ≥ 1 and R ≥ 0 Abell/ACO clusters are D e = 105.0 ± 5.6 h −1 Mpc and D e = 87.2 ± 4.1 h −1 Mpc, respectively, where D e is the equivalent void diameter. We have identified the poor clusters, groups, and galaxies populating the voids of rich clusters and constructed radial density profiles of the voids, which show the presence of a void hierarchy.

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“…• affected strongly by the galactic obscuration (Abell 1958;Bahcall & Soneira 1982b). The inclusion of clusters with estimated redshifts (Figs.…”

Section: The Cluster Samplesmentioning

confidence: 99%

Section: Automated Comparison Of the Void Cataloguesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A study of the large voids in the spatial distribution of galaxy clusters in the Northern Galactic Hemisphere

Stavrev¹

2000

Astron. Astrophys. Suppl. Ser.

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“…Chandrasekhar's theory (and in particular his classical formula see Chandrasekhar 1943b) is widely employed to quantify dynamical friction in a variety of situations, even if the theory developed is based on the hypothesis that the stars are distributed uniformly and it is well known that in stellar systems, the stars are not uniformly distributed, (Elson et al 1987;Wybo & Dejonghe 1995;Zwart et al 1997) in galactic systems as well, the galaxies are not uniformly distributed (Peebles 1980;Bahcall & Soneira 1982;Sarazin 1988;Liddle & Lyth 1993;White et al 1993;Strauss & Willick 1995). It is evident that an analysis of dynamical friction taking account of the inhomogeneity of astronomical systems can provide a more realistic representation of the evolution of these systems.…”

Section: Introductionmentioning

confidence: 99%

Numerical tests of dynamical friction in gravitational inhomogeneous systems

Popolo

2003

A&A

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“…For example, one may observe with a neutrino telescope 1 a cluster of several events within a small solid angle, or one may observe a large void in the distribution of rich clusters of galaxies. 2 One then wishes to determine the likelihood of the observed cluster or void arising as a statistical fluctuation, under the assumption that the objects are actually randomly distributed. Unless this probability is low, it is not reasonable to regard the signal detected by the telescope as evidence for an astrophysical point source of neutrinos, nor to regard the rich-cluster void as dramatic evidence for very large scale structure in the universe.…”

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confidence: 99%

Poisson clusters and Poisson voids

1986

Phys. Rev. Lett.

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Expressions are derived for the expected abundance of clusters and voids in a sample of randomly distributed objects.PACS numbers: 02.50.-fs, 05.40. +j The interpretation of an observed distribution of pointlike objects often involves assessing the significance of clusters of voids. For example, one may observe with a neutrino telescope 1 a cluster of several events within a small solid angle, or one may observe a large void in the distribution of rich clusters of galaxies. 2 One then wishes to determine the likelihood of the observed cluster or void arising as a statistical fluctuation, under the assumption that the objects are actually randomly distributed. Unless this probability is low, it is not reasonable to regard the signal detected by the telescope as evidence for an astrophysical point source of neutrinos, nor to regard the rich-cluster void as dramatic evidence for very large scale structure in the universe.One way to test the hypothesis that a set of points is randomly distributed is to check the validity of the Poisson formula,for the probability that a randomly selected region of volume V contains k points, if n is the mean density of the points. However, for clusters so dense or voids so dilute that the corresponding Poisson probability is extremely small, it is far more useful to know the expected number of clusters or voids located anywhere in the entire observed region. In principle, the expected abundance of such dense clusters or dilute voids could be determined by Monte Carlo simulations. However, rare occurrences are not so easily simulated, and at any rate it is evidently desirable to be able to express the answer in an analytic form. Thus, in this Letter, we derive such expressions for the expected abundance of clusters and voids in a sample of randomly distributed objects, in the limit in which the clusters or voids are rare. These formulas can be generalized to the case of correlated distributions. To illustrate their use, we apply our results to the distribution of rich clusters of galaxies in the sky. The Poisson probability P k is independent of the shape of the region in question. In contrast, to define what constitutes a cluster or void requires some specification of an acceptable shape, and the expected abundance of such configurations will, in general, depend on that specification. For example, we may decide that k objects distributed in d dimensions constitute a cluster if there is a cube of volume Kand a priori specified orientation which contains these k objects and no others. Then, as we will show, the expected number of such clusters per unit volume iswhere n is the mean density of the objects, and k is large compared to n V. For k comparable to n K, the mean number of objects in the volume V, there are typically many overlapping clusters, and the abundance of clusters is not of great interest; there is considerable arbitrariness in counting the clusters when they overlap. The OinV/k) correction in Eq.(2) depends on how the overlapping clusters are counted.A void in a d-di...

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An approximately 300 MPC void of rich clusters of galaxies

Cited by 31 publications

References 0 publications

A study of the large voids in the spatial distribution of galaxy clusters in the Northern Galactic Hemisphere

A study of the large voids in the spatial distribution of galaxy clusters in the Northern Galactic Hemisphere

Numerical tests of dynamical friction in gravitational inhomogeneous systems

Poisson clusters and Poisson voids

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