A Simple Void‐searching Algorithm

Aikio, Janne; Mähönen, Petri

doi:10.1086/305509

Cited by 49 publications

(62 citation statements)

References 20 publications

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“…To calculate the separation between each isolated galaxy and its nearest neighboring SDSS galaxy, we introduce the concept of a distance field (Stavrev 1990). Such an approach has been applied also by Frisch et al (1995), Lindner et al (1995), and Aikio & Maehoenen (1998).…”

Section: Nearest Neighbor and Comparison With A Field Samplementioning

confidence: 99%

A Catalog of Very Isolated Galaxies from the Sloan Digital Sky Survey Data Release 1

et al. 2005

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We present a new catalog of isolated galaxies obtained through an automated systematic search. These 2980 isolated galaxies were found in %2099 deg 2 of sky in the Sloan Digital Sky Survey Data Release 1 (SDSS DR1) photometry. The selection algorithm, implementing a variation on the criteria developed by Karachentseva in 1973, proved to be very efficient and fast. This catalog will be useful for studies of the general galaxy characteristics. Here we report on our results.

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Section: Nearest Neighbor and Comparison With A Field Samplementioning

confidence: 99%

A Catalog of Very Isolated Galaxies from the Sloan Digital Sky Survey Data Release 1

et al. 2005

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“…two void-detection algorithms that are distinguished by their ease of use and clarity of conception. The Ðrst algorithm, based on that of Ryden (1995), identiÐes voids as nonoverlapping spheres ; we call this the "" sphere algorithm.ÏÏ The second algorithm, based on that of Aikio & (1998), permits voids to be nonspherical ; we call Mahonen this the "" AM algorithm.ÏÏ Both void-detection algorithms start by deÐning a continuous scalar Ðeld within the galaxy survey. At any…”

Section: Void-detection Algorithmsmentioning

confidence: 99%

“…The introduction of additional parameters makes the search through parameter space far more time-consuming. Thus, instead of approximating the shape of voids by Ðtting ellipsoids to them, we adopted the more Ñexible scheme of Aikio & (1998 ; the AM algorithm). Mahonen To implement the AM algorithm, we start with the Ðeld as deÐned on the Cartesian grid that we have superim-D f posed on the galaxy survey.…”

Section: Void-detection Algorithmsmentioning

confidence: 99%

“…The full spectrum of void sizes in a particular galaxy sample is given by the fraction of the total volume of the F f (V ), sample found in voids with volume ºV . The left column of Figure 6 shows the distribution of void volumes using F 0 , the original algorithm of Aikio & (1998), in which Mahonen f \ 0. The right column of Figure 6 displays using our F 0.2 , usual underdense criterion, f \ 0.2.…”

Section: Void-detection Algorithmsmentioning

confidence: 99%

“…Although this algorithm is conceptually simple, it has the disadvantage of forcing voids to be spherical. Thus, we also employ a more sophisticated algorithm, based on that of Aikio & (1998 ; hereafter the AM algorithm), Mahonen which does not constrain voids to be any particular shape. The original AM algorithm deÐnes voids as empty regions ; our modiÐcation of the original deÐnes voids as underdense regions.…”

Section: Introductionmentioning

confidence: 99%

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The Size and Shape of Voids in Three‐dimensional Galaxy Surveys

Schmidt¹,

Ryden²,

Melott³

2001

ApJ

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The sizes and shapes of voids in a galaxy survey depend not only on the physics of structure formation, but also on the sampling density of the survey and on the algorithm used to deÐne voids. Using an N-body simulation with a qCDM power spectrum, we study the properties of voids in samples with di †erent number densities of galaxies, in both redshift space and real space. When voids are deÐned as totally empty regions of space, their characteristic volume is strongly dependent on sampling density ; when they are deÐned as regions whose density is 0.2 times the mean galaxy density, the dependence is less strong. We compare two void-Ðnding algorithms, one in which voids are nonoverlapping spheres, and one, based on the algorithm of Aikio & that does not predeÐne the shape of a void. Mahonen, Regardless of the algorithm chosen, the characteristic void size is larger in redshift space than in real space, and is larger for low sampling densities than for high sampling densities. We deÐne an elongation statistic Q that measures the tendency of voids to be stretched or squashed along the line of sight. Using this statistic, we Ðnd that at sufficiently high sampling densities (comparable to the number density of galaxies), large voids tend to be slightly elongated along the line of sight in redshift space.

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Observations and Morphology of the Cosmic Web

Weygaert

Bond

2008

A Pan-Chromatic View of Clusters of Galaxies and the Large-Scale Structure

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A Simple Void‐searching Algorithm

Cited by 49 publications

References 20 publications

A Catalog of Very Isolated Galaxies from the Sloan Digital Sky Survey Data Release 1

A Catalog of Very Isolated Galaxies from the Sloan Digital Sky Survey Data Release 1

The Size and Shape of Voids in Three‐dimensional Galaxy Surveys

Observations and Morphology of the Cosmic Web

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