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What is the best way to divide a rugged landscape? Since ancient times, watersheds separating adjacent water systems that flow, for example, toward different seas, have been used to delimit boundaries. Interestingly, serious and even tense…

Geophysics · Physics 2014-12-19 N. A. M. Araújo , K. J. Schrenk , H. J. Herrmann , J. S. Andrade

Superclusters are the most massive structures in the universe. To what degree they are actually bound against an accelerating expansion of the background is of significant cosmological and astrophysical interest. In this study, we introduce…

Cosmology and Nongalactic Astrophysics · Physics 2025-11-05 B. A. Seidel , K. Dolag , R. -S. Remus , J. G. Sorce , E. Hernández-Martínez , I. Khabibullin , N. Aghanim

Galaxy superclusters, the largest galaxy structures in the cosmic web, are formed due to the gravitational collapse (although they are not usually gravitationally bound). Their geometrical properties can shed light on the structure…

Cosmology and Nongalactic Astrophysics · Physics 2023-04-20 Satadru Bag , Lauri Juhan Liivamägi , Maret Einasto

The problem of dimension reduction is of increasing importance in modern data analysis. In this paper, we consider modeling the collection of points in a high dimensional space as a union of low dimensional subspaces. In particular we…

Machine Learning · Statistics 2020-06-12 Weiwei Li , Jan Hannig , Sayan Mukherjee

The evolution of marginally bound supercluster-like objects in an accelerating LambdaCDM Universe is followed, by means of cosmological simulations, from the present time to an expansion factor a = 100. The objects are identified on the…

The large-scale structure of the universe can only be observed via luminous tracers of the dark matter. However, the clustering statistics of tracers are biased and depend on various properties, such as their host-halo mass and assembly…

Cosmology and Nongalactic Astrophysics · Physics 2017-08-24 Giorgia Pollina , Nico Hamaus , Klaus Dolag , Jochen Weller , Marco Baldi , Lauro Moscardini

We report here the first systematic study of the supercluster-void network in the LCDM concordance cosmology in which voids and superclusters are treated on an equal footing. Superclusters are defined as individual members of an over-dense…

Astrophysics · Physics 2009-07-07 S. F. Shandarin , J. V. Sheth , V. Sahni

We have examined the spatial distribution of substructure in clusters of galaxies using Einstein X-ray observations. Subclusters are found to have a markedly anisotropic distribution that reflects the surrounding matter distribution on…

Astrophysics · Physics 2009-10-28 Michael J. West , Christine Jones , William Forman

Subspace clustering is an important unsupervised clustering approach. It is based on the assumption that the high-dimensional data points are approximately distributed around several low-dimensional linear subspaces. The majority of the…

Machine Learning · Computer Science 2021-12-20 Maryam Abdolali , Nicolas Gillis

We apply the principal component analysis and Spearman's correlation test to study the properties of superclusters drawn from the SDSS DR7. We analyse possible selection effects in the supercluster catalogue, study the physical and…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-30 M. Einasto , L. J. Liivamagi , E. Saar , J. Einasto , E. Tempel , E. Tago , V. J. Martinez

We use catalogues of superclusters of galaxies from the 2dF Galaxy Redshift Survey to study the properties of galaxies in superclusters. We compare the properties of galaxies in high and low density regions of rich superclusters, in poor…

Visual grouping is a key mechanism in human scene perception. There, it belongs to the subconscious, early processing and is key prerequisite for other high level tasks such as recognition. In this paper, we introduce an efficient, realtime…

Computer Vision and Pattern Recognition · Computer Science 2016-09-23 Dominik Alexander Klein , Dirk Schulz , Armin Bernd Cremers

To obtain a physically well-motivated definition of superclusters, we proposed in our previous work to select superclusters with an overdensity criterion that selects only those objects that will collapse in the future, including those that…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-23 Gayoung Chon , Hans Boehringer , Saleem Zaroubi

Two-dimensional high-resolution density field of galaxies of the Early Data Release of the Sloan Digital Sky Survey with a smoothing lengths 0.8 h^{-1} Mpc is applied to extract clusters of galaxies, and a low-resolution field with…

Astrophysics · Physics 2011-03-03 J. Einasto , G. H"utsi , M. Einasto , E. Saar , D. L. Tucker , V. M"uller , P. Hein"am"aki , S. S. Allam

We studied superclusters of galaxies in a volume-limited sample extracted from the Sloan Digital Sky Survey Data Release 7 (SDSS/DR7) and from mock catalogues based on a semi-analytical model of galaxy evolution in the Millenium Simulation.…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-20 M. V. Costa-Duarte , L. Sodré , F. Durret

In this paper, we present a deep extension of Sparse Subspace Clustering, termed Deep Sparse Subspace Clustering (DSSC). Regularized by the unit sphere distribution assumption for the learned deep features, DSSC can infer a new data…

Computer Vision and Pattern Recognition · Computer Science 2017-09-26 Xi Peng , Jiashi Feng , Shijie Xiao , Jiwen Lu , Zhang Yi , Shuicheng Yan

The universe's large-scale structure forms a vast, interconnected network of filaments, sheets, and voids known as the cosmic web. For decades, astronomers have observed that the orientations of neighboring galaxy clusters within these…

Cosmology and Nongalactic Astrophysics · Physics 2025-06-25 Michael J. West , Roberto De Propris , Maret Einasto , Z. L. Wen , J. L. Han

The large scale structure of the universe is a complex web of clusters, filaments, and voids. Its properties are informed by galaxy redshift surveys and measurements of peculiar velocities. Wiener Filter reconstructions recover…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-16 Helene M. Courtois , Daniel Pomarede , R. Brent Tully , Yehuda Hoffman , Denis Courtois

We present a method for hierarchical image segmentation that defines a disaffinity graph on the image, over-segments it into watershed basins, defines a new graph on the basins, and then merges basins with a modified, size-dependent version…

Computer Vision and Pattern Recognition · Computer Science 2015-05-04 Aleksandar Zlateski , H. Sebastian Seung

Mode-based clustering methods define clusters to be the basins of attraction of the modes of a density estimate. The most common version is mean shift clus- tering which uses a gradient ascent algorithm to find the basins. Rodriguez and…

Methodology · Statistics 2018-05-14 Isabella Verdinelli , Larry Wasserman