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Wide-angle, moderately deep redshift surveys such as that conducted as part of the Sloan Digital Sky Survey (SDSS) allow study of the relationship between the structural elements of the large-scale distribution of galaxies -- including…

Astrophysics · Physics 2009-11-10 Michael S. Vogeley , Fiona Hoyle , Randall R. Rojas , David M. Goldberg

Based on a recent photometric redshift galaxy catalogue, we have searched for galaxy clusters in the Stripe~82 region of the Sloan Digital Sky Survey by applying the Adami & MAzure Cluster FInder (AMACFI). Extensive tests were made to…

Superclusters are the largest relatively isolated systems in the cosmic web. Using the SDSS BOSS survey we search for the largest superclusters in the redshift range $0.43<z<0.71$. We generate a luminosity-density field smoothed over $8…

Cosmology and Nongalactic Astrophysics · Physics 2016-03-16 H. Lietzen , E. Tempel , L. J. Liivamägi , A. Montero-Dorta , M. Einasto , A. Streblyanska , C. Maraston , J. A. Rubiño-Martín , E. Saar

We measure the large-scale intrinsic alignments of galaxy clusters in the Sloan Digital Sky Survey (SDSS) using subsets of two cluster catalogues: 6625 clusters with 0.1<z<0.3 from the maxBCG cluster catalogue (Koester et al. 2007, 7500 sq.…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-30 A. Smargon , R. Mandelbaum , N. Bahcall , M. Niederste-Ostholt

The Pisces-Cetus supercluster (redshift z~0.06) is one of the richest nearby (z<0.1) superclusters of galaxies, and emerges as a remarkable filament of galaxies at the edges of the two-degree-field galaxy redshift survey and the ongoing…

Astrophysics · Physics 2009-11-13 Scott C. Porter , Somak Raychaudhury

We interpret and model the statistical weak lensing measurements around 130,000 groups and clusters of galaxies in the Sloan Digital Sky Survey presented by Sheldon et al. 2007 (Paper I). We present non-parametric inversions of the 2D shear…

We analyse a catalogue of simulated clusters within the theoretical framework of the Spherical Collapse Model (SCM), and demonstrate that the relation between the infall velocity of member galaxies and the cluster matter overdensity can be…

Cosmology and Nongalactic Astrophysics · Physics 2015-03-13 Guido Cupani , Marino Mezzetti , Fabio Mardirossian

Imaging data from the Sloan Digital Sky Survey is used to measure the empirical size-richness relation for a large sample of galaxy clusters. Using population subtraction methods, we determine the radius at which the cluster galaxy number…

In this work, we identify and analyse the properties of cluster-cluster filaments within a cosmological simulation assuming that they are structures connecting maxima of the density field defined by dark matter halos with masses $M \, \ge…

Cosmology and Nongalactic Astrophysics · Physics 2020-11-25 Luis A. Pereyra , Mario A. Sgró , Manuel E. Merchán , Federico A. Stasyszyn , Dante J. Paz

It is important to identify the discriminative features for high dimensional clustering. However, due to the lack of cluster labels, the regularization methods developed for supervised feature selection can not be directly applied. To learn…

Machine Learning · Statistics 2025-07-16 Zhaoyu Xing , Yang Wan , Juan Wen , Wei Zhong

We revisit the scaling relations and star-forming histories of local elliptical galaxies using a novel selection method applied to the Sloan Digital Sky Survey DR7. We combine two probability-based automated spectroscopic and morphological…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-03 J. A. L. Aguerri , M. Huertas-Company , J. Sánchez Almeida , C. Munoz-Tunon

In cluster analysis, a common first step is to scale the data aiming to better partition them into clusters. Even though many different techniques have throughout many years been introduced to this end, it is probably fair to say that the…

Machine Learning · Computer Science 2023-05-30 Eduardo J. Aguilar , Valmir C. Barbosa

Methods. We used different galaxy classification techniques: human labeling, multi-photometry diagrams, Naive Bayes, Logistic Regression, Support Vector Machine, Random Forest, k-Nearest Neighbors, and k-fold validation. Results. We present…

Astrophysics of Galaxies · Physics 2021-06-09 I. B. Vavilova , D. V. Dobrycheva , M. Yu. Vasylenko , A. A. Elyiv , O. V. Melnyk , V. Khramtsov

We present a novel method for automatically detecting and characterising semi-resolved star clusters: clusters where the observational point-spread function (PSF) is smaller than the cluster's radius, but larger than the separations between…

We present the "C4 Cluster Catalog", a new sample of 748 clusters of galaxies identified in the spectroscopic sample of the Second Data Release (DR2) of the Sloan Digital Sky Survey (SDSS). The C4 cluster--finding algorithm identifies…

Superclusters are the largest, observed matter density structures in the Universe. Recently Chon et al.(2013) presented the first supercluster catalogue constructed with a well-defined selection function based on the X-ray flux-limited…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-22 Gayoung Chon , Hans Boehringer , Chris Collins , Martin Krause

We investigate properties of the correlation function of clusters of galaxies using geometrical models. On small scales the correlation function depends on the shape and the size of superclusters. On large scales it describes the geometry…

Astrophysics · Physics 2015-06-24 J. Einasto , M. Einasto , P. Frisch , S. Gottlöber , V. Müller , V. Saar , A. A. Starobinsky , D. Tucker

This paper presents a model for a dynamical system where particles dominate edges in a complex network. The proposed dynamical system is then extended to an application on the problem of community detection and data clustering. In the case…

Social and Information Networks · Computer Science 2017-05-17 Paulo Roberto Urio , Zhao Liang

We analyse the first publicly released deep field of the UKIDSS Deep eXtragalactic Survey (DXS) to identify candidate galaxy over-densities at z~1 across ~1 sq. degree in the ELAIS-N1 field. Using I-K, J-K and K-3.6um colours we identify…

We extract groups of galaxies from the SDSS Data Release 5 with the purpose of studying the supercluster-void network and environmental properties of groups therein. We use a modified friends-of-friends (FoF) method with adopted variable…

Astrophysics · Physics 2009-06-23 E. Tago , J. Einasto , E. Saar , E. Tempel , M. Einasto , J. Vennik , V. Müller
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