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Clustering real world data often faced with curse of dimensionality, where real world data often consist of many dimensions. Multidimensional data clustering evaluation can be done through a density-based approach. Density approaches based…

Databases · Computer Science 2010-12-30 Rahmat Widia Sembiring , Jasni Mohamad Zain

Base on Gaia Second Data Release and the combination of nonparametric bivariate density estimation with the least square ellipse fitting, we derive the shape parameters of the sample clusters. By analyzing the dislocation of the sample…

Astrophysics of Galaxies · Physics 2021-12-08 Qingshun Hu , Yu Zhang , Ali Esamdin

We present a comparison of two samples of z>0.8 galaxy clusters selected using different wavelength-dependent techniques and examine the physical differences between them. We consider 18 clusters from the X-ray selected XMM-LSS distant…

Cosmology and Nongalactic Astrophysics · Physics 2018-04-19 J. P. Willis , M. E. Ramos-Ceja , A. Muzzin , F. Pacaud , H. K. C. Yee , G. Wilson

The first SRG/eROSITA all-sky X-ray survey, eRASS1, resulted in a catalogue of over twelve thousand optically-confirmed galaxy groups and clusters in the western Galactic hemisphere. Using the eROSITA images of these objects, we measure and…

Cosmology and Nongalactic Astrophysics · Physics 2025-03-19 J. S. Sanders , Y. E. Bahar , E. Bulbul , V. Ghirardini , A. Liu , N. Clerc , M. E. Ramos-Ceja , T. H. Reiprich , F. Balzer , J. Comparat , M. Kluge , F. Pacaud , X. Zhang

Numerical simulations with varying realism indicate an emergent principle -- multiphase condensation and large cavity power occur when the ratio of the cooling time to the free-fall time ($t_{\rm cool}/t_{\rm ff}$) falls below a threshold…

Astrophysics of Galaxies · Physics 2022-08-22 Kartick C Sarkar , Arjun Dey , Prateek Sharma

We present a comparison of X-ray and optical luminosities and luminosity functions of cluster candidates from a joint optical/X-ray survey, the ROSAT Optical X-Ray Survey. Completely independent X-ray and optical catalogs of 23 ROSAT fields…

This is the first in a series of papers in which we measure accurate weak-lensing masses for 51 of the most X-ray luminous galaxy clusters known at redshifts 0.15<z<0.7, in order to calibrate X-ray and other mass proxies for cosmological…

Deep learning technology has enabled successful modeling of complex facial features when high quality images are available. Nonetheless, accurate modeling and recognition of human faces in real world scenarios `on the wild' or under adverse…

Computer Vision and Pattern Recognition · Computer Science 2020-11-30 S. W. Arachchilage , E. Izquierdo

We introduce a new, non-parametric method to infer deprojected 3D mass profiles $M(r)$ of galaxy clusters from weak gravitational lensing observations. The method assumes spherical symmetry and a moderately small convergence, $\kappa…

Cosmology and Nongalactic Astrophysics · Physics 2024-12-20 Tobias Mistele , Amel Durakovic

We investigate the galactic axes orientations within 18 selected clusters, sub-structures of the Local Supercluster. For every cluster we map the parameter \Delta_{11} (Flin & God{\l}owski 1986) describing the galactic axes alignment with…

Astrophysics · Physics 2009-10-31 W. Godlowski , M. Ostrowski

The cosmological constraining power of modern galaxy cluster catalogs can be improved by obtaining low-scatter mass proxy measurements for even a small fraction of sources. In the context of large upcoming surveys that will reveal the…

Cosmology and Nongalactic Astrophysics · Physics 2017-12-04 Adam B. Mantz , Steven W. Allen , R. Glenn Morris , Anja von der Linden

We present a new cluster detection algorithm designed for finding high-redshift clusters using optical/infrared imaging data. The algorithm has two main characteristics. First, it utilises each galaxy's full redshift probability function,…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-13 Caroline van Breukelen , Lee Clewley

Given the importance of clusters to the fields of cosmology and galaxy evolution, it is critical to understand how the cluster detection process affects (biases) ones scientific conclusions derived from a given cluster sample. I review the…

Astrophysics · Physics 2007-05-23 Marc Postman

We present a detailed analysis of the surface brightness distribution of the brightest cluster galaxy (BCG) in each of 24 galaxy clusters at 0.03<z<0.13. We use two-dimensional profile fitting to model the surface brightness out to r=300…

Astrophysics · Physics 2014-10-13 Anthony H. Gonzalez , Ann I. Zabludoff , Dennis Zaritsky

We measure the velocity dispersions of clusters of galaxies selected by the redMaPPer algorithm in the first three years of data from the Dark Energy Survey (DES), allowing us to probe cluster selection and richness estimation, $\lambda$,…

When it comes to clustering nonconvex shapes, two paradigms are used to find the most suitable clustering: minimum cut and maximum density. The most popular algorithms incorporating these paradigms are Spectral Clustering and DBSCAN. Both…

Machine Learning · Computer Science 2019-07-02 Sibylle Hess , Wouter Duivesteijn , Philipp Honysz , Katharina Morik

We discuss topological aspects of cluster analysis and show that inferring the topological structure of a dataset before clustering it can considerably enhance cluster detection: theoretical arguments and empirical evidence show that…

Machine Learning · Computer Science 2022-07-04 Moritz Herrmann , Daniyal Kazempour , Fabian Scheipl , Peer Kröger

Based on the ROSAT All-Sky Survey we are constructing a sample of the X-ray brightest galaxy clusters for cosmological studies. We have already completed the compilation of a sample of about 1000 clusters in the sky excluding a 40 degree…

Astrophysics · Physics 2007-05-23 H. Boehringer , P. Schuecker , S. Komossa , J. Retzlaff , T. H. Reiprich , W. Voges

This paper presents a novel clustering algorithm from the SPINEX (Similarity-based Predictions with Explainable Neighbors Exploration) algorithmic family. The newly proposed clustering variant leverages the concept of similarity and…

Machine Learning · Computer Science 2024-07-11 MZ Naser , Ahmed Naser

We study the projection effects on various observables of clusters of galaxies at redshift near zero, including cluster richness, velocity dispersion, X-ray luminosity, three total mass estimates (velocity-based, temperature-based and…

Astrophysics · Physics 2009-10-28 Renyue Cen