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We present the clustering of galaxy clusters as a useful addition to the common set of cosmological observables. The clustering of clusters probes the large-scale structure of the Universe, extending galaxy clustering analysis to the…

Cosmology and Nongalactic Astrophysics · Physics 2014-02-03 Annalisa Mana , Tommaso Giannantonio , Jochen Weller , Ben Hoyle , Gert Huetsi , Barbara Sartoris

Context. An automatic tool to derive structural parameters of semi-resolved star clusters located in crowded stellar fields in nearby galaxies is needed for homogeneous processing of archival frames. Aims. We have developed a program that…

Astrophysics of Galaxies · Physics 2015-12-31 D. Narbutis , D. Semionov , R. Stonkutė , P. de Meulenaer , T. Mineikis , A. Bridžius , V. Vansevičius

Face clustering is a promising way to scale up face recognition systems using large-scale unlabeled face images. It remains challenging to identify small or sparse face image clusters that we call hard clusters, which is caused by the…

Computer Vision and Pattern Recognition · Computer Science 2022-07-26 Yingjie Chen , Huasong Zhong , Chong Chen , Chen Shen , Jianqiang Huang , Tao Wang , Yun Liang , Qianru Sun

Clustered standard errors and approximate randomization tests are popular inference methods that allow for dependence within observations. However, they require researchers to know the cluster structure ex ante. We propose a procedure to…

Econometrics · Economics 2022-01-14 Yong Cai

Observations of young star clusters in a variety of galaxies have been used to constrain basic properties related to star-formation, such as the fraction of stars found in clusters (Gam) and the shape of the cluster mass function. However,…

Astrophysics of Galaxies · Physics 2024-12-05 Miranda Caputo , Rupali Chandar , Angus Mok , Sean Linden , Paul Goudfrooij , Bradley C. Whitmore

A new clustering accuracy measure is proposed to determine the unknown number of clusters and to assess the quality of clustering of a data set given in any dimensional space. Our validity index applies the classical nonparametric…

Methodology · Statistics 2022-02-15 Soumita Modak

The surface mass density of a cluster of galaxies, and thus its total mass, can be estimated from its lens magnification. The magnification can be determined from the variation in number counts of its background galaxies. In the weak…

Astrophysics · Physics 2009-10-30 Eelco van Kampen

Weak lensing is one of the best available diagnostic tools to measure the total density profiles of distant clusters of galaxies. Unfortunately, it suffers from the well-known mass-sheet degeneracy, so that weak lensing analyses cannot lead…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-28 Alessandro Sonnenfeld , Giuseppe Bertin , Marco Lombardi

Downsampling and feature extraction are essential procedures for 3D point cloud understanding. Existing methods are limited by the inconsistent point densities of different parts in the point cloud. In this work, we analyze the limitation…

Computer Vision and Pattern Recognition · Computer Science 2022-12-06 Qi Wang , Sheng Shi , Jiahui Li , Wuming Jiang , Xiangde Zhang

Quantitative analysis of the structure of star clusters is crucial for understanding their formation and evolution. In this article, we explore the application of fractal dimension analysis to study the evolution of star clusters, also…

Astrophysics of Galaxies · Physics 2025-07-01 N. Ussipov , A. Akhmetali , M. Zaidyn , A. Akniyazova , A. Sakan , M. Kalambay , B. Shukirgaliyev

Stellar blends, where two or more stars appear blended in an image, pose a significant visualization challenge in astronomy. Traditionally, distinguishing these blends from single stars has been costly and resource-intensive, involving…

Instrumentation and Methods for Astrophysics · Physics 2024-07-30 Chinedu Eleh , Yunli Zhang , Rafael Bidese , Benjamin W. Priest , Amanda L. Muyskens , Roberto Molinari , Nedret Billor

Many young star clusters appear to be fractal, i.e. they appear to be concentrated in a nested hierarchy of clusters within clusters. We present a new algorithm for statistically analysing the distribution of stars to quantify the level of…

Astrophysics of Galaxies · Physics 2017-01-20 S. E. Jaffa , A. P. Whitworth , O. Lomax

Clusters of galaxies, the most massive virialized systems known, provide a powerful tool for studying the structure, the mass density, and the cosmology of our universe. Clusters furnish one of the best estimates of the dynamical mass…

Astrophysics · Physics 2007-05-23 Neta A. Bahcall

We present an innovative and widely applicable approach for the detection and classification of stellar clusters, developed for the PHANGS-HST Treasury Program, an $NUV$-to-$I$ band imaging campaign of 38 spiral galaxies. Our pipeline first…

In this paper a relative number density parameter, called the neighborhood function, is introduced so that the crowded nature of the neighborhood of individual sources can be described. With this parameter one can determine the probability…

Astrophysics · Physics 2009-11-13 Yi-Ping Qin , Lian-Zhong Lv , Fu-Wen Zhang , Bin-Bin Zhang , Jin Zhang

Stellar clusters are critical constituents within galaxies: they are the result of highest-density star formation, and through their spatially and temporally correlated feedback they regulate their host galaxy evolution. We present a novel…

Astrophysics of Galaxies · Physics 2024-08-12 Marta Reina-Campos , Oleg Y. Gnedin , Alison Sills , Hui Li

Most stars do not form in isolation but as part of a cluster comprising anywhere between a few dozen to several million stars with stellar densities ranging from 0.01 to several 10$^5$ \Msun pc$^{-3}$. The majority of these clusters…

Astrophysics of Galaxies · Physics 2015-05-13 S. Pfalzner

Analysing the weak lensing distortions of the images of faint background galaxies provides a means to constrain the mass distribution of cluster galaxies and potentially to test the extent of their dark matter halos as a function of the…

Astrophysics · Physics 2008-02-03 Bernhard Geiger

The distortion of images of faint, high-redshift galaxies by light deflection at foreground clusters of galaxies can be used to determine the (projected) mass distribution of the clusters. In the case of strong distortions, which lead to…

Astrophysics · Physics 2007-05-23 Peter Schneider , Carolin Seitz

We present results from a systematic study of star formation in local galaxy clusters using 22 micron data from the Wide-field Infrared Survey Explorer (WISE). The 69 systems in our sample are drawn from the Cluster Infall Regions Survey…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-30 Sun Mi Chung , Peter R. Eisenhardt , Anthony H. Gonzalez , Spencer A. Stanford , Mark Brodwin , Daniel Stern , Thomas Jarrett