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Clusters of galaxies are important laboratories for understanding both galaxy evolution and constraining cosmological quantities. Any analysis of clusters, however, is best done when one can reliably determine which galaxies are members of…

Astrophysics · Physics 2009-10-31 R. J. Brunner , L. M. Lubin

Application of K-Means algorithm is restricted by the fact that the number of clusters should be known beforehand. Previously suggested methods to solve this problem are either ad hoc or require parametric assumptions and complicated…

Machine Learning · Computer Science 2019-12-05 Sukavanan Nanjundan , Shreeviknesh Sankaran , C. R. Arjun , G. Paavai Anand

We discuss various analytical approximation methods for following the evolution of cosmological density perturbations into the strong (i.e. nonlinear) clustering regime. These methods can be classified into five types: (i) simple…

Astrophysics · Physics 2008-11-26 Varun Sahni , Peter Coles

We present a machine learning (ML) pipeline to identify star clusters in the multi{color images of nearby galaxies, from observations obtained with the Hubble Space Telescope as part of the Treasury Project LEGUS (Legacy ExtraGalactic…

Astrophysics of Galaxies · Physics 2021-02-10 Gustavo Perez , Matteo Messa , Daniela Calzetti , Subhransu Maji , Dooseok Jung , Angela Adamo , Mattia Siressi

We report on the identification of 54 embedded clusters around 217 massive protostellar candidates of which 34 clusters are new detections. The embedded clusters are identified as stellar surface density enhancements in the 2 $\mu$m All Sky…

Astrophysics · Physics 2018-06-19 M. S. N. Kumar , E. Keto , E. Clerkin

The method of Hol\'y, Sokol and \v{C}ern\'y (Applied Soft Computing, 2017, Vol. 60, p. 752-762) clusters objects based on their incidence in a large number of given sets. The idea is to minimize the occurrence of multiple objects from the…

Artificial Intelligence · Computer Science 2021-02-03 Ondřej Sokol , Vladimír Holý

Density-based clustering is the most popular clustering algorithm since it can identify clusters of arbitrary shape as long as they are separated by low-density regions. However, a high-density region that is not separated by low-density…

Machine Learning · Computer Science 2025-02-17 Hao Shu

We develop the Blooming Tree Algorithm, a new technique that uses spectroscopic redshift data alone to identify the substructures and the surrounding groups of galaxy clusters, along with their member galaxies. Based on the estimated…

Astrophysics of Galaxies · Physics 2018-06-21 Heng Yu , Antonaldo Diaferio , Ana Laura Serra , Marco Baldi

The sample of known star clusters, the fundamental building blocks of galaxies, in the Milky Way is still extremely incomplete for objects beyond a distance of 1-2kpc. Many of the more distant and young clusters are compact and hidden…

Astrophysics of Galaxies · Physics 2017-07-19 D. Froebrich

We study the relationship between the field star formation and cluster formation properties in a large sample of nearby dwarf galaxies. We use optical data from the Hubble Space Telescope and from ground-based telescopes to derive the ages…

Stars form predominantly in groups usually denoted as clusters or associations. The observed stellar groups display a broad spectrum of masses, sizes and other properties, so it is often assumed that there is no underlying structure in this…

Solar and Stellar Astrophysics · Physics 2016-02-03 S. Pfalzner , H. Kirk , A. Sills , J. S. Urquhart , J. Kauffmann , M. A. Kuhn , A. Bhandare , K. M. Menten

A direct approach to studying the galaxy-halo connection is to analyze groups and clusters of galaxies that trace the underlying dark matter halos, emphasizing the importance of identifying galaxy clusters and their associated brightest…

Cosmology and Nongalactic Astrophysics · Physics 2025-01-22 Hai-Xia Ma , Tsutomu T. Takeuchi , Suchetha Cooray , Yongda Zhu

We propose the DPSM method, a density-based node clustering approach that automatically determines the number of clusters and can be applied in both data space and graph space. Unlike traditional density-based clustering methods, which…

Machine Learning · Computer Science 2024-11-05 Feiping Nie , Yitao Song , Jingjing Xue , Rong Wang , Xuelong Li

We study the potential of weak lensing surveys to detect clusters of galaxies, using a fast Particle Mesh cosmological N-body simulation algorithm specifically tailored to investigate the statistics of these mass-selected clusters. In…

Astrophysics · Physics 2009-11-10 Joseph F. Hennawi , David N. Spergel

The problem of finding clusters in complex networks has been extensively studied by mathematicians, computer scientists and, more recently, by physicists. Many of the existing algorithms partition a network into clear clusters, without…

Disordered Systems and Neural Networks · Physics 2009-11-11 David Gfeller , Jean-Cédric Chappelier , Paolo De Los Rios

Close encounters between stars in star forming regions are important as they can perturb or destroy protoplanetary discs, young planetary systems, and stellar multiple systems. We simulate simple, viralised, equal-mass $N$-body star…

Astrophysics of Galaxies · Physics 2023-04-26 Krisada Rawiraswattana , Simon P. Goodwin

Galaxy clusters are usually detected in blind optical surveys via suitable filtering methods. We present an optimal matched filter which maximizes their signal-to-noise ratio by taking advantage of the knowledge we have of their intrinsic…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-19 Fabio Bellagamba , Matteo Maturi , Takashi Hamana , Massimo Meneghetti , Satoshi Miyazaki , Lauro Moscardini

Star clusters stand at the intersection of much of modern astrophysics: the interstellar medium, gravitational dynamics, stellar evolution, and cosmology. Here we review observations and theoretical models for the formation, evolution, and…

Astrophysics of Galaxies · Physics 2019-09-11 Mark R. Krumholz , Christopher F. McKee , Joss Bland-Hawthorn

Investigations of mass segregation are of vital interest for the understanding of the formation and dynamical evolution of stellar systems on a wide range of spatial scales. Our method is based on the minimum spanning tree (MST) that serves…

Astrophysics of Galaxies · Physics 2015-05-28 C. Olczak , R. Spurzem , Th. Henning

Most density-based clustering methods largely rely on how well the underlying density is estimated. However, density estimation itself is also a challenging problem, especially the determination of the kernel bandwidth. A large bandwidth…

Machine Learning · Statistics 2015-12-08 Teng Qiu , Yongjie Li