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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

We propose methods for the analysis of hierarchical clustering that fully use the multi-resolution structure provided by a dendrogram. Specifically, we propose a loss for choosing between clustering methods, a feature importance score and a…

Methodology · Statistics 2023-01-31 Luben M. C. Cabezas , Rafael Izbicki , Rafael B. Stern

Star clusters are often hard to find, as they may lie in a dense field of background objects or, because in the case of embedded clusters, they are surrounded by a more dispersed population of young stars. This paper discusses four…

Astrophysics of Galaxies · Physics 2011-02-16 S. Schmeja

We use automated surface photometry and pattern classification techniques to morphologically classify galaxies. The two-dimensional light distribution of a galaxy is reconstructed using Fourier series fits to azimuthal profiles computed in…

Astrophysics · Physics 2009-11-07 S. C. Odewahn , S. H. Cohen , R. A. Windhorst , N. S. Philip

Clustering aims to form groups of similar data points in an unsupervised regime. Yet, clustering complex datasets containing critically intertwined shapes poses significant challenges. The prevailing clustering algorithms widely depend on…

Machine Learning · Computer Science 2025-05-08 Arghya Pratihar , Kushal Bose , Swagatam Das

We devise improved photometric parameters for the morphological classification of galaxies using a bright sample from the First Data Release of the Sloan Digital Sky Survey. In addition to using an elliptical aperture concentration index…

We propose a novel method of deep spatial matching (DSM) for image retrieval. Initial ranking is based on image descriptors extracted from convolutional neural network activations by global pooling, as in recent state-of-the-art work.…

Computer Vision and Pattern Recognition · Computer Science 2019-11-19 Oriane Siméoni , Yannis Avrithis , Ondrej Chum

Spectral clustering has shown a superior performance in analyzing the cluster structure. However, its computational complexity limits its application in analyzing large-scale data. To address this problem, many low-rank matrix approximating…

Machine Learning · Computer Science 2020-07-23 Djallel Bouneffouf

We explore unsupervised machine learning for galaxy morphology analyses using a combination of feature extraction with a vector-quantised variational autoencoder (VQ-VAE) and hierarchical clustering (HC). We propose a new methodology that…

We have developed a multiscale structure identification algorithm for the detection of overdensities in galaxy data that identifies structures having radii within a user-defined range. Our "multiscale probability mapping" technique combines…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-03 Anthony G. Smith , Andrew M. Hopkins , Richard W. Hunstead , Kevin A. Pimbblet

The total masses of galaxy clusters characterize many aspects of astrophysics and the underlying cosmology. It is crucial to obtain reliable and accurate mass estimates for numerous galaxy clusters over a wide range of redshifts and mass…

Instrumentation and Methods for Astrophysics · Physics 2022-03-30 Sheng-Chieh Lin , Yuanyuan Su , Gongbo Liang , Yuanyuan Zhang , Nathan Jacobs , Yu Zhang

Galaxy edges or truncations are low-surface-brightness (LSB) features located in the galaxy outskirts that delimit the distance up to where the gas density enables efficient star formation. As such, they could be interpreted as a…

Astrophysics of Galaxies · Physics 2023-12-20 Jesús Fernández , Fernando Buitrago , Benjamín Sahelices

We present a new method to detect meteor showers using the Density-Based Spatial Clustering of Applications with Noise algorithm (DBSCAN; Ester et al. 1996). DBSCAN is a modern cluster detection algorithm that is well suited to the problem…

Earth and Planetary Astrophysics · Physics 2018-03-14 Glenn Sugar , Althea Moorhead , Peter Brown , Bill Cooke

Classifying galaxies is an essential step for studying their structures and dynamics. Using GalaxyZoo2 (GZ2) fractions thresholds, we collect 545 and 11,735 samples in non-galaxy and galaxy classes, respectively. We compute the Zernike…

Instrumentation and Methods for Astrophysics · Physics 2025-01-20 Hamed Ghaderi , Nasibe Alipour , Hossein Safari

In order to study the galaxy population of galaxy clusters with photometric data one must be able to accurately discriminate between cluster members and non-members. The redMaPPer cluster finding algorithm treats this problem…

Cosmology and Nongalactic Astrophysics · Physics 2015-08-19 Eduardo Rozo , Eli S. Rykoff , Matthew Becker , Rachel M. Reddick , Risa H. Wechsler

We investigate the cosmological implications of studying galaxy clustering using a tomographic approach applied to the final BOSS DR12 galaxy sample, including both auto- and cross-correlation functions between redshift shells. We model the…

In this paper we propose a Deep Autoencoder MIxture Clustering (DAMIC) algorithm based on a mixture of deep autoencoders where each cluster is represented by an autoencoder. A clustering network transforms the data into another space and…

Machine Learning · Computer Science 2019-03-28 Shlomo E. Chazan , Sharon Gannot , Jacob Goldberger

Clustering is a commonly used method for exploring and analysing data where the primary objective is to categorise observations into similar clusters. In recent decades, several algorithms and methods have been developed for analysing…

Machine Learning · Computer Science 2021-02-17 Bryar A. Hassan , Tarik A. Rashid

We present Classification of Cluster GAlaxy MEmbers (C$^2$-GaMe), a classification algorithm based on a suite of machine learning models that differentiates galaxies into orbiting, infalling, and background (interloper) populations, using…

Cosmology and Nongalactic Astrophysics · Physics 2023-09-25 Daniel Farid , Han Aung , Daisuke Nagai , Arya Farahi , Eduardo Rozo

We describe the construction of catalogues of galaxy clusters from the APM Galaxy survey using an automated algorithm based on Abell-like selection criteria. We investigate the effects of varying several parameters in our selection…

Astrophysics · Physics 2015-06-24 Gavin Dalton , Steve Maddox , Will Sutherland , George Efstathiou