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Two colour photometry of the cluster A1689 reveals a `relative magnification-bias' between lensed blue and red background galaxies, arising from a dependence of the faint galaxy count-slope on colour. The colour distribution is skewed…

Astrophysics · Physics 2007-05-23 Tom Broadhurst

The properties of clusters of galaxies offer key insights into the assembly process of structure in the universe. Numerical simulations of cosmic structure formation in a hierarchical, dark matter dominated universe suggest that galaxy…

Astrophysics · Physics 2008-11-26 Julia M. Comerford , Priyamvada Natarajan

The Gaia Data Release 2 (DR2) provided an unprecedented volume of precise astrometric and excellent photometric data. In terms of data mining the Gaia catalogue, machine learning methods have shown to be a powerful tool, for instance in the…

Astrophysics of Galaxies · Physics 2019-07-03 A. Castro-Ginard , C. Jordi , X. Luri , T. Cantat-Gaudin , L. Balaguer-Núñez

Clusters of galaxies can be identified from peaks in weak lensing aperture mass maps constructed from weak lensing shear catalogs. Such purely gravitational cluster selection considerably differs from traditional cluster selections based on…

Cosmology and Nongalactic Astrophysics · Physics 2025-04-25 Masamune Oguri , Satoshi Miyazaki

Parametric modeling of galaxy cluster density profiles from weak lensing observations leads to a mass bias, whose detailed understanding is critical in deriving accurate mass-observable relations for constraining cosmological models.…

Cosmology and Nongalactic Astrophysics · Physics 2021-11-17 Martin W. Sommer , Tim Schrabback , Douglas E. Applegate , Stefan Hilbert , Behzad Ansarinejad , Benjamin Floyd , Sebastian Grandis

In machine learning and data mining, Cluster analysis is one of the most widely used unsupervised learning technique. Philosophy of this algorithm is to find similar data items and group them together based on any distance function in…

Machine Learning · Statistics 2018-10-09 Kumarjit Pathak , Jitin Kapila

Clustering is one of the most fundamental and wide-spread techniques in exploratory data analysis. Yet, the basic approach to clustering has not really changed: a practitioner hand-picks a task-specific clustering loss to optimize and fit…

Machine Learning · Computer Science 2019-11-01 Yibo Jiang , Nakul Verma

As language models become more general purpose, increased attention needs to be paid to detecting out-of-distribution (OOD) instances, i.e., those not belonging to any of the distributions seen during training. Existing methods for…

Machine Learning · Computer Science 2024-07-19 Aryan Gulati , Xingjian Dong , Carlos Hurtado , Sarath Shekkizhar , Swabha Swayamdipta , Antonio Ortega

Clustering analysis of functional data, which comprises observations that evolve continuously over time or space, has gained increasing attention across various scientific disciplines. Practical applications often involve functional data…

Methodology · Statistics 2024-06-19 Tingyu Zhu , Lan Xue , Carmen Tekwe , Keith Diaz , Mark Benden , Roger Zoh

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 propose a Fourier-based approach for optimization of several clustering algorithms. Mathematically, clusters data can be described by a density function represented by the Dirac mixture distribution. The density function can be smoothed…

Machine Learning · Computer Science 2019-09-24 Soheil Mehrabkhani

We aim to investigate the polarization properties of a starless core in a very early evolutionary stage. Linear polarization data reveal the properties of the dust grains in the distinct phases of the interstellar medium. Our goal is to…

Solar and Stellar Astrophysics · Physics 2014-09-17 Felipe Alves , Pau Frau , Josep M. Girart , Gabriel A. P. Franco , Fábio P. Santos , Helmut Wiesemeyer

We present an algorithm of clustering of many-dimensional objects, where only the distances between objects are used. Centers of classes are found with the aid of neuron-like procedure with lateral inhibition. The result of clustering does…

Computer Vision and Pattern Recognition · Computer Science 2007-05-23 Leonid B. Litinskii , Dmitry E. Romanov

Clusters of galaxies have a huge mass which can act as gravitational lenses. Galaxies behind clusters can be distorted to form arcs in images by the lenses. Herein a search was done for giant lensed arcs by galaxy clusters using the SDSS…

Cosmology and Nongalactic Astrophysics · Physics 2013-10-21 S. M. Liang , Z. L. Wen , J. L. Han , Y. Y. Jiang

K-means algorithm is a very popular clustering algorithm which is famous for its simplicity. Distance measure plays a very important rule on the performance of this algorithm. We have different distance measure techniques available. But…

Machine Learning · Computer Science 2014-05-30 Mr. Dibya Jyoti Bora , Dr. Anil Kumar Gupta

Currently, density-based clustering algorithms are widely applied because they can detect clusters with arbitrary shapes. However, they perform poorly in measuring global density, determining reasonable cluster centers or structures,…

Machine Learning · Computer Science 2023-11-02 Mingjie Cai , Zhishan Wu , Qingguo Li , Feng Xu , Jie Zhou

Median clustering extends popular neural data analysis methods such as the self-organizing map or neural gas to general data structures given by a dissimilarity matrix only. This offers flexible and robust global data inspection methods…

Machine Learning · Computer Science 2009-09-04 Barbara Hammer , Alexander Hasenfuß , Fabrice Rossi

The dynamics of Saturn's satellite system offer a rich framework for studying orbital stability and resonance interactions. Traditional methods for analysing such systems, including Fourier analysis and stability metrics, struggle with the…

Earth and Planetary Astrophysics · Physics 2026-03-16 Eraldo Pereira Marinho , Nelson Callegari Junior , Fabricio Aparecido Breve , Caetano Mazzoni Ranieri

In this paper we tackle the issue of clustering trajectories of geolocalized observations. Using clustering technics based on the choice of a distance between the observations, we first provide a comprehensive review of the different…

Machine Learning · Statistics 2015-08-21 Philippe Besse , Brendan Guillouet , Jean-Michel Loubes , Royer François

We study the CLASH sample of galaxy clusters using a new deprojection method for weak gravitational lensing observations. This method is non-parametric, allowing us to infer mass profiles, or equivalently circular velocities, without having…

Cosmology and Nongalactic Astrophysics · Physics 2025-09-11 Tobias Mistele , Federico Lelli , Stacy McGaugh , James Schombert , Benoit Famaey
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