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Importance sampling is a Monte Carlo method which designs estimators of expectations under a target distribution using weighted samples from a proposal distribution. When the target distribution is complex, such as multimodal distributions…

Methodology · Statistics 2026-02-04 Anas Cherradi , Yazid Janati , Alain Durmus , Sylvain Le Corff , Yohan Petetin , Julien Stoehr

We describe an objective and automated method for detecting clusters of galaxies from optical imaging data. This method is a variant of the so-called `matched-filter' technique pioneered by Postman et al. (1996). With simultaneous use of…

Astrophysics · Physics 2009-10-30 Wataru Kawasaki , Kazuhiro Shimasaku , Mamoru Doi , Sadanori Okamura

Automating the design of microstrip antennas has been an active area of research for the past decade. By leveraging machine learning techniques such as Genetic Algorithms (GAs) or, more recently, Deep Neural Networks (DNNs), a number of…

Signal Processing · Electrical Eng. & Systems 2024-10-07 Ali Al-Zawqari , Ali Safa , Gert Vandersteen

In this work, we combine ellipticity and major axis position angle measurements from the Sloan Digital Sky Server Data Release 16 (SDSS DR16) with the group finder algorithm of Rodriguez \& Merch\'an to determine the alignment of the…

Astrophysics of Galaxies · Physics 2022-06-01 Facundo Rodriguez , Manuel Merchán , M. Celeste Artale

We develop the maximum-entropy weak shear mass reconstruction method presented in earlier papers by taking each background galaxy image shape as an independent estimator of the reduced shear field and incorporating an intrinsic smoothness…

Astrophysics · Physics 2009-11-07 P. J. Marshall , M. P. Hobson , S. F. Gull , S. L. Bridle

A wide range of (multivariate) temporal (1D) and spatial (2D) data analysis tasks, such as grouping vehicle sensor trajectories, can be formulated as clustering with given metric constraints. Existing metric-constrained clustering…

Machine Learning · Computer Science 2024-06-04 Zhangyu Wang , Gengchen Mai , Krzysztof Janowicz , Ni Lao

In this fourth paper of a series on the precision of ages of stellar populations obtained through the full-spectrum fitting technique, we present a first systematic analysis that compare the age, metallicity and reddening of star clusters…

Astrophysics of Galaxies · Physics 2022-03-21 Randa Asa'd , Paul Goudfrooij , A. M. As'ad

Cluster matching by permuting cluster labels is important in many clustering contexts such as cluster validation and cluster ensemble techniques. The classic approach is to minimize the euclidean distance between two cluster solutions which…

Artificial Intelligence · Computer Science 2007-05-31 Jens Oehlschlägel

We present a new algorithm to search for distant clusters of galaxies on catalogues deriving from imaging data, as those of the ESO Imaging Survey. Our algorithm is a matched filter one, similar to that adopted by Postman et al. (1996),…

Astrophysics · Physics 2007-05-23 C. Lobo , A. Iovino , D. Lazzati , G. Chincarini

We present a procedure to solve the inverse Ising problem, that is to find the interactions between a set of binary variables from the measure of their equilibrium correlations. The method consists in constructing and selecting specific…

Disordered Systems and Neural Networks · Physics 2015-05-30 Simona Cocco , Rémi Monasson

With the unprecedented increase of known star clusters, quick and modern tools are needed for their analysis. In this work, we develop an artificial neural network trained on synthetic clusters to estimate the age, metallicity, extinction,…

The study of spin systems with disorder and frustration is known to be a computationally hard task. Standard heuristics developed for optimizing and sampling from general Ising Hamiltonians tend to produce correlated solutions due to their…

Disordered Systems and Neural Networks · Physics 2022-11-22 Adrien Vandenbroucque , Ezequiel Ignacio Rodríguez Chiacchio , Ewan Munro

We present a new method of constraining the mass and velocity anisotropy profiles of galaxy clusters from kinematic data. The method is based on a model of the phase space density which allows the anisotropy to vary with radius between two…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-13 Radoslaw Wojtak , Ewa L. Lokas , Gary A. Mamon , Stefan Gottloeber

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 engineer a new probabilistic Monte-Carlo algorithm for isomorphism testing. Most notably, as opposed to all other solvers, it implicitly exploits the presence of symmetries without explicitly computing them. We provide extensive…

Data Structures and Algorithms · Computer Science 2020-11-19 Markus Anders , Pascal Schweitzer

We present a new algorithm to detect inter-cluster galaxy filaments based upon the assumption that the orientations of constituent galaxies along such filaments are non-isotropic. We apply the algorithm to the 2dF Galaxy Redshift Survey…

Astrophysics · Physics 2009-11-10 Kevin A. Pimbblet

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

We present a new method for reconstructing two-dimensional mass maps of galaxy clusters from the image distortion of background galaxies. In contrast to most previous approaches, which directly convert locally averaged image ellipticities…

Astrophysics · Physics 2007-05-23 Stella Seitz , Peter Schneider , Matthias Bartelmann

We report weak-lensing masses for 51 of the most X-ray luminous galaxy clusters known. This cluster sample, introduced earlier in this series of papers, spans redshifts 0.15 < z_cl < 0.7, and is well suited to calibrate mass proxies for…

The maximum-entropy method is applied to the problem of reconstructing the projected mass density of a galaxy cluster using its gravitational lensing effects on background galaxies. We demonstrate the method by reconstructing the mass…

Astrophysics · Physics 2009-10-30 S. L. Bridle , M. P. Hobson , A. N. Lasenby , Richard Saunders