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Studies of galaxy clusters have proved crucial in helping to establish the standard model of cosmology, with a universe dominated by dark matter and dark energy. A theoretical basis that describes clusters as massive, multi-component,…

Cosmology and Nongalactic Astrophysics · Physics 2011-09-26 Steven W. Allen , August E. Evrard , Adam B. Mantz

We propose an ambitious new method that models the intracluster medium in clusters of galaxies as a set of X-ray emitting smoothed particles of plasma. Each smoothed particle is described by a handful of parameters including temperature,…

Astrophysics · Physics 2010-11-05 J. R. Peterson , P. J. Marshall , K. Andersson

Anomaly detection and localization in images is a growing field in computer vision. In this area, a seemingly understudied problem is anomaly clustering, i.e., identifying and grouping different types of anomalies in a fully unsupervised…

Computer Vision and Pattern Recognition · Computer Science 2024-04-19 Andrei-Timotei Ardelean , Tim Weyrich

We investigate how observations of strong lensing can be used to infer cosmological parameters, in particular the equation of state of dark energy. We focus on the growth of the critical lines of lensing clusters with the source redshift as…

Cosmology and Nongalactic Astrophysics · Physics 2012-04-03 Britta Zieser , Matthias Bartelmann

Measuring similarity between two objects is the core operation in existing clustering algorithms in grouping similar objects into clusters. This paper introduces a new similarity measure called point-set kernel which computes the similarity…

Machine Learning · Computer Science 2022-01-07 Kai Ming Ting , Jonathan R. Wells , Ye Zhu

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…

This work presents a novel method for fitting superquadrics to point clouds under the contamination of noise and outliers, which has many applications for shape modeling across diverse fields. Unlike prior approaches that either exclusively…

Computer Vision and Pattern Recognition · Computer Science 2026-05-19 Mingyang Zhao , Sipu Ruan , Xiaohong Jia

(Abridged) This is the first of a series of papers in which we derive simultaneous constraints on cosmological parameters and X-ray scaling relations using observations of the growth of massive, X-ray flux-selected galaxy clusters. Our data…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-14 Adam Mantz , Steven W. Allen , David Rapetti , Harald Ebeling

We analyse the clustering of cosmic large scale structure using a consistent modified gravity perturbation theory, accounting for anisotropic effects along and transverse to the line of sight. The growth factor has a particular scale…

We measure the non-axisymmetry in the luminosity distribution in the inner few kpc of the remnants of advanced mergers of galaxies with a view to understand the relaxation in the central regions. For this, we analyze the images from the…

Astrophysics · Physics 2009-11-11 Chanda J. Jog , Aparna Maybhate

We present the first results of our application of photometric redshifts to the study of galaxy populations in high-redshift clusters. For this survey, we are examining a sample of galaxy clusters at z > 0.6 which have already been…

Astrophysics · Physics 2007-05-23 L. M. Lubin , R. J. Brunner

We present the results of a search for galaxy clusters in the first 36 XMM-Newton pointings on the COSMOS field. We reach a depth for a total cluster flux in the 0.5-2 keV band of 3x10-15 ergs cm-2 s-1, having one of the widest XMM-Newton…

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

To understand the photophysics of molecular aggregates, exciton model of J- and H-aggregate has been extensively utilized. However, it lacks consideration of crystal symmetry. Although discrete molecules may lack symmetry, their aggregates…

Mesoscale and Nanoscale Physics · Physics 2023-10-10 Qingyun Wan , Chi-Ming Che

This talk reviews the scientific motivations, the potential difficulty and recent advances in cosmology using cluster number-counts in the X-ray band. Our forward modelling approach shows that many of the practical and conceptual…

Cosmology and Nongalactic Astrophysics · Physics 2022-05-12 Marguerite Pierre

Considerable progress has been made over the last decade in the study of the evolutionary trends of the population of galaxy clusters in the Universe. In this review we focus on observations in the X-ray band. X-ray surveys with the ROSAT…

Astrophysics · Physics 2008-11-26 Piero Rosati , Stefano Borgani , Colin Norman

We discuss a method to constrain the intrinsic three-dimensionale shapes of galaxy clusters by combining X-Ray and Sunyaev-Zeldovich observations. The method is applied to a sample of 25 X-Ray selected clusters, with measured…

Astrophysics · Physics 2011-07-18 E. De Filippis , M. Sereno , M. W. Bautz , G. Longo

We place constraints on the average density (Omega_m) and clustering amplitude (sigma_8) of matter using a combination of two measurements from the Sloan Digital Sky Survey: the galaxy two-point correlation function, w_p, and the…

Axions or ALPs are hypothetical particles predicted by BSM theories, which make one of the dark matter candidates. These particles can convert into photons and vice-versa in the presence of magnetic field, with a probability decided by its…

Cosmology and Nongalactic Astrophysics · Physics 2024-09-19 Harsh Mehta , Suvodip Mukherjee

We present the results of our dynamical state proxy measurements performed on 28 strong lensing galaxy clusters from the Sloan Giant Arcs Survey (SGAS). Using Chandra ACIS-I/S X-ray data supplemented with HST WFC3 imaging, we measure four…