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The morphology of clusters of galaxies may be described with a set of parameters which contain information about the formation and evolutionary history of these systems. In this paper we present a preliminary study of the morphological…

Astrophysics · Physics 2009-11-10 V. Strazzullo , M. Paolillo , G. Longo , E. Puddu , S. G. Djorgovski , R. R. De Carvalho , R. R. Gal

The $\Lambda$CDM model of structure formation makes strong predictions on concentration and shape of DM (dark matter) halos, which are determined by mass accretion processes. Comparison between predicted shapes and observations provides a…

Cosmology and Nongalactic Astrophysics · Physics 2018-06-13 Mauro Sereno , Keiichi Umetsu , Stefano Ettori , Jack Sayers , I-Non Chiu , Massimo Meneghetti , Jesús Vega-Ferrero , Adi Zitrin

Weak gravitational lensing and the Sunyaev-Zel'dovich effect provide complementary information on the composition of clusters of galaxies. Preliminary results from cluster SZ observations with the Very Small Array are presented. A Bayesian…

Astrophysics · Physics 2007-05-23 P. J. Marshall , K. Lancaster , M. P. Hobson , K. J. B. Grainge

We use the Millennium Simulation, a 10 billion particle simulation of the growth of cosmic structure, to construct a new model of galaxy clustering. We adopt a methodology that falls midway between the traditional semi-analytic approach and…

Astrophysics · Physics 2009-11-11 Lan Wang , Cheng Li , Guinevere Kauffmann , Gabriella De Lucia

Galaxy cluster analyses based on high-resolution observations of the Sunyaev-Zeldovich (SZ) effect have become common in the last decade. We present PreProFit, the first publicly available code designed to fit the pressure profile of galaxy…

Instrumentation and Methods for Astrophysics · Physics 2019-11-27 Fabio Castagna , Stefano Andreon

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

We investigate the utility of a new, self-similar pressure profile for fitting Sunyaev-Zel'dovich (SZ) effect observations of galaxy clusters. Current SZ imaging instruments - such as the Sunyaev-Zel'dovich Array (SZA) - are capable of…

The detection of galaxy clusters in present and future surveys enables measuring mass-to-light ratios, clustering properties or galaxy cluster abundances and therefore, constraining cosmological parameters. We present a new technique for…

Cosmology and Nongalactic Astrophysics · Physics 2010-11-17 Begoña Ascaso , David Wittman , Narciso Benítez , the DLS collaboration

As one of the most powerful probes of cosmological structure formation, the abundance of massive galaxy clusters is a sensitive probe of modifications to gravity on cosmological scales. In this paper, we present results from N-body…

Cosmology and Nongalactic Astrophysics · Physics 2015-03-17 Simone Ferraro , Fabian Schmidt , Wayne Hu

Most Sunyaev--Zel'dovich (SZ) and X-ray analyses of galaxy clusters try to constrain the cluster total mass and/or gas mass using parameterised models and assumptions of spherical symmetry and hydrostatic equilibrium. By numerically…

We propose a Bayesian approach for model-based clustering of multivariate categorical data where variables are allowed to be associated within clusters and the number of clusters is unknown. The approach uses a two-layer mixture of finite…

Methodology · Statistics 2024-07-09 Gertraud Malsiner-Walli , Bettina Grün , Sylvia Frühwirth-Schnatter

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

Knowledge of mass and concentration of galaxy clusters is crucial to understand their formation and evolution. Unbiased estimates require the understanding of the shape and orientation of the halo as well as its equilibrium status. We…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-11 Mauro Sereno , Stefano Ettori , Keiichi Umetsu , Alessandro Baldi

We have reanalyzed a data set of 99 low redshift ($ z < 0.1 $) Abell clusters and determined their shapes. For this, three different measures are used. We use Monte-Carlo simulations to investigate the errors in the methods. The corrected…

Astrophysics · Physics 2015-06-24 P. A. M. de Theije , P. Katgert , E. van Kampen

The knowledge of the dynamical state of galaxy clusters allows to alleviate systematics when observational data from these objects are applied in cosmological studies. Evidence of correlation between the state and the morphology of the…

Cosmology and Nongalactic Astrophysics · Physics 2021-01-06 Valentina Capalbo , Marco De Petris , Federico De Luca , Weiguang Cui , Gustavo Yepes , Alexander Knebe , Elena Rasia

We derive a model for Sunyaev--Zel'dovich data from a galaxy cluster which uses an Einasto profile to model the cluster's dark matter component. This model is similar to the physical models for clusters previously used by the Arcminute…

Cosmology and Nongalactic Astrophysics · Physics 2020-02-11 Kamran Javid , Yvette C. Perrott , Clare Rumsey , Richard D. E. Saunders

We introduce a density-based clustering method called skeleton clustering that can detect clusters in multivariate and even high-dimensional data with irregular shapes. To bypass the curse of dimensionality, we propose surrogate density…

Machine Learning · Statistics 2023-03-09 Zeyu Wei , Yen-Chi Chen

Galaxy clusters are considered as excellent probes for cosmology. For that purpose, their mass needs to be measured and their structural properties needs to be understood. We propose a method for galaxy cluster mass reconstruction which…

Cosmology and Nongalactic Astrophysics · Physics 2010-08-19 Xinzhong Er , Guoliang Li , Peter Schneider

Observations of the X-ray band wavelength reveal an evident ellipticity of many galaxy clusters atmospheres. The modeling of the intracluster gas with an ellipsoidal $\beta$-model leads to different estimates for the total gravitational…

Astrophysics · Physics 2009-09-29 Ph. Jetzer , P. Koch , R. Piffaretti , D. Puy , S. Schindler

This chapter reviews the application of Artificial Intelligence (AI) techniques to the study of galaxy clusters, covering both theoretical developments and their use as tools to infer cluster properties from a variety of observational…

Cosmology and Nongalactic Astrophysics · Physics 2026-05-22 Gustavo Yepes , Daniel de Andrés