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We present the results of a simple but robust morphological classification of a statis- tically complete sample of 108 of the most X-ray luminous clusters at 0.15 < z < 0.7 observed with Chandra. Our aims are to (a) identify the most…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-03 Andrew W. Mann , Harald Ebeling

We study Bayesian estimation of finite mixture models in a general setup where the number of components is unknown and allowed to grow with the sample size. An assumption on growing number of components is a natural one as the degree of…

Statistics Theory · Mathematics 2022-03-18 Ilsang Ohn , Lizhen Lin

Numerical simulations of clusters of galaxies provide a unique way to follow the dynamics of these systems. The models reveal many characteristics of the merging process of subclusters: shock structure and strength, temperature distribution…

Astrophysics · Physics 2007-05-23 Sabine Schindler

Galaxy clusters, the most massive, dark-matter-dominated, and most recently assembled structures in the Universe, are key tools for probing cosmology. However, uncertainties in scaling relations that connect cluster mass to observables like…

Cosmology and Nongalactic Astrophysics · Physics 2025-09-24 Giulia Cerini , Elena Bellomi , Nico Cappelluti , Sabina Khizroev , Erwin T. Lau , Priyamvada Natarajan , John ZuHone

Based on the earlier work of Gunn and McCrea we model the formation of globular clusters in merging galaxies. Neutral hydrogen observations of dwarf irregular galaxies as well as more luminous systems are used to provide the key parameters…

Astrophysics · Physics 2011-02-11 F. D. A. Hartwick

We present a high-resolution simulation of globular cluster formation in a galaxy merger. For the first time in such a simulation, individual star clusters are directly identified and followed on their orbits. We quantitatively compare star…

Astrophysics · Physics 2009-11-10 Yuexing Li , Mordecai-Mark Mac Low , Ralf S. Klessen

Galaxy groups and clusters are formidable cosmological probes. They permit the studying of the environmental effects on galaxy formation. A reliable detection of galaxy groups is an open problem and is important for ongoing and future…

Cosmology and Nongalactic Astrophysics · Physics 2018-10-17 Elmo Tempel , Maarja Kruuse , Rain Kipper , Taavi Tuvikene , Jenny G. Sorce , Radu S. Stoica

Bayesian clustering typically relies on mixture models, with each component interpreted as a different cluster. After defining a prior for the component parameters and weights, Markov chain Monte Carlo (MCMC) algorithms are commonly used to…

Methodology · Statistics 2024-07-30 Alexander Dombowsky , David B. Dunson

In the most prominent current scenario of galaxy formation, galaxies form hierarchically through the merger of smaller systems. Such mergers could leave behind dynamical signatures which may linger long after the event. In particular, the…

Astrophysics · Physics 2011-03-10 K. M. Perrett , D. A. Stiff , D. A. Hanes , T. J. Bridges

Many processes in chemistry and physics take place on timescales that cannot be explored using standard molecular dynamics simulations. This renders the use of enhanced sampling mandatory. Here we introduce an enhanced sampling method that…

Chemical Physics · Physics 2020-06-12 Jayashrita Debnath , Michele Parrinello

The clustering of bounded data presents unique challenges in statistical analysis due to the constraints imposed on the data values. This paper introduces a novel method for model-based clustering specifically designed for bounded data.…

Methodology · Statistics 2025-05-16 Luca Scrucca

Clustering mixed data presents numerous challenges inherent to the very heterogeneous nature of the variables. A clustering algorithm should be able, despite of this heterogeneity, to extract discriminant pieces of information from the…

Machine Learning · Computer Science 2022-05-10 Robin Fuchs , Denys Pommeret , Cinzia Viroli

Globular clusters (GCs) are sensitive tracers of galaxy assembly histories but interpreting the information they encode is challenging because mergers are thought to promote both the formation and disruption of GCs. We use simulations with…

The dynamical history of most merging galaxies is not well understood. Correlations between galaxy interaction and star formation have been found in previous studies, but require the context of the physical history of merging systems for…

Model-based clustering of moderate or large dimensional data is notoriously difficult. We propose a model for simultaneous dimensionality reduction and clustering by assuming a mixture model for a set of latent scores, which are then linked…

Methodology · Statistics 2024-06-04 Lorenzo Ghilotti , Mario Beraha , Alessandra Guglielmi

Various galaxy merger detection methods have been applied to diverse datasets. However, it is difficult to understand how they compare. We aim to benchmark the relative performance of machine learning (ML) merger detection methods. We…

Classifier combination methods need to make best use of the outputs of multiple, imperfect classifiers to enable higher accuracy classifications. In many situations, such as when human decisions need to be combined, the base decisions can…

Statistics Theory · Mathematics 2012-06-11 Edwin Simpson , Stephen Roberts , Ioannis Psorakis , Arfon Smith

We study the gravitational stability of gaseous streams in the complex environment of a galaxy merger, because mergers are known to be places of ongoing massive cluster formation and bursts of star formation. We find an analytic stability…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-04 Andres Escala , Fernando Becerra , Luciano del Valle , Esteban Castillo

During cluster mergers, the intracluster gas and member galaxies undergo dynamic evolution, but at different timescales and reach different states. We collect 24 galaxy clusters in quasi-equilibrium state as indicated by the X-ray image,…

Astrophysics of Galaxies · Physics 2025-09-29 Z. S. Yuan , J. L. Han , H. Böhringer , Z. L. Wen , G. Chon

Merging galaxy clusters allows to study the different mass components, dark and baryonic, separately. Also their occurrence enables to test the $\Lambda$CDM scenario and they could put constrains in the self interacting cross section of the…