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Imaging data from the Sloan Digital Sky Survey is used to measure the empirical size-richness relation for a large sample of galaxy clusters. Using population subtraction methods, we determine the radius at which the cluster galaxy number…

Mode-based clustering methods define clusters to be the basins of attraction of the modes of a density estimate. The most common version is mean shift clus- tering which uses a gradient ascent algorithm to find the basins. Rodriguez and…

Methodology · Statistics 2018-05-14 Isabella Verdinelli , Larry Wasserman

A standard method to study the mass distribution in galaxy clusters is through strong lensing of background galaxies in which the positions of multiple images of the same source constrain the surface mass distribution of the cluster.…

Cosmology and Nongalactic Astrophysics · Physics 2012-01-26 Ole Host

Measurements of the surface brightness distribution and of the velocity dispersion profile have been so far used to infer the inner dynamics of globular clusters. We show that those observations do not trace back the dark matter potentially…

Astrophysics · Physics 2007-05-23 Francois Roueff , Pierre Salati , Richard Taillet

The general relativistic description of galaxy clustering provides a complete and unified treatment of all the effects in galaxy clustering such as the redshift-space distortion, gravitational lensing, Sachs-Wolfe effects, and their…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-22 Jaiyul Yoo

The mean shift algorithm is a non-parametric and iterative technique that has been used for finding modes of an estimated probability density function. It has been successfully employed in many applications in specific areas of machine…

Computer Vision and Pattern Recognition · Computer Science 2014-07-14 Youness Aliyari Ghassabeh

In this paper we present a new statistic for quantifying galaxy morphology based on measurements of the Gini coefficient of galaxy light distributions. This statistic is easy to measure and is commonly used in econometrics to measure how…

Astrophysics · Physics 2009-11-07 Roberto Abraham , Sidney van den Bergh , Preethi Nair

A brief introduction is given to some aspects of the statistical description of the luminous matter distribution. I review the features of the redshift surveys that arise in the statistical analysis of the galaxy clustering. Special topics…

Astrophysics · Physics 2007-05-23 Vicent J. Martinez

In a previous work General Relativity has been presented as a microscopic theory of finite and discrete point-like fields that we associate to a classical description of gravitons. The standard macroscopic continuous field is retrieved as…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Manoelito M. de Souza , Robson N. Silveira

One of the popular measures of central tendency that provides better representation and interesting insights of the data compared to the other measures like mean and median is the metric mode. If the analytical form of the density function…

Machine Learning · Computer Science 2019-06-04 Chandramouli Kamanchi , Raghuram Bharadwaj Diddigi , Prabuchandran K. J. , Shalabh Bhatnagar

The magnification effect of gravitational lensing is a powerful probe of the distribution of matter in the universe, yet it is frequently overlooked due to the fact that its signal to noise is smaller than that of lensing shear. Because its…

Cosmology and Nongalactic Astrophysics · Physics 2014-04-23 Anne H. Bauer , Enrique Gaztañaga , Pol Martí , Ramon Miquel

Observed clusters should be modelled by considering the distribution function to be a random variable that quantifies the degree of excitation of the system's normal modes. A system of canonical coordinates for the space of DFs is…

Astrophysics of Galaxies · Physics 2021-08-11 Jun Yan Lau , James Binney

Although general relativity underlies modern cosmology, its applicability on cosmological length scales has yet to be stringently tested. Such a test has recently been proposed, using a quantity, EG, that combines measures of large-scale…

Cosmology and Nongalactic Astrophysics · Physics 2010-03-11 Reinabelle Reyes , Rachel Mandelbaum , Uros Seljak , Tobias Baldauf , James E. Gunn , Lucas Lombriser , Robert E. Smith

Ridges in galaxy density fields measured by photometric surveys are 2D projections of filaments in the cosmic web, and so should lens light from background galaxies. We report on a detection of this effect in Dark Energy Survey Year 3 data…

Cosmology and Nongalactic Astrophysics · Physics 2026-03-06 Mehraveh Nikjoo , Joe Zuntz , Ben Moews

Despite consistent progress in numerical simulations, the observable properties of galaxy clusters are difficult to predict ab initio. It is therefore important to compare both theoretical and observational results to a direct measure of…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-15 Henk Hoekstra , Matthias Bartelmann , Haakon Dahle , Holger Israel , Marceau Limousin , Massimo Meneghetti

We develop a new method which measures the projected density distribution w_p(r_p)n of photometric galaxies surrounding a set of spectroscopically-identified galaxies, and simultaneously the projected correlation function w_p(r_p) between…

Cosmology and Nongalactic Astrophysics · Physics 2015-03-17 Wenting Wang , Y. P. Jing , Cheng Li , Teppei Okumura , Jiaxin Han

Wide-area imaging surveys are one of the key ways of advancing our understanding of cosmology, galaxy formation physics, and the large-scale structure of the Universe in the coming years. These surveys typically require calculating…

Astrophysics of Galaxies · Physics 2020-10-07 P. W. Hatfield , I. A. Almosallam , M. J. Jarvis , N. Adams , R. A. A. Bowler , Z. Gomes , S. J. Roberts , C. Schreiber

The density ratio of two probability distributions is one of the fundamental tools in mathematical and computational statistics and machine learning, and it has a variety of known applications. Therefore, density ratio estimation from…

Machine Learning · Statistics 2024-06-28 Masanari Kimura , Howard Bondell

We constructed the composite Luminosity Function (LF) of cluster galaxies in the g,r and i bands from the photometry of a mixed (Abell and X-ray selected) sample of the cores of 65 clusters, ranging in redshift from 0.05 to 0.25. The…

Astrophysics · Physics 2010-11-04 Bianca Garilli , Dario Maccagni , Stefano Andreon

We present a maximum-likelihood analysis of galaxy-galaxy lensing effects in galaxy clusters and in the field. The aim is to determine the accuracy and robustness of constraints that can be obtained on galaxy halo properties in both…

Astrophysics · Physics 2009-11-10 Marceau Limousin , Jean Paul Kneib , Priyamvada Natarajan