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We study the redshift space correlation function of galaxy clusters for observational samples constructed in different surveys. We explore correlation amplitudes, pairwise velocity distributions and bias factors. Systematics in cluster…

Astrophysics · Physics 2009-11-07 N. D. Padilla , D. G. Lambas

The Northern Sky Optical Cluster Survey is a project to create an objective catalog of galaxy clusters over the entire high-galactic-latitude Northern sky, with well understood selection criteria. We use the object catalogs generated from…

Astrophysics · Physics 2016-08-30 R. R. Gal , R. R. DeCarvalho , S. C. Odewahn , S. G. Djorgovski , V. E. Margoniner

In this paper, we first propose a new iterative algorithm, called the K-sets+ algorithm for clustering data points in a semi-metric space, where the distance measure does not necessarily satisfy the triangular inequality. We show that the…

Data Structures and Algorithms · Computer Science 2017-05-12 Cheng-Shang Chang , Chia-Tai Chang , Duan-Shin Lee , Li-Heng Liou

Measuring the evolution in the clustering of galaxies over a large redshift range is a challenging problem. For a two-dimensional galaxy catalog, however, we can measure the galaxy-galaxy angular correlation function which provides…

Astrophysics · Physics 2009-10-31 Robert J. Brunner , Andrew J. Connolly , Alex S. Szalay

The upcoming XMM Large Scale Structure Survey (XMM-LSS) will ultimately provide a unique mapping of the distribution of X-ray sources in a contiguous 64 sq. deg. region. In particular, it will provide the 3-dimensional location of about 900…

Astrophysics · Physics 2009-11-07 Alexandre Refregier , Ivan Valtchanov , Marguerite Pierre

Identifying the underlying models in a set of data points contaminated by noise and outliers, leads to a highly complex multi-model fitting problem. This problem can be posed as a clustering problem by the projection of higher order…

Computer Vision and Pattern Recognition · Computer Science 2018-08-01 Ruwan Tennakoon , Alireza Sadri , Reza Hoseinnezhad , Alireza Bab-Hadiashar

An important aspect of the shape of a distribution is the level of asymmetry. Strong asymmetries play a role in many ecosystems and are found in the size and reproductive success of individuals. But the standard third moment coefficient of…

Methodology · Statistics 2022-09-23 Mario Schlemmer

In the near future a new generation of CCD based galaxy surveys will enable high precision determination of the N-point correlation functions. The resulting information will help to resolve the ambiguities associated with two-point…

Astrophysics · Physics 2009-10-30 Istvan Szapudi

We present models for the three-point correlation function (3PCF) of both dark matter and galaxies. We show that models based on the halo model can reasonably match the dark matter 3PCF obtained from high-resolution $N$-body simulations. On…

Astrophysics · Physics 2009-11-10 Yu Wang , Xiaohu Yang , H. J. Mo , Frank C. van den Bosch , YaoQuan Chu

In the classical transformer attention scheme, we are given three $n \times d$ size matrices $Q, K, V$ (the query, key, and value tokens), and the goal is to compute a new $n \times d$ size matrix $D^{-1} \exp(QK^\top) V$ where $D =…

Data Structures and Algorithms · Computer Science 2023-10-09 Josh Alman , Zhao Song

We exploit the VST ATLAS quasar/QSO catalogue to perform three measurements of the quasar halo mass profile. First, we make a new estimate of the angular auto-correlation function of $\approx230,000$ ATLAS quasars with $z_{photo}\lesssim…

Cosmology and Nongalactic Astrophysics · Physics 2024-11-01 Alice M. Eltvedt , T. Shanks , N. Metcalfe , B. Ansarinejad , L. F. Barrientos , D. N. A. Murphy , D. M. Alexander

The growing availability of three-dimensional point process data asks for a development of suitable analysis techniques. In this paper, we focus on two recently developed summary statistics, the conical and the cylindrical $K$-function,…

Methodology · Statistics 2016-04-15 Farzaneh Safavimanesh , Claudia Redenbach

We discuss statistical techniques for detecting and quantifying bimodality in astronomical datasets. We concentrate on the KMM algorithm, which estimates the statistical significance of bimodality in such datasets and objectively partitions…

Astrophysics · Physics 2009-10-22 Keith M. Ashman , Christina M. Bird , Steven E. Zepf

In many applications of X-ray computed tomography, an unsupervised segmentation of the reconstructed 3D volumes forms an important step in the image processing chain for further investigation of the digitized object. Therefore, the goal is…

Computer Vision and Pattern Recognition · Computer Science 2023-03-09 Thomas Lang

Scaling relations of galaxy clusters are a powerful probe of cosmic isotropy in the late Universe. Owing to their strong cosmological dependence, galaxy cluster scaling relations can obtain tight constraints on the spatial variation of…

Cosmology and Nongalactic Astrophysics · Physics 2024-06-05 Konstantinos Migkas

Previous work on three-point statistics of cosmic shear has mainly concentrated on the convergence, or on aperture measures of the shear. However, as has become clear recently for the two-point statistics of cosmic shear, the basic quantity…

Astrophysics · Physics 2009-11-07 Peter Schneider , Marco Lombardi

We study the problem of clustering sequences of unlabeled point sets taken from a common metric space. Such scenarios arise naturally in applications where a system or process is observed in distinct time intervals, such as biological…

Data Structures and Algorithms · Computer Science 2017-10-17 Tamal K. Dey , Alfred Rossi , Anastasios Sidiropoulos

We explore an alternative method to the usual shear correlation function approach for the estimation of aperture mass statistics in weak lensing survey data. Our approach builds on the direct estimator method. In this paper, we extend our…

Cosmology and Nongalactic Astrophysics · Physics 2021-10-13 Lucas Porth , Robert E. Smith

High order correlations in the cosmic matter density have become increasingly valuable in cosmological analyses. However, computing such correlation functions is computationally expensive. We aim to circumvent these challenges by designing…

Cosmology and Nongalactic Astrophysics · Physics 2022-11-23 Zachery Brown , Gebri Mishtaku , Regina Demina

One emerging application of machine learning methods is the inference of galaxy cluster masses. In this note, machine learning is used to directly combine five simulated multiwavelength measurements in order to find cluster masses. This is…

Cosmology and Nongalactic Astrophysics · Physics 2020-01-08 J. D. Cohn , Nicholas Battaglia