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We present a new non-parametric method to quantify morphologies of galaxies based on a particular family of learning machines called support vector machines. The method, that can be seen as a generalization of the classical CAS…

Astrophysics · Physics 2009-11-13 M. Huertas-Company , D. Rouan , L. Tasca , G. Soucail , O. Le Fevre

To demonstrate the feasibility of studying the epoch of massive galaxy cluster formation in a more systematic manner using current and future galaxy surveys, we report the discovery of a large sample of proto-cluster candidates in the 1.62…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-18 Yi-Kuan Chiang , Roderik Overzier , Karl Gebhardt

We present the first cluster catalogue extracted from the UKIRT Infrared Deep Sky Survey Early Data Release. The catalogue is created using UKIDSS Ultra Deep Survey infrared J and K data combined with 3.6 micro-m and 4.5 micro-m Spitzer…

We present the results of a weak lensing survey of six high-redshift (z > 0.5), X-ray selected clusters of galaxies. We have obtained ultra-deep R-band images of each cluster with the Keck Telescope, and have measured a weak lensing signal…

Astrophysics · Physics 2009-10-31 D. Clowe , G. Luppino , N. Kaiser , I. Gioia

The spin of galaxy clusters encodes key information about their formation, dynamics, and the influence of large-scale structure. However, whether clusters possess statistically significant spin and how to measure it observationally remain…

Astrophysics of Galaxies · Physics 2025-11-25 Xiao-xiao Tang , Peng Wang , Yu Rong , Weiguang cui , Min Bao

We present an extensive spectroscopic follow-up campaign of 29 strong lensing (SL) selected galaxy clusters discovered primarily in the Second Red-Sequence Cluster Survey (RCS-2). Our spectroscopic analysis yields redshifts for 52…

Weak gravitational lensing has been used extensively in the past decade to constrain the masses of galaxy clusters, and is the most promising observational technique for providing the mass calibration necessary for precision cosmology with…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-14 Rachel Mandelbaum , Uros Seljak , Tobias Baldauf , Robert E. Smith

We demonstrate the ability of convolutional neural networks (CNNs) to mitigate systematics in the virial scaling relation and produce dynamical mass estimates of galaxy clusters with remarkably low bias and scatter. We present two models,…

Cosmology and Nongalactic Astrophysics · Physics 2020-12-23 Matthew Ho , Markus Michael Rau , Michelle Ntampaka , Arya Farahi , Hy Trac , Barnabas Poczos

We consider methods with which to answer the question "is any observed galaxy cluster too unusual for Lambda-CDM?" After emphasising that many previous attempts to answer this question will overestimate the confidence level at which…

Cosmology and Nongalactic Astrophysics · Physics 2017-01-03 Ian Harrison , Shaun Hotchkiss

From the poor cluster catalog of White et al. (1996), we define a sample of 71 optically-selected poor galaxy clusters. The surface-density enhance- ment we require for our clusters falls between that of the loose associations of Turner and…

Astrophysics · Physics 2009-10-28 Michael J. Ledlow , Chris Loken , Jack O. Burns , John M. Hill , Richard A. White

This paper is the first in a series in which we perform an extensive comparison of various galaxy-based cluster mass estimation techniques that utilise the positions, velocities and colours of galaxies. Our primary aim is to test the…

We study the clustering of galaxies detected at $i<22.5$ in the Science Verification observations of the Dark Energy Survey (DES). Two-point correlation functions are measured using $2.3\times 10^6$ galaxies over a contiguous 116 deg$^2$…

Measuring cosmic shear in wide-field imaging surveys requires accurate knowledge of the redshift distribution of all sources. The clustering-redshift technique exploits the angular cross-correlation of a target galaxy sample with unknown…

Cosmology and Nongalactic Astrophysics · Physics 2021-04-15 J. L. van den Busch , H. Hildebrandt , A. H. Wright , C. B. Morrison , C. Blake , B. Joachimi , T. Erben , C. Heymans , K. Kuijken , E. N. Taylor

We have developed a new method, K2, optimized for the detection of galaxy clusters in multicolor images. Based on the Red Sequence approach, K2 detects clusters using simultaneous enhancements in both colors and position. The detection…

Cosmology and Nongalactic Astrophysics · Physics 2014-11-20 Karun Thanjavur , Jon Willis , David Crampton

Stochasticity of bright stars introduces uncertainty and bias into derived structural parameters of star clusters. We have simulated a grid of cluster $V$-band images, observed with Subaru Suprime-Cam with age, mass, and size representing a…

Astrophysics of Galaxies · Physics 2018-03-14 D. Narbutis , R. Stonkutė , P. de Meulenaer , T. Mineikis , V. Vansevičius

We describe the selection of galaxies targeted in eight low redshift clusters (APMCC0917, A168, A4038, EDCC442, A3880, A2399, A119 and A85; $0.029 < z < 0.058$) as part of the Sydney-AAO Multi-Object integral field Spectrograph Galaxy…

The survey data of Wide-field Infrared Survey Explorer (WISE) provide an opportunity for the identification of galaxy clusters. We present an efficient method for detecting galaxy clusters by combining the WISE data with SuperCOSMOS and…

Astrophysics of Galaxies · Physics 2014-07-21 W. W. Xu , Z. L. Wen , J. L. Han

The caustic skeleton is a parameter-free and mathematically rigorous formalism for tracing the hierarchical formation history of the multiscale cosmic web from the singularities in the underlying dark matter flow. In the present study, we…

Cosmology and Nongalactic Astrophysics · Physics 2026-04-21 Benjamin Hertzsch , Job Feldbrugge , Rien van de Weygaert

We use the 2dF Galaxy Redshift Survey data to compile catalogues of superclusters for the Northern and Southern regions of the 2dFGRS, altogether 543 superclusters at redshifts 0.009 < z < 0.2. We analyse methods of compiling supercluster…

We present a new method of constraining the mass and velocity anisotropy profiles of galaxy clusters from kinematic data. The method is based on a model of the phase space density which allows the anisotropy to vary with radius between two…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-13 Radoslaw Wojtak , Ewa L. Lokas , Gary A. Mamon , Stefan Gottloeber
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