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We introduce an analytic model of the diffuse intergalactic medium in galaxy clusters based on a polytropic equation of state for the gas in hydrostatic equilibrium with the cluster gravitational potential. This model is directly applicable…

Cosmology and Nongalactic Astrophysics · Physics 2014-11-20 G. Esra Bulbul , Nicole Hasler , Massimiliano Bonamente , Marshall Joy

Rich and massive clusters of galaxies at intermediate redshift are capable of magnifying and distorting the images of background galaxies. A comparison of different mass estimators among these clusters can provide useful information about…

Astrophysics · Physics 2009-10-30 Xiang-Ping Wu , Tzihong Chiueh , Li-Zhi Fang , Yan-Jie Xue

We present observations using the Small Array of the Arcminute Microkelvin Imager (AMI; 14-18 GHz) of four Abell and three MACS clusters spanning 0.171-0.686 in redshift. We detect Sunyaev-Zel'dovich (SZ) signals in five of these without…

We have derived accurate distances to Galactic globular clusters by combining data from the Gaia Early Data Release 3 with distances based on Hubble Space telescope HST data and literature based distances. We determine distances either…

Astrophysics of Galaxies · Physics 2021-07-14 Holger Baumgardt , Eugene Vasiliev

Until now it has been impossible to observationally measure how star cluster scale height evolves beyond 1Gyr as only small samples have been available. Here we establish a novel method to determine the scale height of a cluster sample…

Solar and Stellar Astrophysics · Physics 2015-06-22 Anne S. M. Buckner , Dirk Froebrich

For precision cosmological studies it is important to know the local properties of the reference point from which we observe the Universe. Particularly for the determination of the Hubble constant with low-redshift distance indicators, the…

Cosmology and Nongalactic Astrophysics · Physics 2019-12-25 Hans Boehringer , Gayoung Chon , Chris A. Collins

We address the question of how well the density profile of galaxy clusters can be determined by combining strong lensing and velocity dispersion data. We use cosmological dark matter simulations of clusters to test the reliability of the…

Astrophysics · Physics 2010-12-01 M. Meneghetti , M. Bartelmann , A. Jenkins , C. Frenk

We discuss a method to build up and study a sample of distant galaxies, with 2<z<5, using the gravitational amplification effect in cluster-lenses for which the mass distribution is well known. The candidates are selected close to the…

Astrophysics · Physics 2009-10-30 R. Pello , J. P. Kneib , G. Bruzual , J. M. Miralles

The uniformity of the helium-to-hydrogen abundance ratio in X-ray emitting intracluster medium (ICM) is one of the commonly adopted assumptions in X-ray analyses of galaxy clusters and cosmological constraints derived from these…

Astrophysics · Physics 2011-02-11 Fang Peng , Daisuke Nagai

The recently approved COBRAS/SAMBA cosmic microwave background mission will also have a major impact on measurements of the Sunyaev-Zeldovich effect. The frequency of three of the channels (150 GHz, 217 GHz, 353 GHz) are chosen to optimize…

Astrophysics · Physics 2007-05-23 Martin G. Haehnelt

Globular clusters are among the first objects used to establish the distance scale of the Universe. In the 1970-ies it has been recognized that the differential magnitude distribution of old globular clusters is very similar in different…

Cosmology and Nongalactic Astrophysics · Physics 2012-01-20 M. Rejkuba

We show that by directly correlating the cluster kinetic Sunyaev Zeldovich (KSZ) flux, the cluster peculiar velocity power spectrum can be measured to $\sim 10%$ accuracy by future large sky coverage KSZ surveys. This method is almost free…

Astrophysics · Physics 2007-05-23 Pengjie Zhang , Albert Stebbins , Roman Juszkiewicz , Hume Feldman

Using the simulation of Katz & White we have tested the viability of X-ray analysis for constraining the intrinsic shapes of clusters of galaxies considering the effects of both substructure and steep temperature gradients. We restrict…

Astrophysics · Physics 2009-10-22 D. A. Buote , J. C. Tsai

We present the results of a 6.1 square degree survey for clusters of galaxies via their Sunyaev- Zel'dovich (SZ) effect at 31 GHz. From late 2005 to mid 2007 the Sunyaev-Zel'dovich Array (SZA) observed four fields of roughly 1.5 square…

Although distance measures are used in many machine learning algorithms, the literature on the context-independent selection and evaluation of distance measures is limited in the sense that prior knowledge is used. In cluster analysis,…

Machine Learning · Computer Science 2021-08-24 Michael C. Thrun

Mass is the most fundamental property of galaxy clusters. However, measuring it is still a challenge. Calibrating mass from intracluster medium observables such as the Sunyaev-Zel'dovich (SZ) effect is subject to uncertainty and biases…

Cosmology and Nongalactic Astrophysics · Physics 2024-04-25 Mohini Pachchigar , Yvette Perrott , Tulasi Parashar

We present results from a deep Chandra observation of MS1137.5+66, a distant (z=0.783) and massive cluster of galaxies. Only a few similarly massive clusters are currently known at such high redshifts; accordingly, this observation provides…

Sensitive surveys of the Cosmic Microwave Background will detect thousands of galaxy clusters via the Sunyaev-Zel'dovich (SZ) effect. Two SZ observables, the central or maximum and integrated Comptonization parameters y_max and Y, relate in…

Astrophysics · Physics 2009-11-13 Daniel R. Wik , Craig L. Sarazin , Paul M. Ricker , Scott W. Randall

We extend the formalism for the calculation of the relativistic corrections to the Sunyaev-Zel'dovich effect for clusters of galaxies and include the multiple scattering effects. We present a systematic method for the inclusion of the…

Astrophysics · Physics 2011-02-11 Naoki Itoh , Youhei Kawana , Satoshi Nozawa , Yasuharu Kohyama

We have constrained the spatial variation of the fine structure constant using multi-frequency measurements of the thermal Sunyaev-Zeldovich effect of 618 X-ray selected clusters. Although our results are not competitive with the ones from…

Cosmology and Nongalactic Astrophysics · Physics 2016-12-22 I. de Martino , C. J. A. P. Martins , H. Ebeling , D. Kocevski
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