Combining Optical and X-ray Observations of Galaxy Clusters to Constrain Cosmological Parameters

Galaxy clusters have their unique advantages for cosmology. Here we collect a new sample of 10 lensing galaxy clusters with X-ray observations to constrain cosmological parameters.The redshifts of lensing clusters lie between 0.1 and 0.6, and the redshift range of their arcs is from 0.4 to 4.9. Thes...

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Bibliographic Details
Published in:arXiv.org
Main Authors: Yu, Heng, Zong-Hong, Zhu
Format: Paper
Language:English
Published: Ithaca Cornell University Library, arXiv.org 28.11.2010
Subjects:
Algorithms
Astronomical models
Cosmology
Galactic clusters
Galaxies
Gravitation theory
Gravitational lenses
Hubble constant
Luminosity
Mass distribution
Optimization
Parameters
Red shift
Satellite observation
Star & galaxy formation
ISSN:2331-8422
Online Access:Get full text
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Summary:Galaxy clusters have their unique advantages for cosmology. Here we collect a new sample of 10 lensing galaxy clusters with X-ray observations to constrain cosmological parameters.The redshifts of lensing clusters lie between 0.1 and 0.6, and the redshift range of their arcs is from 0.4 to 4.9. These clusters are selected carefully from strong gravitational lensing systems which have both X-ray satellite observations and optical giant luminous arcs with known redshift. Giant arcs usually appear in the central region of clusters, where mass can be traced with luminosity quite well. Based on gravitational lensing theory and cluster mass distribution model we can derive an Hubble constant independent ratio between two angular diameter distances. One is the distance of lensing source and the other is that between the deflector and the source. Since angular diameter distance relies heavily on cosmological geometry, we can use these ratios to constrain cosmological models. Meanwhile X-ray gas fractions of galaxy clusters can also be a cosmological probe. Because there are a dozen parameters to be fitted, we introduce a new analytic algorithm, Powell's UOBYQA (Unconstrained Optimization By Quadratic Approximation), to accelerate our calculation. Our result proves that this algorithm is an effective fitting method for such continuous multi-parameter constraint. We find an interesting fact that these two approaches are sensitive to \(\Omega_{\Lambda}\) and \(\Omega_{M}\) separately. Combining them we can get quite good fitting values of basic cosmological parameters: \(\Omega_{M}=0.26_{-0.04}^{+0.04}\), and \(\Omega_{\Lambda}=0.82_{-0.16}^{+0.14}\) .
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ISSN:2331-8422
DOI:10.48550/arxiv.1011.6060