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Title:

PROJECTION EFFECTS IN MASS-SELECTED GALAXY-CLUSTER SAMPLES

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Selection of galaxy clusters by mass is now possible due to weak gravitational lensing effects. It is an important question then whether this type of selection reduces the projection effects prevalent in optically selected cluster samples. We address this question using simulated data, from which we construct synthetic cluster catalogues both wi...

Selection of galaxy clusters by mass is now possible due to weak gravitational lensing effects. It is an important question then whether this type of selection reduces the projection effects prevalent in optically selected cluster samples. We address this question using simulated data, from which we construct synthetic cluster catalogues both with Abell’s criterion and an aperture-mass estimator sensitive to gravitational tidal effects. The signal-to-noise ratio of the latter allows to some degree to control the properties of the cluster sample. For the first time, we apply the cluster-detection algorithm proposed by Schneider to large-scale structure simulations. We find that selection of clusters through weak gravitational lensing is more reliable in terms of completeness and spurious detections. Choosing the signal-to-noise threshold appropriately, the completeness can be increased up to 100%, and the fraction of spurious detections can significantly be reduced compared to Abell-selected cluster samples. We also investigate the accuracy of mass estimates in cluster samples selected by both luminosity and weaklensing effects. We find that mass estimates from gravitational lensing, for which we employ the ζ-statistics by Kaiser et al., are significantly more accurate than those obtained from galaxy kinematics via the virial theorem. 1. Minimize

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The Pennsylvania State University CiteSeerX Archives

Year of Publication:

2013-08-06

Source:

http://arxiv.org/pdf/astro-ph/9902153v1.pdf

http://arxiv.org/pdf/astro-ph/9902153v1.pdf Minimize

Document Type:

text

Language:

en

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is particularly annoying because clusters constitute an important

is particularly annoying because clusters constitute an important Minimize

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520 Astronomy & allied sciences *(computed)*

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Metadata may be used without restrictions as long as the oai identifier remains attached to it.

Metadata may be used without restrictions as long as the oai identifier remains attached to it. Minimize

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Title:

Cluster deprojection with joint lensing, X-ray, and Sunyaev-Zeldovich data

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Abstract. We propose a new cluster deprojection algorithm for recovering cluster structure along the line of sight (los) based on the Richardson-Lucy (RL) algorithm, which recovers a nonnegative theoretical distribution from a given projection. To optimize our reconstruction we combine X-ray and Sunyaev-Zeldovich (SZ) data with gravitational len...

Abstract. We propose a new cluster deprojection algorithm for recovering cluster structure along the line of sight (los) based on the Richardson-Lucy (RL) algorithm, which recovers a nonnegative theoretical distribution from a given projection. To optimize our reconstruction we combine X-ray and Sunyaev-Zeldovich (SZ) data with gravitational lensing maps. The combination of these three data types constrains the structure of rich clusters of galaxies. To validate our new approach, we apply the algorithm to gas–dynamical cluster simulations. A reconstruction using the lensing potential is shown. 1. Richardson-Lucy deprojection algorithm Resolving the los-structure of 3d objects can be formulated as inversion problem, ψ(x) = φ(ζ)P(x|ζ)dζ, where φ(ζ) is the function of interest, ψ(x) is the function accessible through measurement, and the integral kernel P(x|ζ) is normalized and non–negative as ψ(x) and φ(ζ) represent probability distribution functions. Using Bayes theorem for conditional probabilities, a two step iterative reconstruction algorithm (Lucy, 1974; Lucy, 1994) ψ r ∫ (x) = φ r (ζ)P(x|ζ)dζ φ r+1 (ζ) = φ r ∫ ψ(x) (ζ) ψr (x) P(x|ζ)dx for approximating φ(ζ) can be derived, with φ r+1 being the (r + 1)-st estimate. For systems with axial symmetry inclined with respect to the los an explicit expression for P(x|ζ) was derived by Binney et al. (1990). 2. The proposed algorithm The three observables depend differently on the los-structure of the 3d gravitational potential (Reblinsky & Bartelmann (1999)): Lensing potential ψ(x,y) ∝ φ(R,Z)dz Minimize

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The Pennsylvania State University CiteSeerX Archives

Year of Publication:

2013-08-06

Source:

http://arxiv.org/pdf/astro-ph/9909155v1.pdf

http://arxiv.org/pdf/astro-ph/9909155v1.pdf Minimize

Document Type:

text

Language:

en

DDC:

006 Special computer methods *(computed)*

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Metadata may be used without restrictions as long as the oai identifier remains attached to it.

Metadata may be used without restrictions as long as the oai identifier remains attached to it. Minimize

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Title:

ASTRONOMY AND ASTROPHYSICS Cosmic shear and halo abundances: analytical versus

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A&A manuscript no. (will be inserted by hand later) Your thesaurus codes are:

A&A manuscript no. (will be inserted by hand later) Your thesaurus codes are: Minimize

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The Pennsylvania State University CiteSeerX Archives

Year of Publication:

2013-01-03

Source:

http://arxiv.org/pdf/astro-ph/9907250v2.pdf

http://arxiv.org/pdf/astro-ph/9907250v2.pdf Minimize

Document Type:

text

Language:

en

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Metadata may be used without restrictions as long as the oai identifier remains attached to it.

Metadata may be used without restrictions as long as the oai identifier remains attached to it. Minimize

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Title:

Cosmic shear and halo abundances: Analytical versus numerical results

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. The aperture mass has been shown in a series of recent publications to be a useful quantitative tool for weak lensing studies, ranging from cosmic shear to the detection of a mass-selected sample of dark matter haloes. Quantitative analytical predictions for the aperture mass have been based on a number of simplifying assumptions. In this pape...

. The aperture mass has been shown in a series of recent publications to be a useful quantitative tool for weak lensing studies, ranging from cosmic shear to the detection of a mass-selected sample of dark matter haloes. Quantitative analytical predictions for the aperture mass have been based on a number of simplifying assumptions. In this paper, we test the reliability of these assumptions and the quality of the analytic approximations, using ray-tracing simulations through a cosmological density field generated by very large N-body simulations. We find that those analytic predictions which take into account the non-linear evolution of the matter distribution, such as the dispersion of the aperture mass and the halo abundance, are surprisingly accurately reproduced with our numerical results, whereas the predictions for the skewness, based on quasi-linear theory, are rather imprecise. In particular, we verify numerically that the probability distribution of the aperture mass decrease. Minimize

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The Pennsylvania State University CiteSeerX Archives

Year of Publication:

2009-04-13

Source:

http://www.mpa-garching.mpg.de/~maria/greenreports/mpa99/MPA1189.ps.gz

http://www.mpa-garching.mpg.de/~maria/greenreports/mpa99/MPA1189.ps.gz Minimize

Document Type:

text

Language:

en

DDC:

520 Astronomy & allied sciences *(computed)*

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Title:

ASTRONOMY AND ASTROPHYSICS Cosmic shear and halo abundances: Analytical versus

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Description:

A&A manuscript no. (will be inserted by hand later) Your thesaurus codes are:

A&A manuscript no. (will be inserted by hand later) Your thesaurus codes are: Minimize

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The Pennsylvania State University CiteSeerX Archives

Year of Publication:

2013-01-03

Source:

http://arxiv.org/pdf/astro-ph/9907250v1.pdf

http://arxiv.org/pdf/astro-ph/9907250v1.pdf Minimize

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text

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en

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Title:

Projection Effects in Clusters of Galaxies

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This dissertation is organized as follows. In the first two chapters the necessary theoretical framework is briefly reviewed: the standard picture of structure formation and evolution in chapter 1 and the relevant details about gravitational lensing in chapter 2, where especially the ap statistics is introduced. The ap statistics is then used in...

This dissertation is organized as follows. In the first two chapters the necessary theoretical framework is briefly reviewed: the standard picture of structure formation and evolution in chapter 1 and the relevant details about gravitational lensing in chapter 2, where especially the ap statistics is introduced. The ap statistics is then used in chapter 3 to investigate the statistical properties of cosmic shear using LSS ray tracing simulations from numerical --body data. In addition, the number of haloes computed from semianalytical estimates are compared to results obtained from the ray tracing simulations. In chapter 4 the possible use of the ap statistic for a mass based selection of clusters of galaxies is analyzed with respect to projection effects and compared to the optical Abell selection criterion. Then, in chapter 5 the novel multiple--data Richardson--Lucy cluster reconstruction algorithm is derived and tested using synthetical data generated from gas-dynamical simulations. Finally, chapter 6 discusses the main results obtained in this thesis, puts them into a broader cosmological context and proposes future research Minimize

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The Pennsylvania State University CiteSeerX Archives

Year of Publication:

2009-04-18

Source:

http://edoc.ub.uni-muenchen.de/archive/00000415/01/Reblinsky_Katrin.pdf

http://edoc.ub.uni-muenchen.de/archive/00000415/01/Reblinsky_Katrin.pdf Minimize

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text

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en

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Title:

Projection effects in clusters of galaxies

Publisher:

Ludwig-Maximilians-Universität München

Year of Publication:

2000-03-09

Document Type:

Dissertation ; NonPeerReviewed

Subjects:

Fakultät für Physik

Fakultät für Physik Minimize

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http://edoc.ub.uni-muenchen.de/415/

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Title:

Cluster deprojection with joint lensing, X-ray, and Sunyaev-Zeldovich data

Author:

Description:

We propose a new cluster deprojection algorithm for recovering cluster structure along the line of sight (los) based on the Richardson-Lucy (RL) algorithm, which recovers a nonnegative theoretical distribution from a given projection. To optimize our reconstruction we combine X-ray and Sunyaev-Zeldovich (SZ) data with gravitational lensing maps....

We propose a new cluster deprojection algorithm for recovering cluster structure along the line of sight (los) based on the Richardson-Lucy (RL) algorithm, which recovers a nonnegative theoretical distribution from a given projection. To optimize our reconstruction we combine X-ray and Sunyaev-Zeldovich (SZ) data with gravitational lensing maps. The combination of these three data types constrains the structure of rich clusters of galaxies. To validate our new approach, we apply the algorithm to gas-dynamical cluster simulations. A reconstruction using the lensing potential is shown. ; Comment: 2 pages including 2 figures, uses PASP conference proceedings style. Poster contribution to "Gravitational Lensing: Recent Progress and Future Goals", Boston University, July 1999, ed. T.G. Brainerd and C.S. Kochanek Minimize

Year of Publication:

1999-09-09

Document Type:

text

Subjects:

Astrophysics

Astrophysics Minimize

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Title:

Projection effects in mass-selected galaxy-cluster samples

Author:

Description:

Selection of galaxy clusters by mass is now possible due to weak gravitational lensing effects. It is an important question then whether this type of selection reduces the projection effects prevalent in optically selected cluster samples. We address this question using simulated data, from which we construct synthetic cluster catalogues both wi...

Selection of galaxy clusters by mass is now possible due to weak gravitational lensing effects. It is an important question then whether this type of selection reduces the projection effects prevalent in optically selected cluster samples. We address this question using simulated data, from which we construct synthetic cluster catalogues both with Abell's criterion and an aperture-mass estimator sensitive to gravitational tidal effects. The signal-to-noise ratio of the latter allows to some degree to control the properties of the cluster sample. For the first time, we apply the cluster-detection algorithm proposed by Schneider to large-scale structure simulations. We find that selection of clusters through weak gravitational lensing is more reliable in terms of completeness and spurious detections. Choosing the signal-to-noise threshold appropriately, the completeness can be increased up to 100%, and the fraction of spurious detections can significantly be reduced compared to Abell-selected cluster samples. We also investigate the accuracy of mass estimates in cluster samples selected by both luminosity and weak-lensing effects. We find that mass estimates from gravitational lensing, for which we employ the zeta-statistics by Kaiser et al., are significantly more accurate than those obtained from galaxy kinematics via the virial theorem. ; Comment: 14 pages incuding 17 figures. Accepted for publication in Astronomy & Astrophysics Minimize

Year of Publication:

1999-02-10

Document Type:

text

Subjects:

Astrophysics

Astrophysics Minimize

DDC:

520 Astronomy & allied sciences *(computed)*

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Title:

Cosmic shear and halo abundances: Analytical versus numerical results

Author:

Description:

The aperture mass has been shown in a series of recent publications to be a useful quantitative tool for weak lensing studies, ranging from cosmic shear to the detection of a mass-selected sample of dark matter haloes. Quantitative analytical predictions for the aperture mass have been based on a number of simplifying assumptions. In this paper,...

The aperture mass has been shown in a series of recent publications to be a useful quantitative tool for weak lensing studies, ranging from cosmic shear to the detection of a mass-selected sample of dark matter haloes. Quantitative analytical predictions for the aperture mass have been based on a number of simplifying assumptions. In this paper, we test the reliability of these assumptions and the quality of the analytic approximations, using ray-tracing simulations through a cosmological density field generated by very large N-body simulations. We find that those analytic predictions which take into account the non-linear evolution of the matter distribution, such as the dispersion of the aperture mass and the halo abundance, are surprisingly accurately reproduced with our numerical results, whereas the predictions for the skewness, based on quasi-linear theory, are rather imprecise. In particular, we verify numerically that the probability distribution of the aperture mass decreases exponentially for values much larger than the rms. Given the good overall agreement, comparisons between the observed distribution of the aperture mass and the theoretical values provide a powerful tool for testing cosmological models. ; Comment: 13 pages including 9 figures, minor revisions to match published version Minimize

Year of Publication:

1999-07-19

Document Type:

text

Subjects:

Astrophysics

Astrophysics Minimize

DDC:

520 Astronomy & allied sciences *(computed)*

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