3k Sn S Clusters Hunting The Cosmological Parameters With Precision Cosmology
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3k Sn S Clusters Hunting The Cosmological Parameters With Precision Cosmology
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Author : Domingos Barbosa
language : en
Publisher: Springer Science & Business Media
Release Date : 2013-11-11
3k Sn S Clusters Hunting The Cosmological Parameters With Precision Cosmology written by Domingos Barbosa and has been published by Springer Science & Business Media this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013-11-11 with Science categories.
A JENAM 2002 Workshop, Porto, Portugal, 3-5 September 2002
The British National Bibliography
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Author : Arthur James Wells
language : en
Publisher:
Release Date : 2004
The British National Bibliography written by Arthur James Wells and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2004 with Bibliography, National categories.
American Book Publishing Record
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Author :
language : en
Publisher:
Release Date : 2004
American Book Publishing Record written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2004 with American literature categories.
Precision Cosmology With Galaxy Cluster Surveys
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Author : Hao-Yi Wu
language : en
Publisher: Stanford University
Release Date : 2011
Precision Cosmology With Galaxy Cluster Surveys written by Hao-Yi Wu and has been published by Stanford University this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011 with categories.
The acceleration of the universe, which is often attributed to "dark energy, " has posed one of the main challenges to fundamental physics. Galaxy clusters provide one of the most sensitive probes of dark energy because their abundance reflects the growth rate of large-scale structure and the expansion rate of the universe. Several large galaxy cluster surveys will soon provide tremendous statistical power to constrain the properties of dark energy; however, the constraining power of these surveys will be determined by how well systematic errors are controlled. Of these systematic errors, the dominant one comes from inferring cluster masses using observable signals of clusters, the so-called "observable--mass distribution." This thesis focuses on extracting dark energy information from forthcoming large galaxy cluster surveys, including how we maximize the cosmological information, how we control important systematics, and how precisely we need to calibrate theoretical models. We study how multi-wavelength follow-up observations can improve cluster mass calibration in optical surveys. We also investigate the impact of theoretical uncertainties in calibrating the spatial distributions of galaxy clusters on dark energy constraints. In addition, we explore how the formation history of galaxy clusters impacts the self-calibration of cluster mass. In addition, we use N-body simulations to develop a new statistical sample of cluster-size halos in order to further understand the observable--mass distribution. We study the completeness of subhalos in our cluster sample by comparing them with the satellite galaxies in the Sloan Digital Sky Survey. We also study how subhalo selections impact the inferred correlation between formation time and optical mass tracers, including cluster richness and velocity dispersion.
Optical Galaxy Cluster Detection Across A Wide Redshift Range
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Author :
language : en
Publisher:
Release Date : 2009
Optical Galaxy Cluster Detection Across A Wide Redshift Range written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2009 with categories.
The past decade is one of the most exciting period in the history of physics and astronomy. The discovery of cosmic acceleration dramatically changed our understanding about the evolution and constituents of the Universe. To accommodate the new acceleration phase into our well established Big Bang cosmological scenario under the frame work of General Relativity, there must exist a very special substance that has negative pressure and make up about 73% of the total energy density in our Universe. It is called Dark Energy. For the first time people realized that the vast majority of our Universe is made of things that are totally different from the things we are made of. Therefore, one of the major endeavors in physics and astronomy in the coming years is trying to understand, if we can, the nature of dark energy. Understanding dark energy cannot be achieved from pure logic. We need empirical evidence to finally determine about what is dark energy. The better we can constrain the energy density and evolution of the dark energy, the closer we will get to the answer. There are many ways to constrain the energy density and evolution of dark energy, each of which leads to degeneracy in certain directions in the parameter space. Therefore, a combination of complimentary methods will help to reduce the degeneracies and give tighter constraints. Dark energy became dominate over matter in the Universe only very recently (at about z (almost equal to) 1.5) and will affect both the cosmological geometry and large scale structure formation. Among the various experiments, some of them constrain the dark energy mainly via geometry (such as CMB, Supernovae) while some others provides constraints from both structures and geometry (such as BAO, Galaxy Clusters) Galaxy clusters can be used as a sensitive probe for cosmology. A large cluster catalog that extends to high redshift with well measured masses is indispensable for precisely constraining cosmological parameters. Detecting clusters in optical bands is very efficient. Multi-color CCD photometry allows combined detection and redshift estimation for clusters across broad redshift ranges. However, the lack of precise information about galaxy positions along the line of sight leads to contamination by projection, which plagues both cluster detection and the measurement of their properties. The dominance of red sequence galaxies, tightly clustered along the E/S0 ridgeline, provides a powerful method for de-projecting field galaxies. We developed an Error Corrected Gaussian Mixture Model to fit the galaxies color distribution around clusters by taking into account the measurement errors. By this technique, we can detect the red sequence color clustering and extract unbiased information about the evolution of the red sequence ridgeline and its width. Precision measurements of ridgelines yields better estimates of cluster richness and possibly their dynamical state, leading to better estimates of cluster mass. By using the red sequence clustering in color space identified from the Error Corrected Gaussian Mixture Model, together with the projected NFW filter in the projected RA/DEC plane, we developed a new and efficient cluster finding algorithm that can reliably detect galaxy clusters across the redshift range from 0.1 to 1.4. We have also run the cluster finder on legacy SDSS DR7 data and assembled an approximately volume limited cluster catalog across redshifts from 0.1 to 0.5. The algorithm has been tested against a Monte Carlo mock catalog, showing the identified clusters are highly complete and pure. With the completion of this thesis, we build the first and essential step towards precision cluster cosmology. Meanwhile, the large optical cluster catalog across a wide redshift range makes possible the systematic and detailed investigation of cluster formation and evolution.
End To End Cluster Cosmology Constraining Cosmological Parameters With X Ray Selected Galaxy Clusters
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Author : Jethro Venn Ridl
language : en
Publisher:
Release Date : 2017
End To End Cluster Cosmology Constraining Cosmological Parameters With X Ray Selected Galaxy Clusters written by Jethro Venn Ridl and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2017 with categories.
Cosmological Constraints From The Sdss Maxbcg Cluster Catalog
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Author :
language : en
Publisher:
Release Date : 2009
Cosmological Constraints From The Sdss Maxbcg Cluster Catalog written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2009 with categories.
We use the abundance and weak lensing mass measurements of the SDSS maxBCG cluster catalog to simultaneously constrain cosmology and the richness-mass relation of the clusters. Assuming a flat?CDM cosmology, we find?(?{sub m}/0.25){sup 0.41} = 0.832 ± 0.033 after marginalization over all systematics. In common with previous studies, our error budget is dominated by systematic uncertainties, the primary two being the absolute mass scale of the weak lensing masses of the maxBCG clusters, and uncertainty in the scatter of the richness-mass relation. Our constraints are fully consistent with the WMAP five-year data, and in a joint analysis we find?8 = 0.807 ± 0.020 and?{sub m} = 0.265 ± 0.016, an improvement of nearly a factor of two relative to WMAP5 alone. Our results are also in excellent agreement with and comparable in precision to the latest cosmological constraints from X-ray cluster abundances. The remarkable consistency among these results demonstrates that cluster abundance constraints are not only tight but also robust, and highlight the power of optically-selected cluster samples to produce precision constraints on cosmological parameters.
Studies Into The Averaging Problem
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Author : Tharake S. Wijenayake
language : en
Publisher:
Release Date : 2016
Studies Into The Averaging Problem written by Tharake S. Wijenayake and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016 with Anisotropy categories.
With the tremendous improvement in the precision of available astrophysical data in the recent past, it becomes increasingly important to examine some of the underlying assumptions behind the standard model of cosmology and take into consideration nonlinear and relativistic corrections which may affect it at percent precision level. Due to its mathematical rigor and fully covariant and exact nature, Zalaletdinov's macroscopic gravity (MG) is arguably one of the most promising frameworks to explore nonlinearities due to inhomogeneities in the real Universe. We study the application of MG to precision cosmology, focusing on developing a self-consistent cosmology model built on the averaging framework that adequately describes the large-scale Universe and can be used to study real data sets. We first implement an algorithmic procedure using computer algebra systems to explore new exact solutions to the MG field equations. After validating the process with an existing isotropic solution, we derive a new homogeneous, anisotropic and exact solution. Next, we use the simplest (and currently only) solvable homogeneous and isotropic model of MG and obtain an observable function for cosmological expansion using some reasonable assumptions on light propagation. We find that the principal modification to the angular diameter distance is through the change in the expansion history. We then linearize the MG field equations and derive a framework that contains large-scale structure, but the small scale inhomogeneities have been smoothed out and encapsulated into an additional cosmological parameter representing the averaging effect. We derive an expression for the evolution of the density contrast and peculiar velocities and integrate them to study the growth rate of large-scale structure. We find that increasing the magnitude of the averaging term leads to enhanced growth at late times. Thus, for the same matter content, the growth rate of large scale structure in the MG model is stronger than that of the standard model. Finally, we constrain the MG model using Cosmic Microwave Background temperature anisotropy data, the distance to supernovae data, the galaxy power spectrum, the weak lensing tomography shear-shear cross-correlations and the baryonic acoustic oscillations. We find that for this model the averaging density parameter is very small and does not cause any significant shift in the other cosmological parameters. However, it can lead to increased errors on some cosmological parameters such as the Hubble constant and the amplitude of the linear matter spectrum at the scale of 8h-1Mpc. Further studies are needed to explore other solutions and models of MG as well as their effects on precision cosmology.
Synthetic Source Injection In The Dark Energy Survey
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Author : Megan M. Tabbutt
language : en
Publisher:
Release Date : 2023
Synthetic Source Injection In The Dark Energy Survey written by Megan M. Tabbutt and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2023 with categories.
Presented here is the Dark Energy Survey's (DES) Synthetic Source Injection (SSI) methodology and applications to precision cosmology for our Year 6 analysis of large-scale structure. Our methodology is predicated on injecting models of real objects obtained from our very high signal-to-noise Deep Field observations into our single-epoch wide field images which are then processed identically to the original wide images. Inherent to this methodology, is that the synthetic sources automatically inherit the same systematics of the real wide field data, a highly sought after achievement for many systematics modeling pipelines that is nearly impossible to achieve from forward modeling techniques alone. In the end, we obtain wide field photometry catalogs of the deep field objects including their inheritance of the systematics. These catalogs are a Monte Carlo sampling of the transfer function of the survey. They can be used for calibration and diagnostics, as well as aid in the calculation and validation of our key project analysis and consequentially our measurement of cosmological parameter constraints through the photometric redshift calibration of the weak lensing sources and the magnification bias estimate for the lens galaxy samples. Both of which are critical to the measurements of the three 2-point correlation functions: cosmic shear, galaxy clustering and galaxy-galaxy lensing, from which we constrain cosmological parameters. This methodology was introduced for our year 3 analysis, and was the first example of using SSI to directly calibrate the cosmological measurements from a wide field survey. The refinement and expansion of the methodology is presented here. Specifically, we improved our mirroring of the wide field image processing pipeline to now fully recreate it. We refactored our code-base to be able to run our SSI at multiple super-computing centers, minimizing wall time and maximizing allocations. We also developed a new injection scheme that injects sources which are preferentially more useful to the cosmological analyses. These as well as other updates, our initial year 6 SSI results, and their applications to precision cosmology will be discussed at length in this thesis.