Cosmology with robust galaxy cluster weak lensing mass measurements
Abstract/Contents
- Abstract
- Galaxy clusters—the largest nodes on the cosmic web of dark matter—compress the mass of 10^15 Suns into a volume of order ∼Mpc^3. Their extreme gravitational influence gives rise to several unique observational signatures, such as X-ray emission from diffuse baryonic matter that is heated and ionized by the cluster's gravitational squeeze, and the prominent weak lensing signal imprinted upon the shapes of background galaxy images as light travels through a cluster's gravitational field. These and other measurable cluster properties can be used to obtain cluster masses and constrain cosmology. Clusters are powerful dark energy probes, both as tracers of cosmic structure growth and the universe's geometry. The former experiment counts the number of clusters in mass and redshift bins using large astronomical surveys like the forthcoming Large Synoptic Survey Telescope (LSST). The latter is based upon the gas mass fraction f_gas=M_gas/M_total of clusters. Leveraging the fact that clusters are so large they contain a representative sample of the universe, the mass fraction of intracluster gas, the dominant baryonic component of clusters, can be related to the cosmic baryon fraction (Ω_b/Ω_m) using a small correction factor from hydrodynamic simulations. Since the absolute f_gas of massive clusters is redshift-independent, while its measured apparent f_gas depends on distance, it serves as a standard quantity to constrain dark energy. The key challenge for both experiments is measuring cluster masses accurately. In this thesis we address this need for accurate galaxy cluster masses with robust weak lensing measurements. We focus on a subset of 10 clusters from the forthcoming fgas cosmology sample (in prep.). These are relaxed galaxy clusters—undisturbed, symmetric systems, with no signs of recent merging activity—which enables reliable M_total measurements based on the assumption of hydrostatic equilibrium. Chandra X-ray imaging yields precise measurements of relative M_total and M_gas between clusters in the sample, however they suffer from an unknown bias. Accurate weak lensing masses measured from wide-field SuprimeCam photometry provide the needed absolute calibration, enabling robust f_gas measurements, as well as constraints on Ω_m and dark energy properties.
Description
| Type of resource | text |
|---|---|
| Form | electronic resource; remote; computer; online resource |
| Extent | 1 online resource. |
| Place | California |
| Place | [Stanford, California] |
| Publisher | [Stanford University] |
| Copyright date | 2019; ©2019 |
| Publication date | 2019; 2019 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Author | Wright, Adam R |
|---|---|
| Degree supervisor | Allen, Steven W. (Steven Ward) |
| Thesis advisor | Allen, Steven W. (Steven Ward) |
| Thesis advisor | Blandford, Roger D |
| Thesis advisor | Macintosh, Bruce, 1966- |
| Degree committee member | Blandford, Roger D |
| Degree committee member | Macintosh, Bruce, 1966- |
| Associated with | Stanford University, Department of Physics. |
Subjects
| Genre | Theses |
|---|---|
| Genre | Text |
Bibliographic information
| Statement of responsibility | Adam Wright. |
|---|---|
| Note | Submitted to the Department of Physics. |
| Thesis | Thesis Ph.D. Stanford University 2019. |
| Location | electronic resource |
Access conditions
- Copyright
- © 2019 by Adam R. Wright
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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