Challenges for dark energy science : color gradients and blended objects
Abstract/Contents
- Abstract
- Some of the most exciting scientific challenges at present in cosmology are in understanding the nature of dark matter and dark energy. The billions of galaxies observed by Legacy Survey of Space and Time (LSST) will dramatically improve the statistical power of weak lensing observations and help probe the mass distribution in the universe more accurately. This increased statistical sensitivity means that potential systematic biases must be carefully identified, quantified, and minimized. My thesis will address two such systematic biases: galaxy color gradients and blending. In the first part of the thesis, I will describe how shape measurements of galaxies with varying spectral energy distribution across their profile -- called "color gradients" -- when seen by a chromatic point spread function can be biased. I estimate this bias expected for the LSST using simulations of parametric galaxies and realistic galaxy images. The second part of my thesis focuses on the blending challenge for the LSST where a significant fraction of the lensed galaxy images will overlap with images of other objects, affecting the accuracy of flux and shape measurements. I discuss two novel approaches to infer the presence of objects that go undetected because of blending and compare their performance to existing detection algorithms
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 | 2020; ©2020 |
| Publication date | 2020; 2020 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Author | Kamath, Sowmya |
|---|---|
| Degree supervisor | Burchat, P. (Patricia) |
| Thesis advisor | Burchat, P. (Patricia) |
| Thesis advisor | Allen, Steven |
| Thesis advisor | Church, Sarah Elizabeth |
| Degree committee member | Allen, Steven |
| Degree committee member | Church, Sarah Elizabeth |
| Associated with | Stanford University, Department of Physics. |
Subjects
| Genre | Theses |
|---|---|
| Genre | Text |
Bibliographic information
| Statement of responsibility | Sowmya Kamath |
|---|---|
| Note | Submitted to the Department of Physics |
| Thesis | Thesis Ph.D. Stanford University 2020 |
| Location | electronic resource |
Access conditions
- Copyright
- © 2020 by Sowmya Kamath
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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