Dissertation/Thesis Abstract

Mass and Light Correlated with Galaxies on Local and Cosmic Scales: Weak Gravitational Lensing in the Deep Lens Survey
by Choi, Ami, Ph.D., University of California, Davis, 2011, 108; 3499418
Abstract (Summary)

In this dissertation, we describe the results of applying weak gravitational lensing techniques to probe the connection between luminous galaxies and the dark matter halos in which they live. Specifically, we study galaxy-shear correlations in the Deep Lens Survey, and we investigate how this function changes with observable galaxy properties such as stellar mass, luminosity, color, and redshift. In Chapter 3, we examine the galaxy-shear correlation function on a large range of scales from small radii where the dominant contribution is from halos associated with individual galaxies to large radii where the dominant contribution is from neighboring galaxies and large-scale structure. We study the lensing signal for galaxies binned by luminosity and find that more luminous galaxies are more massive. More interestingly, the galaxy-shear correlation function shows features consistent with satellite and 2-halo terms from the halo model and cannot be fit with a single power law out to 15 Mpc. We also find more correlated large scale structure mass at lower redshift, consistent with the paradigm of bottom-up hierarchical structure formation. In Chapter 4, we focus on a subset of the survey with ancillary infrared data that allow estimates of stellar mass. We study the lensing signal for galaxies binned by stellar mass and infer the nature and evolution of the relationship between virial mass and stellar mass. We show that stellar mass and virial mass scale such that galaxies with smaller stellar masses also have smaller virial masses. This work has implications for the idea of downsizing, but does not yet have the S/N to provide competitive constraints.

In the process of making lensing measurements on the Deep Lens Survey, we have also investigated errors related to the two most important variables: shapes and photometric redshifts. we discuss our findings in the context of the survey characteristics in Chapter 2 and in the simulations section of Chapter 3. While neither the shapes nor the photometric redshifts are perfect, their associated errors can be reasonably controlled such that the results of the scientific analysis discussed above are meaningful. We conclude and comment on future work in Chapter 5. The Appendix contains a useful reference for equations related to lensing formalism and the halo model.

Indexing (document details)
Advisor: Tyson, John A.
Commitee: Fassnacht, Christopher D., Wittman, David M.
School: University of California, Davis
Department: Physics
School Location: United States -- California
Source: DAI-B 73/07(E), Dissertation Abstracts International
Subjects: Astrophysics, Astronomy
Keywords: Dark matter, Galaxy surveys, Gravitational lensing, Light correlation with galaxies, Mass correlation with galaxies
Publication Number: 3499418
ISBN: 9781267238443
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