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Title: Wide-field optical and infrared observations of weak gravitational lensing
Author: Gray, M.
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 2001
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Gravitational lensing is a powerful and versatile tool that allows us to directly link the observed distribution of light with the underlying distribution of dark matter. In this thesis, I apply several weak gravitational lensing techniques to clusters and superclusters of galaxies observed with newly developed wide-field optical and infrared arrays. Chapter 1 summarizes our current cosmological model and the dark matter problem, and develops the theory of gravitational lensing in the wider context of recent observational technological advances. Chapter 2 is concerned with the commissioning of the Cambridge Infrared Survey Instrument (CIRSI) over three observing runs from 1988-2000. I outline the scientific benefits of wide-field infrared imaging and the unique capabilities of CIRSI, and document the evolution of the instrumental qualities and reduction strategies over this period of time. The process involved was important for characterizing the camera performance and developing the software pipeline necessary to handle the large volumes of data produced by the instrument. In the subsequent two chapters I present the first scientific results from CIRSI. In Chapter 3, I discuss the detection of a depletion of the surface number density of background galaxies behind a massive cluster due to gravitational lensing. Here I extend the original optical test to near-infrared wavelengths which, in principle, offer significant advantages: the flatter number-count slope and the more accurate colour discrimination between foreground and background populations both serve to boost the lensing signal. The unique wide-field capabilities of CIRSI allow me to simultaneously measure the properties of the lensed and unlensed background populations and to use the method to estimate the mass of the rich cluster Abell 2219 (z = 0.22).
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available