Mapping the Universe with weak lensing

  • Benjamin Samuel Mawdsley

Student thesis: Doctoral Thesis


Cosmological observations have led to the development of a standard model of cosmology, known as ΛCDM. In this model, we believe the majority of the Universe consists of matter and energy which does not interact electromagnetically, and the main challenge to the field is how to detect these invisible, yet dominant components of the Universe.
One avenue lies in the fact that the dark matter does feel the force of gravity. Furthermore, gravitational potentials influence the path of photons in such a way that images become distorted, in an effect known as gravitational lensing. Through the use of gravitational lensing, dark matter can be detected despite it being non luminous, as it is believed to constitute the majority of the matter in the Universe. Using measurements of lensing across large areas of the sky, it is possible to produce maps of the dark matter.
In this thesis, I present mass maps that have been made using lensing measurements from a leading current experiment, the Dark Energy Survey.
I develop a new pipeline to produce these mass maps in a more accurate way, thoroughly testing them using a wide range of statistics. I also present work that analyses how these mass maps can be used to provide us with constraints on the fundamental properties of the Universe, through measuring the topology of the maps, and find that such an approach can lead to improving cosmological constraints. Finally, I present work examining the immediate future of the field of mass mapping, evaluating the likely quality of the next generation of mass maps and the extent to which they can improve our knowledge of the Universe.
Date of Award2020
Original languageEnglish
SupervisorDavid Bacon (Supervisor) & Robert Nichol (Supervisor)

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