University of Cambridge
Tracing the Cosmos: Probing Cosmology with the Large Scale Structure of the Universe
Abstract
dc:description.abstractIn this thesis I will present work on constraining and testing cosmological models with different probes of the large scale structure of the Universe. I will introduce different large scale structure observables and discuss relevant modelling approaches. In particular, I will motivate the use of complementary probes to examine some of the tensions between different datasets widely discussed within cosmology. One such tension is the disagreement between local measurements of the Universe’s expansion rate using the so-called distance ladder and the expansion rate inferred from the Cosmic Microwave Background (CMB). I present work that aims to exploit a novel feature in the distribution of matter in the Universe, the so called matter-radiation equality scale, to obtain independent estimates of the expansion rate. I develop a method to isolate the information from this feature in galaxy surveys, demonstrate its robustness, and present an application to current data as well as forecasts for the next generation of cosmological surveys. Another widely discussed tension is between the amplitude of matter density fluctuations observed in the late universe and predictions from model fits to early universe data. Recent observations have found a slightly smaller abundance of structures than is expected within the standard cosmological model. I obtain independent estimates of the abundance of structures in the late universe using combinations of galaxy surveys and the gravitational lensing of the CMB. Finally, I present the first detection of the three-point correlation between galaxies and CMB lensing. I show that the detection is robust to potential sources of systematic bias and present a comparison to model predictions. This signal can be used to constrain the evolution of structure on smaller scales where non-linear processes are dominant. In summary, I will present methods of probing cosmology with observations of cosmic structure including galaxy surveys and gravitational lensing of the CMB. I will describe new methods to analyse these observations and obtain competitive constraints on cosmological model parameters by working with state of the art data sets. These novel constraints are complementary to other analyses and will contribute to furthering our understanding of the physics of our Universe and shed light on some of the tantalising hints at physics beyond the current standard model of cosmology.
Degree
thesis:*- Name dc:type.qualificationname
- Doctor of Philosophy (PhD)
- Level dc:type.qualificationlevel
- Doctoral
- Grantor dc:publisher.institution
- University of Cambridge
- Year dc:date.issued
- 2024
Author and committee
dc:creator, dc:contributor.*- Author dc:creator
-
- Farren, Gerrit
- Advisor dc:contributor.advisor
-
- Sherwin, Blake
Subjects
dc:subject × 6Rights
dc:rightsIdentifiers
dc:identifier.*- DOI dc:identifier.doi
- https://doi.org/10.17863/cam.112076
- OAI identifier oai:identifier
- oai:www.repository.cam.ac.uk:1810/374089