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Evolution of matter density perturbations in viable f (R) theories of gravity
In the ΛCDM model, the late-time accelerated expansion of the Universe is explained via a dark energy fluid in the form of a cosmological constant. Such a cosmological constant dominates the energy budget of the Universe today, and yet, it is still a poorly understood species because it is not obser...
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| Format: | Thesis |
| Language: | English |
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Department of Mathematics and Applied Mathematics
2020
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| _version_ | 1867613152433143808 |
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| access_status_str | Open Access |
| author | Dlamini, Simthembile |
| author2 | de La Cruz-Dombriz, Alvaro |
| author_browse | Dlamini, Simthembile de La Cruz-Dombriz, Alvaro |
| author_facet | de La Cruz-Dombriz, Alvaro Dlamini, Simthembile |
| author_sort | Dlamini, Simthembile |
| collection | Thesis |
| description | In the ΛCDM model, the late-time accelerated expansion of the Universe is explained via a dark energy fluid in the form of a cosmological constant. Such a cosmological constant dominates the energy budget of the Universe today, and yet, it is still a poorly understood species because it is not observed yet. A competitive theoretical approach to understand this is via the so-called f (R) extended theories of gravity, which explain the late acceleration epoch of the Universe resorting to a geometrical modification of the field equations. We illustrate how f (R) theories are constructed and how both the analysis of the cosmological expansion and the growth of matter density perturbations in these theories may differ from the standard Einsteinian results. We study the evolution of matter density perturbations in a viable f (R) model (Hu-Sawicki model) and explain why the Hu-Sawicki model is indeed a viable alternative to ΛCDM by discussing the Dynamical System approach as a method used to obtain the cosmological background solutions. A complete comparison of density perturbations in both the ΛCDM model and Hu-Sawicki model is presented. |
| format | Thesis |
| id | oai:open.uct.ac.za:11427/31500 |
| institution | University of Cape Town (South Africa) |
| language | eng |
| last_indexed | 2026-06-10T12:31:35.974Z |
| license_str | Not specified — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UCTD — University of Cape Town Open Access Repository |
| publishDate | 2020 |
| publishDateRange | 2020 |
| publishDateSort | 2020 |
| publisher | Department of Mathematics and Applied Mathematics |
| publisherStr | Department of Mathematics and Applied Mathematics |
| record_format | dspace |
| source_str | UCTD — University of Cape Town Open Access Repository |
| spelling | oai:open.uct.ac.za:11427/31500 Evolution of matter density perturbations in viable f (R) theories of gravity Dlamini, Simthembile de La Cruz-Dombriz, Alvaro Mathematics and Applied Mathematics In the ΛCDM model, the late-time accelerated expansion of the Universe is explained via a dark energy fluid in the form of a cosmological constant. Such a cosmological constant dominates the energy budget of the Universe today, and yet, it is still a poorly understood species because it is not observed yet. A competitive theoretical approach to understand this is via the so-called f (R) extended theories of gravity, which explain the late acceleration epoch of the Universe resorting to a geometrical modification of the field equations. We illustrate how f (R) theories are constructed and how both the analysis of the cosmological expansion and the growth of matter density perturbations in these theories may differ from the standard Einsteinian results. We study the evolution of matter density perturbations in a viable f (R) model (Hu-Sawicki model) and explain why the Hu-Sawicki model is indeed a viable alternative to ΛCDM by discussing the Dynamical System approach as a method used to obtain the cosmological background solutions. A complete comparison of density perturbations in both the ΛCDM model and Hu-Sawicki model is presented. 2020-03-06T09:58:22Z 2020-03-06T09:58:22Z 2019 2020-03-05T07:14:20Z Master Thesis Masters MSc http://hdl.handle.net/11427/31500 eng application/pdf Department of Mathematics and Applied Mathematics Faculty of Science |
| spellingShingle | Mathematics and Applied Mathematics Dlamini, Simthembile Evolution of matter density perturbations in viable f (R) theories of gravity |
| thesis_degree_str | Master's |
| title | Evolution of matter density perturbations in viable f (R) theories of gravity |
| title_full | Evolution of matter density perturbations in viable f (R) theories of gravity |
| title_fullStr | Evolution of matter density perturbations in viable f (R) theories of gravity |
| title_full_unstemmed | Evolution of matter density perturbations in viable f (R) theories of gravity |
| title_short | Evolution of matter density perturbations in viable f (R) theories of gravity |
| title_sort | evolution of matter density perturbations in viable f r theories of gravity |
| topic | Mathematics and Applied Mathematics |
| url | http://hdl.handle.net/11427/31500 |
| work_keys_str_mv | AT dlaminisimthembile evolutionofmatterdensityperturbationsinviablefrtheoriesofgravity |