A study of relativistic fluids with applications to cosmology: A variational approach
| dc.contributor.advisor | Osano, Bob | |
| dc.contributor.author | Oreta, Timothy | |
| dc.date.accessioned | 2022-03-15T12:14:03Z | |
| dc.date.available | 2022-03-15T12:14:03Z | |
| dc.date.issued | 2021 | |
| dc.date.updated | 2022-03-14T11:04:49Z | |
| dc.description.abstract | This thesis examines relativistic fluids. We have used the variational approach to develop tools for studying the dynamics of relativistic fluids to apply this to cosmological modelling. Studies like these go beyond the standard model in cosmology. Researchers believe that such extensions to the standard cosmological model are pivotal to resolving some of the long-standing cosmological problems. An example of such problems is the origin, growth (from quantum electromagnetic fluctuations to large-scale magnetic fields during inflation) and evolution of cosmological magnetic fields that exhibit as large-scale (cosmological) magnetic fields in late time. One other example is the coincidence problem. The standard approach in such studies is to use modelling in the form of the single-fluid formalism. As an alternative one can consider the single-fluid and multi-fluid formalisms that incorporate aspects of electrodynamics and thermodynamics, respectively in the context of the variational approach. This might help us make progress in trying to either resolve some of these problems or at least open up new ways of addressing them. In this regard, we have extended the well-known M¨ueller-Israel-Stewart (hereafter MIS) formalism to allow us to examine the effect on fluid flow in which the components of the multi-species fluids interact thermodynamically. We use the extension to the MIS theory in the context of interacting species to study the growth of dark matter and dark energy, and find that either interaction or entrainment involving dark energy and dark matter suggests a mutual relative modulation of the growth behaviour of the two densities. This may aid in resolving the coincidence problem. Our examination of inflation-generated, large-scale magnetic fields reveals a super-adiabatically evolving mode from the beginning of the radiation-dominated epoch to either much later during the epoch or probably extending far into the era of matter domination which may account for late time, large-scale magnetic fields. | |
| dc.identifier.apacitation | Oreta, T. (2021). <i>A study of relativistic fluids with applications to cosmology: A variational approach</i>. (). ,Faculty of Science ,Department of Mathematics and Applied Mathematics. Retrieved from http://hdl.handle.net/11427/36098 | en_ZA |
| dc.identifier.chicagocitation | Oreta, Timothy. <i>"A study of relativistic fluids with applications to cosmology: A variational approach."</i> ., ,Faculty of Science ,Department of Mathematics and Applied Mathematics, 2021. http://hdl.handle.net/11427/36098 | en_ZA |
| dc.identifier.citation | Oreta, T. 2021. A study of relativistic fluids with applications to cosmology: A variational approach. . ,Faculty of Science ,Department of Mathematics and Applied Mathematics. http://hdl.handle.net/11427/36098 | en_ZA |
| dc.identifier.ris | TY - Doctoral Thesis AU - Oreta, Timothy AB - This thesis examines relativistic fluids. We have used the variational approach to develop tools for studying the dynamics of relativistic fluids to apply this to cosmological modelling. Studies like these go beyond the standard model in cosmology. Researchers believe that such extensions to the standard cosmological model are pivotal to resolving some of the long-standing cosmological problems. An example of such problems is the origin, growth (from quantum electromagnetic fluctuations to large-scale magnetic fields during inflation) and evolution of cosmological magnetic fields that exhibit as large-scale (cosmological) magnetic fields in late time. One other example is the coincidence problem. The standard approach in such studies is to use modelling in the form of the single-fluid formalism. As an alternative one can consider the single-fluid and multi-fluid formalisms that incorporate aspects of electrodynamics and thermodynamics, respectively in the context of the variational approach. This might help us make progress in trying to either resolve some of these problems or at least open up new ways of addressing them. In this regard, we have extended the well-known M¨ueller-Israel-Stewart (hereafter MIS) formalism to allow us to examine the effect on fluid flow in which the components of the multi-species fluids interact thermodynamically. We use the extension to the MIS theory in the context of interacting species to study the growth of dark matter and dark energy, and find that either interaction or entrainment involving dark energy and dark matter suggests a mutual relative modulation of the growth behaviour of the two densities. This may aid in resolving the coincidence problem. Our examination of inflation-generated, large-scale magnetic fields reveals a super-adiabatically evolving mode from the beginning of the radiation-dominated epoch to either much later during the epoch or probably extending far into the era of matter domination which may account for late time, large-scale magnetic fields. DA - 2021_ DB - OpenUCT DP - University of Cape Town KW - Cosmology KW - relativistic fluids KW - variational approach KW - single-fluid KW - multi-fluid KW - dark energy KW - dark-matter KW - thermodynamics KW - interaction KW - entrainment KW - inflation KW - magnetic fields. LK - https://open.uct.ac.za PY - 2021 T1 - A study of relativistic fluids with applications to cosmology: A variational approach TI - A study of relativistic fluids with applications to cosmology: A variational approach UR - http://hdl.handle.net/11427/36098 ER - | en_ZA |
| dc.identifier.uri | http://hdl.handle.net/11427/36098 | |
| dc.identifier.vancouvercitation | Oreta T. A study of relativistic fluids with applications to cosmology: A variational approach. []. ,Faculty of Science ,Department of Mathematics and Applied Mathematics, 2021 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/36098 | en_ZA |
| dc.language.rfc3066 | eng | |
| dc.publisher.department | Department of Mathematics and Applied Mathematics | |
| dc.publisher.faculty | Faculty of Science | |
| dc.subject | Cosmology | |
| dc.subject | relativistic fluids | |
| dc.subject | variational approach | |
| dc.subject | single-fluid | |
| dc.subject | multi-fluid | |
| dc.subject | dark energy | |
| dc.subject | dark-matter | |
| dc.subject | thermodynamics | |
| dc.subject | interaction | |
| dc.subject | entrainment | |
| dc.subject | inflation | |
| dc.subject | magnetic fields. | |
| dc.title | A study of relativistic fluids with applications to cosmology: A variational approach | |
| dc.type | Doctoral Thesis | |
| dc.type.qualificationlevel | Doctoral | |
| dc.type.qualificationlevel | PhD |