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Exact evolution of discrete relativistic cosmological models
Stockholm University, Faculty of Science, Department of Physics.
Stockholm University, Faculty of Science, Department of Physics.
2013 (English)In: Journal of Cosmology and Astroparticle Physics, ISSN 1475-7516, E-ISSN 1475-7516, no 11, 010- p.Article in journal (Refereed) Published
Abstract [en]

We study the effects of inhomogeneities on the evolution of the Universe, by considering a range of cosmological models with discretized matter content. This is done using exact and fully relativistic methods that exploit the symmetries in and about submanifolds of spacetimes that themselves possess no continuous global symmetries. These methods allow us to follow the evolution of our models throughout their entire history, far beyond what has previously been possible. We find that while some space-like curves collapse to anisotropic singularities in finite time, others remain non-singular forever. The resulting picture is of a cosmological spacetime in which some behaviour remains close to Friedmann-like, while other behaviours deviate radically. In particular, we find that large-scale acceleration is possible without any violation of the energy conditions.

Place, publisher, year, edition, pages
2013. no 11, 010- p.
Keyword [en]
gravity, cosmological simulations, GR black holes
National Category
Astronomy, Astrophysics and Cosmology
Identifiers
URN: urn:nbn:se:su:diva-99903DOI: 10.1088/1475-7516/2013/11/010ISI: 000327843900011OAI: oai:DiVA.org:su-99903DiVA: diva2:690349
Note

AuthorCount:4;

Funding agencies:

STFC, ST/J001546/1; Erasmus Mundus Joint Doctorate Program from the EACEA of the European Commission, 2011-1640 

Available from: 2014-01-23 Created: 2014-01-20 Last updated: 2017-12-06Bibliographically approved
In thesis
1. Cosmological models, nonideal fluids and viscous forces in general relativity
Open this publication in new window or tab >>Cosmological models, nonideal fluids and viscous forces in general relativity
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis addresses the open questions of providing a cosmological model describing an accelerated expanding Universe without violating the energy conditions or a model that contributes to the physical interpretation of the dark energy. The former case is analyzed considering a closed model based on a regular lattice of black holes using the Einstein equation in vacuum. In the latter case I will connect the dark energy to the Shan-Chen equation of state. A comparison between these two proposals is then discussed. As a complementary topic I will discuss the motion of test particles in a general relativistic spacetime undergoing friction effects. This is modeled following the formalism of Poynting-Robertson whose link with the Stokes’ formula is presented. The cases of geodesic and non-geodesic motion are compared and contrasted for Schwarzschild, Tolman, Pant-Sah and Friedman metrics respectively.

Place, publisher, year, edition, pages
Stockholm: Department of Physics, Stockholm University, 2014. 94 p.
Keyword
gravity, exact model, black hole, friction
National Category
Astronomy, Astrophysics and Cosmology
Research subject
Theoretical Physics
Identifiers
urn:nbn:se:su:diva-107130 (URN)978-91-7447-982-9 (ISBN)
Public defence
2014-11-07, room FP41, AlbaNova universitetscentrum, Roslagstullsbacken 21, Stockholm, 13:00 (English)
Opponent
Supervisors
Available from: 2014-10-14 Created: 2014-09-03 Last updated: 2015-03-17Bibliographically approved

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