Change search
ReferencesLink to record
Permanent link

Direct link
Tilted cosmological models of Bianchi type V
Umeå University, Faculty of Science and Technology, Physics.
Umeå University, Faculty of Science and Technology, Physics.
2006 (English)In: Physical Review D. Particles and fields, ISSN 0556-2821, Vol. 73, no 4, 044008-044019 p.Article in journal (Refereed) Published
Abstract [en]

Cosmological models of Bianchi types Vand I containing a perfect fluid with a linear equation of state plus cosmological constant are investigated. In general, these spacetimes are tilted and describe fluids with expansion, shear, and vorticity. We use a tetrad approach where our variables are the Riemann tensor, the Ricci rotation coefficients, and a subset of the tetrad vector components. This set, called S, describes a spacetime when its elements are constrained by certain integrability conditions and due to a theorem by Cartan S gives a complete local description of the spacetime. With the help of the Lie algebra, the full line element is constructed up to quadratures in terms of the elements in S. The system obtained by imposing the integrability conditions and Einstein’s equations on the elements in S can be reduced to an integrable system of five coupled first order ordinary differential equations. In general, exact solutions to this system are hard to find, but the linearized equations around the open Friedmann models are easily integrated. The full system is also studied numerically and the perturbative solutions agree well with the numerical ones in the appropriate domains. We also give some examples of numerical solutions in the nonperturbative regime.

Place, publisher, year, edition, pages
2006. Vol. 73, no 4, 044008-044019 p.
URN: urn:nbn:se:umu:diva-2891DOI: 10.1103/PhysRevD.73.044008OAI: diva2:141217
Available from: 2008-01-16 Created: 2008-01-16Bibliographically approved
In thesis
1. Perturbative Methods in General Relativity
Open this publication in new window or tab >>Perturbative Methods in General Relativity
2008 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Einstein's theory of general relativity is a cornerstone in the process of gaining increased understanding about problems of gravitational nature. It can be applied to problems on the huge length scales of cosmology and as far as we know it does not break down before the Planck scale is approached. Irrespective of scale, a perturbative approach is often a very useful way to reduce the Einstein system to manageable complexity and size.

The projects included in this thesis can be divided into three subcategories. In the first category the keyword is photon-photon scattering. General relativity predicts that scattering can take place on a flat background due to the curvature of space-time caused by the photons themselves. The coupling equations and cross-section are found and a comparison with the corresponding quantum field theoretical results is done to leading order. Moreover, photon-photon scattering due to exchange of virtual electron-positron pairs is considered as an effective field theory in terms of the Heisenberg-Euler Lagrangian resulting in a possible setup for experimental detection of this phenomenon using microwave cavities. The second category of projects is related to cosmology. Here linear perturbations around a flat FRW universe with a cosmological constant are considered and the corresponding temperature variations of the cosmic microwave background radiation are found. Furthermore, cosmological models of Bianchi type V are investigated using a method based on the invariant scheme for classification of metrics by Karlhede. The final category is slowly rotating stars. Here the problem of matching a perfect fluid interior of Petrov type D to an exterior axisymmetric vacuum solution is treated perturbatively up to second order in the rotational parameter.

Place, publisher, year, edition, pages
Umeå: Fysik, 2008. 53 p.
General relativity, perturbation theory, photon-photon scattering, cosmology, FRW models with cosmological constant, Bianchi type V, slowly rotating stars, Hartle formalism
National Category
Physical Sciences
urn:nbn:se:umu:diva-1488 (URN)978-91-7264-493-9 (ISBN)
Public defence
2008-02-07, N420, Naturvetarhuset, Umeå, 14:00
Available from: 2008-01-16 Created: 2008-01-16Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full text

Search in DiVA

By author/editor
Bradley, Michael
By organisation
In the same journal
Physical Review D. Particles and fields

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Altmetric score

Total: 54 hits
ReferencesLink to record
Permanent link

Direct link