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Evolution of initially contracting Bianchi Class A models in the presence of an ultra-stiff anisotropic pressure fluid

dc.creatorBarrow, John David
dc.creatorGanguly, Chandrima
dc.date.accessioned2016-04-01
dc.date.accessioned2018-11-24T23:26:45Z
dc.date.available2016-04-21T12:14:50Z
dc.date.available2018-11-24T23:26:45Z
dc.date.issued2016-05-12
dc.identifierhttps://www.repository.cam.ac.uk/handle/1810/255111
dc.identifier.urihttp://repository.aust.edu.ng/xmlui/handle/123456789/3876
dc.description.abstractWe study the behaviour of Bianchi class A universes containing an ultra-stiff isotropic ghost field and a fluid with anisotropic pressures which is also ultra-stiff on the average. This allows us to investigate whether cyclic universe scenarios, like the ekpyrotic model, do indeed lead to isotropisation on approach to a singularity (or bounce) in the presence of dominant ultra-stiff pressure anisotropies. We specialise to consider the closed Bianchi type IX universe and show that when the anisotropic pressures are stiffer on average than any isotropic ultra-stiff fluid then, if they dominate on approach to the singularity, it will be anisotropic. We include an isotropic ultra-stiff ghost fluid with negative energy density in order to create a cosmological bounce at finite volume in the absence of the anisotropic fluid. When the dominant anisotropic fluid is present it leads to an anisotropic cosmological singularity rather than an isotropic bounce. The inclusion of anisotropic stresses generated by collisionless particles in an anisotropically expanding universe is therefore essential for a full analysis of the consequences of a cosmological bounce or singularity in cyclic universes.
dc.languageen
dc.publisherInstitute of Physics
dc.publisherClassical and Quantum Gravity
dc.rightshttp://creativecommons.org/licenses/by/4.0/
dc.rightshttp://creativecommons.org/licenses/by/4.0/
dc.rightshttp://creativecommons.org/licenses/by/4.0/
dc.rightsAttribution 4.0 International
dc.rightsAttribution 4.0 International
dc.rightsAttribution 4.0 International
dc.titleEvolution of initially contracting Bianchi Class A models in the presence of an ultra-stiff anisotropic pressure fluid
dc.typeArticle


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