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dc.contributor.authorBarrow, JD
dc.contributor.authorGanguly, Chandrima
dc.date.accessioned2018-03-12T15:35:07Z
dc.date.available2018-03-12T15:35:07Z
dc.identifier.urihttps://www.repository.cam.ac.uk/handle/1810/273924
dc.description.abstractWe study a model of a cyclic, spatially homogeneous, anisotropic mixmaster universe of Bianchi type IX 'mixmaster' universe, containing the a radiation field with non-comoving ('tilted' with respect to the tetrad frame of reference) velocities and vorticity. We employ a combination of numerical and approximate analytic methods to investigate the consequences of the second law of thermodynamics on the evolution. We model a smooth cycle-to-cycle evolution of the mixmaster universe, bouncing at a finite minimum, by the device of adding a comoving 'ghost' field with negative energy density. In the absence of a cosmological constant, an increase in entropy, injected at the start of each cycle, causes an increase in the volume maxima, increasing approach to flatness, falling velocities and vorticities, and growing anisotropy at the expansion maxima of successive cycles. We find that the velocities oscillate rapidly as they evolve and change logarithmically in time relative to the expansion volume. When the conservation of momentum and angular momentum constraints are imposed, the spatial components of these velocities fall to smaller values when the entropy density increases, and vice versa. Isotropisation is found to occur when a positive cosmological constant is added because the sequence of oscillations ends and the dynamics expand forever, evolving towards a quasi de Sitter asymptote with constant velocity amplitudes. The case of a single cycle of evolution with a negative cosmological constant added is also studied.
dc.description.sponsorshipJ. D. B. is supported by the Science and Technology Facilities Council (STFC) of the United Kingdom. C. G. is supported by the Jawaharlal Nehru Memorial Trust Cambridge International Scholarship.
dc.publisherAmerican Physical Society
dc.titleEvolution of cyclic mixmaster universes with noncomoving radiation
dc.typeArticle
prism.issueIdentifier12
prism.number123534
prism.publicationNamePhysical Review D - Particles, Fields, Gravitation and Cosmology
prism.volume96
dc.identifier.doi10.17863/CAM.20899
dcterms.dateAccepted2017-12-06
rioxxterms.versionofrecord10.1103/PhysRevD.96.123534
rioxxterms.versionAM
rioxxterms.licenseref.urihttp://www.rioxx.net/licenses/all-rights-reserved
rioxxterms.licenseref.startdate2017-12-06
dc.contributor.orcidBarrow, John [0000-0002-6083-9751]
rioxxterms.typeJournal Article/Review
pubs.funder-project-idScience and Technology Facilities Council (ST/P000673/1)
cam.issuedOnline2017-12-15


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