Constraining competing models of dark energy with cosmological observations

dc.contributor.authorPavlov, Anatoly
dc.date.accessioned2015-08-11T18:52:49Z
dc.date.available2015-08-11T18:52:49Z
dc.date.graduationmonthAugust
dc.date.issued2015-08-01
dc.description.abstractThe last decade of the 20th century was marked by the discovery of the accelerated expansion of the universe. This discovery puzzles physicists and has yet to be fully understood. It contradicts the conventional theory of gravity, i.e. Einstein’s General Relativity (GR). According to GR, a universe filled with dark matter and ordinary matter, i.e. baryons, leptons, and photons, can only expand with deceleration. Two approaches have been developed to study this phenomenon. One attempt is to assume that GR might not be the correct description of gravity, hence a modified theory of gravity has to be developed to account for the observed acceleration of the universe’s expansion. This approach is known as the ”Modified Gravity Theory”. The other way is to assume that the energy budget of the universe has one more component which causes expansion of space with acceleration on large scales. Dark Energy (DE) was introduced as a hypothetical type of energy homogeneously filling the entire universe and very weakly or not at all interacting with ordinary and dark matter. Observational data suggest that if DE is assumed then its contribution to the energy budget of the universe at the current epoch should be about 70% of the total energy density of the universe. In the standard cosmological model a DE term is introduced into the Einstein GR equations through the cosmological constant, a constant in time and space, and proportional to the metric tensor g[subscript]mu[subscript]nu. While this model so far fits most available observational data, it has some significant conceptual shortcomings. Hence there are a number of alternative cosmological models of DE in which the dark energy density is allowed to vary in time and space.
dc.description.advisorBharat Ratra
dc.description.degreeDoctor of Philosophy
dc.description.departmentDepartment of Physics
dc.description.levelDoctoral
dc.identifier.urihttp://hdl.handle.net/2097/20345
dc.language.isoen_US
dc.publisherKansas State University
dc.rights© the author. This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s).
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/
dc.subjectAstronomy
dc.subjectAstrophysics
dc.subjectPhysics
dc.subjectTheoretical physics
dc.subjectQuantum physics
dc.subjectStatistics
dc.subjectCosmology
dc.subjectNumerical Simulations
dc.subjectData Analysis
dc.subject.umiTheoretical Physics (0753)
dc.titleConstraining competing models of dark energy with cosmological observations
dc.typeDissertation

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