Effect of Inhomogeneities on High Precision Measurements of Cosmological Distances

dc.contributor.authorPeel, Austinen_US
dc.contributor.authorTroxel, Michael A.en_US
dc.contributor.authorIshak-Boushaki, Mustaphaen_US
dc.contributor.utdAuthorPeel, Austinen_US
dc.contributor.utdAuthorTroxel, Michael A.en_US
dc.contributor.utdAuthorIshak-Boushaki, Mustaphaen_US
dc.date.accessioned2015-02-16T23:44:32Z
dc.date.available2015-02-16T23:44:32Z
dc.date.created2014-12-30en_US
dc.date.issued2014-12-30en_US
dc.description.abstractWe study effects of inhomogeneities on distance measures in an exact relativistic Swiss-cheese model of the Universe, focusing on the distance modulus. The model has ΛCDM background dynamics, and the "holes" are nonsymmetric structures described by the Szekeres metric. The Szekeres exact solution of Einstein's equations, which is inhomogeneous and anisotropic, allows us to capture potentially relevant effects on light propagation due to nontrivial evolution of structures in an exact framework. Light beams traversing a single Szekeres structure in different ways can experience either magnification or demagnification, depending on the particular path. Consistent with expectations, we find a shift in the distance modulus μ to distant sources due to demagnification when the light beam travels primarily through the void regions of our model. Conversely, beams are magnified when they propagate mainly through the overdense regions of the structures, and we explore a small additional effect due to time evolution of the structures. We then study the probability distributions of Δμ = μ_{ΛCDM} – μ_{SC} for sources at different redshifts in various Swiss-cheese constructions, where the light beams travel through a large number of randomly oriented Szekeres holes with random impact parameters. We find for Δμ the dispersions 0.004 ≤ σ_{Δμ} ≤ 0.008 mag for sources with redshifts 1.0 ≤ ȥ ≤ 1.5, which are smaller than the intrinsic dispersion of, for example, magnitudes of type Ia supernovae. The shapes of the distributions we obtain for our Swiss-cheese constructions are peculiar in the sense that they are not consistently skewed toward the demagnification side, as they are in analyses of lensing in cosmological simulations. Depending on the source redshift, the distributions for our models can be skewed to either the demagnification or the magnification side, reflecting a limitation of these constructions. This could be the result of requiring the continuity of Einstein's equations throughout the overall spacetime patchwork, which imposes the condition that compensating overdense shells must accompany the underdense void regions in the holes. The possibility to explore other uses of these constructions that could circumvent this limitation and lead to different statistics remains open.en_US
dc.description.sponsorshipUS National Science Foundation (grant no. AST-1109667).en_US
dc.identifier.bibliographicCitationPeel, A., M. A. Troxel, and M. Ishak. 2014. "Effect of inhomogeneities on high precision measurements of cosmological distances." Physical Review D - Particles, Fields, Gravitation and Cosmology 90(12), doi:10.1103/PhysRevD.90.123536en_US
dc.identifier.issn1550-7998en_US
dc.identifier.issue12en_US
dc.identifier.urihttp://hdl.handle.net/10735.1/4326
dc.identifier.volume90en_US
dc.language.isoenen_US
dc.publisherAmerican Physical Societyen_US
dc.relation.urihttp://dx.doi.org/10.1103/PhysRevD.90.123536
dc.rights©2014 American Physical Societyen_US
dc.sourcePhysical Review D - Particles, Fields, Gravitation and Cosmology
dc.subjectSzerkeres, Peter, 1940-en_US
dc.subjectCosmologyen_US
dc.subjectMathematical modelsen_US
dc.subjectSwiss Cheese modelen_US
dc.subjectEinstein field equationsen_US
dc.titleEffect of Inhomogeneities on High Precision Measurements of Cosmological Distancesen_US
dc.type.genreArticleen_US

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