How flat is our Universe really?

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dc.contributor.authorOkouma, PM
dc.contributor.authorFantaye, Y
dc.contributor.authorBassett, B A
dc.date.accessioned2021-10-08T07:11:41Z
dc.date.available2021-10-08T07:11:41Z
dc.date.issued2013
dc.description.abstractDistance measurement provide no constraints on curvature independent of assumptions about the dark energy, raising the question, how flat is our Universe if we make no such assumptions? Allowing for general evolution of the dark energy equation of state with 20 free parameters that are allowed to cross the phantom divide, w(z) = -1, we show that while it is indeed possible to match the first peak in the Cosmic Microwave Background with non-flat models and arbitrary Hubble constant, H_0, the full WMAP7 and supernova data alone imply -0.12 < Omega_k < 0.01 (2sigma). If we add an H_0 prior, this tightens significantly to Omega_k = 0.002 pm 0.009 . These constitute the most conservative and model-independent constraints on curvature available today, and illustrate that the curvature-dynamics degeneracy is broken by current data, with a key role played by the Integrated Sachs Wolfe effect rather than the distance to the surface of last scattering. If one imposes a quintessence prior on the dark energy (-1 leq w(z) leq 1) then just the WMAP7 and supernova data alone force the Universe to near flatness: Omega_k = 0.013 pm 0.012. Finally, allowing for curvature, we find that all datasets are consistent with a Harrison-Zel'dovich spectral index, n_s = 1, at 2sigma, illustrating the interplay between early and late-universe constraints.
dc.identifier.apacitationOkouma, P., Fantaye, Y., & Bassett, B. A. (2013). How flat is our Universe really?. <i>Physics Letters, B</i>, 719(43103), 1 - 4. http://hdl.handle.net/11427/34669en_ZA
dc.identifier.chicagocitationOkouma, PM, Y Fantaye, and B A Bassett "How flat is our Universe really?." <i>Physics Letters, B</i> 719, 43103. (2013): 1 - 4. http://hdl.handle.net/11427/34669en_ZA
dc.identifier.citationOkouma, P., Fantaye, Y. & Bassett, B.A. 2013. How flat is our Universe really?. <i>Physics Letters, B.</i> 719(43103):1 - 4. http://hdl.handle.net/11427/34669en_ZA
dc.identifier.issn0370-2693
dc.identifier.issn1873-2445
dc.identifier.ris TY - Journal Article AU - Okouma, PM AU - Fantaye, Y AU - Bassett, B A AB - Distance measurement provide no constraints on curvature independent of assumptions about the dark energy, raising the question, how flat is our Universe if we make no such assumptions? Allowing for general evolution of the dark energy equation of state with 20 free parameters that are allowed to cross the phantom divide, w(z) = -1, we show that while it is indeed possible to match the first peak in the Cosmic Microwave Background with non-flat models and arbitrary Hubble constant, H_0, the full WMAP7 and supernova data alone imply -0.12 < Omega_k < 0.01 (2sigma). If we add an H_0 prior, this tightens significantly to Omega_k = 0.002 pm 0.009 . These constitute the most conservative and model-independent constraints on curvature available today, and illustrate that the curvature-dynamics degeneracy is broken by current data, with a key role played by the Integrated Sachs Wolfe effect rather than the distance to the surface of last scattering. If one imposes a quintessence prior on the dark energy (-1 leq w(z) leq 1) then just the WMAP7 and supernova data alone force the Universe to near flatness: Omega_k = 0.013 pm 0.012. Finally, allowing for curvature, we find that all datasets are consistent with a Harrison-Zel'dovich spectral index, n_s = 1, at 2sigma, illustrating the interplay between early and late-universe constraints. DA - 2013 DB - OpenUCT DP - University of Cape Town IS - 43103 J1 - Physics Letters, B LK - https://open.uct.ac.za PY - 2013 SM - 0370-2693 SM - 1873-2445 T1 - How flat is our Universe really? TI - How flat is our Universe really? UR - http://hdl.handle.net/11427/34669 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/34669
dc.identifier.vancouvercitationOkouma P, Fantaye Y, Bassett BA. How flat is our Universe really?. Physics Letters, B. 2013;719(43103):1 - 4. http://hdl.handle.net/11427/34669.en_ZA
dc.language.isoeng
dc.publisher.departmentDepartment of Mathematics and Applied Mathematics
dc.publisher.facultyFaculty of Science
dc.sourcePhysics Letters, B
dc.source.journalissue43103
dc.source.journalvolume719
dc.source.pagination1 - 4
dc.source.urihttps://dx.doi.org/10.1016/j.physletb.2012.12.070
dc.subject.otherAstrophysics - Cosmology and Nongalactic Astrophysics
dc.subject.otherGeneral Relativity and Quantum Cosmology
dc.titleHow flat is our Universe really?
dc.typeJournal Article
uct.type.publicationResearch
uct.type.resourceJournal Article
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