Constraints on anisotropic cosmic expansion from supernovae

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dc.contributor.authorKalus, Benedict
dc.contributor.authorSchwarz, Dominik J.
dc.contributor.authorSeikel, Marina
dc.contributor.authorWiegand, Alexander
dc.date.accessioned2018-02-06T11:22:59Z
dc.date.available2018-02-06T11:22:59Z
dc.date.issued2013
dc.description.abstractAIMS. We test the isotropy of the expansion of the Universe by estimating the hemispherical anisotropy of supernova type Ia (SN Ia) Hubble diagrams at low redshifts (z < 0.2). METHODS. We compare the best fit Hubble diagrams in pairs of hemispheres and search for the maximal asymmetric orientation. For an isotropic Universe, we expect only a small asymmetry due to noise and the presence of nearby structures. This test does not depend on the assumed content of the Universe, the assumed model of gravity, or the spatial curvature of the Universe. The expectation for possible fluctuations due to large scale structure is evaluated for the Λ cold dark matter (ΛCDM) model and is compared to the supernova data from the Constitution set for four different light curve fitters, thus allowing a study of the systematic effects. RESULTS. The expected order of magnitude of the hemispherical asymmetry of the Hubble expansion agrees with the observed one. The direction of the Hubble asymmetry is established at 95% confidence level (C.L.) using both, the MLCS2k2 and the SALT II light curve fitter. The highest expansion rate is found towards (ℓ, b) ≈ (−35◦, −19◦), which agrees with directions reported by other studies. Its amplitude is not in contradiction to expectations from the ΛCDM model. The measured Hubble anisotropy is ∆H/H ∼ 0.026. With 95% C.L. the expansion asymmetry is ∆H/H < 0.038.en_US
dc.description.accreditationWeb of Science
dc.identifier.citationKalus, B. et al. (2013). Constraints on anisotropic cosmic expansion from supernovae. Astronomy & Astrophysics, 553: A56en_US
dc.identifier.issn0004-6361
dc.identifier.urihttp://dx.doi.org/10.1051/0004-6361/201220928
dc.identifier.urihttp://hdl.handle.net/10566/3477
dc.language.isoenen_US
dc.privacy.showsubmitterFALSE
dc.publisherEdp Sciencesen_US
dc.rightsThis is the pre-print version (From arXiv:1212.3691) of the article published online at: http://dx.doi.org/10.1051/0004-6361/201220928
dc.status.ispeerreviewedTRUE
dc.subjectIsotropyen_US
dc.subjectExpansion of the universeen_US
dc.subjectHemispherical anisotropy of supernovaen_US
dc.subjectSupernova type Ia (SN Ia)en_US
dc.titleConstraints on anisotropic cosmic expansion from supernovaeen_US
dc.typeArticleen_US

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