Can a void mimic the Λ in ΛCDM?




Peter Sundell, Edvard Mörtsell, Iiro Vilja

2015

Journal of Cosmology and Astroparticle Physics

8

27

1475-7516

DOIhttps://doi.org/10.1088/1475-7516/2015/08/037(external)



We investigate the Lema\^{i}tre-Tolman-Bondi (LTB) models, whose early time evolution and bang time are homogeneous and the distance - redshift relation and local Hubble parameter are inherited from the ΛCDM model. We show that the obtained LTB models and the ΛCDM model predict different relative local expansion rates and that the Hubble functions of the models diverge increasingly with redshift. The LTB models show tension between baryon acoustic oscillation and supernova observations and including cosmic microwave background observations only accentuates the better fit of the ΛCDM model compared to the LTB model. The result indicates that additional degrees of freedom are needed to explain the observations, for example by renouncing spherical symmetry, homogeneous bang time, or the early time homogeneity assumption.




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