English

Another coincidence problem for $\Lambda$CDM?

Cosmology and Nongalactic Astrophysics 2015-06-22 v1

Abstract

Over the last nine years of cosmic microwave background observations, the Wilkinson Microwave Anisotropy Probe (WMAPWMAP) results were consistent with a Λ\LambdaCDM cosmological model in which the age of the Universe is one Hubble time, and the time-averaged value of the deceleration parameter is consistent with zero. This curious observation has been put forward as a new coincidence problem for the Λ\LambdaCDM concordance cosmology, which is in fact a `greater' coincidence than the near equality of the density parameters of matter and the cosmological constant. At the moment of writing these conference proceedings, the Planck Collaboration has released its first cosmological data, which revealed a small shift in the Λ\LambdaCDM cosmological parameters when compared to WMAPWMAP. We show that under the assumption of a spatially flat Λ\LambdaCDM cosmology, Planck's results remove this coincidence problem for Λ\LambdaCDM at greater than 99\% confidence level.

Keywords

Cite

@article{arxiv.1409.0901,
  title  = {Another coincidence problem for $\Lambda$CDM?},
  author = {Pim van Oirschot and Juliana Kwan and Geraint F. Lewis},
  journal= {arXiv preprint arXiv:1409.0901},
  year   = {2015}
}

Comments

3 pages, 1 figure, proceedings of the 13th Marcel Grossmann meeting

R2 v1 2026-06-22T05:47:03.359Z