An alternative to the cosmological 'concordance model'

Details An alternative to the cosmological 'concordance model' An alternative to the cosmological 'concordance model'

2003-04-14

arxiv.org/abs/astro-ph/0304237v2

Astron.Astrophys.412:35-44,2003

Astronomy and Astrophysics

Astrophysics

Revised version, accepted by A&A. New section and figures added

Scientific paper

10.1051/0004-6361:20031425

Precision measurements of the cosmic microwave background by WMAP are believed to have established a flat $\Lambda$-dominated universe, seeded by nearly scale-invariant adiabatic primordial fluctuations. However by relaxing the hypothesis that the fluctuation spectrum can be described by a single power law, we demonstrate that an Einstein-de Sitter universe with {\em zero} cosmological constant can fit the data as well as the best concordance model. Moreover unlike a $\Lambda$-dominated universe, such an universe has no strong integrated Sachs-Wolfe effect, so is in better agreement with the low quadrupole seen by WMAP. The main problem is that the Hubble constant is required to be rather low: $H_0 \simeq 46$ km/s/Mpc; we discuss whether this can be consistent with observations. Furthermore for universes consisting only of baryons and cold dark matter, the amplitude of matter fluctuations on cluster scales is too high, a problem which seems generic. However, an additional small contribution ($\Omega_X \sim 0.1$) of matter which does not cluster on small scales, e.g. relic neutrinos with mass of order eV or a `quintessence' with $w \sim 0$, can alleviate this problem. Such models provide a satisfying description of the power spectrum derived from the 2dF galaxy redshift survey and from observations of the Ly-$\alpha$ forest. We conclude that Einstein-de Sitter models can indeed accommodate all data on the large scale structure of the Universe, hence the Hubble diagram of distant Type Ia supernovae remains the only {\em direct} evidence for a non-zero cosmological constant.

Affiliated with

Also associated with

No associations

Rating

An alternative to the cosmological 'concordance model' does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with An alternative to the cosmological 'concordance model', we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and An alternative to the cosmological 'concordance model' will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-547633