Royal Astronomical Society | 2017 Mar 30
[c][youtube]https://www.youtube.com/watch?v=VF0Lg7CfCYA[/youtube]Enigmatic 'dark energy', thought to make up 68% of the universe, may not exist at all, according to a Hungarian-American team. The researchers believe that standard models of the universe fail to take account of its changing structure, but that once this is done the need for dark energy disappears. ...
A short animation that shows the expansion of the universe in the standard 'Lambda
Cold Dark Matter' cosmology, which includes dark energy (top left panel red), the new
Avera model, that considers the structure of the universe and eliminates the need for
dark energy (top middle panel, blue), and the Einstein-de Sitter cosmology, the original
model without dark energy (top right, green). The panel at the bottom shows the
increase of the 'scale factor' (an indication of the size) as a function of time. The
growth of structure can also be seen in the top panels. One dot roughly represents an
entire galaxy cluster. Units of scale are Megaparsecs (Mpc). Credit: István Csabai et al[/c][hr][/hr]
normal and dark matter appear to fill the universe with a foam-like structure, where galaxies are located on the thin walls between bubbles, and are grouped into superclusters. The insides of the bubbles are in contrast almost empty of both kinds of matter.
Using a computer simulation to model the effect of gravity on the distribution of millions of particles of dark matter, the scientists reconstructed the evolution of the universe, including the early clumping of matter, and the formation of large scale structure.
Unlike conventional simulations with a smoothly expanding universe, taking the structure into account led to a model where different regions of the cosmos expand at different rate. The average expansion rate though is consistent with present observations, which suggest an overall acceleration. ...
Concordance Cosmology without Dark Energy - Gábor Rácz et al
- Monthly Notices of the RAS (online 11 Feb 2017) DOI: 10.1093/mnrasl/slx026
arXiv.org > astro-ph > arXiv:1607.08797 > 29 Jul 2016 (v1), 12 Feb 2017 (v2)