Only dark energy with dark matter fits with COSMOS results

To illustrate the different growth patterns of structures in the Universe, astronomers made computer simulations showing the evolution of the large-scale structure for two different cosmological models; one corresponds to a dark-energy-dominated universe (so-called LambdaCDM), the other to a Universe without dark energy (so-called SCDM).

Only the first of these two models matches the results of the new study of the COSMOS survey, confirming, for the first time ever using natural "weak lenses", the accelerated expansion of the Universe.

The simulations both evolve the matter distribution to the present time, starting at redshift of five, which is roughly the redshift of the most distant sources used in the analysis of COSMOS.

This corresponds to a time 12.9 billion years ago for the LambdaCDM simulation and 8.7 billion years ago for SCDM.

When dark energy is present, galaxy clusters grow more slowly and it changes the way the Universe expands, leading to more distant — and more efficiently lensed — galaxies.