2017/01/14 by Andre Maeder · 1 voice
Physics and Astronomy · #astro-ph.CO
paper · pdf · doi:10.3847/1538-4357/834/2/194
published as Astrophys. J. 834, 194 (2016) · 16 pages, 10 figures
The hypothesis is made that, at large scales where General Relativity may be applied, the empty space is scale invariant. This establishes a relation between the cosmological constant and the scale factor of the scale invariant framework. This relation brings major simplifications in the scale invariant equations for cosmology, which now contain a new term, depending on the derivative of the scale factor, that opposes to gravity and produces an accelerated expansion. The displacements due to the acceleration term make a high contribution Omegal to the energy-density of the Universe, satisfying an equation of the form Omegam+Ωk+Omegal = 1. The models do not demand the existence of unknown particles. There is a family of flat models with different density parameters Omegam < 1. Numerical integrations of the cosmological equations for different values of the curvature and density parameter k and Omegam are performed. The presence of even tiny amounts of matter in the Universe tends to kill scale invariance. The point is that for Omegam = 0.3 the effect is not yet completely killed. The models with non-zero density start explosively with first a braking phase followed by a continuously accelerating expansion. Several observational properties are examined, in particular the distances, the m--z diagram, the Omegam vs. lambda plot. Comparisons with observations are also performed for the Hubble constant H0 vs. Omegam, for the expansion history in the plot H(z)/(z+1) vs. redshift z and for the transition redshift from braking to acceleration. These first dynamical tests are satisfied by the scale invariant models, which thus deserve further studies.