http://arxiv.org/abs/1701.03964
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 Omega_l to the energy-density of the Universe, satisfying an equation of the form Omega_m+\Omega_k+Omega_l = 1. The models do not demand the existence of unknown particles. There is a family of flat models with different density parameters Omega_m < 1.
Numerical integrations of the cosmological equations for different values of the curvature and density parameter k and Omega_m are performed. The presence of even tiny amounts of matter in the Universe tends to kill scale invariance. The point is that for Omega_m = 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 Omega_m vs. lambda plot. Comparisons with observations are also performed for the Hubble constant H_0 vs. Omega_m, 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.
A. Maeder
Tue, 17 Jan 17
18/81
Comments: 16 pages, 10 figures
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