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Toward a Unified Description of Dark Energy and Dark Matter from the Abnormally Weighting Energy Hypothesis

Research paper by A. Fuzfa, J. -M. Alimi

Indexed on: 27 Jun '07Published on: 27 Jun '07Published in: Astrophysics



Abstract

The Abnormally Weighting Energy (AWE) hypothesis consists of assuming that the dark sector of cosmology violates the weak equivalence principle (WEP) on cosmological scales, which implies a violation of the strong equivalence principle for ordinary matter. In this paper, dark energy (DE) is shown to result from the violation of WEP by pressureless (dark) matter. This allows us to build a new cosmological framework in which general relativity (GR) is satisfied at low scales, as WEP violation depends on the ratio of the ordinary matter over dark matter densities, but at large scales, we obtain a general relativity-like theory with a different value of the gravitational coupling. This explanation is formulated in terms of a tensor-scalar theory of gravitation without WEP for which there exists a revisited convergence mechanism toward GR. The consequent DE mechanism build upon the anomalous gravity of dark matter (i) does not require any violation of the strong energy condition $p<-\rho c^2/3$, (ii) offers a natural way-out of the coincidence problem thanks to the non-minimal couplings to gravitation, (iii) accounts fairly for supernovae data from various very simple couplings and with density parameters very close to the ones of the concordance model $\Lambda CDM$, therefore suggesting an explanation to its remarkable adequacy. Finally, (iv) this mechanism ends up in the future with an Einstein-de Sitter expansion regime once the attractor is reached.