The Dark Energy of Abnormally Weighting Dark Matter

by André Füzfa (Namur / Meudon)

Wednesday 6 Dec 2006, 13:00 → 14:00 Europe/Brussels

Cycl06

Informal discussion. Dark energy is presented as a consequence of the violation of the weak equivalence principle (WEP) by some pressureless (dark) matter. Indeed, this implies a violation of the strong equivalence principle for ordinary matter which results in a variation of the effective gravitational coupling constant on large-scales. This explanation is formulated in terms of a tensor-scalar theory of gravitation without WEP for which there exists a convergence mechanism toward a general relativity-like theory with a different value of the bare gravitational coupling. The attractor is shown to depend on the local ratio of ordinary matter over abnormally weighting dark matter and to reduce to general relativity values when the last is sub-dominant. During matter-dominated era, the gravitational coupling is pushed toward the attracting value, producing the expected cosmic acceleration in the observable frame. The consequent dark energy mechanism build upon the anomalous gravity of dark matter (i) does not require a 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 very simple couplings, (iv) ends up with an Einstein-de Sitter expansion regime once the attractor is reached. This mechanism is expected to have strong impacts on Cosmic Microwave Background, Large-Scale Structures formation and possibly inflation.