Dark energy as the anomalous gravity of dark matter
Université de Namur
Wed, Sep. 19th 2007, 14:15
Salle Claude Itzykson, Bât. 774, Orme des Merisiers
In order to describe both dark matter (DM) and dark energy (DE), we have introduced the AWE (Abnormally Weighting Energy) hypothesis in which the dark sector is assumed to violate the weak equivalence principle (WEP) on cosmological scales. This explains cosmic acceleration by an increasingly stronger gravitational coupling of ordinary matter to the background expansion. This interpretation can be viewed as a Mach-Dirac principle where the variation of the mass of the DM particles induces a variation of baryon's gravitational coupling. In this new picture, general relativity is satisfied at low scales, as WEP violation depends on the concentration dark matter, but at large scales, we obtain a different value of the gravitational coupling. The corresponding DE mechanism exhibits AWEsome properties: (i) it does not require any negative pressures; (ii) it offers a natural way out of the coincidence problem; (iii) it suggests an explanation to the remarkable adequacy of the concordance model LCDM and (iv) it avoids an eternal cosmic acceleration. For all these reasons, the AWE hypothesis can be hoped to reduce dark energy to a new property of gravitation: the anomalous gravity of dark matter.