Unification of dark matter and dark energy: the inhomogeneous Chaplygin gas

Abstract

We extend the world model of Kamenshchik et al. to large perturbations by formulating a Zeldovich-like approximation. We sketch how this model unifies dark matter with dark energy in a geometric setting reminiscent of M -theory.After nearly two decades of reign [1], the Einstein-de Sitter dust model has been swept aside by observations of high redshift supernovae [2] which suggest that the Hubble expansion is accelerating. When combined with the Boomerang/Maxima data [3] showing that the location of the first acoustic peak in the power spectrum of the microwave background is consistent with the inflationary prediction Ω = 1, the evidence for a net equation of state of the cosmic fluid lying in the range −1 ≤ w = P/ρ < −1/3 is compelling. Parametrically, w = P DE /(ρ DE + ρ DM ) = −Ω Λ gives a ratio of unclustered dark energy to clustered dark matter of order 7:3, thereby also resolving the longstanding Ω DM < 1 puzzle [1,4] implied by peculiar velocity fields. The theoretical implications of these dicoveries are profound. Simply appending a † Permanent address: Rudjer Bošković Institute,

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