engleski

Chaplygin-gas cosmology: unification of dark matter and dark energy

In order to explain the current accelerated Hubble expansion, aside from the cosmological constant, a variety ofmodels based on `quintessence' and `k-essence' have been put forward.One characteristic of the aforementioned models is theassumption that dark energy is separate and distinct from dark matter. A rather different idea, which has been dubbed 'quartessence', is that both dark energy and dark matter are aspects of a unified theory. The first definite quartessence model was based upon the Chaplygin gas, a fluid obeying an exotic equation of state in which the pressure is a negative inverse of the density, p = - A/rho. This equation of stateis obtained in the Dirac-Born-Infeld theory for a 3+1 dimensional D-branein a 4+1 bulk. Solving the field equation in a FRW universe shows that the model interpolates between dust at small scale factor a and a cosmological constant at large a.

Chaplygin-gas; dark matter; dark energy

pozvano predavanje (paralel session)