Accelerated Universe from Modified Chaplygin Gas and Tachyonic Fluid

Abstract

A cosmological model with an exotic fluid is investigated. We show that the equation of state of this “modified Chaplygin” gas can describe the current accelerated expansion of the universe. We then reexpress it as FRW cosmological model containing a scalar field ϕ and find its self-interacting potential. Moreover motivated by recent works on tachyon field theory, a map for this exotic fluid as a normal scalar field ϕ with Lagrangian Lϕ=ϕ˙22−U(ϕ) to the tachyonic field T with Lagrangian LT=−V(T)1−T˙2 is obtained.

Keywords

• dark energy
• dark matter
• unified dark sector