Variable cosmological term $\Lambda (t)$

Abstract

We present the case of time-varying cosmological term $\Lambda (t)$. The main idea arises by proposing that as in the cosmological constant case, the scalar potential is identified as $V(\varphi )=2\Lambda$, with $\Lambda$ a constant, this identification should be kept even when the cosmological term has a temporal dependence, i.e., $V(\varphi (t))=2\Lambda (t)$. We Use the Lagrangian formalism for a scalar field $\varphi$ with standard kinetic energy and arbitrary potential $V(\varphi )$ and apply this model to the Friedmann-Robertson-Walker (FRW)cosmology. Exact solutions of the field equations are obtained by a special ansatz to solve the Einstein-Klein-Gordon equation and a particular potential for the scalar field and barotropic perfect fluid. We present the evolution on this cosmological term with different scenarios.

Latex source, 12 pages, 3 figures, accepted in Astrophysics Space Science

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