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arXiv · 1608.02777

$\Lambda(t)$ cosmology induced by a slowly varying Elko field

S. H. Pereira·S. S. A. Pinho·J. M. Hoff da Silva·J. F. Jesus
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Abstract

In this work the exact Friedmann-Robertson-Walker equations for an Elko spinor field coupled to gravity in an Einstein-Cartan framework are presented. The torsion functions coupling the Elko field spin-connection to gravity can be exactly solved and the FRW equations for the system assume a relatively simple form. In the limit of a slowly varying Elko spinor field there is a relevant contribution to the field equations acting exactly as a time varying cosmological model $\Lambda(t)=\Lambda_*+3\beta H^2$, where $\Lambda_*$ and $\beta$ are constants. Observational data using distance luminosity from magnitudes of supernovae constraint the parameters $\Omega_m$ and $\beta$, which leads to a lower limit to the Elko mass. Such model mimics, then, the effects of a dark energy fluid, here sourced by the Elko spinor field. The density perturbations in the linear regime were also studied in the pseudo-Newtonian formalism.

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S. H. Pereira, S. S. A. Pinho, J. M. Hoff da Silva, J. F. Jesus. 2016-08-09. $\Lambda(t)$ cosmology induced by a slowly varying Elko field. https://doi.org/10.1088/1475-7516%2F2017%2F01%2F055

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