Pereira, S. H. [UNESP]Pinho SS, A. [UNESP]Hoff Da Silva, J. M. [UNESP]Jesus, J. F. [UNESP]2018-12-112018-12-112017-01-27Journal of Cosmology and Astroparticle Physics, v. 2017, n. 1, 2017.1475-7516http://hdl.handle.net/11449/174215In 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 Λ(t) = Λ∗ + 3βH2, where Λ∗ and β are constants. Observational data using distance luminosity from magnitudes of supernovae constraint the parameters Ωm and β, 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.engCosmology of theories beyond the SMDark energy theorySupernova type Ia - standard candlesResenha10.1088/1475-7516/2017/01/055Acesso aberto2-s2.0-850128803992-s2.0-85012880399.pdf