Cosmological imprints of the stealth scalar field
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We study some cosmological models endowed with a peculiar scalar field known as stealth field. The models are constructed by considering a scalar field \(\phi \) obeying a non-minimal coupling to the gravitational field where the matter content is provided by both dust and a perfect fluid. Moreover, we analyze the stealth field implications in the cosmology by assuming a power-law behavior for the scale factor. Surprisingly, we find that stealth configurations that emerge, which in principle have no back-reaction to the background space-time, do contribute to the cosmological dynamics. We provide analytical expressions of these contributions to the energy density coming from the matter sources considered as well as for the pressure in the power-law scenario. This is a first signal that the stealth fields contributions are quantifiable. In the de Sitter cosmology, we found stealth does not have contributions either to cosmological constant or deceleration parameter. Additionally, we discuss the behaviors of the self-interaction potential for some particular values of the parameters involved.
Authors thank to Eloy Ayón-Beato for enlightening discussions. Special thanks to Carlos Manuel Rodríguez. CC acknowledges partial support by CONACyT Grant CB-2012-177519-F and grant PROMEP, CA-UV, Álgebra, Geometría y Gravitación. This work was partially supported by SNI (México). VHC acknowledges partial support by DIUV-REG-50/2013. AA acknowledges partial support by CONACyT Grant Estancias Posdoctorales Vinculadas al Fortalecimiento de Calidad del Posgrado Nacional 2017.