Bouncing Galileon Cosmologies
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In this article, nonsingular, homogeneous and isotropic bouncing solutions of the conformal Galileon model were presented, and it was shown that such solutions necessarily begin with a radiation-dominated contracting phase.Abstract:
We present nonsingular, homogeneous and isotropic bouncing solutions of the conformal Galileon model. We show that such solutions necessarily begin with a radiation-dominated contracting phase. This is followed by a quintom scenario in which the background equation of state crosses the cosmological constant boundary allowing for a nonsingular bounce which in turn is followed by Galilean Genesis. We analyze the spectrum of cosmological perturbations in this background. Our results show that the fluctuations evolve smoothly and without any pathology, but the adiabatic modes form a blue tilted spectrum. In order to achieve a scale-invariant primordial power spectrum as required by current observations, we introduce a light scalar field coupling to the Galileon kinetically. We find two couplings which yield a scale-invariant spectrum, one of which requires a fine tuning of the initial conditions. This model also predicts a blue tilted spectrum of gravitational waves stemming from quantum vacuum fluctuations in the contracting phase.read more
Citations
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DBI Realizations of the Pseudo-Conformal Universe and Galilean Genesis Scenarios
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The Paths of Gravity in Galileon Cosmology
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Note on the production of scale-invariant entropy perturbation in the Ekpyrotic universe
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