Bouncing Galileon cosmologies

By Taotao Qiu, Jarah Evslin, Yi-Fu Cai, Mingzhe Li, Xinmin Zhang. 2011

204 citations recorded by the source corpus.

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.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/a1bed376390adc991cf0b1904f6942b29f6eb1e3

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Citations in the corpus

Exploring bouncing cosmologies with cosmological surveys (2014, background): “The Galileon model might realize a nonsingular bounce as well, but was found to suffer from a severe graceful-exit problem from the bouncing phase to the phase of regular thermal expansion [107, 108].”
Generalized Galileons: instabilities of bouncing and Genesis cosmologies and modified Genesis (2016, background): “Likewise, bouncing Universe models with generalized Galileons can be arranged in such a way that no ghost or gradient instabilities occur at and near the bounce [20–23].”
Horndeski theory and beyond: a review (2019, background): “This opens up Pandora’s box of nonsingular bouncing cosmology [99, 100, 101] as well as blue gravitational waves from inflation [29] (see, however, [102]).”
G-bounce (2011, methodology): “For further development see [77] and [78].”
The Effective Field Theory of nonsingular cosmology (2016, methodology): “By adding the effective operators like R(3)δg00, (R(3))2 or ∇iR((3))∇R((3)) to the original G-bounce models [27, 47], within the framework of EFT the whole Lagrangian tends to be like the ones in eq.”
Towards a nonsingular bouncing cosmology (2012, background): “In this section, we present a nonsingular bouncing solution in terms of a single field having the desirable features of both the ghost condensate and Galileon-inspired models.”
f(T) teleparallel gravity and cosmology (2015, methodology): “A nonsingular bounce solution can also be achieved by making use of matter fields with the NEC violation, such as in the quintom bounce [392–394], the Lee-Wick bounce [395, 396], the ghost condensate bounce [397–399], the braneworld bounce [400–402], the Galileon bounce [403, 404], and the bounce mo”