Deformed matter bounce with dark energy epoch

Abstract

We extend the Loop Quantum Cosmology matter bounce scenario in order to include a dark energy era, which ends abruptly at a Rip singularity where the scale factor and the Hubble rate diverge. In the "deformed matter bounce scenario", the Universe is contracting from an initial non-causal matter dominated era until it reaches a minimal radius. After that it expands in a decelerating way, until at late times, where it expands in an accelerating way, thus the model is described by a dark energy era that follows the matter dominated era. Depending on the choice of the free parameters of the model, the dark energy era is quintessential like which follows the matter domination era, and eventually it crosses the phantom divide line and becomes phantom. At the end of the dark energy era, a Rip singularity exists, where the scale factor and Hubble rate diverge, however the physical system cannot reach the singularity, since the effective energy density and pressure become complex. This indicates two things, firstly that the ordinary Loop Quantum Cosmology matter bounce evolution stops, thus ending the infinite repetition of the ordinary matter bounce scenario. Secondly, the fact that both the pressure and the density become complex indicates probably that the description of the cosmic evolution within the theoretical context of Loop Quantum Cosmology, ceases to describe the physics of the system and possibly a more fundamental theory of quantum gravity is needed near the would be Rip singularity. We describe the qualitative features of the model and we also investigate how this cosmology could be realized by a viscous fluid in the context of Loop Quantum Cosmology. In addition to this, we show how this deformed model can be realized by a canonical scalar field filled Universe, in the context of Loop Quantum Cosmology. Finally, we demonstrate how the model can be generated by a vacuum F (R) gravity.

Bouncing Cosmologies with Dark Matter and Dark Energy

“…Thus, a matter bounce scenario based on the matter content observed in the universe today can naturally predict scale-invariant perturbations with a slight red tilt and a small tensor-to-scalar ratio [7]. Further properties of such a matter bounce scenario with dark matter and dark energy, as well as some extensions thereof, have been studied in [8,[14][15][16][17][18][19][20].…”

The asymptotic behavior of bouncing cosmological models in F(𝒢) gravity theory

“…In addition, it has been verified that in a sum of two exponential functions model of the scale factor, asymptotic behavior at late-time cosmic acceleration is similar to that of the model discussed above. Recently there was an paper [38] one can demonstrated that in the context of LQC, it is possible to realize a deformed matter bounce scenario, in which the deformation practically alters the late-time behavior of the model. Would be interesting to apply the proposed mechanism for the constructed in our paper models.…”

Dark matter and baryogenesis in the Fermi-bounce curvaton mechanism

“…We dispose now of all the necessary ingredients to calculate the power spectrum of the primordial scalar gravitational perturbations. Indeed, if we substitute (35) into (20), we find that the power spectrum of the primordial curvature perturbations is expressed by the relation…”

“…We wish to remark that recently bouncing cosmologies involving dark matter (and dark energy) have received much attention in the literature, and that distinctive and falsifiable predictions on CMB observables have been derived that will be tested in the near future [13][14][15][16][17][18][19][20] (for a recent review see also [21]). With respect to this vast literature the gist of our proposal relies on the deployment of fermionic matter fields.…”