Deformed Matter Bounce with Dark Energy Epoch
  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 and scalar field in the context
of LQC.
