Cosmological Fluids with Logarithmic Equation of State
  We investigate the cosmological applications of fluids having an equation of
state which is the analog to the one related to the isotropic deformation of
crystalline solids, that is containing logarithmic terms of the energy density,
allowing additionally for a bulk viscosity. We consider two classes of
scenarios and we show that they are both capable of triggering the transition
from deceleration to acceleration at late times. Furthermore, we confront the
scenarios with data from Supernovae type Ia (SN Ia) and Hubble function
observations, showing that the agreement is excellent. Moreover, we perform a
dynamical system analysis and we show that there exist asymptotic accelerating
attractors, arisen from the logarithmic terms as well as from the viscosity,
which in most cases correspond to a phantom late-time evolution. Finally, for
some parameter regions we obtain a nearly de Sitter late-time attractor, which
is a significant capability of the scenario since the dark energy, although
dynamical, stabilizes at the cosmological constant value.
