Modeling dark energy through an Ising fluid with network interactions
  We show that the dark energy effects can be modeled by using an \emph{Ising
perfect fluid} with network interactions, whose low redshift equation of state,
i.e. $\omega_0$, becomes $\omega_0=-1$ as in the $\Lambda$CDM model. In our
picture, dark energy is characterized by a barotropic fluid on a lattice in the
equilibrium configuration. Thus, mimicking the spin interaction by replacing
the spin variable with an occupational number, the pressure naturally becomes
negative. We find that the corresponding equation of state mimics the effects
of a variable dark energy term, whose limiting case reduces to the cosmological
constant $\Lambda$. This permits us to avoid the introduction of a vacuum
energy as dark energy source by hand, alleviating the coincidence and fine
tuning problems. We find fairly good cosmological constraints, by performing
three tests with supernovae Ia, baryonic acoustic oscillation and cosmic
microwave background measurements. Finally, we perform the AIC and BIC
selection criteria, showing that our model is statistically favored with
respect to the CPL parametrization.
