New limit on logotropic unified dark energy models

Testing the equation of state for viscous dark energy

“…As shown in Fig. 1 and Table II, Hence, the model (33) with α = 1 provides effectively the same results as the general model (8) with α ∈ R, since there is no correlation among α and the other parameters, as shown in Fig. 1.…”

“…The ΛCDM model is also depicted for comparison with our model (the black dashed line). Note that the power-law model (8) transforms into the ΛCDM model for Ω x = const = Ω Λ , which corresponds to the particular case A = B = 0. In addition, the difference among the cases α = 1 and α ∈ R becomes more remarkable in the bottom-right panel, where min χ 2 Σ3 depends on B.…”

“…Along the paper we have considered two cosmological scenarios where dark energy is assumed to be described by a viscous fluid, through bulk viscosity, what leads to an effective pressure that can explain the late-time accelerating expansion. For that, and inspired on some hydrodynamics considerations, we have explored two different EoS for viscous dark energy: the power-law model (8), precisely, its variant (33) with α = 1 and the logarithmic model (9). By using data from Supernovae Ia, BAO, H(z) measurements and CMB, we have analysed the viability of these scenarios and compared to ΛCDM model.…”

“…The component ρ r becomes important just at high redshifts, at which radiation density turns out essential to deal with is the corresponding CMB observational data for redshifts z ≃ 1000. Hence, by setting the spatial curvature to be zero Ω k = 0 and by fixing the radiation-matter ratio (15), the free parameters for both models (8) and (9) turn out:…”

The limiting behavior of the Riemann solution to the isentropic Euler system for logarithmic equation of state with a source term

“…where > 0 is a small parameter. The logarithmic equation of state recently has been introduced in [1][2][3][4] to depict the dynamical evolutionary behavior of late-time universe for the dark energy of fluids. Compared with various generalizations of the Chaplygin gas model, the Logotropic model with the logarithmic equation of state leads to some cosmological behaviors which depends upon a single parameter .…”