Effective field description of the Anton-Schmidt cosmic fluid

Abstract

The effective theory of the Anton-Schmidt cosmic fluid within the Debye approximation is investigated. In this picture, the universe is modeled out by means of a medium without cosmological constant. In particular, the Anton-Schmidt representation of matter describes the pressure of crystalline solids under deformations imposed by isotropic stresses. The approach scheme is related to the fact that the universe deforms under the action of the cosmic expansion itself. Thus, we frame the dark energy term as a function of scalar fields and obtain the corresponding dark energy potential V (ϕ). Different epochs of the universe evolution are investigated in terms of the evolution of ϕ. We show how the Anton-Schmidt equation of state is capable of describing both late and early epochs of cosmic evolution. Finally, numerical bounds on the Anton-Schmidt model with n = −1 are derived through a Markov Chain Monte Carlo analysis on the combination of data coming from type Ia Supernovae, observations of Hubble parameter and baryon acoustic oscillations. Statistical comparison with the ΛCDM model is performed by the AIC and BIC selection criteria. Results are in excellent agreement with the low-redshift data. A further generalization of the model is presented to satisfy the theoretical predictions at early-stage cosmology.

Cosmological evolution with quadratic gravity and nonideal fluids

“…There are three physical viability conditions which should be accounted for when identifying the cosmologically relevant regions inside the full 3-dimensional y-z-phase space. 5 They are the following:…”

“…In the former case a certain single cosmic fluid is adopted to describe two different epochs in the limits of high and low energy, while the latter framework postulates some curvature modifications to the Lagrangian which are dominant at a certain cosmic epoch but dilutes at others. For example, Born-Infeld-like theories can lead to an effective description of the cosmic matter interpolating between dark matter and dark energy dominated epochs as a consequence of the Friedman equations, in terms of the Chaplygin Gas [3,4] or of the Anton-Schmidt fluid [5,6]. Other thermodynamically-motivated fluid models like the Dieterici [7] or the Shan-Chen [8] can as well exhibit a phase transition from a decelerating to an accelerating phase of the universe; the former from a matterdominated epoch to a dark energy epoch, and the latter from an early radiation-dominated epoch to a dark energy epoch.…”

A new logotropic model based on a complex scalar field with a logarithmic potential

“…2 At early times, the pressure is negligible with respect to the energy density and the LDF behaves like the pressureless CDM model. At later times, the negative pressure of the LDF becomes efficient and explains the acceleration of the Universe that * Electronic address: chavanis@irsamc.ups-tlse.fr 1 The original logotropic model [1][2][3][4] has been further studied in [5][6][7][8][9][10][11][12]. 2 The logotropic model is not valid in the primordial Universe so that, in practice, the LDF exhibits a negative pressure, as required to explain the acceleration of the Universe today.…”

Analysis of the H0 tension problem in the Universe with viscous dark fluid

“…Specifically, the main goal of our study is to address the H 0 tension problem as a good opportunity to construct new cosmological models with viscous/inhomogeneous fluids [44][45][46][47][48][49][50][51][52][53][54]. Indeed, in the scientific literature there is nowadays a huge amount of works indicating the ways how the H 0 tension problem can be solved, or at least alleviated.…”