Rigorous theoretical constraint on constant negative EoS parameter $$\omega $$ ω and its effect for the late Universe

Abstract

In this paper, we consider the Universe at the late stage of its evolution and deep inside the cell of uniformity. At these scales, the Universe is filled with inhomogeneously distributed discrete structures (galaxies, groups and clusters of galaxies). Supposing that the Universe contains also the cosmological constant and a perfect fluid with a negative constant equation of state (EoS) parameter (e.g., quintessence, phantom or frustrated network of topological defects), we investigate scalar perturbations of the Friedmann–Robertson–Walker metrics due to inhomogeneities. Our analysis shows that, to be compatible with the theory of scalar perturbations, this perfect fluid, first, should be clustered and, second, should have the EoS parameter . In particular, this value corresponds to the frustrated network of cosmic strings. Therefore, the frustrated network of domain walls with is ruled out. A perfect fluid with neither accelerates nor decelerates the Universe. We also obtain the equation for the nonrelativistic gravitational potential created by a system of inhomogeneities. Due to the perfect fluid with , the physically reasonable solutions take place for flat, open and closed Universes. This perfect fluid is concentrated around the inhomogeneities and results in screening of the gravitational potential.

Perfect fluids withω=constas sources of scalar cosmological perturbations

“…First, in the framework of the ΛCDM model supplemented with an additional perfect fluid characterized by a constant parameter ω in the linear EoS (or, generally speaking, with an arbitrary number of such fluids) there is no theoretical limitation imposed on ω at the level of Einstein equations, as distinct from what was reported before in [32]. In that paper only two values ω = −1 (the vacuum-like EoS) and ω = −1/3 survived.…”

First-Order Cosmological Perturbations Engendered by Point-Like Masses

“…This equation is equivalent to the equation (2.25) in (Burgazli et al 2015) up to designations. Hence, one can make use of its solutions derived by Burgazli et al (2015), simply adjusting the notation.…”

“…This hints at the universality of the presentation (3.7). In particular, the gravitational potentials derived by Burgazli et al (2015) may be interpreted as valid for the Universe filled with quintessence with the parameter −1/3 in the presence of the cosmological constant as well as the nonrelativistic pressureless matter with negligible average energy density.…”

Scalar perturbations in cosmological models with quark nuggets

“…This approach was established in our papers [21][22][23]. An important feature of this approach is that it provides an opportunity to study self-consistency of different cosmological models (see, e.g., [24]). For example, there is a possibility that a small fraction of colored objects escaped hadronization and survived in the form of quark-gluon nuggets [4].…”