Letter: Gravitational Waves in the Generalized Chaplygin Gas Model

Abstract

The consequences of taking the generalized Chaplygin gas as the dark energy constituent of the Universe on the gravitational waves are studied and the spectrum obtained from this model, for the flat case, is analyzed. Besides its importance for the study of the primordial Universe, the gravitational waves represent an additional perspective (besides the CMB temperature and polarization anisotropies) to evaluate the consistence of the different dark energy models and establish better constraints to their parameters. The analysis presented here takes this fact into consideration to open one more perspective of verification of the generalized Chapligin gas model applicability. Nine particular cases are compared: one where no dark energy is present; two that simulate the Λ-CDM model; two where the gas acts like the traditional Chaplygin gas; and four where the dark energy is the generalized Chaplygin gas. The different spectra permit to distinguish the Λ-CDM and the Chaplygin gas scenarios.

Gravitational waves: a 100-year tool applied to the dark energy problem

“…In addition, for the Chaplygin gas, the negligible dependence on the density parameter Ω c 0 is consistent with the idea of a unified dark component [7,8]. Since the gas interpolates both dark energy and matter, the suppression of the dark matter density parameter (see, Figure 2) should not affect the spectrum, as observed.…”

“…The reason for this silence is that no dependence on α was found in our previous works [8,11] on this subject. The spectrum presents no significative differences for 0 ≤ α ≤ 1, in the frequency range studied.…”

“…In this paper, we study the spectrum of gravitational waves due to the X-fluid model and compare the results with a previous work [8], where the cosmological constant and the generalized Chaplygin gas models were taken into account. In section §II these models are described; in §III the GW equations are presented.…”

Modeling the Spectrum of Gravitational Waves in the Primordial Universe

“…This degeneracy is in part expected, since the models must converge to each other when some particular combinations of parameters are considered. In addition, for the Chaplygin gas, the negligible dependence on the density parameter Ω c0 is consistent with the idea of a unified dark component [Fabris et al, 2004, Gorini et al, 2004. Since the gas interpolates both dark energy and matter, the suppression of the dark matter density parameter (see, plots (4-9)) should not affect the spectrum, as observed.…”

“…Gravitational waves represent one of the potential tools that may in near future offer an additional way to constrain the cosmological parameters and distinguish among the models, since gravitons decouple in a very early time in the universe history. In this paper, we study the spectrum of gravitational waves due to the X-fluid model and compare the results with a previous work [Fabris et al, 2004], where the cosmological constant and the generalized Chaplygin gas models were taken into account. In section §2 these models are described; in §3 the GW equations are presented.…”