Exact solutions of a causal viscous FRW cosmology within the Israel–Stewart theory through factorization

Belinchón, José Antonio; Cornejo-Pérez, O.; Cruz, Norman

doi:10.1007/s10714-021-02895-z

Cited by 3 publications

(2 citation statements)

References 40 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For the case when the bulk viscosity coefficient ξ is given as a power law function of the energy density by ξ = ξ 0 ρ 1/2 a cosmological solution of the polynomial type given by H t const. 1 ( ) µ + has been found by applying the standard factorization method [23,24], where H denotes the Hubble rate function.…”

Section: Israel-stewart Cosmological Modelmentioning

confidence: 99%

Parametric factorization of non linear second order differential equations

González Contreras

2024

Phys. Scr.

View full text Add to dashboard Cite

show abstract

Section: Israel-stewart Cosmological Modelmentioning

confidence: 99%

Parametric factorization of non linear second order differential equations

González Contreras

2024

Phys. Scr.

View full text Add to dashboard Cite

show abstract

“…An alternative approach to the scalar field description is one in which inflation is governed by bulk viscosity pressure, providing a sufficient amount of negative pressure, which is essential for the accelerated expansion. In this approach, the dynamical equations are described by a relativistic theory of non-perfect cosmological fluids [24][25][26] (for recent works, we refer to [27][28][29][30][31][32][33][34] and the references therein). A well-developed and commonly employed relativistic theory of non-perfect fluids is due to Müller [35] and Israel and Stewart [36,37] and is normally referred to as the MIS theory.…”

Section: Introductionmentioning

confidence: 99%

Sustaining Quasi De-Sitter Inflation with Bulk Viscosity

Lahiri,

Rezzolla

2024

Symmetry

View full text Add to dashboard Cite

The de-Sitter spacetime is a maximally symmetric Lorentzian manifold with constant positive scalar curvature that plays a fundamental role in modern cosmology. Here, we investigate bulk-viscosity-assisted quasi de-Sitter inflation, that is the period of accelerated expansion in the early universe during which −H˙≪H2, with H(t) being the Hubble expansion rate. We do so in the framework of a causal theory of relativistic hydrodynamics, which takes into account non-equilibrium effects associated with bulk viscosity, which may have been present as the early universe underwent an accelerated expansion. In this framework, the existence of a quasi de-Sitter universe emerges as a natural consequence of the presence of bulk viscosity, without requiring introducing additional scalar fields. As a result, the equation of state, determined by numerically solving the generalized momentum-conservation equation involving bulk viscosity pressure turns out to be time dependent. The transition timescale characterising its departure from an exact de-Sitter phase is intricately related to the magnitude of the bulk viscosity. We examine the properties of the new equation of state, as well as the transition timescale in the presence of bulk viscosity pressure. In addition, we construct a fluid description of inflation and demonstrate that, in the context of the causal formalism, it is equivalent to the scalar field theory of inflation. Our analysis also shows that the slow-roll conditions are realised in the bulk-viscosity-supported model of inflation. Finally, we examine the viability of our model by computing the inflationary observables, namely the spectral index and the tensor-to-scalar ratio of the curvature perturbations, and compare them with a number of different observations, finding good agreement in most cases.

show abstract