Exact Causal Viscous Cosmologies

Mak, M. K.; Harkó, Tiberiu

doi:10.1023/a:1026690710970

Cited by 44 publications

(28 citation statements)

References 15 publications

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“…On the other hand we have not used any such pre-assumed form for the equation of state. There are also some results telling us that the bulk viscous matter can lead to phantom nature in the early period of the universe [29][30][31]. In the present analysis using the causal viscous formalism due to Israel and Stewart, we get the result that the bulk viscous matter will behave like a strong stiff fluid in the early period and it shows the behaviour of the quintessence dark energy in the later universe, such that the equation of state is stabilised at around ω ∼ −0.79 in the far future of the evolution of the universe.…”

Section: Evolution Of Equation Of State Parametermentioning

confidence: 99%

Bulk viscous matter and recent acceleration of the universe based on causal viscous theory

2017

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The evolution of the bulk viscous matter dominated universe has been analysed using the full causal theory for the evolution of the viscous pressure in the context of the recent acceleration of the universe. The form of the viscosity is taken as ξ = αρ 1/2 . We obtained analytical solutions for the Hubble parameter and scale factor of the universe. The model parameters have been computed using the observational data. The evolution of the prominent cosmological parameters was obtained. The age of the universe for the best estimated model parameters is found to be less than observational value. The viscous matter behaves like a stiff fluid in the early phase and evolves to a negative pressure fluid in the later phase. The equation of state is found to be stabilised with value ω > −1. The local as well as generalised second law of thermodynamics is satisfied. The statefinder diagnostic shows that this model is distinct from the standard ΛCDM. One of the marked deviations seen in this model to be compared with the corresponding model using the Eckart approach is that in this model the bulk viscosity decreases with the expansion of the universe, while in the Eckart formalism it increases from negative values in the early universe towards positive values.

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Section: Evolution Of Equation Of State Parametermentioning

confidence: 99%

Bulk viscous matter and recent acceleration of the universe based on causal viscous theory

2017

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“…The equations (25)(26)(27)(28)(29) and the equation of state (20)(21)(22)(23) can be expressed in a dimension-less way by the following π − monomia:…”

Section: A Dimensional Considerationsmentioning

confidence: 99%

Full Causal Bulk Viscous Cosmologies With Time-Varying Constants

Belinchón¹,

Chakrabarty²

2003

Int. J. Mod. Phys. D

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We study the evolution of a flat Friedmann-Robertson-Walker Universe, filled with a bulk viscous cosmological fluid, in the presence of time varying "constants". The dimensional analysis of the model suggests a proportionality between the bulk viscous pressure of the dissipative fluid and the energy density. On using this assumption and with the choice of the standard equations of state for the bulk viscosity coefficient, temperature and relaxation time, the general solution of the field equations can be obtained, with all physical parameters having a power-law time dependence. The symmetry analysis of this model, performed by using Lie group techniques, confirms the unicity of the solution for this functional form of the bulk viscous pressure. In order to find another possible solution we relax the hypotheses assuming a concrete functional dependence for the "constants".

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“…plays an important role in many physical and technical applications; because of its importance, many scholars have studied it [1][2][3][4][5][6][7]. Recently, A. Cima, A. Gasull, and F. Manosas [8] gave the maximum number of polynomial solutions of some integrable polynomial Abel differential equations; Jaume Giné Claudia and Valls [9] studied the center problem for Abel polynomial differential equations of second kind; Jianfeng Huang and Haihua Liang [10] were devoted to the investigation of Abel equation by means of Lagrange interpolation formula; they gave a criterion to estimate the number of limit cycles of the Abel's equations; Berna Bülbül and Mehmet Sezer [11] introduced a numerical power series algorithm which is based on the improved Taylor matrix method for the approximate solution of Abel-type differential equations; Ni et al [12] discussed the existence and stability of the periodic solutions of (1) and obtained the sufficient conditions which guaranteed the existence and stability of the periodic solutions for (1) from a particular one.…”

Section: Introductionmentioning

confidence: 99%