Accelerated expansion of the universe based on particle creation–destruction processes and dark energy in FLRW universes

Balfagon, Alberto C.

doi:10.1007/s10714-015-1954-9

Cited by 10 publications

(8 citation statements)

References 28 publications

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“…Accelerated expansion of the universe being due to the dark energy, which is the energy density stored in the vacuum state of all existing fields in the universe, is also one of the many possible alternatives. The variable cosmological constant [29,30] is one of the alternatives to explain the dark-energy problem, compatible with observations. A small and positive value of the effective cosmological constant is predicted by observations in the present epoch.…”

Section: Field Equations and Thermodynamicsmentioning

confidence: 54%

Thermodynamics of cosmological models with generalized G and Λ

Singh¹,

Singh²

2018

Turk J Phys

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Abstract:Here we investigate spatially flat Friedmann-Robertson-Walker space-time models of the universe to study the thermodynamic behaviors in light of variables G and Λ . A particular method to find the solutions of Einstein's field equations and mathematical expressions for temperature and entropy of the perfect fluid cosmological models is introduced by using both the equation of state and the assumption G = G0 a n . It is observed that the phantom field of ( ω < −1) is thermodynamically not viable when the temperature increases with the evolution of the universe. The second law of thermodynamics is also constrained by cosmological models with time-dependent G and Λ . The mathematical expressions for the look-back time, proper distance, luminosity distance, and angular diameter distances are obtained for an isotropic stiff-fluid model and their significances are investigated. The most interesting part of the investigation is that the dynamical and physical behaviors of the models are less constrained by the second law of thermodynamics.

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Section: Field Equations and Thermodynamicsmentioning

confidence: 54%

Thermodynamics of cosmological models with generalized G and Λ

Singh¹,

Singh²

2018

Turk J Phys

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“…In this paper, we shall be dealing with adiabatic GPCM so that we shall not be required to resort to either the first or the second order theories. Now, following Balfagon [31], we see that the thermodynamics of an adiabatic open system with a varying particle number N leads to…”

Section: Adiabatic Gpcmmentioning

confidence: 87%

“…Now, using Eqs. ( 4) and ( 5), and noting that ρ = h n ṅ [31], where h is the enthalpy density, we arrive at a very important relation connecting the bulk viscosity with the rate of particle creation-…”

Section: Basic Cosmological Equationsmentioning

confidence: 88%

How to obtain a class of emergent universes with a general form of dissipation?

Saha

2019

Preprint

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In this paper, we have assumed a flat Friedmann-Lemaitré-Robertson-Walker universe endowed with a general form of dissipation. The source of dissipation is considered to be a bulk viscous pressure Π which leads to an adiabatic creation of particles induced by the gravitational field. Further, the cosmic substratum is assumed to satisfy the equation of state p = (γ − 1)ρ and Π is considered to be proportional to H 2k+1 , where H is the Hubble parameter and k is the index of dissipation. This choice of dissipation is consistent with the pioneering works by Barrow and Clifton. Finally, by assuming an exponential form for H given by H = e m(t−t 0 ) , where m is a positive real parameter and which bears all the signatures of an emergent universe, we have been able to establish that the sufficiency of the inequality γk ≤ 0 can produce a class of emergent universes. However, this condition is by no means necessary for the existence of an emergent universe.

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“…Inserting Eq. ( 3) and the relation ṅ + 3Hn = nΓ [10,33,34,35] into Eq. (2) where Γ is the particle creation rate, we obtain ρ + 3H(ρ + p + p e ) = 0, (4) where the effect of particle creation is expressed as an extra pressure…”

Section: Particle Creation In Cosmologymentioning

confidence: 99%

Cosmological scenario based on the particle creation and holographic equipartition

Tu,

Chen,

Huang

2019

Preprint

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We propose a cosmological scenario which describes the evolution history of the universe based on the particle creation and holographic equipartition. The model attempts to solve the inflation of the early universe and the accelerated expansion of the present universe without introducing the dark energy from the perspective of thermodynamics. Throughout the evolution of the universe, we assume that the universe always creates particles in some way and holographic equipartition is always satisfied. Further, we choose that the creation rate of particles is proportional to H 2 in the early universe and to H in the present and late universe, where H is the Hubble parameter. Then we obtain the solutions a(t) ∝ e αt/3 and a(t) ∝ t 1/2 for the early universe and the solutions a(t) ∝ t δ and a(t) ∝ e Ht for the present and late universe, where α and δ are the parameters. Finally, we obtain and analyze two important thermodynamic properties for the present model.

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Accelerated expansion of the universe based on particle creation–destruction processes and dark energy in FLRW universes

Cited by 10 publications

References 28 publications

Thermodynamics of cosmological models with generalized G and Λ

Thermodynamics of cosmological models with generalized G and Λ

How to obtain a class of emergent universes with a general form of dissipation?

Cosmological scenario based on the particle creation and holographic equipartition

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