Reconstruction of cosmic history from a simple parametrization of H

Pacif, S. K. J.; Myrzakulov, Ratbay; Myrzakul, Shynaray

doi:10.1142/s0219887817501110

Cited by 73 publications

(47 citation statements)

References 165 publications

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“…A cosmological model which exhibits an early-time acceleration, middle-time deceleration and a late-time acceleration can provide a better description to cosmic evolution. For the sake of completeness, it is worthy to mention that late-time decelerating models can also be in a good agreement with observations and show a nice fit to some data [52,53].…”

Section: Introductionmentioning

confidence: 69%

The possibility of a stable flat dark energy-dominated Swiss-cheese brane-world universe

Ahmed

Bamba

Salama

2020

Int. J. Geom. Methods Mod. Phys.

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In this paper, we study the possibility of obtaining a stable flat dark energy-dominated universe in a good agreement with observations in the framework of Swiss-cheese Braneworld cosmology. Two different Brane-world cosmologies with black strings have been introduced for any cosmological constant Λ using two empirical forms of the scale factor. In both models, we have performed a fine-tuning between the brane tension and the cosmological constant so that the EoS parameter ω(t) → −1 for the current epoch where the redshift z 0. We then used these fine-tuned values to calculate and plot all parameters and energy conditions. The deceleration-acceleration cosmic transition is allowed in both models, and the jerk parameter j → 1 at late-times. Both solutions predict a future dark energy-dominated universe in which ω = −1 with no crossing to the phantom divide line. While the pressure in the first solution is always negative, the second solution predicts a better behavior of cosmic pressure where the pressure is negative only in the late-time accelerating era but positive in the early-time decelerating era. Since black strings have been proved to be unstable by some authors, this instability can actually reflect doubts on the stability of cosmological models with black strings (Swiss-cheese type brane-worlds cosmological models). For this reason, we have carefully investigated the stability through energy conditions and sound speed. Because of the presence of quadratic energy terms in Swiss-cheese type brane-world cosmology, we have tested the new nonlinear energy conditions in addition to the classical energy conditions. We have also found that constructing non-singular and cyclic solutions through certain ansatze in Swiss-cheese Brane-worlds are not possible.

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Section: Introductionmentioning

confidence: 69%

The possibility of a stable flat dark energy-dominated Swiss-cheese brane-world universe

Ahmed

Bamba

Salama

2020

Int. J. Geom. Methods Mod. Phys.

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“…Parameterizations of Hubble parameter, deceleration parameter, EoS parameter etc. provide the necessary constraint equation (see [29]). In this paper, we employ a generalized varying deceleration parameter of the second degree introduced in [30] of the form,…”

Section: Kinematic Variables and Observational Constraintsmentioning

confidence: 99%

Late-time acceleration with a scalar field source: Observational constraints and statefinder diagnostics

Pacif

Arora

Sahoo

2021

Physics of the Dark Universe

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This article discusses a dark energy cosmological model in the standard theory of gravity -general relativity with a broad scalar field as a source. Exact solutions of Einstein's field equations are derived by considering a particular form of deceleration parameter q, which shows a smooth transition from decelerated to accelerated phase in the evolution of the universe. The external datasets such as Hubble (H(z)) datasets, Supernovae (SN) datasets, and Baryonic Acoustic Oscillation (BAO) datasets are used for constraining the model par parameters appearing in the functional form of q. The transition redshift is obtained at z t = 0.67 +0.26 −0.36 for the combined data set (H(z) + SN + BAO), where the model shows signature-flipping and is consistent with recent observations. Moreover, the present value of the deceleration parameter comes out to be q 0 = −0.50 +0.12 −0.11 and the jerk parameter j 0 = −0.98 +0.06 −0.02 (close to 1) for the combined datasets, which is compatible as per Planck2018 results. The analysis also constrains the omega value i.e., Ω m 0 ≤ 0.269 for the smooth evolution of the scalar field EoS parameter. It is seen that energy density is higher for the effective energy density of the matter field than energy density in the presence of a scalar field. The evolution of the physical and geometrical parameters is discussed in some details with the model parameters' numerical constrained values. Moreover, we have performed the state-finder analysis to investigate the nature of dark energy.

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“…Now we assign the function E(z) with 51 supernova data that these data collected the Refs. [84][85][86][87][88][89][90][91]. We note that the H(z) dataset are measured by techniques of galaxy differential age or cosmic chronometer and radial BAO size methods.…”

Section: Reconstructing and Observational Constraintsmentioning

confidence: 99%

Viscous interaction and stability on dark matter Bose–Einstein condensation with modified Chaplygin gas

2021

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In this paper, the viscous cosmological dynamics are studied in the presence of dark matter Bose-Einstein Condensation (BEC) by curved-FRW background. For this purpose, we use the BEC regime rather than the normal dark matter (the cold dark matter or the barotropic dark matter) with the dark matter Equation of State (EoS) as pdm ∝ p2dm, which arises from the gravitational form. Therefore, we obtain the corresponding continuity equations with the existence of the universe components by considering an interacting model with modified Chaplygin gas. Afterward, we derive the energy density and the pressure of dark energy in terms of the redshift parameter. And then, by introducing a parametrization function and fitting it with 51 supernova data with the likelihood analysis, we find the cosmological parameters versus redshift parameter. In what follows, we plot the corresponding dynamic graphs proportional to redshift, and then we represent the universe is currently undergoing an accelerated expansion phase. Finally, we explore the stability and the instability of the present model with the sound speed parameter.

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Reconstruction of cosmic history from a simple parametrization of H

Cited by 73 publications

References 165 publications

The possibility of a stable flat dark energy-dominated Swiss-cheese brane-world universe

The possibility of a stable flat dark energy-dominated Swiss-cheese brane-world universe

Late-time acceleration with a scalar field source: Observational constraints and statefinder diagnostics

Viscous interaction and stability on dark matter Bose–Einstein condensation with modified Chaplygin gas

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