State finder and Om diagnostics in modified and generalised Chaplygin gas from recent data

2021 ◽  
Author(s):  
P. Thakur
Keyword(s):  
Chaplygin Gas ◽  
Red Shift ◽  
Recent Past ◽  
Eos Parameter ◽  
Deceleration Phase ◽  
Om Diagnostic ◽  
Expected Values ◽  
Best Fit ◽  
The Universe ◽  
Jerk Parameter

A modified and generalised Chaplygin gas (MCG, [Formula: see text] and GCG, [Formula: see text]) has been separately chosen here as a constituent of the universe. Concept of state finder and Om diagnostics are introduced to track the dark energy in the models. Here, observed Hubble data (OHD) and binned Pantheon data of supernovae are used to determine the best-fit equation-of-state (EoS) parameters of these models and these are compared with the [Formula: see text]CDM model. The best-fit value and expected values of cosmological jerk parameter [Formula: see text], snap parameter [Formula: see text] are determined, which are close to each other. A plot of [Formula: see text] with red-shift, with themselves, as well as with deceleration parameter [Formula: see text], shows the evolution of the universe and its possible future. Variations of [Formula: see text] and EoS parameter [Formula: see text] with red-shift show acceleration–deceleration phase transition in the recent past. Lastly, the state finder pair [Formula: see text] and Om diagnostic have been utilized to discriminate the models.

Observational data analysis for generalized cosmic Chaplygin gas in the background of Brans–Dicke theory

2021 ◽  
pp. 2150157
Author(s):  
Ujjal Debnath
Keyword(s):  
Data Analysis ◽  
State Parameter ◽  
Chaplygin Gas ◽  
Information Criteria ◽  
Model Parameters ◽  
Confidence Levels ◽  
Expansion Of The Universe ◽  
Generalized Cosmic Chaplygin Gas ◽  
Best Fit ◽  
The Universe

In this paper, we have considered the generalized cosmic Chaplygin gas (GCCG) in the background of Brans–Dicke (BD) theory and also assumed that the Universe is filled in GCCG, dark matter and radiation. To investigate the data fitting of model parameters, we have constrained the model using recent observations. Using [Formula: see text] minimum test, the best-fit values of the model parameters are determined by OHD+CMB+BAO+SNIa joint data analysis. We have drawn the contour figures for different confidence levels [Formula: see text], [Formula: see text] and [Formula: see text]. To examine the viability of the GCCG model in BD theory, we have also determined △AIC and △BIC using the information criteria (AIC and BIC). Graphically, we have analyzed the natures of the equation of state parameter and deceleration parameter for our best-fit values of model parameters. Also, we have studied the square speed of sound [Formula: see text] which lies in the interval [Formula: see text] for expansion of the Universe. So, our considered model is classically stable by considering the best-fit values of the model parameters due to the data analysis.

scholarly journals A study of modified holographic Ricci dark energy in the framework of f(T) modified gravity and its statefinder hierarchy

2019 ◽  
Vol 97 (5) ◽  
pp. 477-486 ◽  
Author(s):  
Arkaprabha Majumdar ◽  
Surajit Chattopadhyay
Keyword(s):  
Dark Matter ◽  
Fixed Point ◽  
Dark Energy ◽  
Modified Gravity ◽  
Chaplygin Gas ◽  
Modified Chaplygin Gas ◽  
Ricci Dark Energy ◽  
Eos Parameter ◽  
The Universe ◽  
Viable Model

Inspired by the work of Bamba et al. (Phys. Rev. D, 85, 104036 (2012)) the present paper reports a study on the reconstruction of modified holographic Ricci dark energy (MHRDE) in the framework of modified gravity taken as f(T) gravity. A correspondence between modified Chaplygin gas and MHRDE has also been considered and thereinafter the f(T) gravity has been reconstructed via reconstruction of the Hubble parameter. The reconstructed equation of state (EoS) parameter obtained this way has been found to be able to cross the phantom boundary. In the next phase of the work, a viable model of f(T) gravity has been considered and MHRDE has been discussed in this modified gravity frame. The EoS parameter due to the torsion contribution obtained this way has been found to behave like quintessence. The transition of the universe from the dark matter dominated to dark energy (DE) dominated phase is apparent from this model. Also, the model is exhibiting DE domination of the current universe. Finally, the statefinder hierarchy has been discussed through the statefinder and snap parameters. The model has been found to be able to attain the ΛCDM fixed point in the statefinder trajectory.

Reconstruction of f(T) Gravity with Interacting Variable-Generalised Chaplygin Gas and the Thermodynamics with Corrected Entropies

2017 ◽  
Vol 72 (3) ◽  
pp. 231-244 ◽  
Author(s):  
Surajit Chattopadhyay
Keyword(s):  
Power Law ◽  
Correction Term ◽  
Chaplygin Gas ◽  
Logarithmic Correction ◽  
Future Event ◽  
Eos Parameter ◽  
Reconstruction Scheme ◽  
The Universe ◽  
Bounded System ◽  
Future Event Horizon

AbstractThis article reports a study on variable-generalised Chaplygin gas (VGCG) interacting with pressureless dark matter (DM) with interaction term Q chosen in the form Q=3HδρΛ, where ρΛ denotes the density of the VGCG. Detailed cosmology of the interacting VGCG has been studied and a quintom behaviour of the equation of state (EoS) parameter has been observed. A statefinder analysis has shown attainment of ΛCDM fixed point by the interacting VGCG. Subsequently, a reconstruction scheme for f(T) gravity has been presented based on the interacting VGCG with power-law form of scale factor. The EoS parameter corresponding to the reconstructed f(T) has shown quintom behaviour. Finally, we have studied the generalised second law (GSL) of thermodynamics in reconstructed f(T) cosmology considering the universe as a closed bounded system with future event horizon as the cosmological boundary. We have associated two different entropies with the cosmological horizons with a logarithmic correction term and a power-law correction term. We have studied the validity of the GSL for both of these corrections.

CONSTRAINTS ON SIMPLIFIED QUARTESSENCE COSMOLOGY FROM THE LATEST OBSERVATIONAL DATA

2007 ◽  
Vol 16 (11) ◽  
pp. 1783-1789
Author(s):  
PUXUN WU ◽  
SUMEI DONG
Keyword(s):  
Confidence Level ◽  
Deceleration Parameter ◽  
Chaplygin Gas ◽  
Red Shift ◽  
Type Ia Supernovae ◽  
Distance Ratio ◽  
Generalized Chaplygin Gas ◽  
Type Ia ◽  
Ia Supernovae ◽  
The Universe

The simplified generalized Chaplygin gas (GCG) model as a candidate of UDME is studied in this paper. By using the latest 162 ESSENCE type Ia supernovae (Sne Ia ) data, 30 high red shift Sne Ia data and the distance ratio from z = 0.35 to z = 1089 (the red shift of decoupling), we obtain [Formula: see text] and [Formula: see text] at a 95.4% confidence level. In addition the deceleration parameter for this simplified GCG model is investigated, and we find that the universe, at a 1σ confidence level, enters the acceleration era at the red shift zq = 0~ 0.53 - 0.66 and possesses an acceleration -qz = 0~ 0.66 - 0.78 at present.

Interaction of viscous modified Chaplygin gas with f(R, T) gravity

2017 ◽  
Vol 32 (28) ◽  
pp. 1750151 ◽  
Author(s):  
M. Sharif ◽  
Aisha Siddiqa
Keyword(s):  
Energy Momentum Tensor ◽  
Momentum Tensor ◽  
Chaplygin Gas ◽  
Modified Chaplygin Gas ◽  
Field Equations ◽  
Frw Universe ◽  
Eos Parameter ◽  
Total Energy Density ◽  
Conservation Of Energy ◽  
The Universe

We study the evolution of viscous modified Chaplygin gas (MCG) interacting with f(R, T) gravity in flat FRW universe, where T is the trace of energy–momentum tensor. The field equations are formulated for a particular model f(R, T) = R + 2[Formula: see text]T and constraints for the conservation of energy–momentum tensor are obtained. We investigate the behavior of total energy density, pressure and equation of state (EoS) parameter for emergent, intermediate as well as logamediate scenarios of the universe with two interacting models. It is found that the EoS parameter lies in the matter-dominated or quintessence era for all the three scenarios while the bulk viscosity enhances the expansion for the intermediate and logamediate scenarios.

scholarly journals A hybrid model of viscous and Chaplygin gas to tackle the Universe acceleration

2021 ◽  
Vol 81 (4) ◽  
Author(s):  
A. Hernández-Almada ◽  
Miguel A. García-Aspeitia ◽  
M. A. Rodríguez-Meza ◽  
V. Motta
Keyword(s):  
Cosmological Model ◽  
Hybrid Model ◽  
Hubble Constant ◽  
Chaplygin Gas ◽  
Joint Analysis ◽  
Acoustic Oscillations ◽  
Generalized Chaplygin Gas ◽  
Om Diagnostic ◽  
Standard Cosmological Model ◽  
The Universe

AbstractMotivated by two seminal models proposed to explain the Universe acceleration, this paper is devoted to study a hybrid model which is constructed through a generalized Chaplygin gas with the addition of a bulk viscosity. We call the model a viscous generalized Chaplygin gas (VGCG) and its free parameters are constrained through several cosmological data like the Observational Hubble Parameter, Type Ia Supernovae, Baryon Acoustic Oscillations, Strong Lensing Systems, HII Galaxies and using Joint Bayesian analysis. In addition, we implement a Om-diagnostic to analyze the VGCC dynamics and its difference with the standard cosmological model. The hybrid model shows important differences when compared with the standard cosmological model. Finally, based on our Joint analysis we find that the VGCG could be an interesting candidate to alleviate the well-known Hubble constant tension.

Cosmological scenario in κ(R,T) gravity

2021 ◽  
Author(s):  
Archana Dixit ◽  
Anirudh Pradhan ◽  
Raghavendra Chaubey
Keyword(s):  
Deceleration Parameter ◽  
Chaplygin Gas ◽  
Cosmic Acceleration ◽  
Accelerated Expansion ◽  
Eos Parameter ◽  
Dominant Component ◽  
Cosmological Scenario ◽  
Deterministic Solution ◽  
Time Periodic ◽  
The Universe

In this paper, we investigate the cosmic acceleration and the behavior of dark energy (DE) in the structure of the recently proposed [Formula: see text] gravity theory [G. R. P. Teruel, [Formula: see text] gravity, Eur. Phys. J. C 78 (2018) 660]. In this study, we obtained some fascinating cosmological features that are coherent with observational evidences and the touchstone [Formula: see text]CDM model. To find the deterministic solution, we consider a periodic deceleration parameter [Formula: see text], where [Formula: see text] [M. Shen and L. Zhao, Oscillating quintom model with time periodic varying deceleration parameter, Chin. Phys. Lett. 31 (2014) 010401], which predicts the decelerating and accelerating phases of the universe. The Equation of State (EoS) parameter also supports the idea of DE, which is the dominant component and it is responsible for the universe’s accelerated expansion. Here, we also construct cosmographic parameters, like, [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], and studied their evolution in spatially flat [Formula: see text] gravity. We find that these observations are sufficient in comparison with the universe’s physical and kinematic properties and also consistent with ongoing (OHD[Formula: see text][Formula: see text][Formula: see text]JLA) observation. Next, we apply the geometric diagnostics, the state-finder ([Formula: see text]) in [Formula: see text] gravity to discriminate from the [Formula: see text]CDM model. We found that our model lies in quintessence and the Chaplygin Gas region. Finally, the model approaches [Formula: see text]CDM at the present epoch of the universe.

scholarly journals OBSERVATIONAL CONSTRAINTS ON DARK ENERGY MODEL

2005 ◽  
Vol 14 (03n04) ◽  
pp. 599-608 ◽  
Author(s):  
YUNGUI GONG
Keyword(s):  
Dark Energy ◽  
General Model ◽  
Wilkinson Microwave Anisotropy Probe ◽  
First Year ◽  
Deceleration Phase ◽  
Type Ia ◽  
Model Independent ◽  
Best Fit ◽  
The Universe ◽  
Special Case

The recent observations support that our Universe is flat and expanding with acceleration. We analyze a general class of quintessence models by using the recent type Ia supernova and the first year Wilkinson Microwave Anisotropy Probe (WMAP) observations. For a flat universe dominated by a dark energy with constant ω which is a special case of the general model, we find that [Formula: see text] and ωQ≤-0.82, and the turnaround redshift zTwhen the universe switched from the deceleration phase to the acceleration phase is zT= 0.65. For the general model, we find that Ωm0~0.3, ωQ0~-1.0, β~0.5 and zT~0.67. A model independent polynomial parametrization of dark energy is also considered, the best fit model gives Ωm0= 0.40±0.14, ωQ0= -1.4 and zT= 0.37.

scholarly journals Mixed fluid cosmological model in f(R, T) gravity

2020 ◽  
Vol 98 (11) ◽  
pp. 1015-1022 ◽  
Author(s):  
Parbati Sahoo ◽  
Barkha Taori ◽  
K.L. Mahanta
Keyword(s):  
Cosmological Model ◽  
Bianchi Type ◽  
Type I ◽  
Time Varying ◽  
Eos Parameter ◽  
Barotropic Fluid ◽  
Rotationally Symmetric ◽  
Expansion Of The Universe ◽  
The Universe ◽  
Mixed Fluid

We construct a locally rotationally symmetric (LRS) Bianchi type-I cosmological model in f(R, T) theory of gravity when the source of gravitation is a mixture of barotropic fluid and dark energy (DE) by employing a time-varying deceleration parameter. We observe through the behavior of the state finder parameters (r, s) that our model begins from the Einstein static era and goes to ΛCDM era. The equation of state (EOS) parameter (ωd) for DE varies from the phantom (ω < –1) phase to quintessence (ω > –1) phase, which is consistent with observational results. It is found that the discussed model can reproduce the current accelerating phase of the expansion of the universe.

scholarly journals Dynamical system analysis of FLRW models with Modified Chaplygin gas

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ali Osman Yılmaz ◽  
Ertan Güdekli
Keyword(s):  
Dynamical System ◽  
Equation Of State ◽  
Energy Density ◽  
System Analysis ◽  
Chaplygin Gas ◽  
Modified Chaplygin Gas ◽  
State Spaces ◽  
The Universe ◽  
Matter Energy ◽  
Far Future

AbstractWe investigate Friedmann–Lamaitre–Robertson–Walker (FLRW) models with modified Chaplygin gas and cosmological constant, using dynamical system methods. We assume $$p=(\gamma -1)\mu -\dfrac{A}{\mu ^\alpha }$$ p = ( γ - 1 ) μ - A μ α as equation of state where $$\mu$$ μ is the matter-energy density, p is the pressure, $$\alpha$$ α is a parameter which can take on values $$0<\alpha \le 1$$ 0 < α ≤ 1 as well as A and $$\gamma$$ γ are positive constants. We draw the state spaces and analyze the nature of the singularity at the beginning, as well as the fate of the universe in the far future. In particular, we address the question whether there is a solution which is stable for all the cases.

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