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.

A study on the modified holographic Ricci dark energy in logarithmic f(T) gravity

2013 ◽  
Vol 91 (4) ◽  
pp. 351-354 ◽  
Author(s):  
Antonio Pasqua ◽  
Surajit Chattopadhyay
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Equation Of State ◽  
Energy Density ◽  
Modified Gravity ◽  
State Parameter ◽  
Ricci Dark Energy ◽  
Equation Of State Parameter ◽  
Interaction Term ◽  
The Universe

In this paper, we have studied and investigated the behavior of a modified holographic Ricci dark energy (DE) model interacting with pressureless dark matter (DM) under the theory of modified gravity, dubbed logarithmic f(T) gravity. We have chosen the interaction term between DE and DM in the form Q = 3γHρm and investigated the behavior of the torsion, T, the Hubble parameter, H, the equation of state parameter, ωDE, the energy density of DE, ρDE, and the energy density contribution due to torsion, ρT, as functions of the redshift, z. We have found that T increases with the redshift, z, H increases with the evolution of the universe, ωDE has a quintessence-like behavior, and both energy densities increase going from higher to lower redshifts.

Modified Chaplygin gas equation of state on viscous dissipative extended holographic Ricci dark energy and the cosmological consequences

2016 ◽  
Vol 26 (06) ◽  
pp. 1750042 ◽  
Author(s):  
Surajit Chattopadhyay
Keyword(s):  
Dark Energy ◽  
Bulk Viscosity ◽  
Cold Dark Matter ◽  
Viscosity Coefficient ◽  
Chaplygin Gas ◽  
Modified Chaplygin Gas ◽  
Ricci Dark Energy ◽  
Dissipative Term ◽  
Generalized Second Law ◽  
The Universe

The present paper reports a study on modified Chaplygin gas (MCG)-based reconstruction scheme for extended holographic Ricci dark energy (EHRDE) in the presence of viscous type dissipative term. The dissipative effect has been described by using Eckart approach. Under the assumption that the universe is filled with MCG–EHRDE under the influence of bulk viscosity we have studied the cosmological dynamics, where the bulk viscosity coefficient has been chosen in a particular time varying form [Formula: see text], where [Formula: see text] and [Formula: see text] are constant coefficients and [Formula: see text] is the Hubble parameter. Furthermore, we have reconstructed the potential and dynamics of viscous MCG–EHRDE as scalar field. Thereafter we have studied the statefinder trajectories to discern its departure from [Formula: see text] cold dark matter ([Formula: see text]CDM) and finally investigated validity of the generalized second law (GSL) of thermodynamics considering event horizon as the enveloping horizon of the universe.

DENSITY PERTURBATIONS AND THE CHAPLYGIN GAS

2009 ◽  
Vol 24 (08n09) ◽  
pp. 1674-1677
Author(s):  
SANDRO SILVA E COSTA
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Power Spectrum ◽  
Cosmological Model ◽  
Chaplygin Gas ◽  
Scale Factor ◽  
Modified Chaplygin Gas ◽  
Modern Cosmology ◽  
Density Perturbations ◽  
The Universe

One approach in modern cosmology consists in supposing that dark matter and dark energy are different manifestations of a single 'quartessential' fluid. Following such idea, this work presents a summary of some studies of the evolution of density perturbations in a flat cosmological model with a modified Chaplygin gas acting as a single component. Our goal is to obtain properties of the model which can be used to distinguish it from another cosmological models which have the same solutions for the general evolution of the scale factor of the universe, even without the construction of the power spectrum. Both our analytical and numerical results clearly indicate as one interesting feature of the model the presence of peaks in the evolution of the density constrast.

scholarly journals Astronomical bounds on the modified Chaplygin gas as a unified dark fluid model

2019 ◽  
Vol 623 ◽  
pp. A28
Author(s):  
Hang Li ◽  
Weiqiang Yang ◽  
Liping Gai
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Fluid Model ◽  
Chaplygin Gas ◽  
Linear Perturbation ◽  
Model Parameters ◽  
Modified Chaplygin Gas ◽  
Dark Fluid ◽  
Type Ia ◽  
Linear Perturbation Theory

The modified Chaplygin gas could be considered to abide by the unified dark fluid model because the model might describe the past decelerating matter dominated era and at present time it provides an accelerating expansion of the Universe. In this paper, we have employed the Planck 2015 cosmic microwave background anisotropy, type-Ia supernovae, observed Hubble parameter data sets to measure the full parameter space of the modified Chaplygin gas as a unified dark matter and dark energy model. The model parameters Bs, α, and B determine the evolutional history of this unified dark fluid model by influencing the energy density ρMCG = ρMCG0[Bs + (1 − Bs)a−3(1 + B)(1 + α)]1/(1 + α). We assumed the pure adiabatic perturbation of unified modified Chaplygin gas in the linear perturbation theory. In the light of Markov chain Monte Carlo method, we find that Bs = 0.727+0.040+0.075−0.039−0.079, α = −0.0156+0.0982+0.2346−0.1380−0.2180, B = 0.0009+0.0018+0.0030−0.0017−0.0030 at 2σ level. The model parameters α and B are very close to zero and the nature of unified dark energy and dark matter model is very similar to cosmological standard model ΛCDM.

Pilgrim dark energy models in fractal universe

2016 ◽  
Vol 26 (06) ◽  
pp. 1750049 ◽  
Author(s):  
Abdul Jawad ◽  
Shamaila Rani ◽  
Ines G. Salako ◽  
Faiza Gulshan
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Cold Dark Matter ◽  
Accelerated Expansion ◽  
Freezing And Thawing ◽  
Eos Parameter ◽  
Pilgrim Dark Energy ◽  
Energy Models ◽  
Expansion Behavior ◽  
The Universe

We discuss the cosmological implications of interacting pilgrim dark energy (PDE) models (with Hubble, Granda–Oliveros and generalized ghost cutoffs) with cold dark matter ([Formula: see text]CDM) in fractal cosmology by assuming the flat universe. We observe that the Hubble parameter lies within observational suggested ranges while deceleration parameter represents the accelerated expansion behavior of the universe. The equation of state (EoS) parameter ([Formula: see text]) corresponds to the quintessence region and phantom region for different cases of [Formula: see text]. Further, we can see that [Formula: see text]–[Formula: see text] (where prime indicates the derivative with respect to natural logarithmic of scale factor) plane describes the freezing and thawing regions and also corresponds to [Formula: see text] limit for some cases of [Formula: see text] (PDE parameter). It is also noted that the [Formula: see text]–[Formula: see text] (state-finder parameters) plane corresponds to [Formula: see text] limit and also shows the Chaplygin as well as phantom/quintessence behavior. It is observed that pilgrim dark energy models in fractal cosmology expressed the consistent behavior with recent observational schemes.

scholarly journals TOWARDS CLASSIFICATION OF SIMPLE DARK ENERGY COSMOLOGICAL MODELS

2007 ◽  
Vol 04 (02) ◽  
pp. 313-323 ◽  
Author(s):  
MAREK SZYDLOWSKI ◽  
ALEKSANDRA KUREK
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Cold Dark Matter ◽  
Friedmann Equation ◽  
Chaplygin Gas ◽  
Generalized Chaplygin Gas ◽  
Cosmological Time ◽  
Energy Models ◽  
State Formula ◽  
The Universe

We characterize a class of simple FRW models filled by both dark energy and dark matter in notion of a single potential function of the scale factor a(t); t is the cosmological time. It represents the potential of a fictitious particle — Universe moving in 1-dimensional well V(a) which the positional variable mimics the evolution of the Universe. Then the class of all dark energy models (called a multiverse) can be regarded as a Banach space naturally equipped in the structure of the Sobolev metric. In this paper, we explore the notion of C1 metric introduced in the multiverse which measures distance between any two dark energy models. If we choose cold dark matter as a reference, then we can find how far apart are different models offering explanation of the present accelerating expansion phase of the Universe. We consider both models with dark energy (models with the generalized Chaplygin gas, models with variable coefficient equation of state [Formula: see text] parameterized by redshift z, models with phantom matter) as well as models based on some modification of Friedmann equation (Cardassian models, Dvali–Gabadadze–Porrati brane models). We argue that because observational data still favor the ΛCDM model, all reasonable dark energy models should belong to the nearby neighborhood of this model.

scholarly journals Late time transition of Universe and the hybrid scale factor

2022 ◽  
Vol 82 (1) ◽  
Author(s):  
E. Aydiner ◽  
I. Basaran-Öz ◽  
T. Dereli ◽  
M. Sarisaman
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Time Evolution ◽  
Hubble Parameter ◽  
Energy Condition ◽  
Scalar Fields ◽  
Scale Factor ◽  
Late Time ◽  
Eos Parameter ◽  
The Universe

AbstractIn this study, we propose an interacting model to explain the physical mechanism of the late time transition from matter-dominated era to the dark energy-dominated era of the Universe evolution and to obtain a scale factor a(t) representing two eras together. In the present model, we consider a minimal coupling of two scalar fields which correspond to the dark matter and dark energy interacting through a potential based on the FLRW framework. Analytical solution of this model leads to a new scale factor a(t) in the hybrid form $$a(t)=a_{0} (t/t_{0})^{\alpha } e^{ht/t_{0}}$$ a ( t ) = a 0 ( t / t 0 ) α e h t / t 0 . This peculiar result reveals that the scale factor behaving as $$a (t) \propto (t/t_{0})^{\alpha }$$ a ( t ) ∝ ( t / t 0 ) α in the range $$t/t_{0}\le t_{c}$$ t / t 0 ≤ t c corresponds to the matter-dominated era while $$a(t) \propto \exp (ht/t_{0})$$ a ( t ) ∝ exp ( h t / t 0 ) in the range $$t/t_{0}>t_{c}$$ t / t 0 > t c accounts for the dark energy-dominated era, respectively. Surprisingly, we explore that the transition from the power-law to the exponential expansion appears at the crossover time $$t_{0} \approx 9.8$$ t 0 ≈ 9.8 Gyear. We attain that the presented model leads to precisely correct results so that the crossover time $$t_{0}$$ t 0 and $$\alpha $$ α are completely consistent with the exact solution of the FLRW and re-scaled Hubble parameter $$H_{0}$$ H 0 lies within the observed limits given by Planck, CMB and SNIa data (or other combinations), which lead to consistent cosmological quantities such as the dimensionless Hubble parameter h, deceleration parameter q, jerk parameter j and EoS parameter w. We also discuss time dependent behavior of the dark energy and dark matter to show their roles on the time evolution of the universe. Additionally, we observe that all main results completely depend on the structure of the interaction potential when the parameter values are tuned to satisfy the zero energy condition. Finally, we conclude that interactions in the dark sector may play an important role on the time evolution and provides a mechanism to explain the late time transition of the Universe.

Interacting modified Chaplygin gas in f(T) gravity framework and analysis of its stability against gravitational perturbation

2017 ◽  
Vol 14 (03) ◽  
pp. 1750035 ◽  
Author(s):  
Surajit Chattopadhyay
Keyword(s):  
Modified Gravity ◽  
Cosmic Time ◽  
Chaplygin Gas ◽  
Gravitational Perturbation ◽  
Modified Chaplygin Gas ◽  
Coupling Constant ◽  
Eos Parameter ◽  
Cosmological Application ◽  
Text Model ◽  
Interaction Term

In this work, we investigate the cosmological application of modified Chaplygin gas (MCG) interacting with pressureless dark matter (DM) in the [Formula: see text] modified gravity framework, where [Formula: see text] is the torsion scalar in teleparallelism. The interaction term has been chosen proportional to the MCG density with positive coupling constant. In the Einstein general relativity (GR) framework, the interacting MCG has been found to have equation of state (EoS) parameter behaving like quintessence. However, the [Formula: see text] gravity reconstructed via the interacting MCG has been found to have EoS crossing the phantom boundary of [Formula: see text]. Thus, one can generate a quintom-like EoS from an interacting MCG model in flat universe in the modified gravity cosmology framework. The reconstructed [Formula: see text] model has been found to interpolate between dust and [Formula: see text]CDM. Stability of the reconstructed [Formula: see text] has been investigated and it has been observed that the model is stable against gravitational perturbation. Cosmological evolution of primordial perturbations has also been investigated and the self-interacting potential has been found to increase with cosmic time and the squared speed of sound has been found to be non-negative.

Dark matter (energy) may be indistinguishable from modified gravity (MOND)

2017 ◽  
Vol 26 (12) ◽  
pp. 1743010 ◽  
Author(s):  
C. Sivaram
Keyword(s):  
General Relativity ◽  
Dark Matter ◽  
Dark Energy ◽  
Modified Gravity ◽  
Observational Evidence ◽  
Negative Results ◽  
Newtonian Dynamics ◽  
Special Cases ◽  
The Universe ◽  
Matter Energy

For Newtonian dynamics to hold over galactic scales, large amounts of dark matter (DM) are required which would dominate cosmic structures. Accounting for the strong observational evidence that the universe is accelerating requires the presence of an unknown dark energy (DE) component constituting about 70% of the matter. Several ingenious ongoing experiments to detect the DM particles have so far led to negative results. Moreover, the comparable proportions of the DM and DE at the present epoch appear unnatural and not predicted by any theory. For these reasons, alternative ideas like MOND and modification of gravity or general relativity over cosmic scales have been proposed. It is shown in this paper that these alternate ideas may not be easily distinguishable from the usual DM or DE hypotheses. Specific examples are given to illustrate this point that the modified theories are special cases of a generalized DM paradigm.

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