共查询到20条相似文献，搜索用时 38 毫秒
1.
In this paper, we have considered a model of our universe containing five components as its constituents. Then, we have done
here the statefinder diagnostics for this model. This model can successfully explain the accelerated expansion of the universe
given that it satisfies a certain condition. Here we have considered the modified Chaplygin gas as the dynamically changing
part of the dark energy component of our universe. Chaplygin gas provides early deceleration and late time acceleration of
the universe. The graphical representation of statefinder parameters shows that the total evolution of the universe starts
from radiation era to phantom model. 相似文献
2.
Motivated by some previous works of Rudra et al. we set to explore the background dynamics when dark energy in the form of New Variable Modified Chaplygin gas is coupled to dark matter with a suitable interaction in the universe described by brane cosmology. The main idea is to find out the efficiency of New variable modified Chaplygin gas to play the role of DE. As a result we resort to the technique of comparison with standard dark energy models. Here the RSII brane model have been considered as the gravity theory. An interacting model is considered in order to search for a possible solution of the cosmic coincidence problem. A dynamical system analysis is performed because of the high complexity of the system. The statefinder parameters are also calculated to classify the dark energy model. Graphs and phase diagrams are drawn to study the variations of these parameters and get an insight into the effectiveness of the dark energy model. It is also seen that the background dynamics of New Variable Modified Chaplygin gas is consistent with the late cosmic acceleration. After performing an extensive mathematical analysis, we are able to constrain the parameters of new variable modified Chaplygin gas as m<n to produce the best possible results. Future singularities are studied and it is found that the model has a tendency to result in such singularities unlike the case of generalized cosmic Chaplygin gas. Our investigation leads us to the fact that New Variable Modified Chaplygin gas is not as effective as other Chaplygin gas models to play the role of dark energy. 相似文献
3.
In this work we investigate the background dynamics when dark energy is coupled to dark matter with a suitable interaction
in the universe described by brane cosmology. Here DGP and the RSII brane models have been considered separately. Dark energy
in the form of modified Chaplygin gas is considered. A suitable interaction between dark energy and dark matter is considered
in order to at least alleviate (if not solve) the cosmic coincidence problem. The dynamical system of equations is solved
numerically and a stable scaling solution is obtained. A significant attempt towards the solution of the cosmic coincidence
problem is taken. The statefinder parameters are also calculated to classify the dark energy models. Graphs and phase diagrams
are drawn to study the variations of these parameters. It is also seen that the background dynamics of modified Chaplygin
gas is completely consistent with the notion of an accelerated expansion in the late universe. Finally, it has been shown
that the universe in both the models follows the power law form of expansion around the critical point, which is consistent
with the known results. 相似文献
4.
Atreyee Biswas 《Astrophysics and Space Science》2018,363(10):203
The present work deals with irreversible thermodynamics of universe containing interacting dark fluids. Recent observational evidences reveal that the universe is dominated by two dark components-dark matter and dark energy. The interaction between them leads to spontaneous heat flow between the horizon and the fluid system and as a result the system will no longer be in thermal equilibrium. In this paper dark matter is chosen as pressureless dust while modified Chaplygin gas has been considered as dark energy. In two separate cases we have considered the universe to be bounded by apparent horizon and event horizon and the validity of generalized second law of thermodynamics in the context of irreversible thermodynamics has been studied for both the cases. 相似文献
5.
Jalil Naji 《Astrophysics and Space Science》2014,350(1):385-392
In this paper we consider a correspondence between the holographic dark energy density and interacting generalized cosmic Chaplygin gas energy density in flat FRW universe. Then, we reconstruct the potential of the scalar field which describe the generalized cosmic Chaplygin cosmology. In the special case we obtain time-dependent energy density and study cosmological parameters. We find stability condition of this model which is depend on cosmic parameter. 相似文献
6.
In the present work we assume that the universe is dominated with a two component mixture which do not evolve separately but interact non-gravitationally with one another. we consider the issue of the tachyon as a source of the dark energy and modified Chaplygin gas as background fluid. So we study the interacting between tachyon field and modified Chaplygin gas in different forms of interactions term Q in both flat and non-flat FRW universe. Then we reconstruct the potential and the dynamics of the tachyon field which describe tachyon cosmology. Also we find a equivalence potential for MCG in this model. Next we study two dark components respect to redshift and we find the conditions that are required for the stability of this model. 相似文献
7.
Prabir Rudra 《Astrophysics and Space Science》2012,342(2):579-599
In this work we explore the background dynamics when dark energy is coupled to dark matter with a suitable interaction in the universe described by brane cosmology. Here DGP and the RSII brane models have been considered separately. Dark energy in the form of Generalized Cosmic Chaplygin gas is considered. A suitable interaction between dark energy and dark matter is considered in order to at least alleviate (if not solve) the cosmic coincidence problem. The dynamical system of equations is solved numerically and a stable scaling solution is obtained. A significant attempt towards the solution of the cosmic coincidence problem is taken. The statefinder parameters are also calculated to classify the dark energy models. Graphs and phase diagrams are drawn to study the variations of these parameters. It is also seen that the background dynamics of Generalized Cosmic Chaplygin gas is consistent with the late cosmic acceleration, but not without satisfying certain conditions. It has been shown that the universe in both the models follows the power law form of expansion around the critical point, which is consistent with the known results. Future singularities were studied and our models were declared totally free from any types of such singularities. Finally, some cosmographic parameters were also briefly studied. Our investigation led to the fact that although Generalized cosmic Chaplygin gas with a far lesser negative pressure compared to other dark energy models, can overcome the relatively weaker gravity of RS II brane, with the help of the negative brane tension, yet for the DGP brane model with much higher gravitation, the incompetency of Generalized cosmic Chaplygin gas is exposed, and it cannot produce the accelerating scenario until it reaches the phantom era. 相似文献
8.
In this letter, we have considered a flat FRW universe. Instead of considering only one candidate for the dark energy, we
have considered the interaction between phantom field and modified Chaplygin gas. It has been shown that the potential of
the phantom field increases from a lower value with evolution of the universe. It has been observed that the field has an
increasing tendency and the potential has also an increasing tendency with passage of cosmic time. In the evolution of the
universe the crossing of w=−1 has been realized by this interacting model. 相似文献
9.
In this paper we study FRW bulk viscous cosmology in presence of modified cosmic Chaplygin gas. We obtain generalized Friedmann equations due to bulk viscosity and modified cosmic Chaplygin gas. Then, we calculate time-dependent energy density and discuss Hubble expansion parameter. 相似文献
10.
In this work, we have studied the model of modified Chaplygin gas and its role in accelerating phase of the universe for anisotropic
model. We have assumed that the equation of state of this modified model is valid from the radiation era to ΛCDM model. We
have obtained the possible relation between the hessence and the modified Chaplygin gas. We have also use the statefinder
parameters for characterize different phase of the universe diagrammatically. 相似文献
11.
We investigate the validity of the generalized second law of gravitational thermodynamics in a non-flat FRW universe containing
the interacting generalized Chaplygin gas with the baryonic matter. The boundary of the universe is assumed to be enclosed
by the dynamical apparent horizon. We show that for the interacting generalized Chaplygin gas as a unified candidate for dark
matter and dark energy, the equation of state parameter can cross the phantom divide. We also present that for the selected
model under thermal equilibrium with the Hawking radiation, the generalized second law is always satisfied throughout the
history of the universe for any spatial curvature, independently of the equation of state of the interacting generalized Chaplygin
gas model. 相似文献
12.
《New Astronomy》2020
A flat FLRW (Friedmann–Lemaitre–Robertson–Walker) cosmological model with perfect fluid comprising of variable Chaplygin gas (VCG) has been studied in the context of f(R, T) gravity with particle creation. The solutions of the modified field equations are obtained through three different considered form of scale factors. The effective pressure is negative throughout the evolution of universe, which leads to accelerated expansion of the universe. In addition to that we have also discussed the importance of particle creation pressure on the cosmological parameters, energy conditions and state-finder diagnostic parameters. It is noticed that the time evolution of source function yields almost constant particle production at late times. 相似文献
13.
We investigate the background dynamics when dark energy is coupled to dark matter in the universe described by loop quantum
cosmology. We consider dark energy of the form modified Chaplygin gas. The dynamical system of equations is solved numerically
and a stable scaling solution is obtained. It henceforth resolves the famous cosmic coincidence problem in modern cosmology.
The statefinder parameters are also calculated to classify this dark energy model. 相似文献
14.
In this paper we study FRW bulk viscous cosmology in presence of modified Chaplygin gas. We write modified Friedmann equations due to bulk viscosity and Chaplygin gas and obtain time-dependent energy density for the special case of flat space. 相似文献
15.
Ujjal Debnath 《Astrophysics and Space Science》2007,312(3-4):295-299
In this letter, I have proposed a model of variable modified Chaplygin gas and shown its role in accelerating phase of the
universe. I have shown that the equation of state of this model is valid from the radiation era to quiessence model. The graphical
representations of statefinder parameters characterize different phase of evolution of the universe. All results presented
in the letter concerns the case k=0. 相似文献
16.
Jalil Naji 《Astrophysics and Space Science》2014,350(1):333-338
In this note extended Chaplygin gas equation of state includes bulk and shear viscosities suggested. Bulk viscosity assumed as power law form of density and shear viscosity considered as a constant. We study evolution of dark energy density numerically for several forms of scale factor, and analytically under some assumptions corresponding to early universe. We found our model is stable for infinitesimal viscous parameters. 相似文献
17.
In this work, we have discussed the Maxwell’s electrodynamics in non-linear forms in FRW universe. The energy density and pressure for non-linear electrodynamics have been written in the electro-magnetic universe. The Einstein’s field equations for flat FRW model in loop quantum cosmology have been considered if the universe is filled with the matter and electro-magnetic field. We separately assumed the magnetic universe and electric universe. The interaction between matter and magnetic field have been considered in one section and for some particular form of interaction term, we have found the solutions of magnetic field and the energy density of matter. We have also considered the interaction between the matter and electric field and another form of interaction term has been chosen to solve the field equations. The validity of generalized second law of thermodynamics has been investigated on apparent and event horizons using Gibb’s law and the first law of thermodynamics for magnetic and electric universe separately. 相似文献
18.
In this work, we have considered the DBI-essence dark energy model in FRW Universe. We have found the exact solutions of potential,
warped brane tension and DBI scalar field. We also calculate the statefinder parameters for our model that make it distinguishable
among numerous dark energy models. Moreover, we establish correspondence between DBI-essence and modified Chaplygin gas (MCG)
and hence reconstruct the potential and warped brane tension. By this reconstruction, we observe that DBI scalar field and
potential increase and warped brane tension decreases during evolution of the Universe. Finally, we investigate the validity
of the generalized second law (GSL) of thermodynamics in the presence of DBI-essence and modified Chaplygin gas. It is observed
that the GSL breaks down for DBI-essence model but GSL always satisfied for MCG model. 相似文献
19.
In this paper, we study a cosmological model with the sign-changeable interaction between variable generalized Chaplygin gas (VGCG) and dark matter. The dynamical analysis indicates that there exists a stable scaling attractor, which can help to alleviate the coincidence problem. Furthermore, when the parameters of the model take some fixed values, the attractor corresponds to the phase w=?0.939 and the equation of state of VGCG approaches it from either w>?1 or w<?1 depending on the choice of its initial cosmic density parameter and the ratio of pressure to critical energy density. So, the phantom divide can be crossed. We find the interaction term Q can change its sign from Q<0 to Q>0 as the universe expands, which is different from the usual interaction. Also, we place constraints on the parameters from the point of view of dynamics. 相似文献
20.
Sanjay Sarkar 《Astrophysics and Space Science》2014,349(2):985-993
The paper deals with a spatially homogeneous and anisotropic Bianchi type-I universe filled with two minimally interacting fluids; matter and holographic dark energy components. The nature of the holographic dark energy for Bianchi type-I space time is discussed. An exact solution to Einstein’s field equations in Bianchi type-I line element is obtained using the assumption of linearly varying deceleration parameter. Under the suitable condition, it is observed that the anisotropy parameter of the universe approaches to zero for large cosmic time and the coincidence parameter increases with increasing time. We established a correspondence between the holographic dark energy models with the generalised Chaplygin gas dark energy model. We also reconstructed the potential and dynamics of the scalar field which describes the Chaplygin cosmology. Solution of the field equations shows that a big rip type future singularity will occur for this model. It has been observed that the solutions are compatible with the results of recent observations. 相似文献