Quintom Matter Research Articles

Oscillating quintom scenario with time-dependent periodic deceleration parameter

In this paper, we introduced the deceleration parameter [Formula: see text] in a different manner by proposing a modern law. According to this law, we suggested a time-periodic [Formula: see text]. Furthermore, we used this law to develop a model in which the universe oscillates with quintom matter in a four-dimensional FLRW metric background. Using this model, we obtained the oscillating Hubble parameter [Formula: see text], which remains positive. Consequently, the universe undergoes decelerating expansion and accelerating expansion periodically, avoiding singularities.

Comprehensive analysis of a non-singular bounce in f(R,T) gravitation

The present paper is devoted to the study of bouncing cosmology in $f(R,T)$ modified gravity where we presume $f(R,T) = R + 2 \lambda T$, with $R$ the Ricci scalar, $T$ the trace of energy momentum tensor and $\lambda$ the model parameter. We present here a novel parametrization of Hubble parameter which is apt in representing a successful bouncing scenario undergoing no singularity. We proceed to present a complete analysis of the proposed bouncing model by studying the evolution of primordial curvature perturbations, energy conditions and stability against linear homogeneous perturbations in flat space-time. We also delineate bouncing cosmology for the proposed model by employing Quintom matter. The present article further communicate for the first time that violation of energy-momentum materialize for both the contracting and expanding universes except for the bouncing epoch with energy flow directed away and into the matter fields for the contracting and expanding universe respectively. We further present a thorough investigation about the feasibility of the proposed bouncing scenario against first and generalized second law of thermodynamics. We found that the proposed bouncing scenario obeys the laws of thermodynamics for the constrained parameter space of $\lambda$. The manuscript conclude after investigating the viability of the proposed bouncing model in non minimal $f(R,T)$ gravity where $f(R,T) = R + \chi R T$.

Bouncing Universe with Exotic Radiation

Scenario bouncing can give the cosmology singularity problem a possible way out. Finding a solution for the universe’s bouncing model requires proper estimation of the state equation. We present two such state equations that give us the solution for a bounce. One such case is the exotic radiation, where we assumed that exotic radiation dominated the universe during the bounce occurrence. We also considered another case where quintom matter scenario existed previously, and the newly proposed exotic radiation scenario coexisted. In these two cases, we have shown that all the necessary conditions for the bounce are fulfilled. Such new ways certainly increase support and flexibility for the bouncing universe model.

Oscillating Quintom Model with Time Periodic Varying Deceleration Parameter

We propose a new law for the deceleration parameter that varies periodically with time. According to the law, we give a model of the oscillating universe with quintom matter in the framework of a 4-dimensional Friedmann—Robertson—Walker background. We find that, in the model, the Hubble parameter oscillates and keeps positive. The universe undergoes decelerating expansion and accelerating expansion alternately without singularity

Emergent universe scenario via Quintom matter

The emergent universe scenario provides a possible alternative to bouncing cosmology to avoid the Big Bang singularity problem. In this Letter we study the realization of the emergent universe scenario by making use of Quintom matter with an equation of state across the cosmological constant boundary. We will show explicitly the analytic and numerical solutions of emergent universe in two Quintom models, which are a phenomenological fluid and a nonconventional spinor field, respectively.

Quintom Wormholes

The combination of quintessence and phantom energy in a joint model is referred to as quintom dark energy. This paper discusses traversable wormholes supported by such quintom matter. Two particular solutions are explored, a constant redshift function and a specific shape function. Both isotropic and anisotropic pressures are considered.

Thermodynamics of Spinor Quintom

We discuss the thermodynamic properties of dark energy (DE) with Quintom matter in spinor scenario. (1) Using the Cardy–Verlinde formula, we investigate the conditions of validity of the Generalized Second Law of thermodynamics (GSL) in the four evolutionary phases of Spinor Quintom-B model. We also clarify its relation with three cosmological entropy bounds. (2) We take thermodynamic stability of the combination between Spinor Quintom DE and the Generalized Chaplygin Gas (GCG) perfect fluid into account, and we find that in the case of β>0 and 0<T<T0, the system we consider is thermodynamically stable. (3) Making use of the Maxwell Relation and integrability condition, we derive all thermal quantities as functions of either entropy or volume, and present the relation with quantum perturbation stability.

CYCLIC UNIVERSE WITH QUINTOM MATTER IN LOOP QUANTUM COSMOLOGY

In this paper, we study the possibility of model building of cyclic universe with Quintom matter in the framework of Loop Quantum Cosmology. After a general demonstration, we provide two examples, one with double-fluid and another double-scalar field, to show how such a scenario is obtained. Analytical and numerical calculations are both presented in the paper.

Bouncing universe with non-minimally coupled quintom matter

In this Letter, we study the condition for a generalized DBI action providing a quintom scenario of dark energy. We consider a development of string-inspired quintom by introducing non-minimal coupling. Then we show that the bouncing solution can appear in the universe dominated by the non-minimally coupled quintom matter.

Oscillating universe with quintom matter

In this Letter, we study the possibility of building a model of the oscillating universe with quintom matter in the framework of 4-dimensional Friedmann–Robertson–Walker background. Taking the two-scalar-field quintom model as an example, we find in the model parameter space there are five different types of solutions which correspond to: (I) a cyclic universe with the minimal and maximal values of the scale factor remaining the same in every cycle, (II) an oscillating universe with its minimal and maximal values of the scale factor increasing cycle by cycle, (III) an oscillating universe with its scale factor always increasing, (IV) an oscillating universe with its minimal and maximal values of the scale factor decreasing cycle by cycle, and (V) an oscillating universe with its scale factor always decreasing.

Bouncing universe with Quintom matter

The bouncing universe provides a possible solution to the Big Bang singularity problem. In this paper we study the bouncing solution in the universe dominated by the Quintom matter with an equation of state (EoS) crossing the cosmological constant boundary. We will show explicitly the analytical and numerical bouncing solutions in three types of models for the Quintom matter with an phenomenological EoS, the two scalar fields and a scalar field with a modified Born-Infeld action.