Qualitative stability analysis of cosmological models in $$f(T,\phi )$$ gravity

Samaddar, Amit; Singh, S. Surendra

doi:10.1007/s10714-023-03163-y

Cited by 4 publications

(1 citation statement)

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“…The mathematical form of dynamical system analysis is  y=f(y), where the function f: Y → Y and the over dot represents the derivative with respect to the time Î  t and y = (y 1 , y 2 , y 3 , K.,y n ) ä Y to be an element of the phase space Í  Y n and the function f is a vector field of  n such that f(y) = (f 1 (y), f 2 (y), K.,f n (y)). The differential equation  y=f(y) is called an autonomous differential equation if it doesn't depend on time t, it depends on the current value of y [59]. To discuss the stability analysis, we need to find the critical points of the autonomous differential equation.…”

Section: Observational Fit Of the Model Parameters By Using Hubble Da...mentioning

confidence: 99%

Dynamical system method of viscous fluid in f(T) gravity theory

Samaddar,

Sanasam

2024

Phys. Scr.

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In this paper, using the recently introduced f(T) gravity framework, we have analyzed the viscous fluid cosmological model in the FLRW cosmological model by assuming a specific form of the bulk viscosity coefficient as follows: ς=ς0+ς1H+ς2(\dot H/H) and a non-linear f(T) model, particularly f(T) = T − α√−T, where α is the model parameter. The bulk viscosity coefficients are estimated by using the Hubble 31 data set. Using the phase space technique, we examine the asymptotic behavior of our cosmological bulk viscous model.We found one stable critical point. Phase space analysis and geometrical interpretations are given. We discover that according to our model, the Universe evolved from a matter-dominated decelerated phase (a past attractor) to a stable de-Sitter accelerated epoch (afuture attractor). The evolution of the EoS parameter shows the acceleration phase of the cosmic expansion, whereas the negative behavior of viscosity-induced pressure indicates the accelerated expansion of the universe. Additionally, the cosmic matter-energy density exhibits positive behavior. We look into how statefinder parameters behave for our model. We discover that the trajectory of our model starts at the essence and ends at the CDM region. We use the Om diagnostic test, which reveals that our modeldisplays quintessence behavior. The energy condition criteria are analyzed, and we discover that SEC has been violated, whereas WEC, NEC, and DEC satisfy the positivity criteria. Our f(T) cosmological model, with the influence of bulk viscosity, successfully describes the expansion history of the universe and provides a good fit to recent observational data.

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Section: Observational Fit Of the Model Parameters By Using Hubble Da...mentioning

confidence: 99%

Dynamical system method of viscous fluid in f(T) gravity theory

Samaddar,

Sanasam

2024

Phys. Scr.

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Dynamical System Approach and Thermodynamical Perspective of Hořava‐Lifshitz Gravity

Samaddar,

Singh

2024

Fortschritte der Physik

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The authors have examined a Friedmann Robertson Walker cosmological model in Hořava‐Lifshitz gravity by using a dynamical system approach. A set of autonomous equations is derived and their solutions are calculated. The critical points from these equations and find the characteristics values with the analysis of the physical interpretation of the phase space for this system are assessed. Three stable critical points are found and the values of the physical parameters and the scale factor's expressions at each critical points are displayed in Tables 1, 2, and 3. A hybrid scale factor to develop the model, which results in a phase transition from deceleration to acceleration is used. The suitable values of the parameters are governed by applying the Monte Chain Monte Carlo method technique to the Hubble 46 and joint Hubble 46 and Baryon Acoustic Oscillations 15 datasets. In contrast to the negative behavior of pressure, the positive behavior of energy density and illustrate the Universe's acceleration epoch and the model is represented by the EoS parameter . The authors investigated that the energy conditions and their model violates the strong energy condition. Utilizing diagnostic test, it is found that the model represents phantom behavior. The thermodynamical perspective for the model is also examined. The model accurately explained the Universe's propagation history and fits well with contemporary cosmic data.

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