scholarly journals Anisotropic Quintessence Strange Stars in f(T) Gravity with Modified Chaplygin Gas

2018 ◽  
Vol 2018 ◽  
pp. 1-13 ◽  
Author(s):  
Pameli Saha ◽  
Ujjal Debnath
Keyword(s):  
Equations Of Motion ◽  
Matching Condition ◽  
Chaplygin Gas ◽  
Strange Star ◽  
Energy Conditions ◽  
Modified Chaplygin Gas ◽  
Physical Status ◽  
Unknown Parameters ◽  
Physical Quantities ◽  
Surface Redshift

In this paper, we study the existence of strange star in the background of f(T) modified gravity where T is a scalar torsion. In KB metric space, we derive the equations of motion using anisotropic property within the spherically strange star with modified Chaplygin gas in the framework of modified f(T) gravity. Then we obtain many physical quantities to describe the physical status such as anisotropic behavior, energy conditions, and stability. By the matching condition, we calculate the unknown parameters to evaluate the numerical values of mass, surface redshift, etc., from our model to make comparison with the observational data.

scholarly journals Study of anisotropic compact stars with quintessence field and modified chaplygin gas in f(T) gravity

2019 ◽  
Vol 79 (11) ◽  
Author(s):  
Pameli Saha ◽  
Ujjal Debnath
Keyword(s):  
Compact Star ◽  
Equations Of Motion ◽  
Matching Condition ◽  
Chaplygin Gas ◽  
Compact Stars ◽  
Energy Conditions ◽  
Modified Chaplygin Gas ◽  
Quintessence Field ◽  
Physical Quantities ◽  
Surface Redshift

Abstract In this work, we get an idea of the existence of compact stars in the background of f(T) modified gravity where T is a scalar torsion. We acquire the equations of motion using anisotropic property within the spherically compact star with electromagnetic field, quintessence field and modified Chaplygin gas in the framework of modified f(T) gravity. Then by matching condition, we derive the unknown constants of our model to obtain many physical quantities to give a sketch of its nature and also study anisotropic behavior, energy conditions and stability. Finally, we estimate the numerical values of mass, surface redshift etc from our model to compare with the observational data for different types of compact stars.

scholarly journals Study on Anisotropic Strange Stars in f(T,T) Gravity

2020 ◽  
Author(s):  
Ines G. Salako ◽  
M. Khlopov ◽  
Saibal Ray ◽  
M.Z. Arouko ◽  
Pameli Saha ◽  
...  
Keyword(s):  
Energy Momentum Tensor ◽  
Torsion Tensor ◽  
Equations Of Motion ◽  
Momentum Tensor ◽  
Compact Objects ◽  
Strange Star ◽  
Energy Conditions ◽  
Anisotropic Pressure ◽  
Spacetime Geometry ◽  
Physical Features

In this work, we study the existence of strange star in the background of f(T,T) gravity in the Einstein spacetime geometry, where T is the torsion tensor and T is the trace of the energy-momentum tensor. The equations of motion are derived for anisotropic pressure within the spherically symmetric strange star. We explore the physical features like energy conditions, mass-radius relations, modified TOV equations, principal of causality, adiabatic index, redshift and stability analysis of our model. These features are realistic and appealing to further investigation of properties of compact objects in f(T,T) gravity as well as their observational signatures.

scholarly journals Constraining the Parameters of Modified Chaplygin Gas in Einstein-Aether Gravity

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Ujjal Debnath
Keyword(s):  
Chaplygin Gas ◽  
Joint Analysis ◽  
Distance Modulus ◽  
Modified Chaplygin Gas ◽  
Unknown Parameters ◽  
Data Set ◽  
Type Ia ◽  
Data Points ◽  
Ia Supernovae ◽  
Best Fit

We have assumed FRW model of the universe in Einstein-Aether gravity filled with dark matter and modified Chaplygin gas (MCG) type dark energy. We present the Hubble parameter in terms of some unknown parameters and observational parameters with the redshiftz. From observed Hubble data (OHD) set (12 points), we have obtained the bounds of the arbitrary parameters(A,B)of MCG by minimizing theχ2test. Next due to joint analysis of BAO and CMB observations, we have also obtained the best fit values and the bounds of the parameters(A,B)by fixing some other parameters. We have also taken type Ia supernovae data set (union 2 data set with 557 data points). Next due to joint analysis with SNe, we have obtained the best fit values of parameters. The best fit values and bounds of the parameters are obtained by 66%, 90%, and 99% confidence levels for OHD, OHD + BAO, OHD + BAO + CMB, and OHD + BAO + CMB + SNe joint analysis. The distance modulusμzagainst redshiftzfor our theoretical MCG model in Einstein-Aether gravity has been tested for the best fit values of the parameters and the observed SNe Ia union2 data sample.

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.

scholarly journals Effect of Thrust on the Structural Vibrations of a Nonuniform Slender Rocket

2020 ◽  
Vol 25 (2) ◽  
pp. 29
Author(s):  
Desmond Adair ◽  
Aigul Nagimova ◽  
Martin Jaeger
Keyword(s):  
Natural Frequencies ◽  
Equations Of Motion ◽  
Approximate Solutions ◽  
Mode Shapes ◽  
Algebraic Equations ◽  
Structural Vibrations ◽  
Unknown Parameters ◽  
One Dimensional ◽  
Vibration Problems ◽  
Nonuniform Beam

The vibration characteristics of a nonuniform, flexible and free-flying slender rocket experiencing constant thrust is investigated. The rocket is idealized as a classic nonuniform beam with a constant one-dimensional follower force and with free-free boundary conditions. The equations of motion are derived by applying the extended Hamilton’s principle for non-conservative systems. Natural frequencies and associated mode shapes of the rocket are determined using the relatively efficient and accurate Adomian modified decomposition method (AMDM) with the solutions obtained by solving a set of algebraic equations with only three unknown parameters. The method can easily be extended to obtain approximate solutions to vibration problems for any type of nonuniform beam.

scholarly journals Reduced modified Chaplygin gas cosmology

2015 ◽  
Vol 2015 (2) ◽  
Author(s):  
Jianbo Lu ◽  
Danhua Geng ◽  
Lixin Xu ◽  
Yabo Wu ◽  
Molin Liu
Keyword(s):  
Chaplygin Gas ◽  
Modified Chaplygin Gas

Hertz Contact Force Model With Permanent Indentation in Impact Analysis of Solids

1992 ◽  
Author(s):  
Hamid M. Lankarani ◽  
Parviz E. Nikravesh
Keyword(s):  
Contact Force ◽  
Impact Analysis ◽  
Equations Of Motion ◽  
Solid Particles ◽  
Hertzian Contact ◽  
Contact Period ◽  
Force Model ◽  
Unknown Parameters ◽  
Contact Force Model ◽  
Energy And Momentum

Abstract A continuous analysis method for the direct-central impact of two solid particles is presented. Based on the assumption that local plasticity effects are the sole factor accounting for the dissipation of energy in impact, a Hertzian contact force model with permanent indentation is constructed. Utilizing energy and momentum considerations, the unknown parameters in the model are analytically evaluated in terms of a given coefficient of restitution and velocities before impact. The equations of motion of the two solids may then be integrated forward in time knowing the variation of the contact force during the contact period. For Illustration, an impact of two soft metallic particles is studied.

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