Accelerating imperfect fluid

This paper is keen to study the generalized DBI-inspired non-minimal kinetic coupling inflationary model with non-interacting imperfect fluid in the framework of FRW universe. This is a newly proposed model with an interesting feature of having a correction term [Formula: see text] in the perturbed equation of motion due to the nonlinearity of the kinetic term. The power spectrum remains scale invariant both in large-[Formula: see text] and small-[Formula: see text] limits. In order to discuss the inflationary dynamics, the non-interacting inflaton and imperfect fluid including bulk viscosity are considered to be the cosmic matter contents. We consider large field potential and derive the exact solution of inflaton and perturbed parameters. Further, we investigate the nature of the perturbed parameters in detail, specifically on the potential-driven case, and compare the consequences to the current PLANCK/BICEP observational data. We also analyze the corresponding tensor spectrum, which will be tested by the future observations on primordial gravitational waves.

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Imperfect fluid interacting with the gravitational field in Robertson-Walker universe

Astrophysics and Space Science ◽

10.1007/bf00650086 ◽

1989 ◽

Vol 159 (2) ◽

pp. 271-278 ◽

Cited By ~ 2

Author(s):

R. K. Tarachand Singh ◽

N. Ibotombi Singh

Keyword(s):

Gravitational Field ◽

Imperfect Fluid

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DOES PRESSURE ACCENTUATE GENERAL RELATIVISTIC GRAVITATIONAL COLLAPSE AND FORMATION OF TRAPPED SURFACES?

International Journal of Modern Physics D ◽

10.1142/s0218271813500211 ◽

2013 ◽

Vol 22 (05) ◽

pp. 1350021 ◽

Cited By ~ 1

Author(s):

ABHAS MITRA

Keyword(s):

General Relativity ◽

Gravitational Collapse ◽

Fluid Pressure ◽

Free Fall ◽

Newtonian Gravity ◽

Tangential Pressure ◽

Trapped Surfaces ◽

Imperfect Fluid ◽

Newtonian Case ◽

General Relativistic

It is widely believed that though pressure resists gravitational collapse in Newtonian gravity, it aids the same in general relativity (GR) so that GR collapse should eventually be similar to the monotonous free fall case. But we show that, even in the context of radiationless adiabatic collapse of a perfect fluid, pressure tends to resist GR collapse in a manner which is more pronounced than the corresponding Newtonian case and formation of trapped surfaces is inhibited. In fact there are many works which show such collapse to rebound or become oscillatory implying a tug of war between attractive gravity and repulsive pressure gradient. Furthermore, for an imperfect fluid, the resistive effect of pressure could be significant due to likely dramatic increase of tangential pressure beyond the "photon sphere." Indeed, with inclusion of tangential pressure, in principle, there can be static objects with surface gravitational redshift z → ∞. Therefore, pressure can certainly oppose gravitational contraction in GR in a significant manner in contradiction to the idea of Roger Penrose that GR continued collapse must be unstoppable.

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Inhomogeneous imperfect fluid inflation

Astrophysics and Space Science ◽

10.1007/s10509-016-2988-5 ◽

2016 ◽

Vol 362 (1) ◽

Cited By ~ 4

Author(s):

E. Elizalde ◽

Luis G. T. Silva

Keyword(s):

Imperfect Fluid

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Energy conditions for an imperfect fluid

Classical and Quantum Gravity ◽

10.1088/0264-9381/5/10/011 ◽

1988 ◽

Vol 5 (10) ◽

pp. 1329-1338 ◽

Cited By ~ 79

Author(s):

C A Kolassis ◽

N O Santos ◽

D Tsoubelis

Keyword(s):

Energy Conditions ◽

Imperfect Fluid

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LTB geometry with tilted and nontilted congruences in f(R,T) gravity

International Journal of Modern Physics D ◽

10.1142/s0218271817500997 ◽

2017 ◽

Vol 26 (09) ◽

pp. 1750099 ◽

Cited By ~ 14

Author(s):

Z. Yousaf ◽

M. Zaeem-ul-Haq Bhatti ◽

Aamna Rafaqat

Keyword(s):

Transport Equation ◽

Energy Momentum Tensor ◽

Momentum Tensor ◽

Imperfect Fluid ◽

Dynamical Features ◽

Dust Fluid

We investigate the role of tilted and nontilted congruence in the dynamics of dissipative Lemaître–Tolman–Bondi spacetime in [Formula: see text] gravity. We consider imperfect fluid with its congruences observed by tilted observer and dust fluid filled with LTB geometry observed by the nontilted observer. In order to elaborate the dynamical features of two congruences, we consider well-known [Formula: see text] models and develop relationships between tilted and nontilted dynamical variables. We evaluate the nonzero divergence of energy–momentum tensor for tilted congruence and transport equation for the system in [Formula: see text] gravity. We have also checked the instability regimes for nontilted congruence.

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A New Class of Almost Ricci Solitons and Their Physical Interpretation

International Scholarly Research Notices ◽

10.1155/2016/4903520 ◽

2016 ◽

Vol 2016 ◽

pp. 1-6

Author(s):

K. L. Duggal

Keyword(s):

Physical Model ◽

Dynamic Properties ◽

Fluid Velocity ◽

General Relation ◽

Ricci Soliton ◽

Field Equations ◽

Open Problems ◽

Matter Tensor ◽

Imperfect Fluid ◽

Almost Ricci Soliton

We establish a link between a connection symmetry, called conformal collineation, and almost Ricci soliton (in particular Ricci soliton) in reducible Ricci symmetric semi-Riemannian manifolds. As a physical application, by investigating the kinematic and dynamic properties of almost Ricci soliton manifolds, we present a physical model of imperfect fluid spacetimes. This model gives a general relation between the physical quantities (u,μ,p,α,η,σij) of the matter tensor of the field equations and does not provide any exact solution. Therefore, we propose further study on finding exact solutions of our viscous fluid physical model for which it is required that the fluid velocity vector u be tilted. We also suggest two open problems.

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