Dynamical instability for non-adiabatic spherical collapse

Herrera, L.; Denmat, G. Le; Santos, N. O.

doi:10.1093/mnras/237.1.257

Cited by 147 publications

(118 citation statements)

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“…A pioneer work in this direction was done by Chandrasekhar (Chandrasekhar 1964). Afterwards, this issue has been investigated by many authors for adiabatic, non-adiabatic, anisotropic and shearing viscous fluids (Herrera et al 1989;Chan et al 1989;Chan et al 1994;Chan et al 1993;Herrera et al, arXiv/1010.1518. The dynamical instability of collapsing fluids can be well discussed in term of adiabatic index Γ.…”

Section: Introductionmentioning

confidence: 99%

Newtonian and post Newtonian expansionfree fluid evolution in f(R) gravity

Sharif¹,

Kausar²

2011

Astrophys Space Sci

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We consider a collapsing sphere and discuss its evolution under the vanishing expansion scalar in the framework of f (R) gravity. The fluid is assumed to be locally anisotropic which evolves adiabatically. To study the dynamics of the collapsing fluid, Newtonian and post Newtonian regimes are taken into account. The field equations are investigated for a well-known f (R) model of the form R + δR 2 admitting Schwarzschild solution. The perturbation scheme is used on the dynamical equations to explore the instability conditions of expansionfree fluid evolution. We conclude that instability conditions depend upon pressure anisotropy, energy density and some constraints arising from this theory.

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Section: Introductionmentioning

confidence: 99%

Newtonian and post Newtonian expansionfree fluid evolution in f(R) gravity

Sharif¹,

Kausar²

2011

Astrophys Space Sci

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“…Therefore, the heat flux q(t, r) must be present in the interior of a collapsing star. The energy-momentum tensor representing dissipative isotropic fluid can be written as (Herrera, Santos & Le Denmat 1989)…”

Section: G E N E R a L F O R M U L At I O N O F C O L L A P S I N G Ementioning

confidence: 99%

“…Here, is known as the adiabatic index or ratio of the heat capacity at constant pressure to the heat capacity at constant volume (Herrera et al 1989). …”

Section: R N G R Av I T Y a N D P E Rt U R Bat I O N S C H E M Ementioning

confidence: 99%

Dynamical instability of collapsing stars in the framework of Rn gravity

Kausar

2014

Monthly Notices of the Royal Astronomical Society

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To see the evolution of the physical variables at the surface of a star and to establish the range for an unstable system, we investigate the dynamical instability of a spherically symmetric collapsing star in the framework of R n gravity. For this purpose, we have reformulated the dynamical equations in f(R) theory and perturb them in a specific manner. Under this perturbation scheme, quantities like energy density, pressure and heat flux are obtained and then used in the collapse equation which yield instability range for the ratio of specific heats . Shear-free condition is applied and results are reduced to R 2 , 1 R and R gravity by choosing particular values of n in the f(R) model R n .

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“…As gravitational collapse is a highly dissipative process, we assume that fluid filling the collapsing cylinder is dissipating energy in the form of heat flux q and can be represented by the following energy-momentum tensor [28,33] …”

Section: Dynamical Equationsmentioning

confidence: 99%

Effects of CDTT model on the dynamical instability of cylindrically symmetric collapsing stars

Kausar

2013

J. Cosmol. Astropart. Phys.

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We assume cylindrically symmetric stars which begin collapsing by dissipating energy in the form of heat flux. We wish to study the effects of Carroll-Duvvuri-Trodden-Turner (CDTT) model, f (R) = R + σ µ 4 R , on the range of dynamical instability. For this purpose, perturbation scheme is applied to all the metric functions, material functions and f (R) model to obtain the full set of dynamical equation which control the evolution of the physical variables at the surface of a star. It is found that instability limit involves adiabatic index Γ which depends on the density profile and immense terms of perturbed CDTT model. In addition, model is constrained by some requirement, e.g. positivity of physical quantities. We also reduce our results asymptotically as µ → 0, being the GR results in both the Newtonian and post Newtonian regimes.

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Dynamical instability for non-adiabatic spherical collapse

Cited by 147 publications

References 0 publications

Newtonian and post Newtonian expansionfree fluid evolution in f(R) gravity

Newtonian and post Newtonian expansionfree fluid evolution in f(R) gravity

Dynamical instability of collapsing stars in the framework of Rn gravity

Effects of CDTT model on the dynamical instability of cylindrically symmetric collapsing stars

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