Effects of electromagnetic field on the dynamical instability of expansionfree gravitational collapse

Sharif, M.; Azam, M.

doi:10.1007/s10714-012-1333-8

Cited by 44 publications

(19 citation statements)

References 30 publications

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“…That is, metric and matter parts are at zeroth order perturbation only radially dependent, which also become time dependent for the first order perturbations. These perturbations are described as follows [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][30][31][32][33]:…”

Section: Linear Perturbation Strategy and Power-law F (T ) Modelmentioning

confidence: 99%

Dynamical instability of shear-free collapsing star in extended teleparallel gravity

Jawad

Rani

2015

Eur. Phys. J. C

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We study the spherically symmetric collapsing star in terms of dynamical instability. We take the framework of extended teleparallel gravity with a non-diagonal tetrad, a power-law form of the model presenting torsion and a matter distribution as a non-dissipative anisotropic fluid. The vanishing shear scalar condition is adopted to gain insight in a collapsing star. We apply a first order linear perturbation scheme to the metric, the matter, and f (T ) functions. The dynamical equations are formulated under this perturbation scheme to develop collapsing equation for finding dynamical instability limits in two regimes, such as the Newtonian and the post-Newtonian regime. We obtain a constraint-free solution of a perturbed time dependent part with the help of a vanishing shear scalar. The adiabatic index exhibits the instability ranges through the second dynamical equation which depend on physical quantities such as the density, the pressure components, the perturbed parts of the symmetry of the star, etc. We also develop some constraints on the positivity of these quantities and obtain instability ranges to satisfy the dynamical instability condition.

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Section: Linear Perturbation Strategy and Power-law F (T ) Modelmentioning

confidence: 99%

Dynamical instability of shear-free collapsing star in extended teleparallel gravity

Jawad

Rani

2015

Eur. Phys. J. C

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“…(26) becomesḂ which is linear in B. We are in a position to solve (29) to obtain the metric functions as follows:…”

Section: Eq (26) Becomes a Linear Equation Upon Rearrangement The mentioning

confidence: 99%

“…They showed that the electromagnetic field reduces the unstable region as the collapse proceeds. 29 This investigation is set out as follows: In Sec. 2, we present the general framework for a shearing, radiating sphere undergoing dissipative collapse in the presence of electric charge.…”

Section: Introductionmentioning

confidence: 99%

The Role of the Electromagnetic Field in Dissipative Collapse

Thirukkanesh¹,

Govender

2013

Int. J. Mod. Phys. D

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In this paper, we investigate the effect of charge on the collapse of a radiating, shearing sphere. The junction conditions required for the smooth matching of a general spherically symmetric spacetime (in the absence of rotation) to the exterior Vaidya-ReissnerNordström leads to a temporal evolution equation at the boundary of the collapsing star. We are in a position to integrate these equations in the presence of charge and shear. The solutions obtained here are new and generalize recent treatments of dissipative, shearing collapse to the charged case.

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“…However, the instability range of stars with zero expansion does not depend on the stiffness of the fluid, but rather on other physical parameters [12][13][14], such as the mass distribution, the energy density profile, and the radial and tangential pressure. The impact of the local anisotropy on the plane expansion-free gravitational collapse is studied in [15].…”

Section: Introductionmentioning

confidence: 99%

Dynamical instability and expansion-free condition in $$f(R, T)$$ f ( R , T ) gravity

2015

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A dynamical analysis of a spherically symmetric collapsing star surrounded by a locally anisotropic environment under an expansion-free condition is presented in f (R, T ) gravity, where R corresponds to the Ricci scalar and T stands for the trace of the energy momentum tensor. The modified field equations and evolution equations are reconstructed in the framework of f (R, T ) gravity. In order to acquire the collapse equation we implement the perturbation on all matter variables and dark source components comprising the viable f (R, T ) model. The instability range is described in the Newtonian and post-Newtonian approximation. It is observed that the unequal stresses and density profile define the instability range rather than the adiabatic index. However, the physical quantities are constrained to maintain positivity of the energy density and a stable stellar configuration. IntroductionThe astrophysics and astronomical theories are invigorated largely by the gravitational collapse and instability range explorations of self-gravitating objects. Celestial objects tend to collapse when they exhaust all their nuclear fuel, and gravity takes over as the inward governing force. The gravitating bodies undergoing collapse face contraction to a point, which results in high energy dissipation in the form of heat flux or radiation transport [1]. The end state of stellar collapse has been studied extensively, a continual evolution of a compact object might end up as a naked singularity or as a black hole depending upon the size of a collapsing star and also on the background that plays an important role in pressure-togravity imbalances [2][3][4]. a e-mail: ifra.noureen@gmail.com b e-mail: mzubairkk@gmail.com; drmzubair@ciitlahore.edu.pkThe gravitating objects are interesting only when they are stable against fluctuations; supermassive stars tend to be more unstable in comparison to the less massive stars [5]. The instability problem in a star's evolution is of fundamental importance; Chandrasekhar [6] presented the primary explorations on the dynamical instability of spherical stars. He identified the instability range of a star having mass M and radius r by a factor pertaining to the inequality ≥ 4 3 + n M r . The adiabatic index measures the compressibility of the fluid i.e., the variation of the pressure with a given change in the density. The analysis of expanding and collapsing regions in a gravitational collapse was presented by Sharif and Abbas [7].Herrera et al. [8][9][10][11] presented the dynamical analysis associated with isotropy, local anisotropy, shear, radiation, and dissipation with the help of ; it was established that minor alterations from an isotropic profile or a slight change in shearing effects bring about drastic changes in the range of instability. However, the instability range of stars with zero expansion does not depend on the stiffness of the fluid, but rather on other physical parameters [12][13][14], such as the mass distribution, the energy density profile, and the radial and tan...

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Effects of electromagnetic field on the dynamical instability of expansionfree gravitational collapse

Cited by 44 publications

References 30 publications

Dynamical instability of shear-free collapsing star in extended teleparallel gravity

Dynamical instability of shear-free collapsing star in extended teleparallel gravity

The Role of the Electromagnetic Field in Dissipative Collapse

Dynamical instability and expansion-free condition in $$f(R, T)$$ f ( R , T ) gravity

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