Compact charged stars

Siffert, B. B.; Neto, J. R. T. de Mello; Calvão, Maurício O.

doi:10.1590/s0103-97332007000400023

Cited by 23 publications

(28 citation statements)

References 5 publications

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“…The studies developed in [7,8] form part of a quantity of works where the influence of the electric charge on the structure of spherically symmetric static objects is analyzed. Within this bulk of works, we found studies developed considering polytropic stars with a charge density proportional to the energy density [9][10][11] and with a charge density proportional to the rest mass density [12]. We also found models where incompressible stars (stars with a constant energy density) are considered with an electric charge distribution q(r) following a power-law of the form q(r) = Q(r/R) n .…”

Section: Hydrostatic Equilibrium Of Charged Strange Starsmentioning

confidence: 99%

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Equilibrium and stability of charged strange quark stars

Arbañil

Malheiro

2015

Phys. Rev. D

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The hydrostatic equilibrium and the stability against radial perturbation of charged strange quark stars composed of a charged perfect fluid are studied. For this purpose, it is considered that the perfect fluid follows the MIT bag model equation of state and the radial charge distribution follows a power-law. The hydrostatic equilibrium and the stability of charged strange stars are investigated through the numerical solutions of the Tolman-Oppenheimer-Volkoff equation and the Chandrasekhar's pulsation equation, being these equations modified from their original form to include the electrical charge. In order to appreciably affect the stellar structure, it is found that the total charge should be of order 10 20 [C], implying an electric field of around 10 22 [V/m]. We found the electric charge that produces considerable effect on the structure and stability of the object is close to the star's surface. We obtain that for a range of central energy density the stability of the star decreases with the increment of the total charge and for a range of total mass the electric charge helps to grow the stability of the stars under study. We show that the central energy density used to reach the maximum mass value is the same used to determine the zero eigenfrequency of the fundamental mode when the total charge is fixed, thus indicating that the maximum mass point marks the onset of instability. In other words, when fixing the total charge, the conditions dM dρc > 0 and dM dρc < 0 are necessary and sufficient to determine the stable and unstable equilibrium configurations regions against radial oscillations. We also consider another charge distribution, charge density proportional to the energy density, and show that our results do not depend on this choice and the conditions used to determine regions made of the stable and unstable charged equilibrium configurations are maintained.

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Section: Hydrostatic Equilibrium Of Charged Strange Starsmentioning

confidence: 99%

“…Eq. (6) is the Tolman-Oppenheimer-Volkoff equation [22,23], also known as the hydrostatic equilibrium equation, with the inclusion of the electric charge (see, e.g., [6][7][8][9][10][11]16]). The stellar structure equations, Eqs.…”

Section: Stellar Structure Equationsmentioning

confidence: 99%

Equilibrium and stability of charged strange quark stars

Arbañil

Malheiro

2015

Phys. Rev. D

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“…The integration starts at the center of the star with a prescribed central pressure and ends where the pressure decreases to zero, indicates the surface of the star. Some recent studies include [41][42][43][44]. Such input equations of state do not normally allow for closed-form solutions.…”

Section: Introductionmentioning

confidence: 99%

Some new Wyman–Leibovitz–Adler type static relativistic charged anisotropic fluid spheres compatible to self-bound stellar modeling

Murad

Fatema

2015

Eur. Phys. J. C

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In this work some families of relativistic anisotropic charged fluid spheres have been obtained by solving the Einstein-Maxwell field equations with a preferred form of one of the metric potentials, and suitable forms of electric charge distribution and pressure anisotropy functions. The resulting equation of state (EOS) of the matter distribution has been obtained. Physical analysis shows that the relativistic stellar structure for the matter distribution considered in this work may reasonably model an electrically charged compact star whose energy density associated with the electric fields is on the same order of magnitude as the energy density of fluid matter itself (e.g., electrically charged bare strange stars). Furthermore these models permit a simple method of systematically fixing bounds on the maximum possible mass of cold compact electrically charged self-bound stars. It has been demonstrated, numerically, that the maximum compactness and mass increase in the presence of an electric field and anisotropic pressures. Based on the analytic models developed in this present work, the values of some relevant physical quantities have been calculated by assuming the estimated masses and radii of some well-known potential strange star candidates like PSR J1614-2230, PSR J1903+327, Vela X-1, and 4U 1820-30.

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“…For instance, Cooperstock and de la Cruz [15] and Florides [16] used an equation of the form ρ(r) + q 2 (r)/8π r 4 = constant and studied some prop-erties of the solutions (see also [17]). Polytropic equations were used in [18][19][20][21], where star configurations and their structure were studied, and the Schwarzschild electric limit for the given equation of state and for a given charge was considered. There are also works that treat a quark deconfining phase in compact neutron stars [22], where an unbalance of electric or color charge might appear.…”

Section: Introductionmentioning

confidence: 99%

Incompressible relativistic spheres: Electrically charged stars, compactness bounds, and quasiblack hole configurations

2014

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We investigate the properties of relativistic star spheres made of an electrically charged incompressible fluid, generalizing, thus, the Schwarzschild interior solution. The investigation is carried by integrating numerically the hydrostatic equilibrium equation, i.e., the Tolman-Oppenheimer-Volkoff (TOV) equation, with the hypothesis that the charge distribution is proportional to the energy density. We match the interior to a Reissner-Nordström exterior, and study some features of these star spheres such as the total mass M , the radius R, and the total charge Q. We also display the pressure profile. For star spheres made of a perfect fluid there is the Buchdahl bound, R/M ≥ 9/4, a compactness bound found from generic principles. For the Schwarzschild interior solution there is also the known compactness limit, the interior Schwarzschild limit where the configurations attain infinite central pressure, given by R/M = 9/4, yielding an instance where the Buchdahl bound is saturated. We study this limit of infinite central pressure for the electrically charged stars and compare it with the Buchdahl-Andréasson bound, a limit that, like the Buchdahl bound for the uncharged case, is obtained by imposing some generic physical conditions on charged configurations. We show that the electrical interior Schwarzschild limit of all but two configurations is always below the Buchdahl-Andréasson limit, i.e., we find that the electrical interior Schwarzschild limit does not generically saturate the Buchdahl-Andréasson bound. We also find that the quasiblack hole limit, i.e., the extremal most compact limit for charged incompressible stars, is reached when the matter is highly charged and the star's central pressure tends to infinity. This is one of the two instances where the Buchdahl-Andréasson bound is saturated, the other being the uncharged, interior Schwarzschild solution.

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Compact charged stars

Cited by 23 publications

References 5 publications

Equilibrium and stability of charged strange quark stars

Equilibrium and stability of charged strange quark stars

Some new Wyman–Leibovitz–Adler type static relativistic charged anisotropic fluid spheres compatible to self-bound stellar modeling

Incompressible relativistic spheres: Electrically charged stars, compactness bounds, and quasiblack hole configurations

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