Static solutions of Einstein's field equations for compact stellar objects

Zubairi, Omair; Romero, A.; Weber, Fridolin

doi:10.1088/1742-6596/615/1/012003

Cited by 27 publications

(25 citation statements)

References 19 publications

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“…This result could be a consequence of the dependency of Q on gamma, which implies a direct dependency on the EoS and therefore, varies between the stars. This result is different from the one obtained in Zubairi et al (2015)), where structure equations derived from the γ metric were solved by taking γ as a free parameter set by hand. In that case, since the mass quadrupole is leaded by the mass, its highest values are reached for the more massive stars.…”

Section: Mass Quadrupole Momentcontrasting

confidence: 89%

Moment of inertia of magnetized strange stars

et al. 2021

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The macroscopic structure of magnetized Compact Objects is deformed due to the anisotropy of pressures as a consequence of the magnetic field. In this work, we study the impact of the magnetic deformation in the moment of inertia and mass quadrupole moment of strange stars. In order to do that, we first solve the structure equations using the gamma metric: an axially symmetric metric in spherical coordinates. We also discuss the implication of the magnetic deformation in gravitational wave emissions.

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Section: Mass Quadrupole Momentcontrasting

confidence: 89%

Moment of inertia of magnetized strange stars

et al. 2021

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“…The case α = 0 corresponding to 5D GR is also shown for comparison reasons. We see that we obtain the usual profiles familiar from the standard four-dimensional GR, although the 5D objects are larger and much heavier than their 4D counterparts [49,50]. First, the radius acquires a maximum value, R max , while the star mass still increases.…”

Section: Numerical Resultsmentioning

confidence: 53%

Relativistic strange quark stars in Lovelock gravity

Panotopoulos

Rincón

2019

Eur. Phys. J. Plus

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We study relativistic non-rotating stars in the framework of Lovelock gravity. In particular, we consider the Gauss-Bonnet term in a five-dimensional spacetime, and we investigate the impact of the Gauss-Bonnet parameter on properties of the stars, both isotropic and anisotropic. For matter inside the star, we assume a relativistic gas of de-confined massless quarks. We integrate the modified Tolman-Oppenheimer-Volkoff equations numerically, and we obtain the mass-to-radius profile, the compactness of the star as well as the gravitational red-shift for several values of the Gauss-Bonnet parameter. The maximum star mass and radius are also reported. PACS. XX.XX.XX No PACS code given 1 IntroductionAlthough our observable Universe is clearly four-dimensional, the question "How many dimensions are there?" is one of the fundamental questions High Energy Physics tries to answer. Kaluza-Klein theories [1,2], supergravity [3] and Superstring/M-Theory [4,5] have pushed forward the idea that extra spatial dimensions may exist. In more than four dimensions higher order curvature terms are natural in Lovelock theory [6], and also higher order curvature corrections appear in the low-energy effective equations of Superstring Theory [7].The amount of published works in the literature reveals that Lovelock gravity is an exciting and active field. Black hole physics [8][9][10][11][12][13][14], cosmological solutions [15][16][17][18] and holographic superconductors exploiting the gauge/gravity duality [19] are some of the areas that have been explored in the framework of Lovelock gravity. However, the astrophysical implications of Lovelock theory should also be investigated. Compact objects [20][21][22], such as white dwarfs and neutron stars, are the final fate of stars, and comprise excellent cosmic laboratories to study, test and constrain new physics and/or alternative theories of gravity under extreme conditions that cannot be reached in Earth-based experiments. It is well-known that the properties of compact objects, such as mass and radius, depend both on the equation-of-state (EoS) of ultra-dense matter and on the underlying theory of gravity.A couple of years after the discovery of the neutron by James Chadwick [23,24], neutron stars were predicted to exist by Baade and Zwicky [25]. Indeed, several decades after that, the discoveries of pulsars in the Crab and Vela supernova remnants [26] led to their identification as neutron stars just one year after the discovery of pulsars in 1967 [27]. On the other hand quark matter is by assumption absolutely stable, and as such it may be the true ground state of hadronic matter [28,29]. Therefore a new class of hypothetical compact objects has been postulated to exist. These compact objects could serve as an alternative to neutron stars, and they might offer us a plausible explanation of the puzzling observation of some super-luminous supernovae [30,31], which occur in about one out of every 1000 supernovae explosions, and which are more than 100 times more luminous than regular su...

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“…This can be easily seen using the equations presented before valid in the Einstein frame (without matter P = 0 = ǫ) as follows. If we assume solutions with a constant value for the scalar field, φ = const = φ 0 , that in addition corresponds to an extremum of the potential, V ,φ (φ 0 ) = 0, then the two last equations are automatically satisfied, while the first two are essentially the tt and rr equations of GR with a cosmological constant Λ = V (φ 0 )/2 [56]. For the Starobinsky's model φ 0 = 0 = V (φ 0 ), and we thus obtain the anticipated Schwarzschild black hole solution.…”

Section: Numerical Resultsmentioning

confidence: 99%

Dark stars in Starobinsky’s model

Panotopoulos

Lopes

2018

Phys. Rev. D

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In the present work we study non-rotating dark stars in f (R) modified theory of gravity. In particular, we have considered bosonic self-interacting dark matter modelled inside the star as a Bose-Einstein condensate, while as far as the modified theory of gravity is concerned we have assumed Starobinsky's model R + aR 2 . We solve the generalized structure equations numerically, and we obtain the mass-to-ratio relation for several different values of the parameter a, and for two different dark matter equation-of-states. Our results show that the dark matter stars become more compact in the R-squared gravity compared to General Relativity, while at the same time the highest star mass is slightly increased in the modified gravitational theory. The numerical value of the highest star mass for each case has been reported.

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Static solutions of Einstein's field equations for compact stellar objects

Cited by 27 publications

References 19 publications

Moment of inertia of magnetized strange stars

Moment of inertia of magnetized strange stars

Relativistic strange quark stars in Lovelock gravity

Dark stars in Starobinsky’s model

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