Relativistic stars in Starobinsky gravity with the matched asymptotic expansions method

Arapoğlu, A. Savaş; Çıkıntoğlu, Sercan; Ekşi, K. Yavuz

doi:10.1103/physrevd.96.084040

Cited by 12 publications

(10 citation statements)

References 47 publications

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“…Indeed, the compactness and curvature of a typical NS of mass M = 1.4 M and radius R = 10 km, respectively, are 10 5 and 10 14 times larger than the values probed in solar system tests [33] but they still are in an unexplored regime in the bulk of the NS [27]. There is considerable effort [22,26,[34][35][36][37][38][39][40][41][42][43][44][45][46] to study the mass-radius relation of NSs in modified theories of gravity. In this paper we seek to determine the form of the mass-radius relations for NSs in the EMSG theories in order to determine whether this theory can survive confrontation with observations of NS environments for a selection of four realistic equations of state.…”

Section: Introductionmentioning

confidence: 99%

Constraint on energy-momentum squared gravity from neutron stars and its cosmological implications

et al. 2018

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Deviations from the predictions of general relativity due to energy-momentum squared gravity (EMSG) are expected to become pronounced in the high density cores of neutron stars. We derive the hydrostatic equilibrium equations in EMSG and solve them numerically to obtain the neutron star mass-radius relations for four different realistic equations of state. We use the existing observational measurements of the masses and radii of neutron stars to constrain the free parameter, α, that characterizes the coupling between matter and spacetime in EMSG. We show that −10 −38 cm 3 /erg < α < +10 −37 cm 3 /erg. Under this constraint, we discuss what contributions EMSG can provide to the physics of neutron stars, in particular, their relevance to the so called hyperon puzzle in neutron stars. We also discuss how EMSG alters the dynamics of the early universe from the predictions of the standard cosmological model. We show that EMSG leaves the standard cosmology safely unaltered back to t ∼ 10 −4 seconds at which the energy density of the universe is ∼ 10 34 erg cm −3 .

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Section: Introductionmentioning

confidence: 99%

Constraint on energy-momentum squared gravity from neutron stars and its cosmological implications

et al. 2018

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“…The authors showed that it is possible discriminate modified theories of gravity from General Relativity due to the gravitational redshift of the termal spectrum emerging from the surface of the star. In [23], a stellar structure model in f (R) = R + αR 2 theory was considered, using the method of matched asymptotic expansion to handle the higher order derivatives in field equations. Solutions were found for uniform density stars matching to the Schwarzschild solution outside the star.…”

Section: Introductionmentioning

confidence: 99%

Stellar structure model in hydrostatic equilibrium in the context of $f({\mathscr{R}})$-gravity

André

Kremer

2017

Res. Astron. Astrophys.

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In this work we present a stellar structure model from f (R)-gravity point of view capable to describe some classes of stars (White Dwarfs, Brown Dwarfs, Neutron stars, Red Giants and the Sun). This model was based on f (R)-gravity field equations for f (R) = R + f2R 2 , hydrostatic equilibrium equation and a polytropic equation of state. We compared the results obtained with those found by the Newtonian theory. It has been observed that in these systems, where high curvature regimes emerge, stellar structure equations undergo modifications. Despite the simplicity of this model, the results were satisfactory. The estimated values of pressure, density and temperature of the stars are within those determined by observations. This f (R)-gravity model has been proved to be necessary to describe stars with strong fields such as White Dwarfs, Neutron stars and Brown Dwarfs, while stars with weaker fields, such as Red Giants and the Sun, were best described by the Newtonian

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“…In the Starobinsky model, the interior solutions of relativistic stars also depend on the value of the Ricci scalar [13] as well as the vacuum solutions. The problem being non-well posed prevents finding unique solutions.…”

Section: Discussionmentioning

confidence: 99%

Vacuum solutions around spherically symmetric and static objects in the Starobinsky model

Çıkıntoğlu

2018

Phys. Rev. D

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The vacuum solutions around a spherically symmetric and static object in the Starobinsky model are studied with a perturbative approach. The differential equations for the components of the metric and the Ricci scalar are obtained and solved by using the method of matched asymptotic expansions. The presence of higher order terms in this gravity model leads to the formation of a boundary layer near the surface of the star allowing the accommodation of the extra boundary conditions on the Ricci scalar. Accordingly, the metric can be different from the Schwarzschild solution near the star depending on the value of the Ricci scalar at the surface of the star while matching the Schwarzschild metric far from the star.

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Relativistic stars in Starobinsky gravity with the matched asymptotic expansions method

Cited by 12 publications

References 47 publications

Constraint on energy-momentum squared gravity from neutron stars and its cosmological implications

Constraint on energy-momentum squared gravity from neutron stars and its cosmological implications

Stellar structure model in hydrostatic equilibrium in the context of $f({\mathscr{R}})$-gravity

Vacuum solutions around spherically symmetric and static objects in the Starobinsky model

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