Physical attributes of anisotropic compact stars in f(R, G) gravity

Shamir, M. Farasat; Zia, Saeeda

doi:10.1140/epjc/s10052-017-5010-7

Cited by 66 publications

(20 citation statements)

References 61 publications

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“…Other models considered in the literature are: f (R, R 2 GB ) gravity, which has been studied with anisotropic fluids but isotropic EOS [341,342,343], (anisotropic) stars in non-minimal gravity-electromagnetic coupling models of type f (R)F µν F µν [344] and even with more involved couplings [345], other models with non-minimally coupled scalar fields with several realistic EOS [348], corrections in the Lagrangian density in scalars of the energy-momentum tensor such as T µν T µν [349] with polytropic and strange quark matter (all these yielding slight to moderate increases on the maximum allowed mass depending on the EOS chosen); and scalar-tensor-vector theories [350], where FPS, SLy and BSK21 EOS yield small to moderate increases of M ⋆ for astrophysically viable model parameters.…”

Section: Further Considerationsmentioning

confidence: 99%

Stellar structure models in modified theories of gravity: Lessons and challenges

2020

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The understanding of stellar structure represents the crossroads of our theories of the nuclear force and the gravitational interaction under the most extreme conditions observably accessible. It provides a powerful probe of General Relativity on its strong field regime, and opens fruitful avenues for the exploration of new gravitational physics. The latter can be captured via the so-called modified theories of gravity, which modify the Einstein-Hilbert action of General Relativity and/or some of its building blocks/principles. These theories typically change the Tolman-Oppenheimer-Volkoff equations of stellar's hydrostatic equilibrium, having a large impact on the astrophysical properties of the corresponding stars, and thus opening a new window to constrain these theories with present and future observations of different types of stars. For relativistic stars, such as neutron stars, the uncertainty on the equation of state of matter at supranuclear densities intertwines with the new parameters coming from the modified gravity side, providing a whole new phenomenology for the typical predictions of stellar structure models, such as mass-radius relations, maximum masses, or moment of inertia. For non-relativistic stars, such as white, brown and red dwarfs, the weakening/strengthening of the gravitational force inside astrophysical bodies via the modified Newtonian (Poisson) equation may induce changes on the star's mass, radius, central density or luminosity, having an impact, for instance, in the Chandrasekhar's limit for white dwarfs, or in the minimum mass for stable hydrogen burning for high-mass brown dwarfs. This work aims to provide a broad overview of the main such results achieved in the recent literature for many such modified theories of gravity, by combining the results and constraints obtained from the analysis of relativistic and non-relativistic stars in different scenarios. Moreover, we will build a bridge between the efforts of the community working on different theories, formulations, types of stars, theoretical modellings, and observational aspects, highlighting some of the most promising opportunities in the field.

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Section: Further Considerationsmentioning

confidence: 99%

Stellar structure models in modified theories of gravity: Lessons and challenges

2020

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“…Moreover, the existence of this symmetry leads to a specific form of the unknown functions that appear in the Lagrangian. The method is used to obtain cosmological models in several alternative theory of gravity, for example, scalar tensor theory [83][84][85][86][87][88][89][90][91][92][93][94], f (R) theory [25,26,[95][96][97][98][99][100][101][102], f (T ) theory [103][104][105][106][107][108][109][110], the theories of gravity with a fermionic field [13][14][15][16] and others [111][112][113][114][115][116][117][118][119]. With the help of Noether symmetry, some cosmological analytical solutions for the scalar tensor TG were obtained in Ref [65,120].…”

Section: Introductionmentioning

confidence: 99%

Scalar–tensor teleparallel gravity with boundary term by Noether symmetries

Geçim

Küçükakça

2018

Int. J. Geom. Methods Mod. Phys.

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In the framework of teleparallel gravity, the Friedman-Robertson-Walker cosmological model with scalar tensor theory where scalar field is non-minimally coupled to both the torsion scalar and boundary term is studied. Utilizing the Noether symmetry approach in such a theory, we obtain the explicit forms of the couplings and potential as a function the scalar field. We present some important cosmological solutions for the modified field equations using these functions getting via the Noether symmetry approach. Finally, the interesting cosmological properties of these solutions are discussed in detail, and it is shown that they can describe a universe lead to the late time accelerating expansion.

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“…Laurentis and Lopez-Revelles [34] discuss the detail investigation of the weak field limit of f (R, G) gravity taking into consideration an analytic functions of the Ricci scalar R and the Gauss-Bonnet invariant G, specifically by developing in metric formalism, the Newtonian, Post-Newtonian and Parametrized Post-Newtonian limits starting from general f (R, G) Lagrangian and observed the Newtonian limit of f (R, G) gravity. Shamir and Zia [35] highlighted the materialization of anisotropic compact stars namely Her X1, SAX J 1808-3658, and 4U 1820-30 in the context of f (R, G) theory of gravity and have shown that all three stars behave as usual as for positive values of the f (G) model parameter n. In this work, we obtain the solution of field equations and the behavior of the universe using some kinematical and physical quantities for the f (R, G) gravity model i.e.…”

Section: Ijgmmp-d-19-00459mentioning

confidence: 99%

Thermodynamical aspects of relativistic hydrodynamics in f(R,G) gravity

Shekh,

Arora,

Chirde

et al. 2019

Preprint

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Present investigation devoted to the dynamical study of Relativistic Hydrodynamics with some thermodynamical characteristics in f (R, G) gravity towards spatially homogeneous isotropic cosmological model filled with isotropic fluid. We govern the features of the derived cosmological model by considering the power-law inflation for the average scale factor. The temperature and entropy density of the proposed model are positive definite. We also discuss the energy conditions to our solutions. The strong energy condition violated, which indicates the accelerated expansion of the proposed model.

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Physical attributes of anisotropic compact stars in f(R, G) gravity

Cited by 66 publications

References 61 publications

Stellar structure models in modified theories of gravity: Lessons and challenges

Stellar structure models in modified theories of gravity: Lessons and challenges

Scalar–tensor teleparallel gravity with boundary term by Noether symmetries

Thermodynamical aspects of relativistic hydrodynamics in f(R,G) gravity

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