Anisotropic neutron stars in 
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msup><mml:mi>R</mml:mi><mml:mn>2</mml:mn></mml:msup></mml:math>
 gravity

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.

show abstract

“…(25) have been also considered. If one parameterizes the anisotropy by σ ≡ P ⊥ − P r , Folomeev [227]…”

Section: F (R) Gravitymentioning

confidence: 99%

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

2020

View full text Add to dashboard Cite

show abstract

“…(please see Refs. [1][2][3][4][5][6][7][8][9] and the references therein for reviews). The discussions of the relation of the instability of anisotropic stars with perfect fluid energy condition have been reported in Refs.…”

Section: Introductionmentioning

confidence: 99%

Anisotropic neutron stars and perfect fluid’s energy conditions

Setiawan

Sulaksono

2019

Eur. Phys. J. C

View full text Add to dashboard Cite

It is reported (Estevez-Delgado and Estevez-Delgado in Eur Phys J C 78:673, 2018) recently, that the absence of anisotropic in compact object pressure leads to a solution which is not physically acceptable due to the energy density and speed of sound can not be positive at the origin at the same time. Here, we calculate the pressure and energy density of NSs using realistic EOS predicted by a relativistic mean-field model including hyperons for isotropic and three different anisotropic pressure models such as the one of Doneva and Yazadjiev (

show abstract

“…Then the system of Eqs. (10)-(15) has the following solutions for the metric functions (17), (18) and the anisotropic pressure…”

Section: Static Spherically Symmetric Anisotropic Solutionsmentioning

confidence: 99%

“…Recently it was shown that the "scalarization" can not arise without anisotropy and the anisotropy range can be determined by observations on binary pulsar in the Scalara e-mail: osert@pau.edu.tr b e-mail: f.celiktas@hotmail.com c e-mail: madak@pau.edu.tr Tensor Gravity and General Relativity [10]. The anisotropic star solutions in R 2 gravity can shift the mass-radius curves to the region given by observations [18]. It is interesting to note that anisotropic compact stars were investigated in Rastall theory and found exact solutions which permit the formation of super-massive star [19].…”

Section: Introductionmentioning

confidence: 99%

Anisotropic stars in the non-minimal $$Y(R)F^2$$ Y ( R ) F 2 gravity

2018

View full text Add to dashboard Cite

We investigate anisotropic compact stars in the non-minimal Y (R)F 2 model of gravity which couples an arbitrary function of curvature scalar Y (R) to the electromagnetic field invariant F 2. After we obtain exact anisotropic solutions to the field equations of the model, we apply the continuity conditions to the solutions at the boundary of the star. Then we find the mass, electric charge, and surface gravitational redshift by the parameters of the model and radius of the star. ported via the project number 2018FEBE001 and M.A. via the project number 2018HZDP036 by the

show abstract

Anisotropic neutron stars in R2 gravity

Cited by 36 publications

References 58 publications

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

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

Anisotropic neutron stars and perfect fluid’s energy conditions

Anisotropic stars in the non-minimal $$Y(R)F^2$$ Y ( R ) F 2 gravity

Contact Info

Product

Resources

About