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Related papers: Slowly-Rotating Neutron Stars in Massive Bigravity

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In the present paper we investigate self-consistently slowly rotating neutron and strange stars in R-squared gravity. For this purpose we first derive the equations describing the structure of the slowly rotating compact stars in…

General Relativity and Quantum Cosmology · Physics 2015-06-22 Kalin V. Staykov , Daniela D. Doneva , Stoytcho S. Yazadjiev , Kostas D. Kokkotas

In this work, we study the impact of anisotropy on slowly rotating neutron stars by extending the Hartle-Thorne formalism in general relativity to include anisotropy in pressure up to second order in the angular velocity. We assess the…

General Relativity and Quantum Cosmology · Physics 2024-10-10 L. M. Becerra , E. A. Becerra-Vergara , F. D. Lora-Clavijo

$f(R)$ theories of gravity are one of the most popular alternative explanations for dark energy and therefore studying the possible astrophysical implications of these theories is an important task. In the present paper we make a…

General Relativity and Quantum Cosmology · Physics 2015-06-23 Stoytcho S. Yazadjiev , Daniela D. Doneva , Kostas D. Kokkotas

We study neutron star configurations in a simple shift-symmetric subfamily of degenerate higher-order scalar-tensor (DHOST) theories, whose deviations from General Relativity (GR) are characterized by a single parameter. We compute the…

General Relativity and Quantum Cosmology · Physics 2022-11-09 Hamza Boumaza , David Langlois

In this paper, we study the slowly rotating neutron stars in $f(R, T)$ gravity based on Hartle-Thorne formalism. We first consider the simplest matter-geometry coupled modified gravity, namely $f(R, T)=R+2\chi T$. We compute the mass,…

General Relativity and Quantum Cosmology · Physics 2024-09-16 Masum Murshid , Mehedi Kalam

In this work, we study the influence of $f(R,T)$ gravity on rapidly rotating neutron stars. First we discuss the main aspects of this modified theory of gravity where the gravitational Lagrangian is an arbitrary function of the Ricci scalar…

General Relativity and Quantum Cosmology · Physics 2023-05-03 F. M. da Silva , L. C. N. Santos , C. E. Mota , T. O. F. da Costa , J. C. Fabris

Chern-Simons (CS) modified gravity is an extension to general relativity (GR) in which the metric is coupled to a scalar field, resulting in modified Einstein field equations. In the dynamical theory, the scalar field is itself sourced by…

High Energy Astrophysical Phenomena · Physics 2011-12-16 Yacine Ali-Haïmoud , Yanbei Chen

We present a brief review of general results about non-rotating neutron stars in simple R-square gravity and its extension with a scalar axion field. Modified Einstein equations are presented for metrics in isotropical coordinates. The…

General Relativity and Quantum Cosmology · Physics 2020-07-08 Artyom V. Astashenok , Sergei D. Odintsov

Some models (such as the Skyrme model, a low-energy effective field theory for QCD) suggest that the high-density matter prevailing in neutron star interiors may be significantly anisotropic. Anisotropy is known to affect the bulk…

General Relativity and Quantum Cosmology · Physics 2015-06-05 Hector O. Silva , Caio F. B. Macedo , Emanuele Berti , Luís C. B. Crispino

The masses and radii of neutron stars are discussed in general relativity and scalar-tensor theory of gravity and the differences are compared with the current uncertainties stemming from the nuclear equation of state in the relativistic…

General Relativity and Quantum Cosmology · Physics 2019-07-16 F. J. Fattoyev

We study oscillations and instabilities of relativistic stars using perturbation theory in general relativity and take into account the contribution of a dynamic spacetime. We present the oscillation spectrum as well as the critical values…

General Relativity and Quantum Cosmology · Physics 2020-09-16 C. J. Krüger , K. D. Kokkotas

In the scalar-tensor theories with a massive scalar field the coupling constants, and the coupling functions in general, which are observationally allowed, can differ significantly from those in the massless case. This fact naturally…

General Relativity and Quantum Cosmology · Physics 2016-04-27 Stoytcho S. Yazadjiev , Daniela D. Doneva , Dimitar Popchev

We perform fully relativistic calculations of binary neutron stars in corotating, circular orbit. While Newtonian gravity allows for a strict equilibrium, a relativistic binary system emits gravitational radiation, causing the system to…

General Relativity and Quantum Cosmology · Physics 2016-08-25 T. W. Baumgarte , G. B. Cook , M. A. Scheel , S. L. Shapiro , S. A. Teukolsky

We consider the slowly rotating relativistic stars with a uniform angular velocity in the scalar-tensor gravity, and examine the rotational effect around such compact objects. For this purpose, we derive a 2nd order differential equation…

High Energy Astrophysical Phenomena · Physics 2015-06-12 Hajime Sotani

In the present paper we examine gravitational wave asteroseismology relations for f-modes of rapidly rotating neutron stars. An approach different to the previous studies is employed - first, the moment of inertia is used instead of the…

Solar and Stellar Astrophysics · Physics 2015-12-09 Daniela D. Doneva , Kostas D. Kokkotas

In this review article, we present the main results from our most recent research concerning the oscillations of fast rotating neutron stars. We derive a set of time evolution equations for the investigation of non-axisymmetric oscillations…

General Relativity and Quantum Cosmology · Physics 2021-10-04 Christian J. Krüger , Kostas D. Kokkotas , Praveen Manoharan , Sebastian H. Völkel

Neutron stars are highly compact astrophysical objects and therefore of utmost relevance to learn about theories of gravity. Whereas the proper equation of state of the nuclear matter inside neutron stars is not yet known, and a wide range…

General Relativity and Quantum Cosmology · Physics 2022-04-28 Jutta Kunz

Neutron stars are known to host extremely powerful magnetic fields. Among other effects, one of the consequences of harbouring such fields is the deformation of the neutron star structure, leading, together with rotation, to the emission of…

High Energy Astrophysical Phenomena · Physics 2021-10-27 J. Soldateschi , N. Bucciantini , L. Del Zanna

We construct sequences of rapidly rotating neutron stars in dilatonic Einstein-Gauss-Bonnet theory, employing two equations of state for the nuclear matter. We analyze the dependence of the physical properties of these neutron stars on the…

General Relativity and Quantum Cosmology · Physics 2016-06-22 Burkhard Kleihaus , Jutta Kunz , Sindy Mojica , Marco Zagermann

The discovery of a 2 Msun neutron star provided a robust constraint for the theory of exotic dense matter, bringing into question the existence of strange baryons in the interiors of neutron stars. Although many theories fail to reproduce…

Solar and Stellar Astrophysics · Physics 2013-03-26 M. Bejger
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