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Compact stars consisting of fermions with arbitrary masses and interaction strengths are studied by solving the structure equation of general relativity, the Tolman-Oppenheimer-Volkoff equations. Scaling solutions are derived for a free and…

Astrophysics · Physics 2008-11-26 Gaurav Narain , Jurgen Schaffner-Bielich , Igor N. Mishustin

We study condensation of scalar fields around compact reflecting stars in a box. We propose no light scalar hair behaviors that the neutral compact star cannot support the existence of small single positive mass scalar field in it's…

General Relativity and Quantum Cosmology · Physics 2017-11-21 Yan Peng

Realistic models of neutron and quark stars in the framework of mimetic gravity with Lagrange multiplier constraint are presented. We discuss the effect of mimetic scalar aiming to describe dark matter on mass-radius relation and the moment…

General Relativity and Quantum Cosmology · Physics 2016-09-28 A. V. Astashenok , S. D. Odintsov

We compute families of spherically symmetric neutron-star models in two-derivative scalar-tensor theories of gravity with a massive scalar field. The numerical approach we present allows us to compute the resulting spacetimes out to…

General Relativity and Quantum Cosmology · Physics 2021-05-21 Roxana Rosca-Mead , Christopher J. Moore , Ulrich Sperhake , Michalis Agathos , Davide Gerosa

Mass-varying massive gravity allows the graviton mass to vary according to different environments. We investigate neutron star and white dwarf solutions in this theory and find that the graviton mass can become very large near the compact…

General Relativity and Quantum Cosmology · Physics 2020-03-31 Xue Sun , Shuang-Yong Zhou

In this work, we study the gravitational back-reaction (i.e., the "self-force") of a point mass moving around a non-rotating, compact star on a circular orbit. We find that the additional self-force, comparing with the case with a point…

General Relativity and Quantum Cosmology · Physics 2024-06-05 Xuefeng Feng , Huan Yang

In this study, we present a generalized spherically symmetric, anisotropic and static compact stellar model in $f(T)$ gravity, where $T$ represents the torsion scalar. By employing the Karmarkar condition we have obtained embedding class 1…

General Relativity and Quantum Cosmology · Physics 2018-11-30 Debabrata Deb , Shounak Ghosh , S. K. Maurya , Maxim Khlopov , Saibal Ray

We study the structure of neutron stars in scalar-tensor theories for the nonminimal coupling of the form $(1+\kappa \xi \phi^{2})\cal R$. We solve the hydrostatic equilibrium equations for two different types of scalar field potentials and…

General Relativity and Quantum Cosmology · Physics 2019-04-02 A. Savaş Arapoğlu , K. Yavuz Ekşi , A. Emrah Yükselci

Using a novel and self-consistent approach that avoids the scalar-tensor identification in the Einstein frame, we reanalyze the viability of f(R) gravity within the context of solar-system tests. In order to do so, we depart from a simple…

General Relativity and Quantum Cosmology · Physics 2020-03-06 Carolina Negrelli , Lucila Kraiselburd , Susana J. Landau , Marcelo Salgado

The possible emergence of compact stars has been investigated in the recently introduced modified Gauss-Bonnet $f(\mathcal{G},T)$ gravity, where $\mathcal{G}$ is the Gauss-Bonnet term and ${T}$ is the trace of the energy-momentum tensor.…

General Relativity and Quantum Cosmology · Physics 2017-10-18 M. Farasat Shamir , Mushtaq Ahmad

The LIGO and Virgo Collaborations currently conduct searches for gravitational waves from compact binary coalescences in real-time. For promising candidate events, a sky map and distance estimation are released in low-latency, to facilitate…

High Energy Astrophysical Phenomena · Physics 2019-10-17 Sylvia Biscoveanu , Salvatore Vitale , Carl-Johan Haster

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

This manuscript examines the compact stars in gravity $f (Q)$, where non-metricity $Q$ drives gravitational interactions. To achieve this goal, we consider a spherically symmetric spacetime with the anisotropic fluid distribution. In…

General Physics · Physics 2021-12-22 Sanjay Mandal , G. Mustafa , Zinnat Hassan , P. K. Sahoo

This paper investigates the viability and stability of anisotropic compact stars in the framework of $f(\mathcal{R},\mathrm{T}^{2})$ theory ($\mathcal{R}$ is the Ricci scalar and…

General Relativity and Quantum Cosmology · Physics 2023-05-31 M. Sharif , Sana Manzoor

We investigate the impact of $f(R,L_m,T)$ gravity on the internal structure of compact stars, expecting this theory to manifest prominently in the high-density cores of such stars. In this study, we begin by considering the algebraic…

General Relativity and Quantum Cosmology · Physics 2024-12-05 Takol Tangphati , Izzet Sakalli , Ayan Banerjee , Anirudh Pradhan

In this paper, we consider the mimetic gravitational theory to derive a novel category of anisotropic star models. To end and to put the resulting differential equations into a closed system, the form of the metric potential $g_{rr}$ as…

General Relativity and Quantum Cosmology · Physics 2021-10-11 G. G. L. Nashed

We systematically examine the compactness of neutron stars as Tolman VII solutions in scalar-tensor theory of gravity. As a result, when the coupling constant is confined to values provided by astronomical observations we show that the…

General Relativity and Quantum Cosmology · Physics 2018-06-20 Hajime Sotani , Kostas D. Kokkotas

This work aims to investigate the behaviour of compact stars in the background of $f(R, T)$ theory of gravity. For current work, we consider the Krori-Barua metric potential i.e., $\nu(r)= Br^2+C$ and $\lambda(r)= Ar^2,$ where, $A, B$ and…

General Relativity and Quantum Cosmology · Physics 2023-04-13 M. Farasat Shamir , Zoya Asghar , Adnan Malik

Neutron stars with strong magnetic fields are considered in the framework of f(R) gravity. In order to describe dense matter in magnetic field, the model with baryon octet interacting through $\sigma$$\rho$$\omega$-fields is used. The…

General Relativity and Quantum Cosmology · Physics 2015-06-19 Artyom V. Astashenok , Salvatore Capozziello , Sergei D. Odintsov

We study the interaction of massless scalar fields with self-gravitating neutron stars by means of fully dynamic numerical simulations of the Einstein-Klein-Gordon perfect fluid system. Our investigation is restricted to spherical symmetry…

General Relativity and Quantum Cosmology · Physics 2009-11-07 Florian Siebel , Jose A. Font , Philippos Papadopoulos