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Related papers: Slowly Rotating Relativistic Stars in Scalar-Tenso…

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Differential rotation is central to a great many mysteries in stars and planets. In Part I we predicted the order of magnitude and scaling of the differential rotation in both hydrodynamic and magnetohydrodynamic convection zones. Our…

Solar and Stellar Astrophysics · Physics 2020-09-02 Adam S. Jermyn , Shashikumar M. Chitre , Pierre Lesaffre , Christopher A. Tout

Stars are not perfectly spherically symmetric. They are deformed by rotation and magnetic fields. Until now, the study of stellar shapes has only been possible with optical interferometry for a few of the fastest-rotating nearby stars. We…

In the modern era of abundant X-ray detections and the increasing momentum of gravitational waves astronomy, tests of General Relativity in strong field regime become increasingly feasible and their importance for probing gravity cannot be…

General Relativity and Quantum Cosmology · Physics 2020-09-25 Victor I. Danchev , Daniela D. Doneva , Stoytcho S. Yazadjiev

We show that the spontaneous scalarization scenario in scalar-tensor theories is a specific case of a more general phenomenon. The key fact is that the instability causing the spontaneous growth in scalars is due to the nonminimal coupling…

General Relativity and Quantum Cosmology · Physics 2017-10-10 Fethi M. Ramazanoğlu

Scalar-tensor gravitational theories are important extensions of standard general relativity, which can explain both the initial inflationary evolution, as well as the late accelerating expansion of the Universe. In the present paper we…

General Relativity and Quantum Cosmology · Physics 2017-06-28 J. A. Belinchón , T. Harko , M. K. Mak

The present paper is devoted to a study of the equilibrium configurations of slowly rotating anisotropic stars in the framework of general relativity. For that purpose, we provide the equations of structure where the rotation is treated to…

General Relativity and Quantum Cosmology · Physics 2024-07-23 Philip Beltracchi , Camilo Posada

Neutron stars are the most compact horizonless objects in the Universe, exhibiting the strongest known magnetic fields. They are potential sources of coincident gravitational waves and electromagnetic radiation across the entire spectrum.…

High Energy Astrophysical Phenomena · Physics 2025-08-29 Fabrizio Venturi Piñas , Anson Ka Long Yip , Patrick Chi-Kit Cheong , Milton Ruiz

We present a general formulation to analyze the structure of slowly rotating relativistic stars in a broad class of scalar-tensor theories with disformal coupling to matter. Our approach includes theories with generalized kinetic terms,…

General Relativity and Quantum Cosmology · Physics 2016-06-22 Masato Minamitsuji , Hector O. Silva

A theoretical study of some electrodynamic features of a region close to a {\it slowly-rotating} magnetized relativistic star is performed. To be a little more specific, based on the solution-generating method given by Wald, the magnetic…

Astrophysics · Physics 2007-05-23 Hongsu Kim , Hyung Mok Lee , Chul H. Lee , Hyun Kyu Lee

In the scalar-tensor theory of gravitation it seems nontrivial to establish if solutions of the cosmological equations in the presence of a cosmological constant behave as attractors independently of the initial values. We develop a general…

High Energy Physics - Theory · Physics 2009-11-06 Kei-ichi Maeda , Yasunori Fujii

We study gravitational lensing by clusters of galaxies in the context of the generic class of unconventional gravity theories of the scalar--tensor type. For positive energy scalar fields with any dynamics, the bending of light by a weakly…

Astrophysics · Physics 2010-11-01 Jacob D. Bekenstein , Robert H. Sanders

We present an alternative way of tracing the existence of a scalar field based on the analysis of the gravitational wave spectrum of a vibrating neutron star. Scalar-tensor theories in strong-field gravity can potentially introduce much…

General Relativity and Quantum Cosmology · Physics 2009-11-10 Hajime Sotani , Kostas D. Kokkotas

Compact stars above a critical stellar mass develop large scalar fields in some scalar-tensor theories. This scenario, called spontaneous scalarization, has been an intense topic of study since it passes weak-field gravity tests naturally…

General Relativity and Quantum Cosmology · Physics 2025-08-07 Kıvanç İ. Ünlütürk , Semih Tuna , Oğuzhan K. Yamak , Fethi M. Ramazanoğlu

We investigate the cosmological dynamics in a spatially flat Friedmann--Lema\^{\i}tre--Robertson--Walker geometry in scalar-tensor and scalar-torsion theories where the nonminimally coupled scalar field is a complex field. We derive the…

General Relativity and Quantum Cosmology · Physics 2022-11-23 Andronikos Paliathanasis

We investigate neutron stars in scalar-tensor theories. We examine their secular stability against spherically symmetric perturbations by use of a turning point method. For some choices of the coupling function contained in the theories,…

General Relativity and Quantum Cosmology · Physics 2009-10-31 Tomohiro Harada

We examine the generation of a magnetic field in a solar-like star and its effects on the internal distribution of the angular velocity. We suggest that the evolution of a rotating star with magnetic fields leads to an equilibrium value of…

Astrophysics · Physics 2009-11-11 P. Eggenberger , A. Maeder , G. Meynet

We perform detailed investigation of cosmological perturbations in f(T) theory of gravity coupled with scalar field. Our work emphasizes on the way to gauge fix the theory and we examine all possible modes of perturbations up to second…

General Relativity and Quantum Cosmology · Physics 2013-06-24 Keisuke Izumi , Yen Chin Ong

Tensor-scalar theory of gravity allows the generation of gravitational waves from astrophysical sources, like Supernov\ae{}, even in the spherical case. That motivated us to study the collapse of a degenerate stellar core, within…

Astrophysics · Physics 2009-10-31 J. Novak , J. M. Ibanez

We investigate the effects of the purely toroidal magnetic field on the equilibrium structures of the relativistic stars. The master equations for obtaining equilibrium solutions of relativistic rotating stars containing purely toroidal…

Astrophysics · Physics 2008-11-26 Kenta Kiuchi , Shijun Yoshida

Among the possible extensions of General Relativity that have been put forward in order to address some long standing issues in our understanding of the Universe, Scalar-Tensor Theories have received a lot of attention for their simplicity.…

High Energy Astrophysical Phenomena · Physics 2020-08-12 J. Soldateschi , N. Bucciantini , L. Del Zanna
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