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Detection of the characteristic spectrum of pulsating neutron stars can be a powerful tool not only to probe the nuclear equation of state, but also to test modifications to general relativity. However, the shift in the oscillation spectrum…

General Relativity and Quantum Cosmology · Physics 2018-05-24 Raissa F. P. Mendes , Néstor Ortiz

We study relativistic stars in the simplest model of the de Rham-Gabadadze-Tolley massive gravity which describes the massive graviton without ghost propagating mode. We consider the hydrostatic equilibrium, and obtain the modified…

General Relativity and Quantum Cosmology · Physics 2016-06-15 Taishi Katsuragawa , Shin'ichi Nojiri , Sergei D. Odintsov , Masashi Yamazaki

We investigate theoretical and observational constraints on the mass-radius relations for neutron stars. For that purpose we consider the model of neutron stars taking into considerations strong, weak, electromagnetic and gravitational…

High Energy Astrophysical Phenomena · Physics 2016-06-28 Kuantay Boshkayev , Jorge A. Rueda , Marco Muccino

Axial oscillations relevant to the r-mode instability are studied with slow rotation formalism in general relativity. The approximate equation governing the oscillations is derived with second-order rotational corrections. The equation…

General Relativity and Quantum Cosmology · Physics 2009-10-31 Yasufumi Kojima , Masayasu Hosonuma

Using the nuclear equation of states for a large variety of relativistic and non-relativistic force parameters, we calculate the static and rotating masses and radii of neutron stars. From these equation of states, we also evaluate the…

Solar and Stellar Astrophysics · Physics 2013-12-23 Shailesh K. Singh , S. K. Biswal , M. Bhuyan , T. K. Jha , S. K. Patra

This article provides an overview of stellar instabilities as sources of gravitational waves. The aim is to put recent work on secular and dynamical instabilities in compact stars in context, and to summarize the current thinking about the…

Astrophysics · Physics 2017-08-23 N. Andersson

Nonradial oscillations of relativistic neutron stars with a solid crust are computed in the relativistic Cowling approximation, in which all metric perturbations are ignored. For the modal analysis, we employ three-component relativistic…

Astrophysics · Physics 2009-11-07 Shijun Yoshida , Umin Lee

Neutron stars are compact objects rotating at high speed, up to a substantial fraction of the speed of light (up to 20\% for millisecond pulsars) and possessing ultra-strong electromagnetic fields (close to and sometimes above the quantum…

High Energy Astrophysical Phenomena · Physics 2020-01-13 Jérôme Pétri

The spectrum of oscillating compact objects can be considerably altered in alternative theories of gravity. In particular, it may be enriched by modes with no counterpart in general relativity, tied to the dynamics of additional degrees of…

General Relativity and Quantum Cosmology · Physics 2022-01-21 Raissa F. P. Mendes , Néstor Ortiz , Nikolaos Stergioulas

The aim of this paper is to clarify the stabilities of neutron stars with strong toroidal magnetic fields against non-axisymmetric perturbation. The motivation comes from the fact that super magnetized neutron stars of $\sim 10^{15}$G,…

High Energy Astrophysical Phenomena · Physics 2012-08-21 Kenta Kiuchi , Shijun Yoshida , Masaru Shibata

Neutron stars are among the densest known objects in the universe and an ideal laboratory for the strange physics of super-condensed matter. While the simultaneously measurements of mass and radius of non-rotating neutron stars may impose…

Nuclear Theory · Physics 2020-02-03 P. S. Koliogiannis , Ch. C. Moustakidis

An accreting neutron star is potentially the gravitational wave source. In this study, we examine the gravitational wave frequencies from such an object in the steady state, adopting the Cowling approximation. We can derive the empirical…

High Energy Astrophysical Phenomena · Physics 2026-02-24 Hajime Sotani , Akira Dohi

We present a self-consistent, relativistic model of rapidly rotating neutron stars describing their exterior gravitational field. This is achieved by matching the new solution of Einstein's field equations found by Manko et al. (2000) and…

Astrophysics · Physics 2009-11-07 Matthias Stute , Max Camenzind

The problem of the stability of magnetic fields in stars has a long history and has been investigated in detail in perturbation theory. Here we consider the nonlinear evolution of a non-rotating neutron star with a purely poloidal magnetic…

General Relativity and Quantum Cosmology · Physics 2015-03-19 Riccardo Ciolfi , Samuel K. Lander , Gian Mario Manca , Luciano Rezzolla

The oscillation spectrum of a neutron star is notably rich and intrinsically dependent on the equation of state of nuclear matter. With recent advancements in gravitational-wave and electromagnetic astronomy, we are nearing the capability…

General Relativity and Quantum Cosmology · Physics 2025-05-06 Fabian Gittins , Nils Andersson

We consider both mode calculations and time evolutions of axial r-modes for relativistic uniformly rotating non-barotropic neutron stars, using the slow-rotation formalism, in which rotational corrections are considered up to linear order…

General Relativity and Quantum Cosmology · Physics 2014-11-17 Johannes Ruoff , Kostas D. Kokkotas

In this paper, we investigate the equilibrium configurations and radial perturbations of neutron stars within a subclass of gauge-invariant Scalar-Vector-Tensor (SVT) theories. By solving the generalized Tolman-Oppenheimer-Volkoff (TOV)…

General Relativity and Quantum Cosmology · Physics 2026-05-15 Hamza Boumaza

Universal relations that are insensitive to the equation of state (EoS) are useful in reducing the parameter space when measuring global quantities of neutron stars (NSs). In this paper, we reveal a new universal relation that connects the…

High Energy Astrophysical Phenomena · Physics 2023-08-22 Yong Gao , Lijing Shao , Jan Steinhoff

Unitarity of evolution in gravitational collapses implies existence of macroscopic stable horizonless objects. With such objects in mind, we study the effects of anisotropy of pressures on the stability of stars. We consider stars in four…

High Energy Physics - Theory · Physics 2015-10-05 S. Kalyana Rama

The basic formulation describing quadratic mode coupling in rotating Newtonian stars is presented, focusing on polar modes. Due to the Chandrasekhar-Friedman-Schutz mechanism, the f-mode (fundamental oscillation) is driven unstable by the…

High Energy Astrophysical Phenomena · Physics 2015-12-29 Pantelis Pnigouras , Kostas D. Kokkotas