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The effects of nonlinear oscillations in compact stars are attracting considerable current interest. In order to study such phenomena in the framework of fully nonlinear general relativity, highly accurate numerical studies are required. We…

General Relativity and Quantum Cosmology · Physics 2009-09-24 Michael Gabler , Ulrich Sperhake , Nils Andersson

We utilise the phenomenologically parameterized piecewise polytropic equations of state to study various neutron star properties. We investigate the compliance of these equations of state with several astronomical observations. We also…

Nuclear Theory · Physics 2022-05-04 Jaikhomba Singha , S. Mullai Vaneshwar , Ankit Kumar

We compute spectra from accretion disks around rapidly rotating neutron stars. The full effect of general relativity is considered for the structure calculation of the stars. We take into account the Doppler shift, gravitational redshift…

Astrophysics · Physics 2007-05-23 Sudip Bhattacharyya , Dipankar Bhattacharya , Ranjeev Misra , Arun V. Thampan

We assess the universal relations among second-order moments of relativistic stars, namely the moment of inertia, tidal deformability, and spin-induced quadrupole moment, via reformulated perturbation equations. After constructing the…

General Relativity and Quantum Cosmology · Physics 2025-07-29 Koutarou Kyutoku

Neutron stars and quark stars are ideal laboratories to study fundamental physics at supra nuclear densities and strong gravitational fields. Astrophysical observables, however, depend strongly on the star's internal structure, which is…

General Relativity and Quantum Cosmology · Physics 2023-03-27 Kent Yagi , Nicolas Yunes

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

The realistic models of neutron stars are considered for simple $R+\alpha R^2$ gravity and equivalent Brance-Dicke theory with dilaton field in Einsein frame. For negative values of $\alpha$ we have no acceptable results from astrophysical…

General Relativity and Quantum Cosmology · Physics 2018-12-27 Artyom V. Astashenok , Alexey S. Baigashov , Sergey A. Lapin

General-relativistic equilibria of differentially rotating stars are expected in a number of astrophysical scenarios, from core-collapse supernovae to the remnant of binary neutron-star mergers. The latter, in particular, have been the…

General Relativity and Quantum Cosmology · Physics 2024-06-18 Marie Cassing , Luciano Rezzolla

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

We calculate the total mass, radius, moment of inertia and surface gravitational redshift for neutron stars using various equations of state. The latter are derived from recent meson-exchange potential models, employing both a relativistic…

Nuclear Theory · Physics 2009-10-22 Bao , Engvik , Hjorth-Jensen , Osnes , Oestgaard

Exact models of uniformly rotating strange stars, built of self bound quark matter, are calculated within the framework of general relativity. This is made possible thanks to a new numerical technique capable to handle the strong density…

Astrophysics · Physics 2010-11-19 E. Gourgoulhon , P. Haensel , R. Livine , E. Paluch , S. Bonazzola , J. A. Marck

The universal relationships for compact stars have been investigated employing perturbative approach using canonical (APR) and Brussels-Montreal Skyrme (BSk22, BSk24, BSk26) equations of state describing hadronic matter of neutron stars.…

Nuclear Theory · Physics 2024-08-02 Debasis Atta , Vinay Singh , D. N. Basu

We present a new survey of the radial oscillation modes of neutron stars. This study complements and corrects earlier studies of radial oscillations. We present an extensive list of frequencies for the most common equations of state and…

General Relativity and Quantum Cosmology · Physics 2011-05-23 Kostas. D. Kokkotas , Johannes Ruoff

For relativistic stars rotating slowly and differentially with a positive angular velocity, some properties in relation to the positiveness of the rate of rotational dragging and of the angular momentum density are derived. Also, a new…

General Relativity and Quantum Cosmology · Physics 2009-11-10 M. J. Pareja

Stellar pulsations in rotating relativistic stars are reviewed. Slow rotation approximation is applied to solving the Einstein equations. The rotational effects on the non-axisymmetric oscillations are explicitly shown in the polar and…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Yasufumi Kojima

As some of the most compact stellar objects in the universe, neutron stars are unique cosmic laboratories. The study of neutron stars provides an ideal theoretical testbed for investigating both physics at supra-nuclear densities as well as…

High Energy Astrophysical Phenomena · Physics 2023-05-29 Grigorios Papigkiotis , George Pappas

The excitation of the axial quasi-normal modes of a relativistic star by scattered particles is studied by evolving the time dependent perturbation equations. This work is the first step towards the understanding of more complicated…

General Relativity and Quantum Cosmology · Physics 2009-10-31 V. Ferrari , K. D. Kokkotas

Detection of continuous gravitational waves from rapidly-spinning neutron stars opens up the possibility of examining their internal physics. We develop a framework that leverages a future continuous gravitational wave detection to infer a…

General Relativity and Quantum Cosmology · Physics 2023-02-15 Neil Lu , Karl Wette , Susan M. Scott , Andrew Melatos

Rapid uniform rotation of newborn neutron stars (protoneutron stars) is studied for a range of internal temperatures and entropies per baryon predicted by the existing numerical simulations. Calculations are performed using general…

Astrophysics · Physics 2008-11-26 J-O. Goussard , P. Haensel , J. L. Zdunik

The influence of the rotation on the total masses and radii of the neutron stars are calculated by the Hartle's slow rotation formalism, while the equation of state is considered in a relativistic $\sigma-\omega$ model. Comparing with the…

Astrophysics · Physics 2009-11-10 De-hua Wen , Wei Chen , Xian-ju Wang , Bao-quan Ai , Guo-tao Liu , Dong-qiao Dong , Liang-gang Liu