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We study the orbital and epicyclic frequencies of particles orbiting around rapidly rotating neutron stars and strange stars in a particular scalar-tensor theory of gravity. We find very large deviations of these frequencies, when compared…

High Energy Astrophysical Phenomena · Physics 2014-08-06 Daniela D. Doneva , Stoytcho S. Yazadjiev , Nikolaos Stergioulas , Kostas D. Kokkotas , Tilemachos M. Athanasiadis

We report on numerical calculations of orbital and epicyclic frequencies in nearly circular orbits around rotating neutron stars and strange quark stars. The FPS equation of state was used to describe the neutron star structure while the…

General Relativity and Quantum Cosmology · Physics 2015-03-24 Mateusz Wiśniewicz , Dorota Gondek-Rosińska , Włodzimierz Kluźniak , Nikolaos Stergioulas

It has been suggested that observations of quasi periodic oscillations (QPOs) in the X-ray fluxes from low mass X-ray binaries can be used to constrain the mass of the compact object and the equation of state of its matter. A specific…

Astrophysics · Physics 2007-05-23 D. Gondek-Rosinska , T. Bulik , w. Kluzniak , J. L. Zdunik , E. Gourgoulhon

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

Quasi-periodic X-ray brightness oscillations (QPOs) with frequencies around a kilohertz have now been discovered in more than a dozen neutron stars in low-mass X-ray binary systems using the Rossi X-ray Timing Explorer. There is strong…

Astrophysics · Physics 2009-10-30 M. Coleman Miller , Frederick K. Lamb , Gregory B. Cook

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

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

We investigate the innermost stable circular orbit (ISCO) of a test particle moving on the equatorial plane around rotating relativistic stars such as neutron stars. First, we derive approximate analytic formulas for the angular velocity…

General Relativity and Quantum Cosmology · Physics 2009-10-09 Masaru Shibata , Misao Sasaki

According to various models, the orbital and the epicyclic frequencies of particles moving on a circular orbit around compact objects are related to the quasi-periodic oscillations observed in the X-ray flux of some pulsars or black hole…

General Relativity and Quantum Cosmology · Physics 2016-01-27 Kalin V. Staykov , Daniela D. Doneva , Stoytcho S. Yazadjiev

We compute the binding energy and angular momentum of a test-particle at the last stable circular orbit (LSO) on the equatorial plane around a general relativistic, rotating neutron star (NS). We present simple, analytic, but accurate…

High Energy Astrophysical Phenomena · Physics 2017-08-09 Federico Cipolletta , Christian Cherubini , Simonetta Filippi , Jorge A. Rueda , Remo Ruffini

We construct equilibrium configurations of uniformly rotating neutron stars for selected relativistic mean-field nuclear matter equations of state (EOS). We compute in particular the gravitational mass ($M$), equatorial ($R_{\rm eq}$) and…

Solar and Stellar Astrophysics · Physics 2015-08-06 Federico Cipolletta , Christian Cherubini , Simonetta Filippi , Jorge A. Rueda , Remo Ruffini

We construct self-consistent equilibrium sequences of general relativistic, rotating neutron star models. Special emphasis in put on the determination of the maximum rotation frequency of such objects. Recently proposed models for the…

Astrophysics · Physics 2011-05-23 G. F. Burgio , H. -J. Schulze , F. Weber

We present a systematic study of the properties of pure hadronic and hybrid compact stars. The nuclear equation of state (EoS) for beta-equilibrated neutron star matter was obtained using density dependent effective nucleon-nucleon…

Nuclear Theory · Physics 2015-03-19 Abhishek Mishra , Partha Roy Chowdhury , D. N. Basu

Observations of kHz quasi-periodic oscillations (QPOs) in the X-ray fluxes of low-mass X-ray binaries (LMXBs) have been used in attempts to constrain the external metric of the compact members of these binaries, as well as their masses and…

Astrophysics · Physics 2011-05-12 D. Gondek-Rosinska , N. Stergioulas , T. Bulik , W. Kluzniak , E. Gourgoulhon

Outcomes of numerical relativity simulations of massive core collapses or binary neutron star mergers with moderate masses suggest formations of rapidly and differentially rotating neutron stars. Subsequent fall back accretion may also…

High Energy Astrophysical Phenomena · Physics 2017-11-29 Koji Uryu , Antonios Tsokaros , Luca Baiotti , Filippo Galeazzi , Keisuke Taniguchi , Shin'ichirou Yoshida

It has been suggested that the frequency in the co-rotating innermost stable circular orbit (ISCO) about a compact stellar remnant can be determined through X-ray observations of low-mass X-ray binaries, and that its value can be used to…

Astrophysics · Physics 2016-08-30 N. Stergioulas , W. Kluzniak , T. Bulik

Properties, structure, and thermal evolution of neutron stars are determined by the equation of state of stellar matter. Recent data on isospin-diffusion and isoscaling in heavy-ion collisions at intermediate energies as well as the size of…

Astrophysics · Physics 2009-11-13 Plamen G. Krastev , Bao-An Li , Aaron Worley

A set of theoretical mass-radius relations for rigidly rotating neutron stars with exotic cores, obtained in various theories of dense matter, is reviewed. Two basic observational constraints are used: the largest measured rotation…

High Energy Astrophysical Phenomena · Physics 2016-04-20 P. Haensel , M. Bejger , M. Fortin , J. L. Zdunik

In this paper we compute general-relativistic polytropic models simulating rigidly rotating, pulsating neutron stars. These relativistic compact objects, with a radius of $\sim 10 \, \mathrm{km}$ and mass between $\sim 1.4$ and $3.2$ solar…

General Relativity and Quantum Cosmology · Physics 2014-10-14 Vassilis Geroyannis , Eleftheria Tzelati

We study non-geodesic corrections to the quasicircular motion of charged test particles in the field of magnetized slowly rotating neutron stars. The gravitational field is approximated by the Lense-Thirring geometry, the magnetic field is…

High Energy Astrophysical Phenomena · Physics 2015-06-12 Pavel Bakala , Martin Urbanec , Eva Sramkova , Zdenek Stuchlik , Gabriel Torok
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