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We consider the sector of Horndeski's gravity characterized by the coupling between the kinetic scalar field term and the Einstein tensor. We numerically construct neutron star configurations where the external geometry is identical to the…

General Relativity and Quantum Cosmology · Physics 2015-09-02 Adolfo Cisterna , Térence Delsate , Massimiliano Rinaldi

The Novikov-Thorne accretion disk model is widely employed in astrophysics, yet computing its blackbody spectrum theoretically requires analytical expressions for the orbital parameters -- specific energy, angular momentum, and angular…

General Relativity and Quantum Cosmology · Physics 2025-07-22 Shiyang Hu , Yuxiang Zuo , Dan Li , Chen Deng

Neutron stars are the densest, directly observable stellar objects in the universe and serve as unique astrophysical laboratories to study the behavior of matter under extreme physical conditions. This book chapter is devoted to describing…

High Energy Astrophysical Phenomena · Physics 2018-06-11 N. Degenaar , V. F. Suleimanov

The Neutron Star Interior Composition Explorer (NICER) mission has provided a unique opportunity to constrain the equation of state of neutron stars by using the technique of pulse-profile modelling. This technique requires accurate and…

General Relativity and Quantum Cosmology · Physics 2021-05-12 G. André Oliva , Francisco Frutos-Alfaro

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 apply the Hartle formalism to study equilibrium configurations in the framework of Newtonian gravity. This approach allows one to study in a simple manner the properties of the interior gravitational field in the case of static as well…

Solar and Stellar Astrophysics · Physics 2016-05-04 Kuantay Boshkayev , Hernando Quevedo , Zhanerke Kalymova , Bakytzhan Zhami

We trace a systematic and consistent method to precisely numerate the magnitude range for various structural and isospin compositional properties of the neutron star. Incompressibility, symmetry energy, slope parameter and curvature of a…

Nuclear Theory · Physics 2021-11-29 Ankit Kumar , H. C. Das , S. K. Patra

Models of rotating relativistic stars with a toroidal magnetic field have been computed for a sample of eight equations of state of cold dense matter. Non-rotating models admit important levels of magnetization and quadrupole distortion…

General Relativity and Quantum Cosmology · Physics 2015-06-18 Joachim Frieben , Luciano Rezzolla

We describe the model of surface emission from a rapidly rotating neutron star that is applied to Neutron Star Interior Composition Explorer X-ray data of millisecond pulsars in order to statistically constrain the neutron star mass-radius…

In order to examine the pulse profile from a pulsar, we derive the formula for describing the flux from antipodal hot spots with any static, spherically symmetric spacetime. We find that the pulse profiles are almost independent of the…

High Energy Astrophysical Phenomena · Physics 2017-11-17 Hajime Sotani , Umpei Miyamoto

We develop an effective model for a neutron star with a magnetosphere. It takes into account the electromagnetic torques acting on the magnetic dipole, the friction forces between the crust and the core, and the gravitational corrections.…

Astrophysics · Physics 2009-10-30 H. Casini , R. Montemayor

We discuss slowly-rotating, general relativistic, superfluid neutron stars in the Hartle-Thorne formulation. The composition of the stars is described by a simple two-fluid model which accounts for superfluid neutrons and all other…

General Relativity and Quantum Cosmology · Physics 2023-03-21 Eneko Aranguren , José A. Font , Nicolas Sanchis-Gual , Raül Vera

X-ray astronomy provides information regarding the electromagnetic emission of active galactic nuclei and X-ray binaries. These events provide details regarding the astrophysical environment of black holes and stars, and help us understand…

General Relativity and Quantum Cosmology · Physics 2023-11-01 Kyriakos Destounis , Kostas D. Kokkotas

We investigate quasi-universal relations in neutron stars linking standard observables, such as tidal deformability ($\Lambda$) and normalized moment of inertia ($\bar{I}$), with normalized curvature scalars in general relativity. These…

General Relativity and Quantum Cosmology · Physics 2025-10-07 M. D. Danarianto , A. Sulaksono

We performed a comparison of three different numerical codes for constructing equilibrium models; (I) a code for static equilibrium configurations, (II) an implementation of the Hartle--Thorne slow-rotation approximation, (III) a numerical…

General Relativity and Quantum Cosmology · Physics 2023-04-05 Balázs Kacskovics , Dániel Barta , Mátyás Zsolt Vasúth

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

In this chapter we review the recent results on the equilibrium configurations of static and uniformly rotating neutron stars within the Hartle formalism. We start from the Einstein-Maxwell-Thomas-Fermi equations formulated and extended by…

High Energy Astrophysical Phenomena · Physics 2016-09-03 Kuantay Boshkayev

A model for determining the dimensionless spin parameter and mass of the black hole remnant of black hole-neutron star mergers with arbitrary initial black hole spin angular momentum, binary mass ratio, and neutron star mass and cold…

General Relativity and Quantum Cosmology · Physics 2014-03-11 Francesco Pannarale

The characteristic physical timescales near stellar-mass compact objects are measured in milliseconds. These timescales -- the free-fall time, the fastest stable orbital period, and stellar spin periods -- encode the fundamental physical…

High Energy Astrophysical Phenomena · Physics 2009-02-20 Z. Arzoumanian , S. Bogdanov , J. Cordes , K. Gendreau , D. Lai , J. Lattimer , B. Link , A. Lommen , C. Miller , P. Ray , R. Rutledge , T. Strohmayer , C. Wilson-Hodge , K. Wood

We derive a formula for the nodal precession frequency and the Keplerian period of a particle at an arbitrarily inclined orbit (with a minimum latitudinal angle reached at the orbit) in the post-Newtonian approximation in the external field…

Astrophysics · Physics 2009-11-07 Nail Sibgatullin