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Neutron stars exhibit magnetic fields and densities far beyond those achievable in terrestrial laboratories, offering a natural probe of strongly interacting matter under extreme conditions. Using observationally anchored mass-radius…

Cosmology and Nongalactic Astrophysics · Physics 2026-01-13 Abriana Lyda , Prajwal MohanMurthy

I report on recent work concerning the existence and stability of self-gravitating spheres with anisotropic pressure. After presenting new exact solutions, Chandrasekhar's variational formalism for radial perturbations is generalized to…

Astrophysics · Physics 2009-11-10 Krsna Dev , Marcelo Gleiser

We present results on the effect of the stiffness of the equation of state on the dynamical bar-mode instability in rapidly rotating polytropic models of neutron stars in full General Relativity. We determine the change in the threshold for…

General Relativity and Quantum Cosmology · Physics 2015-04-01 Frank Löffler , Roberto De Pietri , Alessandra Feo , Luca Franci , Francesco Maione

The gravitational radiation has been proposed a long time before, as an explanation for the observed relatively low spin frequencies of young neutron stars and of accreting neutron stars in low-mass X-ray binaries as well. In the present…

Solar and Stellar Astrophysics · Physics 2017-05-10 M. C. Papazoglou , C. C. Moustakidis

We study by computational means the dynamical stability against bar-mode deformation of rapidly and differentially rotating stars in a post-Newtonian approximation of general relativity. We vary the compaction of the star $M/R$ (where $M$…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Motoyuki Saijo , Masaru Shibata , Thomas W. Baumgarte , Stuart L. Shapiro

We investigate the radiative stability of Horndeski scalar-tensor theories with luminally propagating gravitational waves (as extensively discussed in the wake of GW170817) and show that in general there is a tension between obtaining…

Cosmology and Nongalactic Astrophysics · Physics 2020-11-25 Johannes Noller , Andrina Nicola

The present work investigates the numerical evolution of linearized oscillations of non-rotating, spherically symmetric neutron stars within the framework of general relativity. We derive the appropriate equations using the (3+1)-formalism.…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Johannes Ruoff

We present new equations of state for applications in core-collapse supernova and neutron star merger simulations. We start by introducing an effective mass parametrization that is fit to recent microscopic calculations up to twice…

Nuclear Theory · Physics 2021-02-15 S. Huth , C. Wellenhofer , A. Schwenk

We construct new models of black hole-neutron star binaries in quasiequilibrium circular orbits by solving Einstein's constraint equations in the conformal thin-sandwich decomposition together with the relativistic equations of…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Keisuke Taniguchi , Thomas W. Baumgarte , Joshua A. Faber , Stuart L. Shapiro

We present our study of stability of differentially rotating, axisymmetric neutron stars described by a polytropic equation of state with $\Gamma = 2$. We focus on quasi-toroidal solutions with a degree of differential rotation $\widetilde…

High Energy Astrophysical Phenomena · Physics 2024-02-29 Paweł Szewczyk , Dorota Gondek-Rosińska , Pablo Cerdá-Durán

Non-radial oscillation modes of a neutron star possess valuable information about its internal structure and nuclear physics. Starting from the quadrupolar order, such modes under general relativity are known as quasi-normal modes since…

General Relativity and Quantum Cosmology · Physics 2024-11-22 Shu Yan Lau , Siddarth Ajith , Victor Guedes , Kent Yagi

The properties of neutron stars are determined by the nature of the matter that they contain. These properties can be constrained by measurements of the star's size. We obtain stringent constraints on neutron-star radii by combining…

High Energy Astrophysical Phenomena · Physics 2020-03-25 Collin D. Capano , Ingo Tews , Stephanie M. Brown , Ben Margalit , Soumi De , Sumit Kumar , Duncan A. Brown , Badri Krishnan , Sanjay Reddy

Using data from 289 numerical relativity simulations of merging binary neutron stars, we identify, for the first time, a robust quasi-universal relation connecting the postmerger peak gravitational-wave frequency and the value of the…

General Relativity and Quantum Cosmology · Physics 2022-05-04 Matteo Breschi , Sebastiano Bernuzzi , Daniel Godzieba , Albino Perego , David Radice

The detection of the GW170817 neutron star merger event has incited an intense research activity towards the understanding of the nuclear matter equation of state. In this paper we compare in particular the pressure-density relation…

Nuclear Theory · Physics 2019-07-09 G. F. Burgio , A. Figura , H. -J. Schulze , J. -B. Wei

In this work, an exact solution of Einstein's field equations in isotropic coordinates for anisotropic matter distribution is obtained by considering a particular metric choice of metric potential $g_{rr}$. To check the feasibility of the…

General Relativity and Quantum Cosmology · Physics 2022-06-29 B. S. Ratanpal , Bhavesh Suthar

This work is based on stability analysis of spherically symmetric collapsing star surrounding in locally anisotropic environment in $f(R,T)$ gravity, where $R$ is Ricci scalar and $T$ corresponds to the trace of energy momentum tensor.…

General Physics · Physics 2014-11-26 Ifra Noureen , M. Zubair

The first results of numerical analysis of classical r-modes of {\it rapidly} rotating compressible stellar models are reported. The full set of linear perturbation equations of rotating stars in Newtonian gravity are numerically solved…

Astrophysics · Physics 2009-10-31 Shin'ichirou Yoshida , Shigeyuki Karino , Shijun Yoshida , Yoshiharu Eriguchi

Triaxial neutron stars can be sources of continuous gravitational radiation detectable by ground-based interferometers. The amplitude of the emitted gravitational wave can be greatly affected by the state of the hydrodynamical fluid flow…

General Relativity and Quantum Cosmology · Physics 2024-04-24 Yufeng Luo , Antonios Tsokaros , Roland Haas , Koji Uryu

We derive a Tolman-Oppenheimer-Volkoff equation in neutron star systems within the modified $f(T, \mathcal{T})$-gravity class of models using a perturbative approach. In our approach $f(T, \mathcal{T})$-gravity is considered to be a static…

General Relativity and Quantum Cosmology · Physics 2017-05-08 Mark Pace , Jackson Levi Said

Regarding a $d-$dimensional spherically symmetric line element in the context of Einstein-$\Lambda$ gravity, the hydrostatic equilibrium equation of stars is obtained. Then, by using the lowest order constrained variational (LOCV) method…

General Relativity and Quantum Cosmology · Physics 2017-01-30 G. H. Bordbar , S. H. Hendi , B. Eslam Panah