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We study the structure of neutron stars in scalar-tensor theories for the nonminimal coupling of the form $(1+\kappa \xi \phi^{2})\cal R$. We solve the hydrostatic equilibrium equations for two different types of scalar field potentials and…

General Relativity and Quantum Cosmology · Physics 2019-04-02 A. Savaş Arapoğlu , K. Yavuz Ekşi , A. Emrah Yükselci

We study nonaxisymmetric perturbations of rotating relativistic stars. modeled as perfect-fluid equilibria. Instability to a mode with angular dependence $\exp(im\phi)$ sets in when the frequency of the mode vanishes. The locations of these…

General Relativity and Quantum Cosmology · Physics 2009-10-30 Nikolaos Stergioulas , John L. Friedman

Evolution of scalar perturbations in a universe containing solid matter with positive pressure is studied. Solution for pure solid is found and matched with solution for ideal fluid, including the case when the pressure to energy density…

General Relativity and Quantum Cosmology · Physics 2015-01-29 Vladimír Balek , Matej Škovran

Neutrino quantum kinetics is a rapidly evolving field in computational astrophysics, with a primary focus on collective neutrino oscillations in core-collapse supernovae and post-merger phases of binary neutron star mergers. In recent…

High Energy Astrophysical Phenomena · Physics 2025-01-30 Hiroki Nagakura , Masamichi Zaizen , Jiabao Liu , Lucas Johns

We study the structure of spherically symmetric and static objects in the presence of a nonminimally coupled scalar field having a potential of the form $V(\phi)=-\mu^2\phi^2/2+\lambda\phi^4/4$. We numerically solve equations of the system…

General Relativity and Quantum Cosmology · Physics 2020-02-14 A. Savaş Arapoğlu , A. Emrah Yükselci

At the supranuclear densities achieved inside a neutron star, matter may exhibit extreme properties. In particular, it may be the case that a suitable average of the speed of sound squared exceeds the so-called conformal limit, i.e.,…

General Relativity and Quantum Cosmology · Physics 2024-12-02 Raissa F. P. Mendes , Caroline F. Sodré , Felipe T. Falciano

We seek to characterize how the change of global rotation rate influences the overall dynamics and large scale flows arising in the convective envelopes of stars covering stellar spectral types from early G to late K. We do so through…

We report on general relativistic calculations of quasiequilibrium configurations of binary neutron stars in circular orbits with zero vorticity. These configurations are expected to represent realistic situations as opposed to corotating…

General Relativity and Quantum Cosmology · Physics 2009-10-31 S. Bonazzola , E. Gourgoulhon , J. -A. Marck

We investigate the effects of general relativity upon the non-axisymmetric ``bar'' mode secular instability of rapidly rotating stars, i.e. the relativistic and compressible analog of the transition from Maclaurin spheroids to Jacobi…

General Relativity and Quantum Cosmology · Physics 2009-10-28 S. Bonazzola , J. Frieben , E. Gourgoulhon

Two classes of stationary axisymmetric solutions of Einstein's equations for isolated differentially rotating matter sources are presented. The asymptotic regime is extracted, with attention to quasilocal gravitational energy, shear and…

General Relativity and Quantum Cosmology · Physics 2025-06-12 Marco Galoppo , David L. Wiltshire

Models of differentially rotating protoneutron stars are calculated, using realistic equations of state of dense hot matter. Various conditions within the stellar interior, corresponding to different stages of protoneutron star evolution,…

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

Next-generation gravitational wave detectors are expected to increase their sensitivity in the kHz band where binary neutron star remnants are expected to emit. In this context, robust predictions of oscillation modes of the post-merger…

General Relativity and Quantum Cosmology · Physics 2025-05-23 Gaël Servignat , Jérôme Novak

In this work, we propose a meta-modelling technique to nuclear matter on the basis of a relativistic density functional with density-dependent couplings. Identical density dependence for the couplings both in the isoscalar and isovector…

Nuclear Theory · Physics 2023-10-31 Prasanta Char , Chiranjib Mondal , Francesca Gulminelli , Micaela Oertel

Pulsars are believed to loose their rotational kinetic energy primarily by a large amplitude low frequency electromagnetic wave which is eventually converted into particle creation, acceleration and followed by a broad band radiation…

High Energy Astrophysical Phenomena · Physics 2014-03-05 J. Pétri

This is the second in a series of papers on the construction and validation of a three-dimensional code for the solution of the coupled system of the Einstein equations and of the general relativistic hydrodynamic equations, and on the…

General Relativity and Quantum Cosmology · Physics 2009-11-07 J. Font , T. Goodale , S. Iyer , M. Miller , L. Rezzolla , E. Seidel , N. Stergioulas , W. Suen , M. Tobias

We study models of uniformly and differentially rotating neutron stars in the framework of post-Newtonian approximation in general relativity as established by Chandrasechar. In particular, we adopt the polytropic equation of state in order…

High Energy Astrophysical Phenomena · Physics 2023-05-05 Athanasios Fotopoulos , Vasileios G. Karageorgopoulos , Vassilis S. Geroyannis

We consider a configuration consisting of a wormhole filled by a perfect fluid. Such a model can be applied to describe stars as well as neutron stars with a nontrivial topology. The presence of a tunnel allows for motion of the fluid,…

Astrophysics of Galaxies · Physics 2015-05-27 V. Dzhunushaliev , V. Folomeev , B. Kleihaus , J. Kunz

The equations describing nonradial adiabatic oscillations of differentially rotating relativistic stars are derived in relativistic slow rotation approximation. The differentially rotating configuration is described by a perturbative…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Adamantios Stavridis , Andrea Passamonti , Kostas Kokkotas

In this work we consider the thermal evolution of rigidly rotating neutron stars. In order to perform such study we first calculate the structure of rotating objects, which is considerably more complicated than that of spherical objects.…

High Energy Astrophysical Phenomena · Physics 2013-07-30 Rodrigo Negreiros , Stefan Schramm , Fridolin Weber

We investigate relativistic spherically symmetric static perfect fluid models in the framework of the theory of dynamical systems. The field equations are recast into a regular dynamical system on a 3-dimensional compact state space,…

General Relativity and Quantum Cosmology · Physics 2009-11-10 J. Mark Heinzle , N. Rohr , C. Uggla