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Gravity compresses the matter in the cores of neutron stars to densities which are significantly higher than the density of ordinary atomic nuclei, thus providing a high-pressure environment in which numerous particle processes - from the…

Astrophysics · Physics 2010-11-19 Fridolin Weber

We find numerical solutions of the coupled system of Einstein-Maxwell's equations with a linear approach, in which the magnetic field acts as a perturbation of a spherical neutron star. In our study, magnetic fields having both poloidal and…

Astrophysics · Physics 2009-11-13 A. Colaiuda , V. Ferrari , L. Gualtieri , J. A. Pons

Benefitting from the unequaled precision of the pulsar timing technique, binary pulsars are important testbeds of gravity theories, providing some of the tightest bounds on alternative theories of gravity. One class of well-motivated…

High Energy Astrophysical Phenomena · Physics 2022-05-13 Junjie Zhao , Paulo C. C. Freire , Michael Kramer , Lijing Shao , Norbert Wex

We examine neutron star properties based on a model of dense matter composed of B=1 skyrmions immersed in a mesonic mean field background. The model realizes spontaneous chiral symmetry breaking non-linearly and incorporates scale-breaking…

Nuclear Theory · Physics 2010-11-11 Prashanth Jaikumar , Manjari Bagchi , Rachid Ouyed

We present the first fully non-linear evolutions of binary neutron star mergers in a moving-punctures approach in Einstein-scalar-Gauss-Bonnet gravity. We study both linear and quadratic-type couplings between the scalar and the…

General Relativity and Quantum Cosmology · Physics 2026-02-12 Llibert Aresté Saló , Ricard Aguilera-Miret , Miguel Bezares , Thomas P. Sotiriou

In a model of spontaneous scalarization of neutron stars proposed by Damour and Esposite-Farese, a general relativistic branch becomes unstable to trigger tachyonic growth of a scalar field $\phi$ toward a scalarized branch. Applying this…

General Relativity and Quantum Cosmology · Physics 2023-02-13 Ratchaphat Nakarachinda , Sirachak Panpanich , Shinji Tsujikawa , Pitayuth Wongjun

We numerically construct compact stars in the scalar-tensor theory of gravity with non-minimal derivative coupling of a scalar field to the curvature and nonzero cosmological constant. There are two free parameters in this model of gravity:…

General Relativity and Quantum Cosmology · Physics 2025-04-08 P. E. Kashargin , A. A. Lebedev , S. V. Sushkov

We consider the effect of scalarization on static and slowly rotating neutron stars for a wide variety of realistic equations of state, including pure nuclear matter, nuclear matter with hyperons, hybrid nuclear and quark matter, and pure…

General Relativity and Quantum Cosmology · Physics 2017-09-28 Zahra Altaha Motahar , Jose Luis Blázquez-Salcedo , Burkhard Kleihaus , Jutta Kunz

Magnetic fields inside and around neutron stars are at the heart of pulsar magnetospheric activity. Strong magnetic fields are responsible for quantum effects, an essential ingredient to produce leptonic pairs and the subsequent broadband…

High Energy Astrophysical Phenomena · Physics 2017-11-08 Jérôme Pétri

Modified theories of gravity that offer viable models for dark energy often rely on mechanisms that screen their effects in high density environments. From this perspective, it would appear that, once solar system constraints are satisfied,…

General Relativity and Quantum Cosmology · Physics 2020-07-24 Bernardo F. de Aguiar , Raissa F. P. Mendes

Neutron stars feature extremely high magnetic fields with deduced field strengths of $10^{15}$ G in the case of magnetars and potentially much higher values inside of the star. In this context we consider the appearance of $\rho^-$ meson…

Solar and Stellar Astrophysics · Physics 2015-04-03 S. Schramm , A. Bhattacharyya , V. Dexheimer , R. Mallick

In the scalar-tensor theories with a massive scalar field the coupling constants, and the coupling functions in general, which are observationally allowed, can differ significantly from those in the massless case. This fact naturally…

General Relativity and Quantum Cosmology · Physics 2016-04-27 Stoytcho S. Yazadjiev , Daniela D. Doneva , Dimitar Popchev

Neutron stars with strong magnetic fields are considered in the framework of f(R) gravity. In order to describe dense matter in magnetic field, the model with baryon octet interacting through $\sigma$$\rho$$\omega$-fields is used. The…

General Relativity and Quantum Cosmology · Physics 2015-06-19 Artyom V. Astashenok , Salvatore Capozziello , Sergei D. Odintsov

Scalar-tensor~(ST) theories of gravity are natural phenomenological extensions to general relativity. Although these theories are severely constrained both by solar system experiments and by binary pulsar observations, a large set of ST…

General Relativity and Quantum Cosmology · Physics 2016-02-10 Carlos Palenzuela , Steve Liebling

Scalar-tensor theories allow for a rich spectrum of quasinormal modes of neutron stars. The presence of the scalar field allows for polar monopole and dipole radiation, as well as for additional higher multipole modes led by the scalar…

General Relativity and Quantum Cosmology · Physics 2024-05-13 Jose Luis Blázquez-Salcedo , Luis Manuel González-Romero , Fech Scen Khoo , Jutta Kunz , Vincent Preut

The density in the core of neutron stars can reach values of about 5 to 10 times nuclear matter saturation density. It is, therefore, a natural assumption that hadrons may have dissolved into quarks under such conditions, forming a hybrid…

Nuclear Theory · Physics 2016-02-17 S. Schramm , V. Dexheimer , R. Negreiros

We investigate the inner crust structure of neutron stars using the Skyrme-Hartree-Fock approach with the Coulomb interaction treated beyond the Wigner-Seitz approximation. Our results suggest that the shell effects associated with unbound…

Nuclear Theory · Physics 2009-11-07 Piotr Magierski , Paul-Henri Heenen

We use neutron star mass and radius measurements to constrain the spontaneous scalarization phenomenon in scalar-tensor theories using Bayesian analysis. Neutron star structures in this scenario can be significantly different from the case…

General Relativity and Quantum Cosmology · Physics 2022-07-06 Semih Tuna , Kıvanç İ. Ünlütürk , Fethi M. Ramazanoğlu

We study the effect of a strong magnetic field on the properties of neutron stars with a quark-hadron phase transition. It is shown that the magnetic field prevents the appearance of a quark phase, enhances the leptonic fraction, decreases…

Nuclear Theory · Physics 2014-11-20 A. Rabhi , H. Pais , P. K. Panda , C. Providencia

We investigate the properties of post-merger remnants of binary neutron star mergers in the framework of Damour-Esposito-Farese-type scalar-tensor theory of gravity with a massive scalar field by numerical relativity simulation. It is found…

General Relativity and Quantum Cosmology · Physics 2024-06-11 Alan Tsz-Lok Lam , Hao-Jui Kuan , Masaru Shibata , Karim Van Aelst , Kenta Kiuchi