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Related papers: Spontaneous Scalarization in Proto-neutron Stars

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Scalar-tensor gravity models are among the prime candidates to explain cosmic acceleration, and compact stars provide unique laboratories for testing such theories. Predictions of scalar-tensor gravity in compact stars can be examined…

High Energy Astrophysical Phenomena · Physics 2025-10-08 Fahimeh Rahimi , Zeinab Rezaei , Adamu Issifu

In scalar-tensor theories, spontaneous scalarization is a phase transition that can occur in ultra-dense environments such as neutron stars. The scalar field develops a non-trivial configuration once the stars exceeds a compactness…

General Relativity and Quantum Cosmology · Physics 2018-03-21 Nicola Franchini , Andrew Coates , Thomas P. Sotiriou

Ferromagnetic spin ordering can take place in neutron stars. This phase transition alters the neutron star equation of state. Here, applying the scalar-tensor theories of gravity, we investigate the structure of neutron stars which are in…

High Energy Astrophysical Phenomena · Physics 2019-03-11 Zeinab Rezaei , Habib Yousefi Dezdarani

We carry out numerical-relativity simulations of coalescing binary neutron stars in a scalar-tensor theory that admits spontaneous scalarization. We model neutron stars with realistic equations of state. We choose the free parameters of the…

General Relativity and Quantum Cosmology · Physics 2015-06-17 Masaru Shibata , Keisuke Taniguchi , Hirotada Okawa , Alessandra Buonanno

It is well known that neutron stars can undergo a phase transition under a certain class of Scalar Tensor Theories of gravity (STT's) where a new order parameter, the {\it scalar charge}, appears within the star. This is the well known…

General Relativity and Quantum Cosmology · Physics 2020-09-02 Juan Carlos Degollado , Marcelo Salgado , Miguel Alcubierre

Scalar-tensor theories of gravity are extensions of General Relativity (GR) including an extra, nonminimally coupled scalar degree of freedom. A wide class of these theories, albeit indistinguishable from GR in the weak field regime,…

General Relativity and Quantum Cosmology · Physics 2016-06-23 Raissa F. P. Mendes , Néstor Ortiz

Complete tensor-scalar and hydrodynamic equations are presented and integrated, for a self-gravitating perfect fluid. The initial conditions describe unstable-equilibrium neutron star configuration, with a polytropic equation of state. They…

General Relativity and Quantum Cosmology · Physics 2009-10-30 J. Novak

We analyze numerically the dynamical transition to spontaneous scalarization in neutron stars in the framework of a scalar-tensor theory of gravity where the scalar field is free but massive, and it is coupled nonminimally to gravity in the…

General Relativity and Quantum Cosmology · Physics 2024-10-04 Juan Carlos Degollado , Néstor Ortiz , Marcelo Salgado

Scalar-tensor theories of gravity are natural phenomenological alternatives to General Relativity, where the gravitational interaction is mediated by a scalar degree of freedom, besides the usual tensor gravitons. In regions of the…

General Relativity and Quantum Cosmology · Physics 2013-04-29 Enrico Barausse , Carlos Palenzuela , Marcelo Ponce , Luis Lehner

Dark matter, an important portion of compact objects, can influence different phenomena in neutron stars. The spontaneous scalarization in the scalar-tensor gravity has been proposed for neutron stars. Here, we investigate the spontaneous…

High Energy Astrophysical Phenomena · Physics 2025-10-08 Fahimeh Rahimi , Zeinab Rezaei

Neutron stars (NSs) in scalar-tensor (ST) theories of gravitation can acquire scalar charges and generate distinct spacetimes from those in General Relativity (GR) through the celebrated phenomenon of spontaneous scalarization. Taking on an…

General Relativity and Quantum Cosmology · Physics 2020-09-30 Rui Xu , Yong Gao , Lijing Shao

A decade ago, it was shown that a wide class of scalar-tensor theories can pass very restrictive weak field tests of gravity and yet exhibit non-perturbative strong field deviations away from General Relativity. This phenomenon was called…

Astrophysics · Physics 2009-11-10 A. W. Whinnett , Diego F. Torres

The main stages in the evolution of a neutron star, from its birth as a proto-neutron star, to its old age as a cold, catalyzed configuration, are described. A proto-neutron star is formed in the aftermath of a successful supernova…

Astrophysics · Physics 2007-05-23 M. Prakash , J. M. Lattimer , J. A. Pons , A. W. Steiner , S. Reddy

We make extensive numerical studies of masses and radii of proto-neutron stars during the first second after their birth in core-collapse supernova events. We use a quasi-static approach for the computation of proto-neutron star structure,…

High Energy Astrophysical Phenomena · Physics 2021-05-26 Edwan Preau , Aurélien Pascal , Jérôme Novak , Micaela Oertel

In a certain class of scalar-Gauss-Bonnet gravity, the black holes and the neutron stars can undergo spontaneous scalarization -- a strong gravity phase transition triggered by a tachyonic instability due to the nonminimal coupling between…

General Relativity and Quantum Cosmology · Physics 2021-10-18 Hao-Jui Kuan , Daniela D. Doneva , Stoytcho S. Yazadjiev

In scalar-tensor theories, compact objects may experience spontaneous scalarization. Recently, it was shown that matter-induced spontaneous scalarization of neutron stars is predominantly associated with a first-order phase transition. Here…

General Relativity and Quantum Cosmology · Physics 2026-01-01 Hyat Huang , Burkhard Kleihaus , Jutta Kunz , Meng-Yun Lai , Eugen Radu , De-Cheng Zou

We investigate the internal structure and the mass-radius relation of neutron stars in a recently proposed scalar-tensor theory dubbed asymmetron in which a massive scalar field undergoes spontaneous scalarization inside neutron stars. We…

General Relativity and Quantum Cosmology · Physics 2017-11-08 Soichiro Morisaki , Teruaki Suyama

We study torsional oscillations of neutron stars in the scalar-tensor theory of gravity using the relativistic Cowling approximation. We compute unperturbed neutron star models adopting realistic equations of state for the neutron star's…

General Relativity and Quantum Cosmology · Physics 2014-12-24 Hector O. Silva , Hajime Sotani , Emanuele Berti , Michael Horbatsch

We present a framework to study generic neutron-star binaries in scalar-tensor theories of gravity. Our formalism achieves this goal by suitably interfacing a post-Newtonian orbital evolution (described by a set of ordinary differential…

General Relativity and Quantum Cosmology · Physics 2014-03-07 Carlos Palenzuela , Enrico Barausse , Marcelo Ponce , Luis Lehner

We study neutron star configurations in a teleparallel gravity model featuring a scalar field coupled to both matter and torsion. In the Einstein frame, the theory includes a derivative coupling between the scalar field and the torsion…

General Relativity and Quantum Cosmology · Physics 2026-03-25 Youcef Kehal , Khireddine Nouicer
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