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Related papers: Fermion-axion stars: static solutions and dynamica…

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The aim of this paper is to study the stability of soliton-like static solutions via non-linear simulations in the context of a special class of massive tensor-multi-scalar-theories of gravity whose target space metric admits Killing…

General Relativity and Quantum Cosmology · Physics 2021-09-22 Riccardo Falcone , Daniela D. Doneva , Kostas D. Kokkotas , Stoytcho S. Yazadjiev

We study the stability of rotating scalar boson stars, comparing those made from a simple massive complex scalar (referred to as mini boson stars), to those with several different types of nonlinear interactions. To that end, we numerically…

General Relativity and Quantum Cosmology · Physics 2021-02-16 Nils Siemonsen , William E. East

We investigate static, spherically symmetric solutions in Einstein-scalar-Gauss-Bonnet gravity non-minimally coupled to a massless real scalar field, both in vacuum and in the presence of fermionic matter. Focusing on a specific quadratic…

General Relativity and Quantum Cosmology · Physics 2025-11-03 Roberto D. Alba Q. , Javier Chagoya , Armando A. Roque

We study the existence of stationary solutions of the Vlasov-Poisson system with finite radius and finite mass in the stellar dynamics case. So far, the existence of such solutions is known only under the assumption of spherical symmetry.…

Mathematical Physics · Physics 2007-05-23 Gerhard Rein

We consider a gravitating spherically symmetric configuration consisting of a scalar field non-minimally coupled to ordinary matter in the form of a perfect fluid. For this system we find static, regular, asymptotically flat solutions for…

Solar and Stellar Astrophysics · Physics 2013-05-29 V. Dzhunushaliev , V. Folomeev , D. Singleton

We solve Einstein equations coupled to a complex scalar field with infinitely large self-interaction, degenerate fermions, and a negative cosmological constant in $(2+1)$ dimensions. Exact solutions for static boson-fermion stars are found…

General Relativity and Quantum Cosmology · Physics 2016-08-25 Kenji Sakamoto , Kiyoshi Shiraishi

In this work, we investigate a static spherically symmetric system in which Einstein gravity is minimally coupled with a self-interacting complex scalar field and a nonlinear electromagnetic field, referred to as Hayward axion stars.…

High Energy Physics - Theory · Physics 2024-07-25 Jun-Ru Chen , Yong-Qiang Wang

We investigate numerically models of the static spherically symmetric boson-fermion stars in the scalar-tensor theory of gravity with massive dilaton field. The proper mathematical model of such stars is interpreted as a nonlinear…

Astrophysics · Physics 2025-10-20 S. S. Yazadjiev , T. L. Boyadjiev , M. D. Todorov , P. P. Fiziev

We investigate the geodesic structure of realistic static and spherically symmetric spacetimes embedding neutron stars in metric $f(R)$ gravity, focusing on the quadratic Starobinsky model $f(R)=aR^2$ with $a<0$. Neutron-star solutions are…

General Relativity and Quantum Cosmology · Physics 2026-03-10 Néstor Rivero González , Álvaro de la Cruz Dombriz , Gonzalo J. Olmo

A model of static boson-fermion star with spherical symmetry based on the scalar-tensor theory of gravity with massive dilaton field is investigated numerically. Since the radius of star is \textit{a priori} an unknown quantity, the…

Numerical Analysis · Mathematics 2025-10-20 T. L. Boyadjiev , M. D. Todorov , P. P. Fiziev , S. S. Yazadjiev

If the dark matter is composed of axions, then axion stars are expected to be abundant in the Universe. We demonstrate in fully non-linear (3+1) numerical relativity the instability of compact axion stars due to the electromagnetic…

High Energy Physics - Phenomenology · Physics 2024-11-26 Liina M. Chung-Jukko , Eugene A. Lim , David J. E. Marsh , Josu C. Aurrekoetxea , Eloy de Jong , Bo-Xuan Ge

A real scalar field coupled to a fermion via a Yukawa term can evade no-go theorems preventing solitonic solutions. For the first time, we study this model within General Relativity without approximations, finding static and spherically…

General Relativity and Quantum Cosmology · Physics 2023-08-31 L. Del Grosso , G. Franciolini , P. Pani , A. Urbano

We re-examine the dynamical stability of the nakedly singular, static, spherical ly symmetric solutions of the Einstein-Klein Gordon system. We correct an earlier proof of the instability of these solutions, and demonstrate that there are…

General Relativity and Quantum Cosmology · Physics 2010-11-19 M. A. Clayton , L. Demopoulos , J. Legare

The theoretical description of compact structures that share some key features with mass varying particles allows for a simple analysis of equilibrium and stability for massive stellar bodies. We investigate static, spherically symmetric…

General Relativity and Quantum Cosmology · Physics 2010-01-05 Alex E. Bernardini , O. Bertolami

The time independent spherically symmetric solutions of General Relativity (GR) coupled to a dynamical unit timelike vector are studied. We find there is a three-parameter family of solutions with this symmetry. Imposing asymptotic flatness…

General Relativity and Quantum Cosmology · Physics 2010-02-05 Christopher Eling , Ted Jacobson

In this manuscript the three types of late-time behavior of spherically symmetric Boson Stars are presented, these are: stable configurations, unstable bounded that collapse to form black holes and unstable unbounded that explode. The…

General Relativity and Quantum Cosmology · Physics 2019-07-22 F. S. Guzman

In previous work, we have found new static, spherically symmetric boson star solutions which generalize the standard boson stars by allowing a particular superposition of scalar fields in which each of the fields is characterized by a fixed…

General Relativity and Quantum Cosmology · Physics 2020-01-08 Miguel Alcubierre , Juan Barranco , Argelia Bernal , Juan Carlos Degollado , Alberto Diez-Tejedor , Miguel Megevand , Darío Núñez , Olivier Sarbach

We review particle-like configurations of complex scalar field, localized by gravity, so-called boson stars. In the simplest case, these solutions posses spherical symmetry, they may arise in the massive Einstein-Klein-Gordon theory with…

General Relativity and Quantum Cosmology · Physics 2022-04-14 Yakov Shnir

Topological stars, or top stars for brevity, are smooth horizonless static solutions of Einstein-Maxwell theory in 5-d that reduce to spherically symmetric solutions of Einstein-Maxwell-Dilaton theory in 4-d. We study linear scalar…

General Relativity and Quantum Cosmology · Physics 2023-09-04 Massimo Bianchi , Giorgio Di Russo , Alfredo Grillo , Jose Francisco Morales , Giuseppe Sudano

This research paper examines the feasibility and stability of compact stars in the context of $f(\mathcal{Q})$ theory, where $\mathcal{Q}$ represents the non-metricity scalar. To achieve this objective, a static spherical line element is…

General Relativity and Quantum Cosmology · Physics 2024-10-23 Shamaila Rani , Muhammad Adeel , M. Zeeshan Gul , Abdul Jawad