Article
Astronomy & Astrophysics
Alexander B. Balakin, Aliya A. Galimova
Summary: The study focuses on the extension of axion-dilaton-aether electrodynamics within the framework of the Einstein-Maxwell-axion-aether theory, applied to a specific cosmological model. A new type of dynamic equilibrium state of the axion-photon system is proposed and examined in the context of electrodynamics with axionic nonlinearity. The nonlinear axion-photon interactions are shown to have the ability to mimic dilaton-photon coupling, with discussions on the stability of the model concerning homogeneous fluctuations of the axion field.
Article
Physics, Particles & Fields
Maria Ortiz-Banos, Mariam Bouhmadi-Lopez, Ruth Lazkoz, Vincenzo Salzano
Summary: This study explores a modified theory of gravity with non-minimal coupling to matter, showing that gravitational coupling to matter can drive accelerated expansion of the universe. Analytical solutions for the functions f1 and f2 were calculated for different energy density contents, supporting the conclusion. Cosmographic analysis was also performed to further understand the impact of gravitational coupling.
EUROPEAN PHYSICAL JOURNAL C
(2021)
Article
Astronomy & Astrophysics
Mahdi Godazgar, Simon Guisset
Summary: This article applies the recent derivations of dual charges in asymptotically flat spacetimes to asymptotically locally anti-de Sitter (AdS) spacetimes. It finds that the dual charge contribution vanishes in the AdS case with a Dirichlet boundary, but is nonvanishing and corresponds to the NUT parameter in the Taub-NUT-AdS solution.
Article
Astronomy & Astrophysics
Guillermo Lara, Miguel Bezares, Marco Crisostomi, Enrico Barausse
Summary: This study investigates neutron star solutions in scalar-tensor theories of gravity with first-order derivative selfinteractions in the action and in the matter coupling. The robustness of the kinetic screening mechanism against general conformal couplings to matter is assessed. It is found that kinetic screening always prevails over scalarization and that kinetic couplings with matter enhance the suppression of scalar gradients inside the star even more, without relying on the nonlinear regime. Fine tuning the kinetic coupling with the derivative self-interactions in the action allows one to partially cancel the latter, resulting in a weakening of kinetic screening inside the star. This effect represents a novel way to break screening mechanisms inside matter sources and provides new signatures that might be testable with astrophysical observations.
Article
Physics, Multidisciplinary
R. Ilin
Summary: This article investigates the Noether currents and integrals of motion in a specific subclass of theories with higher field derivatives, known as theories under differential field transformations in action (DFTA). The article derives a simple representation for the integrals, which consist of old integrals of motion, terms that vanish on the old equations of motion, and surface integrals. In certain cosmological theories with high-order derivatives, it is found that the surface integrals can violate gauge invariance, specifically diffeomorphisms. The article also addresses the ambiguity of the Noether procedure in higher derivative theories and resolves it in a general setting. The obtained results are discussed in the context of several extensions of General Relativity, including mimetic, disformal, and Regge-Teitelboim theories of gravity. The article concludes by calculating the Iyer-Wald black hole entropy from the corrected currents and discussing the derivation of integral constraints on the Sachs-Wolfe effect.
EUROPEAN PHYSICAL JOURNAL PLUS
(2022)
Article
Astronomy & Astrophysics
Kazufumi Takahashi, Rampei Kimura, Hayato Motohashi
Summary: This paper discusses the impact of generalized, non-invertible disformal transformations on the coupling of fermionic matter, finding that an additional condition is required for consistent fermionic matter coupling. A subclass of the generalized disformal Horndeski class is identified that allows for the consistent coupling of ordinary matter fields, including standard model particles.
Article
Physics, Multidisciplinary
Jun Wang, Ling-Xuan Qiang, Tian-Qiang Zhang, Zhi-Song Wang, Lu-Yu Li
Summary: This paper explores the thermodynamics of the Friedmann-Lemaitre-Robertson-Walker universe in f(R) theories of gravity with arbitrary matter-geometry coupling, confirming the equivalence between modified Friedmann equations and the first law of thermodynamics. Laws of thermodynamics are obtained and validated through observational results.
COMMUNICATIONS IN THEORETICAL PHYSICS
(2022)
Article
Astronomy & Astrophysics
Masato Minamitsuji, Shinji Tsujikawa
Summary: We propose a new model of scalarized neutron stars (NSs) realized by a self-interacting scalar field phi nonminimally coupled to the Ricci scalar R of the form F(phi)R. The existence of scalarized NS solutions connecting phi v with phi c whose difference is significant allows sizable corrections to the Arnowitt-Deser-Misner mass and radius of NSs as well as the gravitational force around the NS surface. Unlike the original scenario of spontaneous scalarization induced by a negative nonminimal coupling, the catastrophic instability of cosmological solutions can be avoided.
Article
Physics, Multidisciplinary
G. Mustafa, Abdelghani Errehymy, S. K. Maurya, M. K. Jasim, Allah Ditta
Summary: This manuscript explores the physical aspects of compact stars in f(tau, T) gravity using the Karori-Barua spacetime. It considers three specific compact star models and examines their physical acceptability through calculations and graphical analyses. The results show that the obtained solutions are physically viable and have good properties.
CHINESE JOURNAL OF PHYSICS
(2022)
Article
Astronomy & Astrophysics
Pavel E. Kashargin, Sergey V. Sushkov
Summary: In this study, we investigate neutron star configurations in the scalar-tensor theory of gravity, specifically focusing on the coupling between the kinetic term of a scalar field and the Einstein tensor. We construct neutron star configurations in a general case where the bare cosmological constant and standard kinetic term are non-zero, leading to an asymptotically anti-de Sitter black hole solution with a nontrivial scalar field. The resulting mass-radius diagrams differ significantly from those obtained in general relativity or the special case with vanishing bare cosmological constant and standard kinetic term. Additionally, we find that neutron stars in the theory of gravity with nonminimal derivative coupling are more compact compared to those in general relativity or the special model, and propose a method to estimate the parameter of nonminimal coupling.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2023)
Article
Astronomy & Astrophysics
Tiberiu Harko, Francisco S. N. Lobo, Emmanuel N. Saridakis
Summary: This study investigates the possibility of gravitationally generated particle production through the mechanism of nonminimal torsion-matter coupling. By using the formalism of irreversible thermodynamics in open systems, the physical and cosmological implications of the nonconservation of the energy-momentum tensor are explored, along with the particle creation rates and comoving entropy. The thermodynamics of open systems lead to a generalization of the standard Lambda CDM cosmological paradigm, where the particle creation rates and pressures are considered components of the cosmological fluid energy-momentum tensor.
Article
Physics, Particles & Fields
Durmus Demir, Beyhan Pulice
Summary: In this study, we investigate the extended metric-Palatini gravity theory with the universally-coupled geometric Proca field, derive the corresponding field equations, and discuss its potential roles in astrophysical and collider processes.
EUROPEAN PHYSICAL JOURNAL C
(2022)
Article
Astronomy & Astrophysics
Giovanni Gandolfi, Andrea Lapi, Stefano Liberati
Summary: The study focuses on self-gravitating equilibria of dark matter (DM) halos with non-minimal coupling to gravity, which results in the development of an inner core and a shape closely following the Burkert profile. This non-minimal coupling allows for mass distribution that fits well with rotation curves of dwarf, DM-dominated galaxies and is consistent with observed scaling relations among different galaxies.
ASTROPHYSICAL JOURNAL
(2021)
Article
Physics, Particles & Fields
Kyung Kiu Kim, Seoktae Koh, Gansukh Tumurtushaa
Summary: This work investigates the cosmological solutions in the 8-dimensional Einstein Yang-Mills theory, coupled with a perfect-fluid matter. By considering the effects of extra dimensions, such as compactification and energy conditions, and introducing cosmological constant and energy density dependent on the volume of extra dimensions, several interesting solutions are found, including bouncing universes and oscillatory solutions.
JOURNAL OF HIGH ENERGY PHYSICS
(2023)
Article
Physics, Particles & Fields
Allah Ditta, Ibrar Hussain, G. Mustafa, Abdelghani Errehymy, Mohammed Daoud
Summary: This study explores the physical aspects of wormhole geometry under embedded class-1 spacetime in f (T, tau) gravity, deriving solutions and calculating shape functions that can be used in other modified theories. Validity regions of energy conditions are analyzed, confirming the presence of exotic matter due to violation of the null energy condition.
EUROPEAN PHYSICAL JOURNAL C
(2021)
Article
Astronomy & Astrophysics
A. Hees, O. Minazzoli, J. Larena
GENERAL RELATIVITY AND GRAVITATION
(2015)
Article
Astronomy & Astrophysics
Hendrik Ludwig, Olivier Minazzoli, Salvatore Capozziello
Article
Astronomy & Astrophysics
V. Viswanathan, A. Fienga, O. Minazzoli, L. Bernus, J. Laskar, M. Gastineau
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2018)
Article
Astronomy & Astrophysics
Stefano Bertone, Olivier Minazzoli, Mariateresa Crosta, Christophe Le Poncin-Lafitte, Alberto Vecchiato, Marie-Christine Angonin
CLASSICAL AND QUANTUM GRAVITY
(2014)
Article
Astronomy & Astrophysics
Aurelien Hees, Olivier Minazzoli, Julien Larena
Article
Physics, Multidisciplinary
L. Bernus, O. Minazzoli, A. Fienga, M. Gastineau, J. Laskar, P. Deram
PHYSICAL REVIEW LETTERS
(2019)
Article
Astronomy & Astrophysics
Olivier Minazzoli
Summary: de Sitter spacetimes may be solutions of entangled relativity when taking into account the quantum trace anomaly from matter fields in curved spacetimes. This hypothesis provides an elegant solution to the acceleration of the expansion of the Universe within the strict framework of entangled relativity.
CLASSICAL AND QUANTUM GRAVITY
(2021)
Article
Physics, Particles & Fields
Olivier Minazzoli, Edison Santos
Summary: In this manuscript, it is shown that the external Schwarzschild metric can be a good approximation for exact black hole solutions in entangled relativity. The demonstrations rely on the definition of matter fields, with the case of charged black holes and pure radiation being studied to determine agreement with entangled relativity and general relativity. The external Schwarzschild metric is considered an appropriate mathematical idealization of a spherical black hole in entangled relativity, with a brief discussion on extending to rotating cases.
EUROPEAN PHYSICAL JOURNAL C
(2021)
Article
Physics, Particles & Fields
Denis Arruga, Olivier Minazzoli
Summary: In this manuscript, analytical external spherical solutions of entangled relativity are presented and compared to numerical solutions in a Tolman-Oppenheimer-Volkoff framework. Both types of solutions match perfectly outside spherical compact objects, validating their accuracy. The analytical external solutions, which depend on only two parameters, can be used to easily calculate observables such as X-ray pulse profiles without needing knowledge of the object's internal equation of state.
EUROPEAN PHYSICAL JOURNAL C
(2021)
Article
Astronomy & Astrophysics
L. Bernus, O. Minazzoli, A. Fienga, A. Hees, M. Gastineau, J. Laskar, P. Deram, A. Di Ruscio
Summary: In this study, we investigated the phenomenology of the massless dilaton theory in the Solar system by deriving the modified post-Newtonian equations of motion and analyzing the light time travel. We were able to constrain the linear coupling scenario using the physical properties of the main planets of the Solar system.
Article
Astronomy & Astrophysics
Denis Arruga, Olivier Rousselle, Olivier Minazzoli
Summary: In entangled relativity, compact objects are always heavier than in general relativity for any given density.
Article
Astronomy & Astrophysics
L. Bernus, O. Minazzoli, A. Fienga, M. Gastineau, J. Laskar, P. Deram, A. Di Ruscio
Article
Astronomy & Astrophysics
Olivier Minazzoli, Nathan K. Johnson-McDaniel, Mairi Sakellariadou
Article
Astronomy & Astrophysics
Olivier Minazzoli
Article
Astronomy & Astrophysics
Olivier Minazzoli, Aurelien Hees
