Article
Astronomy & Astrophysics
Hai-Shan Liu, H. Lu, Zi-Yu Tang, Bin Wang
Summary: A higher-derivative gravity theory is proposed, as an extension of the Starobinsky model, which introduces new black holes carrying massive scalar hair. These black holes are found to act as walls separating naked spacetime singularities and wormholes, with the entropy and temperature being the same for both the new hairy black hole and the Schwarzschild black hole at the same mass.
Article
Astronomy & Astrophysics
Eugeny Babichev, William T. Emond, Sabir Ramazanov
Summary: We study black holes in a modified gravity scenario involving a scalar field quadratically coupled to the Gauss-Bonnet invariant. The nonminimal coupling to gravity leads to symmetry restoration near the black hole horizon, prompting the development of the scalar wall in its vicinity. The model is fully consistent with the existence of an inflationary stage and predicts the speed of gravitational waves to be extremely close to unity.
Article
Astronomy & Astrophysics
M. Bousder, M. Bennai
Summary: This study investigates the charge of the 4D-Einstein-Gauss-Bonnet black hole by examining the charge of a particle-antiparticle pair at r(-) and r(+) horizons, showing the existence of two types of Schwarzschild black holes and quantified values for the Einstein-Gauss-Bonnet black hole charge. The study also reveals the Hawking-Bekenstein formula with two logarithmic corrections, where the second correction depends on the cosmological constant and the black hole charge. Finally, the thermodynamics of the EGB-AdS black hole is explored.
Article
Physics, Particles & Fields
S. N. Sajadi
Summary: In this paper, we extend the AdS/QCD model to quadratic gravity to study the influence of gravity. We find an anisotropic black brane solution in a 5D Einstein-Gauss-Bonnet-two Maxwell-dilaton system. The system is characterized by an arbitrary exponent, a dilaton field, a time component of the first Maxwell field, and a magnetic component of the second Maxwell field. We investigate three cases and consider the effects of the theory parameter and the anisotropic parameter. The blackening function exhibits a thermodynamic phase transition between small/large and AdS/large black brane with suitable chemical potential and other parameters.
EUROPEAN PHYSICAL JOURNAL C
(2023)
Article
Physics, Particles & Fields
Li-Ming Cao, Liang-Bi Wu
Summary: This article discusses that in the four-dimensional Einstein-Gauss-Bonnet gravity, to ensure the existence of a well defined linearized gravitational wave equation, the spacetime must be locally conformally flat.
EUROPEAN PHYSICAL JOURNAL C
(2022)
Article
Astronomy & Astrophysics
Kalin Staykov, Daniela D. Doneva
Summary: A new nonlinear mechanism for black hole scalarization, different from the standard spontaneous scalarization, is studied in multiscalar Gauss-Bonnet gravity. Numerical calculations demonstrate the existence of scalarized black holes for different coupling functions and scalar field target spaces.
Article
Astronomy & Astrophysics
Sreejith Nair, Vardarajan Suneeta
Summary: This study investigates the black hole black string phase transition in Einstein-Gauss-Bonnet gravity in the large dimension limit. The results suggest that the geometry at the merger point may not necessarily approach a black hole as the dimensions increase.
Article
Physics, Particles & Fields
Kalin Staykov, Radostina Z. Zheleva
Summary: In this paper, we construct novel non-topological, spontaneously scalarized neutron stars in multi-scalar Gauss-Bonnet gravity with maximally symmetric target space. The theory allows solutions with trivial scalar field for certain classes of coupling functions, which coincide with the general relativistic ones. However, within a certain range of parameters, these solutions lose stability and new branches of solutions with nontrivial scalar field bifurcate from the trivial branch.
EUROPEAN PHYSICAL JOURNAL C
(2022)
Article
Astronomy & Astrophysics
Sandipan Sengupta
Summary: In this study, we establish an Einstein-Gauss-Bonnet theory in four dimensions based on extra dimensions with vanishing metrical length. The effective field equations of the theory depend solely on the four-metric and exhibit a quadratic curvature nonlinearity without higher than second-order derivatives. Unlike previous proposals, our formalism does not require classical regularization of divergences and is not equivalent to Horndeski gravity. The theory is generally covariant and independent of compactification. The vacuum field equations allow for FLRW cosmologies with nonsingular bounce and self-accelerating Universe, as well as spherically symmetric black holes more general than Schwarzschild. Furthermore, the quadratic theory of gravity remains valid against the inclusion of higher Lovelock densities in 5 + 2n dimensions.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Physics, Particles & Fields
S. N. Sajadi, H. R. Safari
Summary: In this paper, we study uncharged, non-conformal, and anisotropic systems with strong interactions using gauge-gravity duality. We obtain an anisotropic black brane solution to a 5D Einstein-Gauss-Bonnet-Axion-Dilaton system at finite temperature and investigate its properties. We also explore transport and diffusion properties and determine the imaginary part of the heavy quark potential in a strongly coupled plasma dual to Gauss-Bonnet gravity.
EUROPEAN PHYSICAL JOURNAL C
(2023)
Article
Physics, Particles & Fields
Dmitry Chirkov, Alex Giacomini, Sergey A. Pavluchenko, Alexey Toporensky
Summary: The paper systematically investigates solutions with static compact extra dimensions and expanding three-dimensional subspace, providing a scheme for constructing solutions with stability analysis. It finds that solutions with negative spatial curvature of extra dimensions are always stable, while those with positive curvature are stable for a narrow range of parameters. Differences between positive and negative curvature cases, including the coexistence with maximally-symmetric solutions, are noted and discussed.
EUROPEAN PHYSICAL JOURNAL C
(2021)
Article
Physics, Particles & Fields
Yi-Li Wang, Xian-Hui Ge
Summary: This paper investigates the Einstein-Maxwell-Gauss-Bonnet-axion theory in 4-dimensional spacetime through a Kaluza-Klein-like process. By obtaining the dyonic black hole solution coupled with higher derivative terms, the behavior of shear viscosity to entropy density ratio at different temperatures is studied. It is found that the ratio of uncharged black holes violates a specific bound at low temperatures, and the main feature of this ratio remains almost unchanged in 4 dimensions.
EUROPEAN PHYSICAL JOURNAL C
(2021)
Article
Astronomy & Astrophysics
Santosh V. Lohakare, B. Mishra, S. K. Maurya, Ksh. Newton Singh
Summary: In this study, the parametrization approach was used to recreate cosmological models, allowing for the incorporation of observational data. The results showed a transition from a decelerating to an accelerating stage of cosmic evolution, driven by quintessence dark energy. The violation of the strong energy conditions and the age of the Universe were also investigated.
PHYSICS OF THE DARK UNIVERSE
(2023)
Article
Computer Science, Interdisciplinary Applications
Junkai Wang, Qiaolin He
Summary: In this paper, a dimensionless model for pure-component two-phase compressible flows is derived with Van der Waals equation of state and generalized Navier boundary condition. Three energy-stable numerical schemes are proposed, one based on the scalar auxiliary variable (SAV) approach and the other based on the Lagrange multiplier approach. Numerical results are presented to demonstrate the effectiveness of the proposed methods.
JOURNAL OF COMPUTATIONAL PHYSICS
(2022)
Article
Astronomy & Astrophysics
Konstantinos F. Dialektopoulos, Jackson Levi Said, Zinovia Oikonomopoulou
Summary: In this work, the dynamical system phase space of Einstein-Gauss-Bonnet theory in cosmological minisuperspace is explored in the context of GW170817. The main features of the theory are bound together through a system of autonomous differential equations in the background of a flat Friedmann-Lemaitre-Robertson-Walker spacetime. The stability criteria of the critical points in this system are analyzed. The phase space of this scalar-tensor gravity is rich due to the fourth-order contributions of the Gauss-Bonnet invariant and the second order contribution of the scalar field together with their coupling dynamics. Additional critical points are found compared to previous works, which may be important for understanding the larger evolution of standard background cosmology within this class of gravitational models.
PHYSICS OF THE DARK UNIVERSE
(2023)
Article
Engineering, Aerospace
Dusko Borka, Vesna Borka Jovanovic, Salvatore Capozziello, Predrag Jovanovic
Summary: We study the velocity distribution of elliptical galaxies within the framework of Non-local Gravity. This approach allows us to reproduce the fundamental plane of elliptical galaxies without assuming the presence of dark matter. By comparing theoretical predictions with observed data, we find that non-local gravity effects can successfully explain the stellar dynamics in elliptical galaxies.
ADVANCES IN SPACE RESEARCH
(2023)
Article
Physics, Multidisciplinary
S. Ghaffari, Giuseppe Gaetano Luciano, S. Capozziello
Summary: We constructed a holographic model for dark energy in the Brans-Dicke cosmology by incorporating the Barrow entropy. The Hubble horizon was used as the IR cutoff to explore the cosmological consequences. We found that both the non-interacting and interacting cases can explain the current accelerated expansion of the universe, unlike the standard holographic dark energy model. Stability analysis showed that the non-interacting model was unstable, while the sign-changeable interacting model was stable only for certain parameter values. The linear interacting model always predicted a stable universe. The consistency of the model with cosmological observations was discussed.
EUROPEAN PHYSICAL JOURNAL PLUS
(2023)
Article
Astronomy & Astrophysics
David Benisty, Salvatore Capozziello
Summary: In this study, the dynamics of the Local Group (LG) of galaxies were examined with regards to contributions from the cosmological constant. The effects of dark energy and dark matter in the f(R) gravity theory were considered in the analysis. Constraints on the Yukawa couplings were derived, and the possibility of replacing dark matter with a MOND-like theory was explored. The study also demonstrated the potential of falsifying MOND-like theories through the calculation of the dark matter to baryonic matter ratio in the LG.
PHYSICS OF THE DARK UNIVERSE
(2023)
Article
Astronomy & Astrophysics
Filippo Bouche, Salvatore Capozziello, Vincenzo Salzano
Summary: Alternative cosmological models are being studied as potential solutions to the weaknesses of the lambda CDM model. Tensions have emerged between the model-dependent analysis of the Cosmic Microwave Background and lower redshift probes as cosmological surveys improve. Two quantum-inspired non-locally extended theories of gravity are reviewed, focusing on their cosmological implications and their potential to address the Hubble and growth tensions. The Deser-Woodard model shows promising features, while further investigation is needed for the non-local cosmology based on Noether symmetries.
Editorial Material
Physics, Multidisciplinary
S. Capozziello, V. G. Gurzadyan
EUROPEAN PHYSICAL JOURNAL PLUS
(2023)
Article
Physics, Multidisciplinary
Stefano Camera, Salvatore Capozziello, Lorenzo Fatibene, Andrea Orizzonte
Summary: We investigate how the cosmological equation of state can be used to scrutinize extended theories of gravity, specifically the Palatini f(R) gravity. The effective equation of state produced by a given model is studied, and the inverse problem of determining which models are compatible with a given effective equation of state is also considered. We find that power-law models are capable of transforming barotropic Equations of State into effective barotropic ones, and the form of equation of state is preserved only for f(R) = R. Additionally, quadratic and non-homogeneous effective Equations of State contain the Starobinsky model and other models.
EUROPEAN PHYSICAL JOURNAL PLUS
(2023)
Article
Astronomy & Astrophysics
Maria Giovanna Dainotti, Giada Bargiacchi, Malgorzata Bogdan, Aleksander Lukasz Lenart, Kazunari Iwasaki, Salvatore Capozziello, Bing Zhang, Nissim Fraija
Summary: By combining high-redshift probes such as GRBs and QSOs with other observational data, it is shown that alternative cosmological models could potentially explain the discrepancy in the Hubble constant. This study uses data from GRBs and QSOs, and applies statistical methods to reduce uncertainties in the estimation of cosmological parameters.
ASTROPHYSICAL JOURNAL
(2023)
Article
Multidisciplinary Sciences
Francesco Bajardi, Salvatore Capozziello, Tiziana Di Salvo, Francesca Spinnato
Summary: The Noether Symmetry Approach is a method for solving the dynamics of physical systems by selecting symmetries. It can be applied in various fields and is useful for selecting viable models and finding exact solutions.
Article
Physics, Particles & Fields
Vittorio De Falco, Francesco Bajardi, Rocco D'Agostino, Micol Benetti, Salvatore Capozziello
Summary: Various astrophysical methods are used to detect possible deviations from General Relativity in this work. A class of f(R) gravity models, selected by the existence of Noether symmetries, is considered. The study determines static and spherically symmetric black hole solutions that encompass small departures from the Schwarzschild geometry. The proposed strategy of using ray-tracing technique and considering the Poynting-Robertson effect proves to be robust and efficient in investigating gravity and detecting small deviations from General Relativity.
EUROPEAN PHYSICAL JOURNAL C
(2023)
Article
Astronomy & Astrophysics
G. G. L. Nashed, S. Capozziello
Summary: This study investigates the possible modifications of general relativity at ultraviolet and infrared scales, particularly considering the possibility of parity violation in strong gravity regime. The Chern-Simons gravity theory is used to account for the parity violation. The study shows that for certain spacetime structures, Chern-Simons gravity is equivalent to general relativity, but it is not applicable to (A)dS-Kerr/Kerr black holes. The thermodynamic quantities and geodesic equation of the black hole are also calculated.
Article
Astronomy & Astrophysics
M. G. Dainotti, A. L. Lenart, A. Chraya, G. Sarracino, S. Nagataki, N. Fraija, S. Capozziello, M. Bogdan
Summary: Currently, there is a debate about cosmological models and their corresponding parameters due to the discrepancy between H-0 obtained from SNe Ia and the Planck data. Considering high redshift probes like gamma-ray bursts (GRBs) is necessary but challenging due to the large range of GRB luminosities. In this study, we use the 3D Dainotti fundamental plane relation to infer cosmological parameters, and by considering selection and evolutionary effects, we obtain a lower intrinsic scatter compared to previous results. Our analysis, using GRB correlations and complemented with SNe Ia and BAO measurements, confirms the parameters of the Lambda cold dark matter model but with the advantage of using probes detected up to z = 5.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Physics, Particles & Fields
Salvatore Capozziello, Rocco D'Agostino, Alessio Lapponi, Orlando Luongo
Summary: We demonstrate the existence of black hole solutions that conform to the thermodynamics of logotropic fluids, which have recently been employed to address cosmological and astrophysical issues, within the framework of the Einstein field equations with a negative cosmological constant. This is accomplished by employing the generalization of logotropic fluids known as the Anton-Schmidt equation of state. We further investigate the construction of the anti-de Sitter metric, satisfying energy conditions, and explore alternative solutions by relaxing the strong energy condition.
EUROPEAN PHYSICAL JOURNAL C
(2023)
Article
Astronomy & Astrophysics
Salvatore Capozziello, Rocco D'Agostino
Summary: This article explores non-local modifications of General Relativity by considering a distortion function in terms of the inverse of the d'Alembert operator. By using numerical methods and a model-independent approach based on current observations, the shape of the distortion function is reconstructed, and the best analytical approximation of the non-local Lagrangian is inferred. The results show that this non-local modification provides a natural explanation for late cosmic acceleration and avoids fine-tuning issues with the cosmological constant.
PHYSICS OF THE DARK UNIVERSE
(2023)
Article
Physics, Particles & Fields
Salvatore Capozziello, Vittorio De Falco, Carmen Ferrara
Summary: In the context of metric-affine gravity, the role of the boundary term in Symmetric Teleparallel Gravity is examined in f(Q,B) models. The field equations are derived and compared to those of f(Q) gravity in the limit of B approaching 0, revealing the dynamic equivalence between f(Q,B) and f(R) gravity. Conservation laws are also obtained. Considering boundary terms in f(Q) gravity represents the final ingredient for the Extended Geometric Trinity of Gravity, allowing for a unified treatment of f(R), f(T,(B) over tilde), and f(Q,B).
EUROPEAN PHYSICAL JOURNAL C
(2023)
Article
Quantum Science & Technology
Carlo Altucci, Francesco Bajardi, Andrea Basti, Nicolo Beverini, Giorgio Carelli, Salvatore Capozziello, Simone Castellano, Donatella Ciampini, Fabrizio Davi, Francesco dell'Isola, Gaetano De Luca, Roberto Devoti, Giuseppe Di Somma, Angela D. V. Di Virgilio, Francesco Fuso, Ivan Giorgio, Aladino Govoni, Enrico Maccioni, Paolo Marsili, Antonello Ortolan, Alberto Porzio, Matteo Luca Ruggiero, Raffaele Velotta
Summary: The GINGER project aims to construct an array of three large frame ring laser gyroscopes with high sensitivity to measure angular velocity with respect to the fixed stars and provide geophysical investigation data.
AVS QUANTUM SCIENCE
(2023)
