Article
Astronomy & Astrophysics
Nicolas R. Bertini, Neven Bilic, Davi C. Rodrigues
Summary: We consider a gravity action with a function of the Ricci scalar and the Gauss-Bonnet invariant, motivated by holographic cosmology. Modified Friedmann equations and power spectra are derived and compared with results from holographic and standard cosmology.
Article
Astronomy & Astrophysics
Miguel A. Garcia-Aspeitia, A. Hernandez-Almada
Summary: The study revisits the Einstein-Gauss-Bonnet model, providing additional evidence for its pros and cons from a cosmological perspective. Results suggest that the acceleration parameter alpha of the EGB model is constrained in background cosmology, and the universe evolution seems to be always in an accelerated state.
PHYSICS OF THE DARK UNIVERSE
(2021)
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
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
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
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
Astronomy & Astrophysics
Salvatore Capozziello, Gamal G. L. Nashed
Summary: We derive a novel class of four-dimensional black hole solutions in Gauss-Bonnet gravity coupled with a scalar field in the presence of Maxwell electrodynamics. The choice of metric ansatz and the presence of the scalar field lead to the emergence of higher-order terms and the creation of monopoles in the metric potentials. The computed invariants associated with the black holes show soft singularities and the solutions exhibit multiple horizons depending on the spacetime.
CLASSICAL AND QUANTUM GRAVITY
(2023)
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
Physics, Multidisciplinary
M. Z. Bhatti, Z. Yousaf, T. Ashraf
Summary: This paper discusses the viable and analytic solution of the spherically symmetric gravastar model under the influence of modification of Gauss-Bonnet gravity, f(G) gravity. The mathematical formalism of the gravastar's three regions and the analysis of different physical features are presented, resulting in an exact and singularity-free model within an alternative theory framework.
CHINESE JOURNAL OF PHYSICS
(2021)
Article
Astronomy & Astrophysics
B. C. Paul, S. D. Maharaj, A. Beesham
Summary: We present a fiat emergent universe model in modified Gauss-Bonnet gravity in four dimensions, which describes the observed universe well and avoids a big-bang singularity. The model assumes that the present universe emerged from a static Einstein universe phase in the infinite past. By reconstructing mimetic modified f(G)-gravity, the functional form of the model is determined with or without matter, successfully accommodating early inflation and late accelerating phases.
INTERNATIONAL JOURNAL OF MODERN PHYSICS D
(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
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
Gulmina Zaman Babar, Farruh Atamurotov, Abdullah Zaman Babar
Summary: This paper explores gravitational lensed photons in a 4 dimensional Einstein-Gauss-Bonnet gravity under weak-field regime, investigating lensing angle and image source brightness magnification in different paradigms. The results are compared with the standard Schwarzschild geometry.
PHYSICS OF THE DARK UNIVERSE
(2021)
Article
Physics, Mathematical
Behnaz Fazlpour, Ali Banijamali
INTERNATIONAL JOURNAL OF GEOMETRIC METHODS IN MODERN PHYSICS
(2019)
Article
Physics, Multidisciplinary
F. Chegini, F. Kheirandish, M. R. Setare
ACTA PHYSICA POLONICA A
(2019)
Article
Astronomy & Astrophysics
S. Bellucci, A. Banijamali, B. Fazlpour, M. Solbi
ASTROPHYSICS AND SPACE SCIENCE
(2019)
Review
Physics, Multidisciplinary
Hamed Adami, Mohammad Reza Setare, Tahsin Cagri Sisman, Bayram Tekin
PHYSICS REPORTS-REVIEW SECTION OF PHYSICS LETTERS
(2019)
Article
Optics
F. Chegini, F. Kheirandish, M. R. Setare
JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS
(2020)
Article
Physics, Mathematical
M. R. Setare, M. Sahraee
INTERNATIONAL JOURNAL OF GEOMETRIC METHODS IN MODERN PHYSICS
(2020)
Article
Physics, Particles & Fields
Mohammad Reza Setare, Hamed Adami
Article
Physics, Nuclear
M. Dehghani, M. R. Setare
INTERNATIONAL JOURNAL OF MODERN PHYSICS A
(2020)
Article
Astronomy & Astrophysics
Vahid Kamali, Michal Artymowski, Mohammad Reza Setare
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2020)
Article
Astronomy & Astrophysics
Suat Dengiz, Ercan Kilicarslan, M. Reza Setare
CLASSICAL AND QUANTUM GRAVITY
(2020)
Article
Physics, Nuclear
M. R. Setare, A. Jalali
INTERNATIONAL JOURNAL OF MODERN PHYSICS A
(2020)
Article
Physics, Mathematical
M. Dehghani, M. R. Setare
Summary: The explicit form of the field equations for Einstein-dilaton gravity with scalar-coupled exponential nonlinear electrodynamics has been obtained. Exact black hole solutions were found in an energy-dependent spherically symmetric geometry, with the scalar field equation solutions obtained by combining two Liouville potentials. Three types of exponentially charged dilatonic black holes were introduced and their thermodynamic properties studied in relation to rainbow functions. The impacts of rainbow functions on the conserved and thermodynamic quantities of the new black hole solutions were explored, showing the validity of the first law of black hole thermodynamics and examining quantum gravitational effects on thermodynamic phase transitions.
INTERNATIONAL JOURNAL OF GEOMETRIC METHODS IN MODERN PHYSICS
(2021)
Article
Physics, Multidisciplinary
M. R. Setare, Kh Ghasemian, D. Jahani
Summary: This study investigated the dwell time corresponding to Klein tunneling of Dirac fermions confined in single-layer graphene under uniaxial strain, and considered the effects of several parameters on traversal time. The results showed the importance of the merging parameter and incident angle in the existence of the Hartman effect.
Article
Physics, Fluids & Plasmas
H. Karimi, M. R. Setare, A. Moradian
Article
Astronomy & Astrophysics
Ali Banijamali, Behnaz Fazlpour, Valerio Faraoni
Article
Astronomy & Astrophysics
Nelson R. F. Braga, Octavio C. Junqueira
Summary: This study investigates the influence of rotation on the transition temperature of strongly interacting matter produced in non-central heavy ion collisions. By using a holographic description of an AdS black hole, the authors extend the analysis to the more realistic case where the matter spreads over a region around the rotational axis. The results show the coexistence of confined and deconfined phases and are consistent with the concept of local temperature in rotating frames developed by Tolman and Ehrenfest.
Article
Astronomy & Astrophysics
Bing Sun, Jiachen An, Zhoujian Cao
Summary: This paper investigates the effect of gravitational constant variation on the propagation of gravitational waves. By employing two analytical methods, the study finds that variations in the gravitational constant result in amplitude and phase corrections for gravitational waves, and the time variation of the gravitational constant can be constrained through the propagation of gravitational waves.
Article
Astronomy & Astrophysics
Abdellah Touati, Zaim Slimane
Summary: This letter presents the first study of Hawking radiation as a tunneling process within the framework of non-commutative gauge theory of gravity. The non-commutative Schwarzschild black hole is reconstructed using the Seiberg-Witten map and the star product. The emission spectrum of outgoing massless particles is computed using the quantum tunneling mechanism. The results reveal pure thermal radiation in the low-frequency scenario, but a deviation from pure thermal radiation in the high-frequency scenario due to energy conservation. It is also found that noncommutativity enhances the correlations between successively emitted particles.
Article
Astronomy & Astrophysics
Shahar Hod
Summary: The travel times of light signals between two antipodal points on a compact star's surface are calculated for two different trajectories. It is shown that, for highly dense stars, the longer trajectory along the surface may have a shorter travel time as measured by asymptotic observers. A critical value of the dimensionless density-area parameter is determined for constant density stars to distinguish cases where crossing through the star's center or following a semi-circular trajectory on the surface has a shorter travel time as measured by asymptotic observers.
