A5090131873- Cosmology and Gravitation Theories
- Black Holes and Theoretical Physics
- Advanced Differential Geometry Research
- Relativity and Gravitational Theory
- Noncommutative and Quantum Gravity Theories
- Pulsars and Gravitational Waves Research
- Geophysics and Gravity Measurements
- Quantum Mechanics and Non-Hermitian Physics
- Quantum Mechanics and Applications
- Gamma-ray bursts and supernovae
- Dark Matter and Cosmic Phenomena
- Astrophysics and Cosmic Phenomena
- Quantum chaos and dynamical systems
- Solar and Space Plasma Dynamics
Transylvania University of Brașov
2023-2025
University of Mons
2016-2023
Institute of Mathematics and Informatics
2023
University of Bremen
2023
University of Tübingen
2023
Sofia University "St. Kliment Ohridski"
2023
Tokyo Institute of Technology
2023
Bulgarian Academy of Sciences
2023
Institute for Nuclear Research and Nuclear Energy
2023
Abstract The unification of quantum mechanics and general relativity has long been elusive. Only recently have empirical predictions various possible theories gravity put to test, where a clear signal properties is still missing. dawn multi-messenger high-energy astrophysics tremendously beneficial, as it allows us study particles with much higher energies travelling longer distances than in terrestrial experiments, but more progress needed on several fronts. A thorough appraisal current...
This work is devoted to the construction of slowly rotating neutron stars in framework nonminimal derivative coupling sector Horndeski theory. We match large radius expansion spherically symmetric solutions with cosmological solutions, and we find that most viable model has only one free parameter. Then, by using several tabulated realistic equations state, establish numerically upper bound for this parameter order construct slow rotation approximation maximal mass observed today. finally...
In this paper, we find new scalarized black holes by coupling a scalar field with the Gauss-Bonnet invariant in teleparallel gravity. The formulation of theory uses torsion instead curvature to describe gravitational interaction, and it turns out that, language, usual term four dimensions decays two distinct boundary terms, invariants. Both can be coupled individually or any combination field, obtain extension equivalent general relativity. study contains familiar Riemannian...
The Einstein-Klein-Gordon Lagrangian is supplemented by a non-minimal coupling of the scalar field to specific geometric invariants: Gauss-Bonnet term and Chern-Simons term. chosen as general quadratic polynomial in allows – depending on parameters for large families hairy black holes exist. These solutions are characterized, namely, number nodes function. fundamental family encompasses whose hairs appear spontaneously presenting shift-symmetric hairs. When an appropriate potential, model...
Black holes play a crucial role in the understanding of gravitational interaction. Through direct observation shadow black hole by event horizon telescope and detection waves merging we now start to have access their properties behaviour, which means behaviour gravity. This further raised demand for models compare with those observations. In this respect, an important question regarding is know if they can support "hairs". While famously forbidden general relativity, particular scalar...
The unification of quantum mechanics and general relativity has long been elusive. Only recently have empirical predictions various possible theories gravity put to test. dawn multi-messenger high-energy astrophysics tremendously beneficial, as it allows us study particles with much higher energies travelling longer distances than in terrestrial experiments, but more progress is needed on several fronts. A thorough appraisal current strategies experimental frameworks, regarding...
Abstract The method of variational bootstrapping, based on canonical completion, allows one to construct a Lagrangian for physical theory depending two sets field variables, starting from guess the equations only such set. This setup is particularly appealing construction modified theories gravity, since can take lessons GR an “educated guess” metric equations; other fields are then fixed by obtained (up terms that completely independent tensor). In present paper, we apply bootstrapping...
The method of variational completion allows one to transform an (in principle, arbitrary) system partial differential equations -- based on intuitive ``educated guess'' into the Euler-Lagrange attached a Lagrangian, by adding canonical correction term. Here, we extend this technique theories that involve at least two sets dynamical variables : show educated guess field with respect these only is sufficient variationally complete and recover Lagrangian for full theory, up terms do not...
In the limit of large quantum excitations, classical and probability distributions for a Schrödinger equation can be compared by using corresponding WKBJ solutions whose rapid oscillations are averaged. This result is extended one-dimensional Hamiltonians with non-usual kinetic part. The validity approach tested Hamiltonian containing relativistic energy operator.
The Einstein-Gauss-Bonnet gravity in five dimensions is extended by scalar fields and the corresponding equations are reduced to a system of non-linear differential equations. A large family regular solutions these shown exist. Generically, spinning black holes with hairs. They can be characterized (but not uniquely) an horizon angular velocity on this horizon. Taking particular limits approach boson star or become extremal, any case limiting configurations remain hairy.
We examine the teleparallel formulation of nonminimally coupled scalar Einstein-Gauss-Bonnet gravity. In formulation, gravity is described by torsion instead curvature, causing usual Gauss-Bonnet invariant expressed through curvature to decay into two separate invariants built from torsion. Consequently, permits broader possibilities for nonminimal couplings between spacetime geometry and field. our theory, there are different branches equations in spherical symmetry depending on how one...
The spinning-hairy black holes that occur in Einstein's gravity, supplemented by a doublet of complex scalar fields, are constructed within an extension the model U(1) gauge symmetry involving massless vector potential. hairy then acquire electric charge and magnetic moment; their domain existence is discussed terms coupling constant.
We discuss boson stars and neutron stars, respectively, in a scalar-tensor gravity model with an explicitly time-dependent real scalar field. While the our -- contrast to do not possess hard core, we find that qualitative effects of formation hair are similar both cases : presence allows type exist for larger central density as well mass at given radius than their General Relativity counterparts. In particular, new types which have radii very close corresponding Schwarzschild hence...
Abstract The method of variational completion allows one to transform an (in principle, arbitrary) system partial differential equations – based on intuitive “educated guess” into the Euler–Lagrange attached a Lagrangian, by adding canonical correction term. Here, we extend this technique theories that involve at least two sets dynamical variables: show educated guess field with respect these variables only is sufficient variationally complete and recover Lagrangian for full theory, up...
The method of variational bootstrapping, based on canonical completion, allows one to construct a Lagrangian for physical theory depending two sets field variables, starting from guess the equations only such set. This setup is particularly appealing construction modified theories gravity since can take lessons GR "educated guess" metric equations; other fields are then fixed by obtained (up terms completely independent tensor). In present paper, we explore applications bootstrapping in...
Einstein gravity supplemented by a scalar field nonminimally coupled to Gauss–Bonnet term provides an example of model scalar-tensor where hairy black holes do exist. We consider the classical equations within metric endowed with NUT-charge and obtain two-parameter family nutty-hairy holes. The pattern these solutions in exterior interior their horizon is studied some details. influence both — hairs on lightlike timelike geodesics emphasized.
We examine the teleparallel formulation of non-minimally coupled scalar Einstein-Gauss-Bonnet gravity. In formulation, gravity is described by torsion instead curvature, causing usual Gauss-Bonnet invariant expressed through curvature to decay into two separate invariants built from torsion. Consequently, permits broader possibilities for non-minimal couplings between spacetime geometry and field. our theory, there are different branches equations in spherical symmetry depending on how one...
In this paper, we find new scalarized black holes by coupling a scalar field with the Gauss-Bonnet invariant in Teleparallel gravity. The formulation of theory uses torsion instead curvature to describe gravitational interaction and it turns out that, language, usual term four dimensions, decays two distinct boundary terms, invariants. Both can be coupled individually, or any combination field, obtain extension equivalent general relativity. study contains familiar Riemannian...