A5011416197- Black Holes and Theoretical Physics
- Cosmology and Gravitation Theories
- Pulsars and Gravitational Waves Research
- Astrophysical Phenomena and Observations
- Relativity and Gravitational Theory
- Particle physics theoretical and experimental studies
- Astrophysics and Cosmic Phenomena
- Noncommutative and Quantum Gravity Theories
- Nonlinear Waves and Solitons
- Geophysics and Gravity Measurements
- Quantum Electrodynamics and Casimir Effect
- Quantum Chromodynamics and Particle Interactions
- Galaxies: Formation, Evolution, Phenomena
- Geophysics and Sensor Technology
- Advanced Differential Geometry Research
- High-Energy Particle Collisions Research
- Seismic Waves and Analysis
- Dark Matter and Cosmic Phenomena
- Advanced Mathematical Physics Problems
- Astronomy and Astrophysical Research
- Fluid Dynamics and Vibration Analysis
- Particle Accelerators and Free-Electron Lasers
- Stability and Controllability of Differential Equations
- Computational Physics and Python Applications
- Neutrino Physics Research
Universidade Federal do ABC
2015-2024
Silesian University in Opava
2018-2023
Czech Academy of Sciences, Institute of Physics
2018-2023
Carl von Ossietzky Universität Oldenburg
2020-2021
Goethe University Frankfurt
2014-2017
University of Tübingen
2011-2017
University of Cambridge
2012-2013
All-Russian research Institute of metrological service
2012
Universidade de São Paulo
2006-2011
Oles Honchar Dnipro National University
2003-2006
Perturbations of black holes, initially considered in the context possible observations astrophysical effects, have been studied for past 10 years string theory, brane-world models, and quantum gravity. Through famous gauge/gravity duality, proper oscillations perturbed called quasinormal modes, allow description hydrodynamic regime dual finite temperature field theory at strong coupling, which can be used to predict behavior quark-gluon plasmas nonperturbative regime. On other hand,...
The WKB approach for finding quasinormal modes of black holes, suggested in Schutz and Will (1985 Astrophys. J. Lett. 291 L33–6) by at the first order later developed to higher orders (Iyer 1987 Phys. Rev. D 35 3621; Konoplya 2003 68 024018; Matyjasek Opala 2017 96 024011), became popular during past decades, because, unlike more sophisticated numerical approaches, it is automatic different effective potentials mostly provides sufficient accuracy. At same time, seeming simplicity resulted...
Collaborative international efforts under the name of Event Horizon Telescope project, using sub- mm very long baseline interferometry, are soon expected to provide first images shadow cast by candidate supermassive black hole in our Galactic center, Sagittarius A*. Observations this would direct evidence existence astrophysical holes. Although it is that holes described axisymmetric Kerr solution, there also exist many other solutions, both general relativity and theories gravity, which...
Following previous work of ours in spherical symmetry, we here propose a new parametric framework to describe the spacetime axisymmetric black holes generic metric theories gravity. In this case, components are functions both radial and polar angular coordinates, forcing double expansion obtain expression. particular, use continued-fraction terms compactified coordinate express dependence, while exploit Taylor cosine angle for dependence. These choices lead superior convergence direction an...
Recently the LIGO and VIRGO Collaborations reported observation of gravitational-wave signal corresponding to inspiral merger two black holes, resulting into formation final hole. It was shown that observations are consistent with Einstein theory gravity high accuracy, limited mainly by statistical error. Angular momentum mass hole were determined rather large allowance tens percents. Here we shall show this indeterminacy in range black-hole parameters allows for some non-negligible...
Einstein's General Theory of Relativity (GR) successfully describes gravity. The most fundamental predictions GR are black holes (BHs), but in spite many convincing BH candidates the Universe, there is no conclusive experimental proof their existence using astronomical observations electromagnetic spectrum. Are BHs real astrophysical objects? Does hold its extreme limit or alternatives needed? prime target to address these questions center our own Galaxy, which hosts closest and...
Blázquez-Salcedo et al. [Phys. Rev. Lett. 126, 101102 (2021)PRLTAO0031-900710.1103/PhysRevLett.126.101102] obtained asymptotically flat traversable wormhole solutions in the Einstein-Dirac-Maxwell theory without using phantom matter. The normalizable numerical found therein require a peculiar behavior at throat: mirror symmetry relatively throat leads to nonsmoothness of gravitational and matter fields. In particular, one must postulate changing sign fermionic charge density throat,...
Various profiles of matter distribution in galactic halos (such as Navarro-Frenk-White, Burkert, Hernquist, Moore, Taylor-Silk and others) are considered here the source term for Einstein equations. We solve these equations find exact solutions which represent metric a central black hole immersed halo. Even though general case solution is numerical, very accurate analytical metric, includes all particular models, found astrophysically relevant regime, when mass galaxy much smaller than...
We demonstrate that the late time oscillatory tails of massive gravitons, present in both theories gravity and effectively extra-dimensional scenarios, could potentially contribute to gravitational waves with very long wavelengths. However, their impact on recent pulsar timing array observations might be relatively small, predominantly consisting radiation emitted by black holes our region Milky Way.
We propose a new parametric framework to describe in generic metric theories of gravity the spacetime spherically symmetric and slowly rotating black holes. In contrast similar approaches proposed so far, we do not use Taylor expansion powers M/r, where M r are mass hole radial coordinate, respectively. Rather, continued-fraction terms compactified coordinate. This choice leads superior convergence properties allows us approximate number known with much smaller set coefficients. The measure...
We test the stability of various wormholes and black holes supported by a scalar field with negative kinetic term. The general axial perturbations monopole type polar are considered in linear approximation. Two classes objects considered: (i) flat asymptotic behavior at one end AdS on other (M-AdS wormholes) (ii) regular asymptotically de Sitter expansion far beyond horizon (the so-called universes). A difficulty such studies is that effective potential for forms an infinite wall throats, if...
Recently it has been argued that the phantom thin-shell wormholes matched with Schwarzschild space-time near radius ring like black holes at early times, but differently late times [1]. Here we consider perturbations of wormhole which was constructed without thin-shells: Bronnikov-Ellis supported by matter and electromagnetic field. This solution is known to be stable under specific equation state matter. We show if one does not use above matching, wormhole, depending on values its...
A ($3+1$)-dimensional Einstein-Gauss-Bonnet theory of gravity has been recently formulated by Glavan and Lin [D. C. Lin, Phys. Rev. Lett. 124, 081301 (2020)] which is different from the pure Einstein theory, i.e., bypasses Lovelock's theorem avoids Ostrogradsky instability. The was in $D>4$ dimensions its action consists Einstein-Hilbert term with a cosmological constant, while Gauss-Bonnet multiplied factor $1/(D\ensuremath{-}4)$. Then, four-dimensional defined as limit...
Here we construct approximate analytical forms for the metric coefficients and fields representing scalarized Einstein-Maxwell black holes with various couplings of scalar field, once parameters system are fixed. By increasing approximation order, one can obtain analytic representation any desired accuracy, what was tested via calculations shadows these by using accurate numerical functions. We share Mathematica code which allows to find an appropriate form values parameters. Scalarization...
Recently, numerical solutions to the field equations of Einstein-scalar-Gauss-Bonnet gravity that correspond black-holes with non-trivial scalar hair have been reported. Here, we employ method continued-fraction expansion in terms a compact coordinate order obtain an analytical approximation for aforementioned solutions. For wide variety coupling functionals Gauss-Bonnet term were able expressions metric functions and field. In addition estimated accuracy these approximations by calculating...
Metric of axially symmetric asymptotically flat black holes in an arbitrary metric theory gravity can be represented the general form which depends on infinite number parameters. We constrain this class metrics by requiring existence additional symmetries, lead to separation variables Hamilton-Jacobi and Klein-Gordon equations, show that once functions change sufficiently moderately some region near hole, black-hole shadow a few deformation parameters only. analyze influence these shadow....
Asymptotically safe gravity is based on the idea that main contribution to Schwarzschild-like black hole spacetime due value of gravitational coupling which depends distance from origin and approaches its classical in far zone. However, at some stage this approach has an arbitrariness choice identification parameter. The two cases are considered here: first, by modified proper length (the Bonanno-Reuter metric), second, Kretschmann scalar metric for case coincides, up redefinition constants,...
We find accurate quasinormal frequencies of a quantum corrected black hole constructed in the renormalization group theory via coordinate-independent iterative procedure, leading to Dymnikova regular hole. show that while fundamental mode is only slightly affected by correction, overtones change at much stronger rate. This outburst occurs because deformation geometry Schwarzschild solely near event horizon. For finding values we developed general procedure allowing one use Leaver method...
Abstract Although the WKB series converges only asymptotically and guarantees exact result solely in eikonal regime, we have managed to derive concise analytical expressions for quasinormal modes grey-body factors of black holes, expanding beyond approximation. Remarkably, these demonstrate unexpectedly strong accuracy. We suggest a comprehensive approach deriving at various orders Two cases are examined as examples: Schwarzschild-de Sitter hole hairy holes within framework Effective Field...
Abstract Quasinormal modes and grey-body factors are spectral characteristics corresponding to different boundary conditions: the former imply purely outgoing waves event horizon infinity, while latter allow for an incoming wave from horizon, thus describing a scattering problem. Nevertheless, we show that there is link between these two characteristics. We establish approximate correspondence quasinormal factors, which becomes exact in high-frequency (eikonal) regime. that, eikonal regime,...
We find quasinormal spectrum of the massive scalar field in background Kerr black holes. show that all found modes are damped under boundary conditions when $\mu M$ is not large, thereby implying stability field. This complements region determined by Beyer inequality for large masses that, similar to case a non-rotating holes, term does contribute regime high damping. Thereby, damping asymptotic should be same as massless
We make an extensive study of evolution gravitational perturbations $D$-dimensional black holes in Gauss-Bonnet theory. There is instability at higher multipoles $\ensuremath{\ell}$ and large coupling $\ensuremath{\alpha}$ for $D=5$, 6, which stabilized $D$. Although a small negative gap the effective potential scalar type exists $D$ whatever $\ensuremath{\alpha}$, it does not lead to any instability.