scholarly journals Newtonian wormholes with spherical symmetry and tidal forces on test particles

2015 ◽  
Vol 24 (09) ◽  
pp. 1542020 ◽  
Author(s):  
Paulo Luz ◽  
José P. S. Lemos
Keyword(s):  
Black Holes ◽  
Mass Density ◽  
Particle Dynamics ◽  
Spherically Symmetric ◽  
Tidal Effects ◽  
Curved Space ◽  
Asymptotically Flat ◽  
Newtonian Gravitation ◽  
Tidal Forces ◽  
Test Particles

A spherically symmetric wormhole in Newtonian gravitation in curved space, enhanced with a connection between the mass density and the Ricci scalar, is presented. The wormhole, consisting of two connected asymptotically flat regions, inhabits a spherically symmetric curved space. The gravitational potential, gravitational field and the pressure that supports the fluid that permeates the Newtonian wormhole are computed. Particle dynamics and tidal effects in this geometry are studied. The possibility of having Newtonian black holes in this theory is sketched.

scholarly journals Particle Motion around Charged Black Holes in Generalized Dilaton-Axion Gravity

2018 ◽  
Vol 2018 ◽  
pp. 1-8
Author(s):  
Susmita Sarkar ◽  
Farook Rahaman ◽  
Irina Radinschi ◽  
Theophanes Grammenos ◽  
Joydeep Chakraborty
Keyword(s):  
Black Holes ◽  
Gravitational Field ◽  
Effective Potential ◽  
Particle Motion ◽  
Spherically Symmetric ◽  
Asymptotically Flat ◽  
Four Dimensions ◽  
Charged Black Holes ◽  
Test Particles ◽  
Massive Particles

The behaviour of massive and massless test particles around asymptotically flat and spherically symmetric, charged black holes in the context of generalized dilaton-axion gravity in four dimensions is studied. All the possible motions are investigated by calculating and plotting the corresponding effective potential for the massless and massive particles as well. Further, the motion of massive (charged or uncharged) test particles in the gravitational field of charged black holes in generalized dilaton-axion gravity for the cases of static and nonstatic equilibrium is investigated by applying the Hamilton-Jacobi approach.

scholarly journals Motion of spinning particles in non asymptotically flat spacetimes

2020 ◽  
Vol 80 (7) ◽  
Author(s):  
Bobir Toshmatov ◽  
Ozodbek Rahimov ◽  
Bobomurat Ahmedov ◽  
Daniele Malafarina
Keyword(s):  
Vacuum Energy ◽  
Spherically Symmetric ◽  
Combined Effects ◽  
Circular Orbits ◽  
Spinning Particles ◽  
Asymptotically Flat ◽  
Asymptotic Flatness ◽  
Test Particles ◽  
Cosmological Context ◽  
Flat Spacetimes

Abstract The assumption of asymptotic flatness for isolated astrophysical bodies may be considered an approximation when one considers a cosmological context where a cosmological constant or vacuum energy is present. In this framework we study the motion of spinning particles in static, spherically symmetric and asymptotically non-flat spacetimes with repulsive cosmological vacuum energy and quintessential field. Due to the combined effects of gravitational attraction and cosmological repulsion, the region where stable circular orbits are allowed is restricted by an innermost and an outermost stable circular orbits. We show that taking into account the spin of test particles may enlarge or shrink the region of allowed stable circular orbits depending on whether the spin is co-rotating or counter-rotating with the angular momentum of the particles.

scholarly journals GENERATING STATIC, SPHERICALLY SYMMETRIC BLACK HOLES IN LOVELOCK GRAVITY

2009 ◽  
Vol 18 (13) ◽  
pp. 2061-2082 ◽  
Author(s):  
S. HABIB MAZHARIMOUSAVI ◽  
O. GURTUG ◽  
M. HALILSOY
Keyword(s):  
Black Holes ◽  
Higher Dimensions ◽  
Matter Field ◽  
Spherically Symmetric ◽  
Lovelock Gravity ◽  
Third Order ◽  
Naked Singularities ◽  
Test Particles ◽  
Higher Dimensional ◽  
Symmetric Black Hole

We present the generalization of a known theorem to generate static, spherically symmetric black hole solutions in higher-dimensional Lovelock gravity. Particular limits such as Gauss–Bonnet (GB) and Einstein–Hilbert (EH) in any dimension N yield all the solutions known to date with an energy–momentum. In our generalization, with special emphasis on third order Lovelock gravity, we have found two different class of solutions characterized by the matter field parameter. Several particular cases are studied and properties related to asymptotic behaviors are discussed. Our general solution, which covers topological black holes as well, splits naturally into distinct classes such as Chern–Simon (CS) and Born–Infeld (BI) in higher-dimensions. The occurence of naked singularities is studied and it is found that the space–time behaves nonsingularly in the quantum-mechanical sense when it is probed with quantum test particles. The theorem is extended to cover Bertotti–Robinson (BR) type solutions in the presence of the GB parameter alone. Finally, we prove also that extension of the theorem for a scalar–tensor source of higher dimensions (N > 4) fails to work.

scholarly journals Regular Bardeen Black Holes in Anti-de Sitter Spacetime versus Kerr Black Holes through Particle Dynamics

Galaxies ◽  
2021 ◽  
Vol 9 (3) ◽  
pp. 63
Author(s):  
Bakhtiyor Narzilloev ◽  
Javlon Rayimbaev ◽  
Ahmadjon Abdujabbarov ◽  
Bobomurat Ahmedov
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Magnetic Charge ◽  
Particle Dynamics ◽  
Kerr Metric ◽  
De Sitter Spacetime ◽  
De Sitter ◽  
Sitter Spacetime ◽  
Test Particles ◽  
Charge Parameter

In this work, test particle dynamics around a static regular Bardeen black hole (BH) in Anti-de Sitter spacetime has been studied. It has been shown for neutral test particles that parameters of a regular Bardeen black hole in Anti-de Sitter spacetime can mimic the rotation parameter of the Kerr metric up to the value a≈0.9 providing the same innermost stable circular orbit (ISCO) radius. We have also explored the dynamics of magnetized particles with a magnetic dipole moment around a magnetically charged regular Bardeen black hole in Anti-de Sitter spacetime. As a realistic astrophysical scenario of the study, we have treated neutron stars orbiting a supermassive black hole (SMBH), in particular, the magnetar PSR J1745-2900 orbiting Sgr A* with the parameter β=10.2, as magnetized test particles. The magnetized particles dynamics shows that the parameter β, negative values of cosmological constant and magnetic charge parameter of the central BH cause a decrease in the ISCO radius. We have compared the effects of the magnetic charge of the Bardeen BH with the spin of rotating Kerr BH and shown that magnetic charge parameter can mimic the spin in the range a/M≃(0,0.7896) when Λ=0 at the range of its values g/M≃(0,0.648).

scholarly journals BULK SHAPE OF BRANE-WORLD BLACK HOLES

2003 ◽  
Vol 18 (09) ◽  
pp. 651-660 ◽  
Author(s):  
ROBERTO CASADIO ◽  
LORENZO MAZZACURATI
Keyword(s):  
Black Holes ◽  
Brane World ◽  
Spherically Symmetric ◽  
Exact Integration ◽  
Asymptotically Flat

We propose a method to extend to the bulk asymptotically flat static spherically symmetric brane-world metrics. We employ the multipole (1/r) expansion in order to allow the exact integration of the relevant equations along the (fifth) extra coordinate and make contact with the parametrized post-Newtonian formalism. We apply our method to three families of solutions previously appeared as candidates of black holes in the brane world and show that the shape of the horizon is very likely a flat "pancake" for astrophysical sources.

scholarly journals TIDAL FORCES IN COLD BLACK HOLE SPACETIMES

2001 ◽  
Vol 10 (04) ◽  
pp. 529-538 ◽  
Author(s):  
K. K. NANDI ◽  
T. B. NAYAK ◽  
A. BHADRA ◽  
P. M. ALSING
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Spherically Symmetric ◽  
Black Hole Spacetimes ◽  
Tidal Forces ◽  
Black Hole Solutions

We investigate here the behavior of a few spherically symmetric static acclaimed black hole solutions in respect of tidal forces in the geodesic frame. It turns out that the forces diverge on the horizon of cold black holes (CBH) while for ordinary ones, they do not. It is pointed out that Kruskal-like extensions do not render the CBH metrics nonsingular. We present a CBH that is available in the Brans–Dicke theory for which the tidal forces do not diverge on the horizon and in that sense it is a better one.

scholarly journals CHARGE-CONFINING GRAVITATIONAL ELECTROVACUUM SHOCK WAVE

2014 ◽  
Vol 29 (03) ◽  
pp. 1450020 ◽  
Author(s):  
EDUARDO GUENDELMAN ◽  
EMIL NISSIMOV ◽  
SVETLANA PACHEVA
Keyword(s):  
Shock Wave ◽  
Nonlinear Electrodynamics ◽  
Spherically Symmetric ◽  
Square Root ◽  
De Sitter ◽  
Asymptotically Flat ◽  
Test Particles ◽  
Additional Constant ◽  
Finite Distance ◽  
Charged Test

In previous publications, we have extensively studied spherically symmetric solutions of gravity coupled to a nonstandard type of nonlinear electrodynamics containing a square-root of the ordinary Maxwell Lagrangian (the latter is known to yield quantum chromodynamic (QCD)-like confinement in a flat spacetime). A class of these solutions describe nonstandard black holes of Reissner–Nordström–(anti-)-de Sitter type with an additional constant radial vacuum electric field, in particular, a non-asymptotically flat Reissner–Nordström-type black hole. Here, we study the ultra-relativistic boost (Lousto–Sanchez extension of Aichelburg–Sexl) limit of the latter and show that, unlike the ordinary Reissner–Nordström case, we obtain a gravitational electrovacuum shock wave as a result of the persistence of the gauge field due to the "square-root" Maxwell Lagrangian term. Next, we show that this gravitational electrovacuum shock wave confines charged test particles (both massive and massless) within a finite distance from its front.

scholarly journals Noether symmetry approach to the non-minimally coupled $$Y(R)F^2$$ gravity

2020 ◽  
Vol 80 (7) ◽  
Author(s):  
Özcan Sert ◽  
Fatma Çeliktaş
Keyword(s):  
Black Holes ◽  
Thermodynamic Properties ◽  
Noether Symmetry ◽  
Spherically Symmetric ◽  
Field Equations ◽  
Lagrange Equations ◽  
Asymptotically Flat ◽  
Symmetry Approach ◽  
Static Solutions ◽  
Symmetry Assumption

Abstract We use Noether symmetry approach to find spherically symmetric static solutions of the non-minimally coupled electromagnetic fields to gravity. We construct the point-like Lagrangian under the spherical symmetry assumption. Then we determine Noether symmetry and the corresponding conserved charge. We derive Euler-Lagrange equations from this point-like Lagrangian and show that these equations are same with the differential equations derived from the field equations of the model. Also we give two new exact asymptotically flat solutions to these equations and investigate some thermodynamic properties of these black holes.

scholarly journals Special Vinberg cones and the entropy of BPS extremal black holes

2021 ◽  
Vol 2021 (11) ◽  
Author(s):  
Dmitri V. Alekseevsky ◽  
Alessio Marrani ◽  
Andrea Spiro
Keyword(s):  
Black Holes ◽  
Symmetric Space ◽  
Explicit Expression ◽  
Spherically Symmetric ◽  
Quadratic Map ◽  
Asymptotically Flat ◽  
Homogeneous Cones ◽  
Extremal Black Holes

Abstract We consider the static, spherically symmetric and asymptotically flat BPS extremal black holes in ungauged N = 2 D = 4 supergravity theories, in which the scalar manifold of the vector multiplets is homogeneous. By a result of Shmakova on the BPS attractor equations, the entropy of this kind of black holes can be expressed only in terms of their electric and magnetic charges, provided that the inverse of a certain quadratic map (uniquely determined by the prepotential of the theory) is given. This inverse was previously known just for the cases in which the scalar manifold of the theory is a homogeneous symmetric space. In this paper we use Vinberg’s theory of homogeneous cones to determine an explicit expression for such an inverse, under the assumption that the scalar manifold is homogeneous, but not necessarily symmetric. As immediate consequence, we get a formula for the entropy of BPS black holes that holds in any model of N = 2 supergravity with homogeneous scalar manifold.

ENERGY LOCALIZATION FOR DILATONIC BLACK HOLE GEOMETRIES WITH A PURE MONOPOLE FIELD

2010 ◽  
Vol 19 (08n10) ◽  
pp. 1253-1258
Author(s):  
I. RADINSCHI ◽  
T. GRAMMENOS
Keyword(s):  
Black Holes ◽  
Dimensional Space ◽  
Spherically Symmetric ◽  
Dilaton Field ◽  
Energy Localization ◽  
Asymptotically Flat ◽  
Adm Mass ◽  
Hairy Black Holes ◽  
Momentum Complex ◽  
Dilatonic Black Hole

The energy distribution of black holes with a dilaton and a pure monopole field is calculated by using Møller's energy–momentum complex. The four-dimensional space–times considered are static, spherically symmetric and asymptotically flat, exact solutions stemming from an action that besides gravity contains a dilaton field and a pure monopole field. The resulting "hairy" black holes have an essential singularity at the origin and two horizons. The energy obtained depends on the value of the dilaton field, the monopole charge and the ADM mass. All the momenta vanish for the space–time geometries considered.

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