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.

CHARGED SPINNING PARTICLES ON CIRCULAR ORBITS IN THE REISSNER–NORDSTRÖM SPACE–TIME

2005 ◽  
Vol 14 (10) ◽  
pp. 1793-1811 ◽  
Author(s):  
DONATO BINI ◽  
ANDREA GERALICO ◽  
FERNANDO DE FELICE
Keyword(s):  
Equatorial Plane ◽  
Space Time ◽  
Circular Orbits ◽  
Spinning Particles ◽  
Arrival Times ◽  
Opposite Charge ◽  
Test Particles

The behavior of charged spinning test particles moving along circular orbits in the equatorial plane of the Reissner–Nordström space–time is studied in the framework of the Dixon–Souriau model completed with standard choices of supplementary conditions. The gravitomagnetic "clock effect," i.e. the delay in the arrival times of two oppositely circulating particles as measured by a static observer, is derived and discussed in the cases in which the particles have equal/opposite charge and spin, the latter being directed along the z-axis.

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 Spherically symmetric analytic solutions and naked singularities in Einstein–Aether theory

2021 ◽  
Vol 81 (4) ◽  
Author(s):  
R. Chan ◽  
M. F. A. da Silva ◽  
V. H. Satheeshkumar
Keyword(s):  
Analytic Solutions ◽  
Spherically Symmetric ◽  
Naked Singularities ◽  
Asymptotically Flat ◽  
First Case ◽  
Killing Horizon ◽  
Flat Spacetimes ◽  
Free Parameters ◽  
Pathological Behavior ◽  
Vacuum Solutions

AbstractWe analyze all the possible spherically symmetric exterior vacuum solutions allowed by the Einstein–Aether theory with static aether. We show that there are three classes of solutions corresponding to different values of a combination of the free parameters, $$c_{14}=c_1+c_4$$ c 14 = c 1 + c 4 , which are: $$ 0< c_{14}<2$$ 0 < c 14 < 2 , $$c_{14} < 0$$ c 14 < 0 , and $$c_{14}=0$$ c 14 = 0 . We present explicit analytical solutions for $$c_{14}=3/2, 16/9, 48/25, -16$$ c 14 = 3 / 2 , 16 / 9 , 48 / 25 , - 16 and 0. The first case has some pathological behavior, while the rest have all singularities at $$r=0$$ r = 0 and are asymptotically flat spacetimes. For the solutions $$c_{14}=16/9, 48/25\, \mathrm {\, and \,}\, -16$$ c 14 = 16 / 9 , 48 / 25 and - 16 we show that there exist no horizons, neither Killing horizon nor universal horizon, thus we have naked singularities. This characteristic is completely different from general relativity. We briefly discuss the thermodynamics for the case $$c_{14}=0$$ c 14 = 0 where the horizon exists.

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 BMS field theories and Weyl anomaly

2021 ◽  
Vol 2021 (7) ◽  
Author(s):  
Arjun Bagchi ◽  
Sudipta Dutta ◽  
Kedar S. Kolekar ◽  
Punit Sharma
Keyword(s):  
Three Dimensions ◽  
Field Theories ◽  
Partition Functions ◽  
Two Dimensional ◽  
Speed Of Light ◽  
Asymptotically Flat ◽  
Weyl Invariance ◽  
Flat Spacetimes ◽  
Liouville Action ◽  
Null Surfaces

Abstract Two dimensional field theories with Bondi-Metzner-Sachs symmetry have been proposed as duals to asymptotically flat spacetimes in three dimensions. These field theories are naturally defined on null surfaces and hence are conformal cousins of Carrollian theories, where the speed of light goes to zero. In this paper, we initiate an investigation of anomalies in these field theories. Specifically, we focus on the BMS equivalent of Weyl invariance and its breakdown in these field theories and derive an expression for Weyl anomaly. Considering the transformation of partition functions under this symmetry, we derive a Carrollian Liouville action different from ones obtained in the literature earlier.

scholarly journals Soft photon theorem in the small negative cosmological constant limit

2021 ◽  
Vol 2021 (8) ◽  
Author(s):  
Nabamita Banerjee ◽  
Karan Fernandes ◽  
Arpita Mitra
Keyword(s):  
Cosmological Constant ◽  
Tree Level ◽  
Leading Order ◽  
Asymptotically Flat ◽  
Soft Factor ◽  
Flat Spacetime ◽  
Electromagnetic Interactions ◽  
Flat Spacetimes ◽  
Perturbative Corrections ◽  
Soft Factors

Abstract We study the effect of electromagnetic interactions on the classical soft theorems on an asymptotically AdS background in 4 spacetime dimensions, in the limit of a small cosmological constant or equivalently a large AdS radius l. This identifies 1/l2 perturbative corrections to the known asymptotically flat spacetime leading and subleading soft factors. Our analysis is only valid to leading order in 1/l2. The leading soft factor can be expected to be universal and holds beyond tree level. This allows us to derive a 1/l2 corrected Ward identity, following the known equivalence between large gauge Ward identities and soft theorems in asymptotically flat spacetimes.

scholarly journals Observations of Hawking radiation: the Page curve and baby universes

2021 ◽  
Vol 2021 (4) ◽  
Author(s):  
Donald Marolf ◽  
Henry Maxfield
Keyword(s):  
Black Holes ◽  
Quantum Systems ◽  
Late Time ◽  
Asymptotically Flat ◽  
Black Hole Information ◽  
Flat Spacetimes ◽  
The Cost ◽  
Baby Universes ◽  
Time Extrapolation ◽  
Asymptotic Observers

AbstractWe reformulate recent insights into black hole information in a manner emphasizing operationally-defined notions of entropy, Lorentz-signature descriptions, and asymptotically flat spacetimes. With the help of replica wormholes, we find that experiments of asymptotic observers are consistent with black holes as unitary quantum systems, with density of states given by the Bekenstein-Hawking formula. However, this comes at the cost of superselection sectors associated with the state of baby universes. Spacetimes studied by Polchinski and Strominger in 1994 provide a simple illustration of the associated concepts and techniques, and we argue them to be a natural late-time extrapolation of replica wormholes. The work aims to be self-contained and, in particular, to be accessible to readers who have not yet mastered earlier formulations of the ideas above.

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