scholarly journals Equatorial circular orbits of neutral test particles in the Kerr-Newman spacetime

2013 ◽  
Vol 88 (2) ◽  
Author(s):  
Daniela Pugliese ◽  
Hernando Quevedo ◽  
Remo Ruffini
Keyword(s):  
Circular Orbits ◽  
Neutral Test ◽  
Test Particles

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 Innermost stable circular orbits of charged spinning test particles

2019 ◽  
Vol 789 ◽  
pp. 393-398 ◽  
Author(s):  
Ming Zhang ◽  
Wen-Biao Liu
Keyword(s):  
Circular Orbits ◽  
Test Particles

Equatorial Circular Orbits of Neutral Test Particlesin Weyl Spacetimes

2014 ◽  
Vol 44 (4) ◽  
pp. 385-397 ◽  
Author(s):  
Framsol López-Suspes ◽  
Guillermo A. González
Keyword(s):  
Circular Orbits ◽  
Neutral Test

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.

Polar trajectories around a black hole in a magnetic field

1989 ◽  
Vol 67 (10) ◽  
pp. 971-973
Author(s):  
K. D. Krori ◽  
J. C. Sarmah
Keyword(s):  
Magnetic Field ◽  
Black Hole ◽  
Angular Momentum ◽  
Test Particle ◽  
Field Parameter ◽  
Schwarzschild Black Hole ◽  
Magnetic Field Parameter ◽  
Neutral Test ◽  
Test Particles ◽  
The Magnetic Field

In this paper, we present a study of the stable polar trajectories ([Formula: see text] = constant plane) of neutral test particles around a Schwarzschild black hole embedded in a magnetic field. We also show how the nature of these trajectories changes with the variation in the angular momentum of the test particle and the magnetic field parameter.

scholarly journals Geodesics in the field of a rotating deformed gravitational source

2016 ◽  
Vol 31 (02n03) ◽  
pp. 1641006 ◽  
Author(s):  
K. A. Boshkayev ◽  
H. Quevedo ◽  
M. S. Abutalip ◽  
Zh. A. Kalymova ◽  
Sh. S. Suleymanova
Keyword(s):  
Angular Momentum ◽  
Gravitational Field ◽  
Angular Velocity ◽  
Circular Orbits ◽  
Frame Dragging ◽  
Test Particles ◽  
Gravitational Source ◽  
Massive Particles ◽  
Analytic Expressions

We investigate equatorial geodesics in the gravitational field of a rotating and deformed source described by the approximate Hartle-Thorne metric. In the case of massive particles, we derive within the same approximation analytic expressions for the orbital angular velocity, the specific angular momentum and energy, and the radii of marginally stable and marginally bound circular orbits. Moreover, we calculate the orbital angular velocity and the radius of lightlike circular geodesics. We study numerically the frame dragging effect and the influence of the quadrupolar deformation of the source on the motion of test particles. We show that the effects originating from the rotation can be balanced by the effects due to the oblateness of the source.

scholarly journals Dynamics and epicyclic motions of particles around the Schwarzschild–de Sitter black hole in perfect fluid dark matter

2021 ◽  
Vol 81 (8) ◽  
Author(s):  
Javlon Rayimbaev ◽  
Sanjar Shaymatov ◽  
Mubasher Jamil
Keyword(s):  
Black Hole ◽  
Dark Matter ◽  
Perfect Fluid ◽  
Matter Field ◽  
De Sitter ◽  
Circular Orbits ◽  
Test Particles ◽  
Remarkable Result ◽  
The Impact ◽  
Twin Peak

AbstractIn this paper, we investigate circular orbits for test particles around the Schwarzschild–de Sitter (dS) black hole surrounded by perfect fluid dark matter. We determine the region of circular orbits bounded by innermost and outermost stable circular orbits. We show that the impact of the perfect fluid dark matter shrinks the region where circular orbits can exist as the values of both innermost and outermost stable circular orbits decrease. We find that for specific lower and upper values of the dark matter parameter there exist double matching values for inner and outermost stable circular orbits. It turns out that the gravitational attraction due to the dark matter contribution dominates over cosmological repulsion. This gives rise to a remarkable result in the Schwarzschild–de Sitter black hole surrounded by dark matter field in contrast to the Schwarzschild–de Sitter metric. Finally, we study epicyclic motion and its frequencies with their applications to twin peak quasi-periodic oscillations (QPOs) for various models. We find the corresponding values of the black hole parameters which could best fit and explain the observed twin peak QPO object GRS 1915+109 from microquasars.

scholarly journals Gravitational Capture Cross-Section of Particles by Schwarzschild-Tangherlini Black Holes

Universe ◽  
2021 ◽  
Vol 7 (8) ◽  
pp. 307
Author(s):  
Bobomurat Ahmedov ◽  
Ozodbek Rahimov ◽  
Bobir Toshmatov
Keyword(s):  
Black Hole ◽  
Cross Section ◽  
Cross Sections ◽  
Capture Cross Section ◽  
Higher Dimensions ◽  
Capture Cross ◽  
Circular Orbits ◽  
Test Particles ◽  
Dimensional Spacetime ◽  
Gravitational Capture

We study the capture cross-section of massless (photon) and massive test particles by the Schwarzschild–Tangherlini black hole, which is a solution of pure general relativity in higher dimensional spacetime with R×SD−2 topology. It is shown that an extra dimension weakens the gravitational attraction of a black hole, and consequently, radii of all the characteristic circular orbits, such as the radius of a photonsphere decrease in the higher dimensions. Furthermore, it is shown that in higher dimensions, there are no stable and bounded circular orbits. The critical impact parameters and capture cross-sections of photons and massive particles are calculated for several higher dimensions and it is shown that they also decrease with increasing dimension. Moreover, we calculate the capture cross-section of relativistic and non-relativistic test particles in the higher dimensions..

scholarly journals Coronal ejection and heating in variable-luminosity X-ray sources

2012 ◽  
Vol 8 (S290) ◽  
pp. 49-52
Author(s):  
Włodek Kluźniak
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Neutron Star ◽  
Neutron Stars ◽  
High Temperatures ◽  
Coronal Heating ◽  
Sudden Increase ◽  
Circular Orbits ◽  
X Ray ◽  
Test Particles

AbstractA sudden increase in stellar luminosity may lead to the ejection of a large part of any optically thin gas orbiting the star. Test particles in circular orbits will become unbound, and will escape to infinity (if radiation drag is neglected), when the luminosity changes from zero to at least one half the Eddington value, or more generally, from L to (LEdd+L)/2 or more. Conversely, a decrease in luminosity will lead to the tightening of orbits of optically thin fluid. Even a modest fluctuation of luminosity of accreting neutron stars or black holes is expected to lead to substantial coronal heating. Luminosity fluctuations may thus account for the high temperatures of the X-ray corona in accreting black hole and neutron star systems.

scholarly journals Parameters of innermost stable circular orbits of spinning test particles: Numerical and analytical calculations

2016 ◽  
Vol 22 (2) ◽  
pp. 138-147 ◽  
Author(s):  
O. Yu. Tsupko ◽  
G. S. Bisnovatyi-Kogan ◽  
P. I. Jefremov
Keyword(s):  
Circular Orbits ◽  
Test Particles
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