Trajectories of photons in modified Hayward black hole spacetime

2019 ◽  
Vol 34 (23) ◽  
pp. 1950182 ◽  
Author(s):  
Jian-Ping Hu ◽  
Yu Zhang ◽  
Li-Li Shi ◽  
Guang-Hai Guo ◽  
Peng-Fei Duan
Keyword(s):  
Black Hole ◽  
Time Delay ◽  
Effective Potential ◽  
Circular Orbit ◽  
Null Geodesic ◽  
Quantum Corrections ◽  
Circular Orbits ◽  
Black Hole Spacetime ◽  
Bound Orbits ◽  
Lapse Function

We study the trajectories of photons in modified Hayward black hole spacetime. Three kinds of horizons are distinguished by analyzing the lapse function of modified Hayward black hole spacetime. Through plotting the effective potential with different values of parameters, it is found that the parameter [Formula: see text] has more conspicuous effects than parameters [Formula: see text] ([Formula: see text] is associated with the time-delay) and [Formula: see text] ([Formula: see text] is related to the 1-loop quantum corrections) for the effective potential. The change of the parameters ([Formula: see text], [Formula: see text] and [Formula: see text]) has an obvious influence on unstable circular orbits. The structure of null geodesic is simpler than that of time-like geodesic. The stable circular orbits and the bound orbits are not included for the photon trajectories. By analyzing the corresponding effective potential, all possible orbits of null geodesic are found. The radius of unstable circular orbit equals 2.8790 for fixed [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text].

Geodesic structure of the Clifton–Barrow black hole space–time

2019 ◽  
Vol 34 (22) ◽  
pp. 1950123
Author(s):  
Li-Li Shi ◽  
Jian-Ping Hu ◽  
Yu Zhang ◽  
Chen Ma ◽  
Peng-Fei Duan
Keyword(s):  
Black Hole ◽  
Circular Orbit ◽  
Orbital Motion ◽  
Null Geodesic ◽  
Space Time ◽  
Circular Orbits ◽  
Test Particles ◽  
Stable Circular Orbit ◽  
Geodesic Structure ◽  
Bound Orbits

In this paper, we investigate the geodesic structure of Clifton–Barrow black hole space–time. Through the numerical analysis of the effective potential and the motion equation, the orbital types of test particles and photons and the corresponding orbital motion diagrams of each orbital types under certain conditions are obtained. We find that angular momentum [Formula: see text] and [Formula: see text] determine the existence of bound orbits and circular orbits. And we also find that the radius of unstable circular orbit decreases with increases in [Formula: see text] while the radius of stable circular orbit increases. Furthermore, as [Formula: see text] increases, the radius of unstable circular orbit increases, while the radius of stable circular orbit decreases. For null geodesic, parameters [Formula: see text] and [Formula: see text] do not affect the types of null orbits. The radius of the unstable circular orbits increases with the increase of [Formula: see text]. However, the radius of the unstable circular orbits remains unchanged as [Formula: see text] increases. Also, we show that the precession direction of the bound orbits of the test particles is counterclockwise for [Formula: see text], but clockwise with [Formula: see text]. Moreover, different energy values have an effect on the curvature of escape and absorb orbits curve.

scholarly journals GEODESIC STRUCTURE OF TEST PARTICLE IN BARDEEN SPACETIME

2012 ◽  
Vol 21 (09) ◽  
pp. 1250077 ◽  
Author(s):  
SHENG ZHOU ◽  
JUHUA CHEN ◽  
YONGJIU WANG
Keyword(s):  
Black Hole ◽  
Energy Level ◽  
Test Particle ◽  
Effective Potential ◽  
Null Geodesic ◽  
Low Velocity ◽  
Effective Potentials ◽  
Black Hole Spacetime ◽  
Geodesic Structure ◽  
Bound Orbits

The Bardeen model describes a regular spacetime, i.e. a singularity-free black hole spacetime. In this paper, by analyzing the behavior of the effective potential for the particles and photons, we investigate the timelike and null geodesic structures in the Bardeen spacetime. At the same time, all kinds of orbits, which are allowed according to the energy level corresponding to the effective potentials, are numerically simulated in detail. We find many-world bound orbits, two-world escape orbits and escape orbits in this spacetime. We also find that bound orbits precession directions are opposite and their precession velocities are different, the inner bound orbits shift along counter-clockwise with high velocity while the exterior bound orbits shift along clockwise with low velocity.

Bekenstein–Hawking entropy by energy quantization from Reissner–Nordström black hole

2016 ◽  
Vol 25 (03) ◽  
pp. 1650034 ◽  
Author(s):  
M. Jakir Hossain ◽  
M. Atiqur Rahman ◽  
M. Ilias Hossain
Keyword(s):  
Black Hole ◽  
Angular Momentum ◽  
Test Particle ◽  
Effective Potential ◽  
Circular Orbits ◽  
Energy Quantization ◽  
Quantum Numbers ◽  
Black Hole Spacetime ◽  
Complete Set ◽  
Large Quantum

We consider the motion of a test particle orbiting around Reissner–Nordström (RN) black hole spacetime. The complete set of equations for radial motion and effective potential is derived. We also derive the radius of the different stable circular orbits of this particle corresponding to different label indexes like the Bohr atomic model. We also quantized the energy of this particle from the quantization of angular momentum and calculated the Bekenstein–Hawking entropy of RN black hole. We also investigate the change of entropy between two nearby states approaches to zero for large quantum numbers.

scholarly journals Circular orbits in the Taub–NUT and massless Taub–NUT spacetime

2017 ◽  
Vol 14 (07) ◽  
pp. 1750101
Author(s):  
Parthapratim Pradhan
Keyword(s):  
Black Hole ◽  
Circular Orbit ◽  
Center Of Mass ◽  
Null Geodesic ◽  
Spherically Symmetric ◽  
Potential Well ◽  
Killing Horizon ◽  
Stable Circular Orbit ◽  
Innermost Stable Circular Orbit

In this work, we study the equatorial causal geodesics of the Taub–NUT (TN) spacetime in comparison with massless TN spacetime. We emphasized both on the null circular geodesics and time-like circular geodesics. From the effective potential diagram of null and time-like geodesics, we differentiate the geodesics structure between TN spacetime and massless TN spacetime. It has been shown that there is a key role of the NUT parameter to changes the shape of pattern of the potential well in the NUT spacetime in comparison with massless NUT spacetime. We compared the innermost stable circular orbit (ISCO), marginally bound circular orbit (MBCO) and circular photon orbit (CPO) of the said spacetime with graphically in comparison with massless cases. Moreover, we compute the radius of ISCO, MBCO and CPO for extreme TN black hole (BH). Interestingly, we show that these three radii coincides with the Killing horizon, i.e. the null geodesic generators of the horizon. Finally in Appendix A, we compute the center-of-mass (CM) energy for TN BH and massless TN BH. We show that in both cases, the CM energy is finite. For extreme NUT BH, we found that the diverging nature of CM energy. First, we have observed that a non-asymptotic flat, spherically symmetric and stationary extreme BH showing such feature.

scholarly journals Particles collision near Kerr–Sen Dilaton-Axion black hole

2019 ◽  
Vol 35 (07) ◽  
pp. 2050033 ◽  
Author(s):  
Ujjal Debnath
Keyword(s):  
Black Hole ◽  
Effective Potential ◽  
Circular Orbit ◽  
Center Of Mass ◽  
Particle Accelerator ◽  
Cauchy Horizon ◽  
Mass Energy ◽  
Axially Symmetric ◽  
Neutral Particles ◽  
Center Of Mass Energy

Here, we consider axially symmetric, stationary, rotating and charged Kerr–Sen Dilaton-Axion black hole as particle accelerator. We find the effective potential and discuss the circular orbit of a particle. We investigate the center of mass energy of two colliding neutral particles with different rest masses falling from rest at infinity to near the non-extremal horizons (event horizon and Cauchy horizon) and extremal horizon of the Kerr–Sen Dilaton-Axion black hole. Analogous to the Compton process, we discuss the collision of a particle and a massless photon. Finally, we find the center of mass energy due to the collision of two photons in the background of Kerr–Sen Dilaton-Axion black hole.

scholarly journals Photon Spheres, ISCOs, and OSCOs: Astrophysical Observables for Regular Black Holes with Asymptotically Minkowski Cores

Universe ◽  
2020 ◽  
Vol 7 (1) ◽  
pp. 2
Author(s):  
Thomas Berry ◽  
Alex Simpson ◽  
Matt Visser
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Circular Orbit ◽  
Schwarzschild Black Hole ◽  
Circular Orbits ◽  
Regular Black Hole ◽  
Astrophysical Interest ◽  
Regular Black Holes ◽  
Recent Advances ◽  
Classical Black Holes

Classical black holes contain a singularity at their core. This has prompted various researchers to propose a multitude of modified spacetimes that mimic the physically observable characteristics of classical black holes as best as possible, but that crucially do not contain singularities at their cores. Due to recent advances in near-horizon astronomy, the ability to observationally distinguish between a classical black hole and a potential black hole mimicker is becoming increasingly feasible. Herein, we calculate some physically observable quantities for a recently proposed regular black hole with an asymptotically Minkowski core—the radius of the photon sphere and the extremal stable timelike circular orbit (ESCO). The manner in which the photon sphere and ESCO relate to the presence (or absence) of horizons is much more complex than for the Schwarzschild black hole. We find situations in which photon spheres can approach arbitrarily close to (near extremal) horizons, situations in which some photon spheres become stable, and situations in which the locations of both photon spheres and ESCOs become multi-valued, with both ISCOs (innermost stable circular orbits) and OSCOs (outermost stable circular orbits). This provides an extremely rich phenomenology of potential astrophysical interest.

scholarly journals MAGNETIZED PARTICLE MOTION AROUND BLACK HOLE IN BRANEWORLD

2011 ◽  
Vol 26 (06) ◽  
pp. 399-408 ◽  
Author(s):  
O. G. RAHIMOV
Keyword(s):  
Magnetic Field ◽  
Black Hole ◽  
Effective Potential ◽  
Particle Motion ◽  
Uniform Magnetic Field ◽  
Radial Motion ◽  
Circular Orbits ◽  
Spinning Particle ◽  
Jacobi Formalism

We investigate the motion of a magnetized particle orbiting around a black hole in braneworld immersed in asymptotically uniform magnetic field. The influence of brane parameter on effective potential of the radial motion of magnetized spinning particle around the braneworld black hole using Hamilton–Jacobi formalism is studied. It is found that circular orbits for photons and slowly moving particles may become stable near r = 3M. It was argued that the radii of the innermost stable circular orbits are sensitive on the change of brane parameter. Similar discussion without Weil parameter has been considered by de Felice et al. in Refs. 1 and 2.

MULTI-BLACK HOLES SOLUTION WITH COSMIC STRINGS

2004 ◽  
Vol 19 (10) ◽  
pp. 1549-1557 ◽  
Author(s):  
F. ÖZDEMIR ◽  
N. ÖZDEMIR ◽  
B. T. KAYNAK
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Angular Momentum ◽  
Cosmic String ◽  
Circular Orbit ◽  
Cosmic Strings ◽  
De Sitter ◽  
Circular Orbits ◽  
Small Oscillations ◽  
String Models

Some black hole-cosmic string models such as Reissner–Nordström, RN–de Sitter, Kerr–Newman and multi-black holes with cosmic string are given. Energy and angular momentum of a timelike particle in circular orbits in multi-black hole space–time are calculated. The geodesic equations for the timelike particles for the far region of the multi-black hole sources are calculated and small oscillations around the circular orbit obtained. It is seen that the particle's orbit precesses like the Lens–Thirring effect.

The null geodesics of the Reissner–Nordström black hole surrounded by quintessence

2015 ◽  
Vol 30 (10) ◽  
pp. 1550049 ◽  
Author(s):  
B. Malakolkalami ◽  
K. Ghaderi
Keyword(s):  
Black Hole ◽  
Effective Potential ◽  
Energy Levels ◽  
Schwarzschild Black Hole ◽  
Circular Orbits ◽  
Null Geodesics

In this paper, by using the effective potential for the photons, we analyze the null geodesics and all kinds of orbits corresponding to the energy levels for the Reissner–Nordström black hole surrounded by quintessence with [Formula: see text] and compare our results with those obtained for the Schwarzschild black hole surrounded by quintessence matter. We also investigate the circular orbits and calculate the angle of deflection of the photons.

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