569 research outputs found
Shadow of a Schwarzschild black hole surrounded by a Bach-Weyl ring
We have studied the shadows of a Schwarzschild black hole surrounded by a
Bach-Weyl ring through the backward ray-tracing method. The presence of
Bach-Weyl ring leads to that the photon dynamical system is non-integrable and
then chaos would appear in the photon motion, which affects sharply the black
hole shadow. The size and shape the black hole shadow depend on the black hole
parameter, the Bach-Weyl ring mass and the Weyl radius between black hole and
ring. Some self-similar fractal structures also appear in the black hole
shadow, which originates from the chaotic lensing. We also study the change of
the image of Bach-Weyl ring with the ring mass and the Weyl radius. Finally, we
analyze the invariant manifolds of Lyapunov orbits near the fixed points and
discuss further the formation of the shadow of a Schwarzschild black hole with
Bach-Weyl ring.Comment: 16 pages,8 figures, the version published in EPJ
Chaos in the motion of a test scalar particle coupling to Einstein tensor in Schwarzschild-Melvin black hole spacetime
We present firstly the equation of motion for a test scalar particle coupling
to Einstein tensor in the Schwarzschild-Melvin black hole spacetime through the
short-wave approximation. Through analysing Poincar\'{e} sections, the power
spectrum, the fast Lyapunov exponent indicator and the bifurcation diagram, we
investigate the effects of coupling parameter on the chaotic behavior of the
particles. With the increase of the coupling strength, we find that the motion
of coupled particle for the chosen parameters becomes more regular and order
for the negative couple constant. While, for the positive one, the motion of
coupled particles first undergoes a series of transitions between chaotic
motion and regular motion and then falls into horizon or escapes to spatial
infinite. Our results show that the coupling brings about richer effects for
the motion of the particles.Comment: 18 pages, 9 figures. The title is changed, some content and
references are modified. Accepted by EPJC for publication;arXiv admin note:
text overlap with arXiv:1604.0278
Particle energy and Hawking temperature
Some authors have recently found that the tunneling approach gives a
different Hawking temperature for a Schwarzschild black hole in a different
coordinate system. In this paper, we find that to work out the Hawking
temperature in a different coordinate system by the tunneling approach, we must
use the correct definition of the energy of the radiating particles. By using a
new definition of the particle energy, we obtain the correct Hawking
temperature for a Schwarzschild black hole in two dynamic coordinate systems,
the Kruskal-Szekers and dynamic Lemaitre coordinate systems.Comment: 11 pages; Accepted by PL
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