Juhua Chen

Absorption and scattering of scalar wave from Schwarzschild black hole surrounded by magnetic field

The magnetic field is one of the most important constituents of the cosmic space and one of the main sources of the dynamics of interacting matter in the universe. The astronomical observations imply the existence of a strong magnetic fields of up to 10 − 10G near supermassive black holes in the active galactic nuclei and even around stellar mass black holes. In this paper, with the quantum scattering theory, we analysis the Schröedinger-type scalar wave equation of black hole immersed in magnetic field and numerically investigate its absorption cross section and scattering cross section. We find that the absorption cross sections oscillate about the geometric optical value in the high frequency regime. Furthermore in low frequency regime, the magnetic field makes the absorption cross section weaker and this effect is more obviously on lower frequency brand. On the other hand, for the effects of scattering cross sections for the black hole immersed in magnetic field, we find that the magnetic field makes the scattering flux weaker and its width narrower in the forward direction. We find that there also exists the glory phenomenon along the backforward direction. At fixed frequency, the glory peak is higher and the glory width becomes narrower due to the black hole immersed in magnetic field.

SCATTERING OF SCALAR WAVE FROM BLACK HOLE IN HOŘAVA–LIFSHITZ GRAVITY

Using the partial wave method, we analyze the Schroedinger-type scalar wave equation from black hole in Hořava–Lifshitz gravity and numerically investigate its absorption cross section and scattering cross section. We find that the absorption cross section oscillates around the geometric optical value in the high frequency regime, and the scattering angle width becomes narrower and the damping oscillation pattern becomes more complex as the angular momentum l increases. With fixed frequency of scalar wave ω, the glory peak becomes lower and the glory width becomes wider as the coupling parameter α increases.

Geodesic Structure of Janis-Newman-Winicour Space-time

In the present paper we study the geodesic structure of the Janis-Newman-Winicour(JNW) space-time which contains a strong curvature naked singularity. This metric is an extension of the Schwarzschild geometry included a massless scalar field. We find that the strength parameter μ of the scalar field takes affection on the geodesic structure of the JNW space-time. By solving the geodesic equation and analyzing the behavior of effective potential, we investigate all geodesic types of the test particle and the photon in the JNW space-time. At the same time we simulate all the geodesic orbits corresponding to the energy levels of the effective potential in the JNW space-time.

Chaotic Motion of a Charged Particle around a Weakly Magnetized Schwarzschild Black Hole Containing Cosmic String

We discuss the conditions where a charged particle that was originally revolving around a weakly magnetized black hole containing cosmic string in the innermost stable circular orbit will escape to infinity after it is kicked by another particle or photon. We find that the motion of the kicked particle is chaotic. The critical escape energy and velocity of the kicked charged particle with different initial radial velocities are obtained.

Spinning Particle in Gravitational Field of Black Hole Involving Global Monopole

In this paper we study the dynamics of trajectory of a spinning particle in a Schwarzschild spacetime involving a global monopole. We set up the equations of motion and find three types of trajectories. We study the conditions that a spinning particle, originally moving in the innermost stable circular orbit around the black hole involving a global monopole, will escape to infinity after it is kicked by another particle or photon. Three types of trajectories of a spinning particle in a Schwarzschild spacetime involving a global monopole are simulated in detail and the escaping energy and velocity of the spinning particle is also obtained in the present paper.

Distribution of entropy of Bardeen regular black hole with corrected state density

We consider corrections to all orders in the Planck length on the quantum state density, and calculate the statistical entropy of the scalar field on the background of the Bardeen regular black hole numerically. We obtain the distribution of entropy which is inside the horizon of black hole and the contribution of the vicinity of horizon takes a great part of the whole entropy.

Critical escape velocity for a charged particle in Ernst spacetime

Motion of a charged particle in Ernst spacetime is discussed. We study the conditions that a charged particle, originally revolving around this black hole in the innermost stable circular orbit (ISCO), will escape to infinity after being kicked by another particle or photon. The motion of the kicked particle is chaotic. The critical escape energy and velocity of the charged particle are obtained in the present paper. Comparing to the Schwarzschild case, the kicked charged particle without the radial velocity needs more energy to escape in Ernst case for l > 0 and less energy to escape for l < 0.