Wave trapping by acoustic black hole: Simultaneous reduction of sound reflection and transmission

2021 ◽  
Vol 118 (11) ◽  
pp. 114101
Author(s):  
Yongzhen Mi ◽  
Wei Zhai ◽  
Li Cheng ◽  
Chenyang Xi ◽  
Xiang Yu
Keyword(s):  
Black Hole ◽  
Reflection And Transmission ◽  
Simultaneous Reduction ◽  
Wave Trapping ◽  
Sound Reflection

A study of the coupled gravitational and electromagnetic perturbations to the Reissner-Nordström black hole: the scattering matrix, energy conversion, and quasi-normal modes

1980 ◽  
Vol 296 (1422) ◽  
pp. 497-526 ◽  
Keyword(s):  
Black Hole ◽  
Electromagnetic Waves ◽  
Wave Equations ◽  
Normal Modes ◽  
Scattering Matrix ◽  
Gravitational Energy ◽  
Reflection And Transmission ◽  
Potential Barriers ◽  
Factor C ◽  
Incident Waves

The reflection and absorption, by the charged spherically symmetric Reissner-Nordström black hole, of an arbitrary superposition of gravitational and electromagnetic waves, with time dependence e iot and analyzed into spherical harmonics of various orders l , are expressed in terms of the complex reflection and transmission amplitudes (for incident waves) by two one-dimensional potential barriers. These amplitudes, expressed in terms of eight quantities (and composing the scattering matrix), are tabulated for various values of o,l (= 2, 3, and 6) and charge of the black hole. By virtue of the coupling of electromagnetic and gravitational perturbations by the charge of the black hole, the energy in an incident wave, which is purely gravitational, is, in part, reflected as electromagnetic waves; and conversely. This transformation of incident gravitational energy into electromagnetic energy (and vice versa) is expressed in terms of a conversion factor C and plotted in a series of graphs as a function of o for various values of l and the charge on the black hole Q * . Finally, the complex frequencies belonging to the quasi-normal modes (i.e., solutions of the underlying wave equations which correspond to purely outgoing waves at infinity and purely ingoing waves at the horizon) are tabulated. It is found that the imaginary part of these frequencies (which determine the damping of arbitrary initial perturbations of the black hole) is very nearly the same for all modes (with different l ’s) and Q * .

THE SCALAR FIELD IN EXTREME REISSNER–NORDSTRÖM–DE SITTER SPACE

2003 ◽  
Vol 18 (26) ◽  
pp. 4829-4836 ◽  
Author(s):  
GUANG-HAI GUO ◽  
YUAN-XING GUI ◽  
JIAN-XIANG TIAN
Keyword(s):  
Black Hole ◽  
Field Equation ◽  
Scalar Field ◽  
Special Interest ◽  
Field Amplitude ◽  
Cosmological Horizon ◽  
De Sitter ◽  
Reflection And Transmission ◽  
Transmission Coefficients ◽  
Tortoise Coordinate

By generalizing the method of I. Brevik et al. the scalar field equation between the outer black hole horizon and the cosmological horizon in the extreme Reissner–Nordström–de Sitter (RNdS) geometry is solved. The field amplitude, as well as the potential, is shown graphically by introducing the "tangent" approximation, which is more exact than that used by I. Brevik et al., of the tortoise coordinate. There are two limiting cases of our special interest. The first one is when the cosmological horizon is very close to the outer horizon of the "black hole." The second one is when they are far apart. And the reflection and transmission coefficients are worked out in the two cases respectively.

scholarly journals HAWKING TEMPERATURE FROM SCATTERING OFF THE CHARGED 2-D BLACK HOLE

1995 ◽  
Vol 10 (37) ◽  
pp. 2853-2861 ◽  
Author(s):  
JIN YOUNG KIM ◽  
H.W. LEE ◽  
Y.S. MYUNG
Keyword(s):  
Black Hole ◽  
Reflection Coefficient ◽  
Potential Barrier ◽  
Hawking Temperature ◽  
Bogoliubov Transformation ◽  
Reflection And Transmission ◽  
Transmission Coefficients ◽  
Approximate Form ◽  
Complicated Form ◽  
Dilaton Black Hole

The charged 2-D black hole is visualized as presenting a potential barrier Vout(r*) to incoming tachyon wave. Since this takes the complicated form, an approximate form VAPP(r*) is used for scattering analysis. We calculate the reflection and transmission coefficients for scattering of tachyon off the charged 2-D black hole. The Hawking temperature is also derived from the reflection coefficient by Bogoliubov transformation. In the limit Q→0, we recover the Hawking temperature of the 2-D dilaton black hole.

Parabolas from Reconstructed Surfaces Observed in Convergent-Beam RHEED Patterns

1990 ◽  
Vol 48 (2) ◽  
pp. 398-399
Author(s):  
M. Gajdardziska-Josifovska
Keyword(s):  
Electron Microscopy ◽  
High Energy ◽  
Two Dimensional ◽  
High Energy Electron ◽  
Reflection And Transmission ◽  
Experimental Diffraction Pattern ◽  
Surface Resonance ◽  
Reconstructed Surfaces ◽  
Reflection Electron Microscopy ◽  
Convergent Beam

Parabolas have been observed in the reflection high-energy electron diffraction (RHEED) patterns from surfaces of single crystals since the early thirties. In the last decade there has been a revival of attempts to elucidate the origin of these surface parabolas. The renewed interest stems from the need to understand the connection between the parabolas and the surface resonance (channeling) condition, the latter being routinely used to obtain higher intensity in reflection electron microscopy (REM) images of surfaces. Several rather diverging descriptions have been proposed to explain the parabolas in the reflection and transmission Kikuchi patterns. Recently we have developed an unifying general treatment in which the parabolas are shown to be K-lines of two-dimensional lattices. Here we want to review the main features of this description and present an experimental diffraction pattern from a 30° MgO (111) surface which displays parabolas that can be attributed to the surface reconstruction.

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