scholarly journals Absorption and Scattering Cross Section of Regular Black Holes

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Hai Huang ◽  
Ping Liao ◽  
Juhua Chen ◽  
Yongjiu Wang
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Cross Section ◽  
Absorption Cross Section ◽  
High Frequency ◽  
Massless Scalar ◽  
Absorption Cross ◽  
High Frequency Region ◽  
Regular Black Hole ◽  
Regular Black Holes

By using the partial wave method, we investigate the absorption of massless scalar wave from regular black hole. We numerically carry out the absorption cross section and find that the larger angular momentum quantum number l is, the smaller the corresponding maximum value of partial absorption cross section is. Comparing with Schwarzschild case, the absorption cross section of regular black holes is strengthened in both low and high frequency regions, and the absorption cross section oscillates around the geometric optical value in the high frequency region. Generally speaking, the scattering flux is strengthened and its scattering width becomes narrower in the forward direction. There are obvious contrast of scattering properties of different type of regular black hole.

scholarly journals On-axis scalar absorption cross section of Kerr–Newman black holes: Geodesic analysis, sinc and low-frequency approximations

2018 ◽  
Vol 27 (11) ◽  
pp. 1843012 ◽  
Author(s):  
Carolina L. Benone ◽  
Luiz C. S. Leite ◽  
Luís C. B. Crispino ◽  
Sam R. Dolan
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Cross Section ◽  
Absorption Cross Section ◽  
Rotation Axis ◽  
Low Frequency ◽  
Massless Scalar ◽  
Massless Scalar Field ◽  
Absorption Cross ◽  
Newman Black Hole

We investigate null geodesics impinging parallel to the rotation axis of a Kerr–Newman black hole, and show that the absorption cross section for a massless scalar field in the eikonal limit can be described in terms of the photon orbit parameters. We compare our sinc and low-frequency approximations with numerical results, showing that they are in excellent agreement.

scholarly journals Absorption by stringy black holes

2021 ◽  
Vol 81 (12) ◽  
Author(s):  
Sérgio V. M. C. B. Xavier ◽  
Carolina L. Benone ◽  
Luís C. B. Crispino
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Cross Section ◽  
Absorption Cross Section ◽  
Massless Scalar ◽  
Absorption Cross ◽  
Charged Black Holes ◽  
Hole Charge ◽  
Newman Black Hole ◽  
The Difference

AbstractWe investigate the absorption of planar massless scalar waves by a charged rotating stringy black hole, namely a Kerr–Sen black hole. We compute numerically the absorption cross section and compare our results with those of the Kerr–Newman black hole, a classical general relativity solution. In order to better compare both charged black holes, we define the ratio of the black hole charge to the extreme charge as Q. We conclude that Kerr–Sen and Kerr–Newman black holes have a similar absorption cross section, with the difference increasing for higher values of Q.

scholarly journals Scalar waves in regular Bardeen black holes: Scattering, absorption and quasinormal modes

2016 ◽  
Vol 25 (09) ◽  
pp. 1641008 ◽  
Author(s):  
Caio F. B. Macedo ◽  
Luís C. B. Crispino ◽  
Ednilton S. de Oliveira
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Cross Section ◽  
Absorption Cross Section ◽  
Quasinormal Modes ◽  
Scalar Fields ◽  
Scattering Cross Section ◽  
Massless Scalar ◽  
Absorption Cross ◽  
Scattering Cross

We discuss the phenomenology of massless scalar fields around a regular Bardeen black hole, namely absorption cross-section, scattering cross-section and quasinormal modes. We compare the Bardeen and Reissner–Nordström black holes, showing limiting cases for which their properties are similar.

Absorption of massless scalar field by rotating black holes

2016 ◽  
Vol 25 (09) ◽  
pp. 1641024 ◽  
Author(s):  
Luiz C. S. Leite ◽  
Luís C. B. Crispino ◽  
Ednilton S. de Oliveira ◽  
Caio F. B. Macedo ◽  
Sam R. Dolan
Keyword(s):  
Black Holes ◽  
Scalar Field ◽  
Cross Section ◽  
Absorption Cross Section ◽  
High Frequency ◽  
Massless Scalar ◽  
Massless Scalar Field ◽  
Absorption Cross ◽  
Frequency Regime ◽  
Selection Of

We compute the absorption cross-section of the Kerr black holes (BH) for the massless scalar field, and present a selection of numerical results, to complement the results of Ref.[C. F. B. Macedo, L. C. S. Leite, E. S. Oliveria, S. R. Dolan and L. C. B. Crispino, Phys. Rev. D 88 (2013) 064033.] We show that, in the high-frequency regime, the cross-section approaches the geodesic capture cross-section. We split the absorption cross-section into corotating and counterrotating contributions, and we show that the counterrotating contribution exceeds the corotating one.

Absorption of zero-mass planar waves by dirty black holes

2018 ◽  
Vol 27 (11) ◽  
pp. 1843017 ◽  
Author(s):  
Caio F. B. Macedo ◽  
Luiz C. S. Leite ◽  
Luís C. B. Crispino
Keyword(s):  
Black Holes ◽  
Cross Section ◽  
Accretion Disks ◽  
Absorption Cross Section ◽  
Scalar Fields ◽  
Massless Scalar ◽  
Absorption Cross ◽  
Thin Spherical Shell ◽  
Nonlinear Nature ◽  
Selection Of

Astrophysical black holes are often with companions, including other gravitating objects, accretion disks, electromagnetic fields, and others. Because of the nonlinear nature of general relativity, it is difficult to account for the gravitational effects of these companions, which can only be investigated analytically for very few cases. In this paper, we consider black holes with surrounding matter — often called dirty black holes — and analyze the absorption cross section of massless scalar fields. We start by laying out the generic setup for spherically symmetric scenarios and then specify for a simple model. We consider planar massless scalar waves impinging upon a Schwarzschild black hole surrounded by a thin spherical shell, and compute the absorption cross section. We present a selection of numerical results complementary to those presented in [C. F. B. Macedo, L. C. S. Leite and L. C. B. Crispino, Phys. Rev. D 93 (2016) 024027, arXiv:1511.08781 [gr-qc]] for arbitrary frequencies, considering different values of the shell position as well as its mass.

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

2012 ◽  
Vol 21 (05) ◽  
pp. 1250045 ◽  
Author(s):  
HAO LIAO ◽  
JUHUA CHEN ◽  
YONGJIU WANG
Keyword(s):  
Black Hole ◽  
Cross Section ◽  
Absorption Cross Section ◽  
High Frequency ◽  
Coupling Parameter ◽  
Absorption Cross ◽  
Scalar Wave ◽  
Fixed Frequency ◽  
Oscillation Pattern ◽  
Frequency Regime

Using the partial wave method, we analyze the Schröedinger-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.

scholarly journals Mimicking Black Holes in General Relativity

2021 ◽  
Author(s):  
Thomas Berry
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Black Hole ◽  
Thin Shell ◽  
Classical General Relativity ◽  
Regular Black Hole ◽  
Regular Black Holes ◽  
Traversable Wormholes ◽  
Hole Model ◽  
Linearised Stability

<p><b>The central theme of this thesis is the study and analysis of black hole mimickers. The concept of a black hole mimicker is introduced, and various mimicker spacetime models are examined within the framework of classical general relativity. The mimickers examined fall into the classes of regular black holes and traversable wormholes under spherical symmetry. The regular black holes examined can be further categorised as static spacetimes, however the traversable wormhole is allowed to have a dynamic (non-static) throat. Astrophysical observables are calculated for a recently proposed regular black hole model containing an exponential suppression of the Misner-Sharp quasi-local mass. This same regular black hole model is then used to construct a wormhole via the "cut-and-paste" technique. The resulting wormhole is then analysed within the Darmois-Israel thin-shell formalism, and a linearised stability analysis of the (dynamic) wormhole throat is undertaken. Yet another regular black hole model spacetime is proposed, extending a previous work which attempted to construct a regular black hole through a quantum "deformation" of the Schwarzschild spacetime. The resulting spacetime is again analysed within the framework of classical general relativity. </b></p><p>In addition to the study of black hole mimickers, I start with a brief overview of the theory of special relativity where a new and novel result is presented for the combination of relativistic velocities in general directions using quaternions. This is succeed by an introduction to concepts in differential geometry needed for the successive introduction to the theory of general relativity. A thorough discussion of the concept of spacetime singularities is then provided, before analysing the specific black hole mimickers discussed above.</p>

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