scholarly journals Wave properties of isothermal magneto-rotational fluids

2009 ◽  
Vol 87 (8) ◽  
pp. 879-894 ◽  
Author(s):  
M. Sharif ◽  
Umber Sheikh
Keyword(s):  
Black Hole ◽  
Kerr Black Hole ◽  
Production Region ◽  
Complex Wave ◽  
Isothermal Plasma ◽  
Veselago Medium ◽  
General Relativistic ◽  
Phase And Group Velocities ◽  
Wave Properties ◽  
Group Velocities

In this paper, the isothermal plasma-wave properties in the neighborhood of the pair-production region for the Kerr black-hole magnetosphere are discussed. We consider the Fourier-analyzed form of the perturbed general relativistic magnetohydrodynamical equations whose determinant leads to a dispersion relation. For the special scenario, the x-components of the complex wave vectors are calculated numerically. Respective components of the propagation vector, attenuation vector, phase and group velocities are shown in graphs. We have investigated, in particular, the existence of a Veselago medium and wave behavior (modes of waves dispersion).

scholarly journals Wave properties of plasma surrounding the event horizon of a nonrotating black hole

2008 ◽  
Vol 86 (11) ◽  
pp. 1265-1285 ◽  
Author(s):  
M Sharif ◽  
G Mustafa
Keyword(s):  
Black Hole ◽  
Event Horizon ◽  
Schwarzschild Black Hole ◽  
Magnetohydrodynamics Equations ◽  
Normal Dispersion ◽  
Isothermal Plasma ◽  
General Relativistic ◽  
Relativistic Magnetohydrodynamics ◽  
Wave Properties ◽  
Complex Dispersion

We study the wave properties of a cold isothermal plasma in the vicinity of a Schwarzschild black-hole event horizon. The Fourier-analyzed perturbed 3+1 general relativistic magnetohydrodynamics equations are examined such that the complex dispersion relations are obtained for nonrotating, rotating nonmagnetized, and rotating magnetized backgrounds. The propagation and attenuation vectors along with the refractive index are obtained (shown graphically) to study the dispersive properties of the medium near the event horizon. The results show that no information can be obtained from the Schwarzschild magnetosphere. Further, the pressure stops the existence of normal dispersion of waves.PACS Nos.: 95.30.Sf, 95.30.Qd, 04.30.Nk

scholarly journals Influence of the geometric configuration of accretion flow on the black hole spin dependence of relativistic acoustic geometry

2018 ◽  
Vol 27 (03) ◽  
pp. 1850023 ◽  
Author(s):  
Pratik Tarafdar ◽  
Tapas K. Das
Keyword(s):  
Black Hole ◽  
Kerr Black Hole ◽  
Geometric Configuration ◽  
Surface Gravity ◽  
Linear Perturbation ◽  
Flow Profile ◽  
White Hole ◽  
Accretion Flow ◽  
Black Hole Spin ◽  
General Relativistic

Linear perturbation of general relativistic accretion of low angular momentum hydrodynamic fluid onto a Kerr black hole leads to the formation of curved acoustic geometry embedded within the background flow. Characteristic features of such sonic geometry depend on the black hole spin. Such dependence can be probed by studying the correlation of the acoustic surface gravity [Formula: see text] with the Kerr parameter [Formula: see text]. The [Formula: see text]–[Formula: see text] relationship further gets influenced by the geometric configuration of the accretion flow structure. In this work, such influence has been studied for multitransonic shocked accretion where linear perturbation of general relativistic flow profile leads to the formation of two analogue black hole-type horizons formed at the sonic points and one analogue white hole-type horizon which is formed at the shock location producing divergent acoustic surface gravity. Dependence of the [Formula: see text]–[Formula: see text] relationship on the geometric configuration has also been studied for monotransonic accretion, over the entire span of the Kerr parameter including retrograde flow. For accreting astrophysical black holes, the present work thus investigates how the salient features of the embedded relativistic sonic geometry may be determined not only by the background spacetime, but also by the flow configuration of the embedding matter.

DISPERSION RELATIONS FOR COLD PLASMA AROUND THE HORIZON OF SCHWARZSCHILD–DE SITTER BLACK HOLE

2010 ◽  
Vol 19 (02) ◽  
pp. 113-135
Author(s):  
M. KHAYRUL HASAN
Keyword(s):  
Black Hole ◽  
Cold Plasma ◽  
Wave Number ◽  
Linear Perturbation ◽  
De Sitter ◽  
Rindler Coordinates ◽  
General Relativistic ◽  
Phase And Group Velocities ◽  
The Waves ◽  
Complex Dispersion

In this paper, we investigate the wave properties of cold plasma in the vicinity of Schawarzchild–de Sitter black hole horizon using 3 + 1 formalism. The general relativistic magnetohydrodynamical equations are formulated for this space–time with the use of Rindler coordinates. We consider both the rotating and nonrotating surroundings with magnetized and nonmagnetized plasmas. Linear perturbation and Fourier analysis techniques are applied by introducing simple harmonic waves. We derive complex dispersion relation from the determinant of Fourier analyzed equations for each case which provides real and complex values of the wave number. From the wave number we determine the phase and group velocities, the refractive index etc., which are used to discuss the characteristics of the waves around the event horizon.

scholarly journals Particle-in-cell simulations of pair discharges in a starved magnetosphere of a Kerr black hole

2018 ◽  
Vol 616 ◽  
pp. A184 ◽  
Author(s):  
Amir Levinson ◽  
Benoît Cerutti
Keyword(s):  
Black Hole ◽  
Pair Production ◽  
Gamma Ray ◽  
Kerr Black Hole ◽  
Particle In Cell ◽  
Spark Gap ◽  
Total Luminosity ◽  
General Relativistic ◽  
Low Amplitude ◽  
Gap Width

We investigate the dynamics and emission of a starved magnetospheric region (gap) formed in the vicinity of a Kerr black hole horizon, using a new, fully general relativistic particle-in-cell code that implements Monte Carlo methods to compute gamma-ray emission and pair production through the interaction of pairs and gamma rays with soft photons emitted by the accretion flow. It is found that when the Thomson length for collision with disk photons exceeds the gap width, screening of the gap occurs through low-amplitude, rapid plasma oscillations that produce self-sustained pair cascades, with quasi-stationary pair and gamma-ray spectra, and with a pair multiplicity that increases in proportion to the pair production opacity. The gamma-ray spectrum emitted from the gap peaks in the TeV band, with a total luminosity that constitutes a fraction of about 10−5 of the corresponding Blandford−Znajek power. This stage is preceded by a prompt discharge phase of duration ∼rg/c, during which the potential energy initially stored in the gap is released as a flare of curvature TeV photons. We speculate that the TeV emission observed in M87 may be produced by pair discharges in a spark gap.

scholarly journals The Response of Black Hole Spark Gaps to External Changes: A Production Mechanism of Rapid TeV Flares?

2022 ◽  
Vol 924 (1) ◽  
pp. 28
Author(s):  
Shota Kisaka ◽  
Amir Levinson ◽  
Kenji Toma ◽  
Idan Niv
Keyword(s):  
Black Hole ◽  
Active Galactic Nuclei ◽  
Kerr Black Hole ◽  
Galactic Nuclei ◽  
One Dimensional ◽  
Particle In Cell ◽  
Abrupt Changes ◽  
Crossing Time ◽  
General Relativistic ◽  
Soft Disk

Abstract We study the response of a starved Kerr black hole magnetosphere to abrupt changes in the intensity of disk emission and in the global magnetospheric current, by means of one-dimensional general relativistic particle-in-cell simulations. Such changes likely arise from the intermittency of the accretion process. We find that in cases where the pair-production opacity contributed by the soft disk photons is modest, as in, e.g., M87, such changes can give rise to delayed, strong teraelectronvolt (TeV) flares, dominated by curvature emission of particles accelerated in the gap. The flare rise time, and the delay between the external variation and the onset of the flare emitted from the outer gap boundary, are of the order of the light-crossing time of the gap. The rapid, large-amplitude TeV flares observed in M87, and perhaps, other active galactic nuclei may be produced by such a mechanism.

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