SCATTERING OF COSMIC STRINGS BY BLACK HOLES: LOOP FORMATION

We study the deformation of a long cosmic string by a nearby rotating black hole. We examine whether the deformation of a cosmic string, induced by the gravitational field of a Kerr black hole, may lead to the formation of a string loop. The segment of the string which enters the ergo-sphere of a rotating black hole gets deformed and, if it is sufficiently twisted, it can self-intersect, chopping off a loop. We find that the formation of a loop, via such a mechanism, is a rare event. It will only arise in a small region of the collision phase space, which depends on the string velocity, the impact parameter and the black hole angular momentum. We conclude that, generically, a long cosmic string is simply scattered, or captured, by a nearby rotating black hole.

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Polarimetric signatures of the photon ring of a black hole that is pierced by a cosmic axion string

Journal of High Energy Physics ◽

10.1007/jhep08(2021)160 ◽

2021 ◽

Vol 2021 (8) ◽

Author(s):

Alexander Gußmann

Keyword(s):

Black Holes ◽

Black Hole ◽

Formation Mechanism ◽

Cosmic String ◽

Cosmic Strings ◽

Supermassive Black Holes ◽

Rotating Black Hole ◽

Aharonov Bohm ◽

Polarized Photons

Abstract A black hole image contains a bright ring of photons that have closely circled the black hole on their way from the source to the detector. Here, we study the photon ring of a rotating black hole which is pierced by a global hyper-light axion-type cosmic string. We show that the coupling 𝜙F$$ \overset{\sim }{F} $$ F ~ between the axion 𝜙 and the photon can give rise to a unique polarimetric structure of the photon ring. The structure emerges due to an Aharonov-Bohm type effect that leads to a change of the polarization directions of linear polarized photons when they circle the black hole. For several parameter choices, we determine concrete polarization patterns in the ring. Measuring these patterns can provide us with a way of determining the value of the coefficient of the mixed anomaly between electromagnetism and the symmetry that gave rise to the cosmic string. Finally, we briefly review a possible formation mechanism of black holes that are pierced by cosmic strings and discuss under which conditions we can expect such objects to be present as supermassive black holes in the center of galaxies.

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Possible imprints of cosmic strings in the shadows of galactic black holes

International Journal of Modern Physics D ◽

10.1142/s0218271814500606 ◽

2014 ◽

Vol 23 (07) ◽

pp. 1450060 ◽

Cited By ~ 22

Author(s):

Vassil K. Tinchev ◽

Stoytcho S. Yazadjiev

Keyword(s):

Black Holes ◽

Black Hole ◽

Cosmic String ◽

Cosmic Strings ◽

Kerr Black Hole ◽

Black Hole Spin ◽

Deficit Angle ◽

Spin Parameter ◽

Shadow Cast

We examine the shadow cast by a Kerr black hole pierced by a cosmic string. The observable images depend not only on the black hole spin parameter and the angle of inclination, but also on the deficit angle yielded by the cosmic string. The dependence of the observable characteristics of the shadow on the deficit angle is explored. The imprints in the black hole shadow left by the presence of a cosmic string can serve in principle as a method for observational detection of such strings.

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GRAVITATIONAL CAPTURE OF COSMIC STRINGS BY A BLACK HOLE

International Journal of Modern Physics D ◽

10.1142/s0218271898000632 ◽

1998 ◽

Vol 07 (06) ◽

pp. 957-967 ◽

Cited By ~ 14

Author(s):

JEAN-PIERRE DE VILLIERS ◽

VALERI FROLOV

Keyword(s):

Black Hole ◽

Impact Parameter ◽

Cosmic String ◽

Initial Velocity ◽

Cosmic Strings ◽

Gravitational Interaction ◽

Equations Of Motion ◽

Great Distance ◽

Schwarzschild Black Hole ◽

Gravitational Capture

The gravitational interaction of an infinitely long cosmic string with a Schwarzschild black hole is studied. We consider a straight string that is initially at a great distance and moving at some initial velocity v (0 < v < c) towards the black hole. The equations of motion of the string are solved numerically to obtain the dependence of the capture impact parameter on the initial velocity.

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Global embeddings and hydrodynamic properties of Kerr black hole

Modern Physics Letters A ◽

10.1142/s0217732316502047 ◽

2016 ◽

Vol 31 (35) ◽

pp. 1650204

Author(s):

Soon-Tae Hong

Keyword(s):

Black Holes ◽

Black Hole ◽

Equatorial Plane ◽

Kerr Black Hole ◽

Kerr Spacetime ◽

Stable Circular Orbit ◽

Massive Particles ◽

Flat Embedding ◽

Bound Orbits ◽

The Impact

In the presence of a rotating Kerr black hole, we investigate hydrodynamics of the massive particles and massless photons to construct relations among number density, pressure and internal energy density of the massive particles and photons around the rotating Kerr black hole and to study an accretion onto the black hole. On equatorial plane of the Kerr black hole, we investigate the bound orbits of the massive particles and photons around the black hole to produce their radial, azimuthal and precession frequencies. With these frequencies, we study the black holes GRO J1655-40 and 4U 1543-47 to explicitly obtain the radial, azimuthal and precession frequencies of the massive particles in the flow of perfect fluid. We next consider the massive particles in the stable circular orbit of radius of 1.0 ly around the supernovas SN 1979C, SN 1987A and SN 2213-1745 in the Kerr curved spacetime, and around the potential supermassive Schwarzschild black holes M87, NGC 3115, NGC 4594, NGC 3377, NGC 4258, M31, M32 and Galatic center, to estimate their radial and azimuthal frequencies, which are shown to be the same results as those in no precession motion. The photon unstable orbit is also discussed in terms of the impact parameter of the photon trajectory. Finally, on the equatorial plane of the Kerr black hole, we construct the global flat embedding structures possessing (9 + 3) dimensionalities outside and inside the event horizon of the rotating Kerr black hole. Moreover, on the plane, we investigate the warp products of the Kerr spacetime.

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MULTI-BLACK HOLES SOLUTION WITH COSMIC STRINGS

International Journal of Modern Physics A ◽

10.1142/s0217751x04017756 ◽

2004 ◽

Vol 19 (10) ◽

pp. 1549-1557 ◽

Cited By ~ 8

Author(s):

F. ÖZDEMIR ◽

N. ÖZDEMIR ◽

B. T. KAYNAK

Keyword(s):

Black Holes ◽

Black Hole ◽

Angular Momentum ◽

Cosmic String ◽

Circular Orbit ◽

Cosmic Strings ◽

De Sitter ◽

Circular Orbits ◽

Small Oscillations ◽

String Models

Some black hole-cosmic string models such as Reissner–Nordström, RN–de Sitter, Kerr–Newman and multi-black holes with cosmic string are given. Energy and angular momentum of a timelike particle in circular orbits in multi-black hole space–time are calculated. The geodesic equations for the timelike particles for the far region of the multi-black hole sources are calculated and small oscillations around the circular orbit obtained. It is seen that the particle's orbit precesses like the Lens–Thirring effect.

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Scattering of a long cosmic string by a rotating black hole

Classical and Quantum Gravity ◽

10.1088/0264-9381/19/23/308 ◽

2002 ◽

Vol 19 (23) ◽

pp. 5987-6007 ◽

Cited By ~ 11

Author(s):

Martin Snajdr ◽

Valeri Frolov ◽

Jean-Pierre De Villiers

Keyword(s):

Black Hole ◽

Cosmic String ◽

Rotating Black Hole

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Confronting the Models of 3 : 2 QPOs with the Evidence of Near Extreme Kerr Black Hole

Proceedings of the International Astronomical Union ◽

10.1017/s1743921312019801 ◽

2012 ◽

Vol 8 (S290) ◽

pp. 239-240

Author(s):

Andrea Kotrlová ◽

Gabriel Török ◽

Eva Šrámková ◽

Zdeněk Stuchlík

Keyword(s):

Black Hole ◽

High Frequency ◽

Kerr Black Hole ◽

Black Hole Mass ◽

Tidal Disruption ◽

Periodic Oscillations ◽

Rotating Black Hole ◽

Spectral Fitting ◽

Generic Problem ◽

The Individual

AbstractThe black hole mass and spin estimates assuming various specific models of the 3 : 2 high frequency quasi-periodic oscillations (HF QPOs) have been carried out in Török et al. (2005, 2011). Here we briefly summarize some current points. Spectral fitting of the spin a ≡ cJ/GM2 in the microquasar GRS 1915 + 105 reveals that this system can contain a near extreme rotating black hole (e.g., McClintock et al., 2011). Confirming the high value of the spin would have significant consequences for the theory of the HF QPOs. The estimate of a > 0.9 is almost inconsistent with the relativistic precession (RP), tidal disruption (TD), and the warped disc (WD) model. The epicyclic resonance (Ep) and discoseismic models assuming the c- and g- modes are instead favoured. However, consideration of all three microquasars that display the 3 : 2 HF QPOs leads to a serious puzzle because the differences in the individual spins, such as a = 0.9 compared to a = 0.7, represent a generic problem almost for any unified orbital 3:2 QPO model.

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On the limiting energy of the collision of elementary particles close to horizon of the rotating black hole

Modern Physics Letters A ◽

10.1142/s0217732320502624 ◽

2020 ◽

Vol 35 (31) ◽

pp. 2050262

Author(s):

A. A. Grib ◽

Yu. V. Pavlov

Keyword(s):

Black Hole ◽

Electromagnetic Radiation ◽

Gravitational Radiation ◽

Charged Particles ◽

Kerr Black Hole ◽

Elementary Particles ◽

Rotating Black Hole ◽

Energy Growth

Arguments are given for the conclusion that the energy of collision of two ultrarelativistic elementary particles due to gravitational radiation cannot exceed the Planck value. Comparison of the gravitational and electromagnetic radiation for charged particles close to the horizon of Kerr black hole is made. If for trans-Planckian energy the black hole can arise it is shown that the energy growth used in scattering for interaction of particles is still limited.

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ABSORPTION OF A PARTICLE BY A ROTATING BLACK HOLE

International Journal of Modern Physics A ◽

10.1142/s0217751x12501552 ◽

2012 ◽

Vol 27 (27) ◽

pp. 1250155 ◽

Cited By ~ 1

Author(s):

LEON HELLER

Keyword(s):

Black Hole ◽

Angular Momentum ◽

Test Particle ◽

Kerr Black Hole ◽

Negative Energy ◽

Positive Energy ◽

Energy Particle ◽

Rotating Black Hole ◽

Particle Approximation

We examine the absorption of a test particle by a near-extreme Kerr black hole, including both positive and negative energy particles. Allowing arbitrary values of the particle's radial momentum at the horizon, we display the region in which the absorption of the particle would "overspin" the black hole and also the region in which it would reduce the area of the black hole. The portions of these regions for a positive energy particle, shrink and disappear as the angular momentum of the initial black hole approaches the extreme Kerr limit. But even in that limit the absorption of a negative energy particle can reduce the area. Proposals to go beyond the test particle approximation are also discussed.

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