scholarly journals Innermost stable circular orbit near dirty black holes in magnetic field and ultra-high-energy particle collisions

Author(s):  
O. B. Zaslavskii
2015 ◽  
Vol 30 (06) ◽  
pp. 1550027 ◽  
Author(s):  
O. B. Zaslavskii

There are different versions of collisions of two particles near black holes with unbound energy E cm in the center of mass frame. The so-called BSW effect arises when a slow fine-tuned "critical" particle hits a rapid "usual" one. We discuss a scenario of collision in the strong magnetic field for which explanation turns out to be different. Both particles are rapid but the nonzero angle between their velocities (which are both close to c, the speed of light) results in a relative velocity close to c and, hence, big E cm .


2015 ◽  
Vol 336 (10) ◽  
pp. 1013-1016 ◽  
Author(s):  
M. Yu. Piotrovich ◽  
Yu. N. Gnedin ◽  
N. A. Silant'ev ◽  
T. M. Natsvlishvili ◽  
S. D. Buliga

2021 ◽  
Vol 81 (1) ◽  
Author(s):  
Monimala Mondal ◽  
Farook Rahaman ◽  
Ksh. Newton Singh

AbstractGeodesic motion has significant characteristics of space-time. We calculate the principle Lyapunov exponent (LE), which is the inverse of the instability timescale associated with this geodesics and Kolmogorov–Senai (KS) entropy for our rotating Kerr–Kiselev (KK) black hole. We have investigate the existence of stable/unstable equatorial circular orbits via LE and KS entropy for time-like and null circular geodesics. We have shown that both LE and KS entropy can be written in terms of the radial equation of innermost stable circular orbit (ISCO) for time-like circular orbit. Also, we computed the equation marginally bound circular orbit, which gives the radius (smallest real root) of marginally bound circular orbit (MBCO). We found that the null circular geodesics has larger angular frequency than time-like circular geodesics ($$Q_o > Q_{\sigma }$$ Q o > Q σ ). Thus, null-circular geodesics provides the fastest way to circulate KK black holes. Further, it is also to be noted that null circular geodesics has shortest orbital period $$(T_{photon}< T_{ISCO})$$ ( T photon < T ISCO ) among the all possible circular geodesics. Even null circular geodesics traverses fastest than any stable time-like circular geodesics other than the ISCO.


2019 ◽  
Vol 209 ◽  
pp. 01053
Author(s):  
Francisco Pedreira

The study of correlations between observations of different messengers from extreme sources of the Universe has emerged as an outstanding way to make progress in astrophysics. The Pierre Auger Observatory is capable of significant contributions as an ultra-high energy particle detector, particularly through its capability to search for inclined showers produced by neutrinos. We describe the neutrino searches made with the Observatory with particular emphasis on the recent results following the detections of gravitational waves from binary mergers with Advanced LIGO and VIRGO, leading to competitive limits.


2016 ◽  
Vol 31 (04) ◽  
pp. 1650029 ◽  
Author(s):  
O. B. Zaslavskii

We consider collision of two particles in rotating spacetimes without horizons. If the metric coefficient responsible for rotation of spacetime is big enough, the energy of collisions in the center of mass frame can be as large as one likes. This can happen in the ergoregion only. The results are model-independent and apply both to relativistic stars and wormholes.


Universe ◽  
2020 ◽  
Vol 6 (12) ◽  
pp. 227
Author(s):  
Oleg B. Zaslavskii

We suggest two new scenarios of high-energy particle collisions in the background of a wormhole. In scenario 1, the novelty consists of the fact that the effect does not require two particles coming from different mouths. Instead, all such scenarios of high energy collisions develop, when an experimenter sends particles towards a wormhole from the same side of the throat. For static wormholes, this approach leads to indefinitely large energy in the center of mass. For rotating wormholes, it makes possible the super-Penrose process (unbounded energies measured at infinity). In scenario 2, one of colliding particles oscillates near the wormhole throat from the very beginning. In this sense, scenario 2 is intermediate between the standard one and scenario 1 since the particle under discussion does not come from infinity at all.


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