2021/03/01 by Bakhtiyor Narzilloev, Javlon Rayimbaev, Ahmadjon Abdujabbarov +2
Physics and Astronomy · #Astrophysical Phenomena and Observations #Black Holes and Theoretical Physics #Charged particle #Dipole #Magnetic dipole #Magnetic field #Parameter space #Quantum Electrodynamics and Casimir Effect #RADIUS #Rotating black hole #Rotating magnetic field #Rotation (mathematics) #gr-qc
paper · pdf · doi:10.1140/epjc/s10052-021-09074-z
published as Eur. Phys. J. C (2021) 81:269 · 14 pages, 11 figures. Accepted for publication in EPJC
openalex publication_date 2021/03/01 · arxiv created 2021/03/20 · openalex created_date 2021/03/29 · arxiv updated 2021/04/06 · openalex updated_date 2026/08/05
Abstract In the present paper, we have investigated the motion of charged particles together with magnetic dipoles to determine how well the spacetime deviation parameter ε <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>ϵ</mml:mi> </mml:math> and external uniform magnetic field can mimic the spin of a rotating Kerr black hole. Investigation of charged particle motion has shown that the deviation parameter ε <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>ϵ</mml:mi> </mml:math> in the absence of an external magnetic fields can mimic the rotation parameter of the Kerr spacetime up to a/M ≈ 0.5 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>a</mml:mi> <mml:mo>/</mml:mo> <mml:mi>M</mml:mi> <mml:mo>≈</mml:mo> <mml:mn>0.5</mml:mn> </mml:mrow> </mml:math> . The combination of an external magnetic field and deviation parameter can do even a better job mimicking the rotation parameter up to a/M≃ 0.93 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>a</mml:mi> <mml:mo>/</mml:mo> <mml:mi>M</mml:mi> <mml:mo>≃</mml:mo> <mml:mn>0.93</mml:mn> </mml:mrow> </mml:math> , which corresponds to the rapidly rotating case. Study of the dynamics of the magnetic dipoles around quasi-Schwarzschild black holes in the external magnetic field has shown that there are degeneracy values of the ISCO radius of test particles at ε crgt;ε ≥ 0.35 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msub> <mml:mi>ϵ</mml:mi> <mml:mrow> <mml:mi>cr</mml:mi> </mml:mrow> </mml:msub> <mml:mo>></mml:mo> <mml:mi>ϵ</mml:mi> <mml:mo>≥</mml:mo> <mml:mn>0.35</mml:mn> </mml:mrow> </mml:math> which may lead to two different values of the innermost stable circular orbit (ISCO) radius. When the deviation parameter is in the range of ε ∈ (-1, 1) <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>ϵ</mml:mi> <mml:mo>∈</mml:mo> <mml:mo>(</mml:mo> <mml:mo>-</mml:mo> <mml:mn>1</mml:mn> <mml:mo>,</mml:mo> <mml:mspace/> <mml:mn>1</mml:mn> <mml:mo>)</mml:mo> </mml:mrow> </mml:math> , it can mimic the spin of a rotating Kerr black hole in the range a/M ∈ (0.0537, 0.3952) <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>a</mml:mi> <mml:mo>/</mml:mo> <mml:mi>M</mml:mi> <mml:mo>∈</mml:mo> <mml:mo>(</mml:mo> <mml:mn>0.0537</mml:mn> <mml:mo>,</mml:mo> <mml:mspace/> <mml:mn>0.3952</mml:mn> <mml:mo>)</mml:mo> </mml:mrow> </mml:math> for magnetic dipoles with values of the magnetic coupling parameter β ∈ [-0.25, 0.25] <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>β</mml:mi> <mml:mo>∈</mml:mo> <mml:mo>[</mml:mo> <mml:mo>-</mml:mo> <mml:mn>0.25</mml:mn> <mml:mo>,</mml:mo> <mml:mspace/> <mml:mn>0.25</mml:mn> <mml:mo>]</mml:mo> </mml:mrow> </mml:math> in corotating orbits.