Dynamics of charged particles and magnetic dipoles around magnetized quasi-Schwarzschild black holes

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 $$\epsilon $$ ϵ 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 $$\epsilon $$ ϵ in the absence of an external magnetic fields can mimic the rotation parameter of the Kerr spacetime up to $$a/M \approx 0.5$$ a / M ≈ 0.5 . The combination of an external magnetic field and deviation parameter can do even a better job mimicking the rotation parameter up to $$a/M\simeq 0.93$$ a / M ≃ 0.93 , 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 $$\epsilon _{cr}>\epsilon \ge 0.35$$ ϵ cr > ϵ ≥ 0.35 which may lead to two different values of the innermost stable circular orbit (ISCO) radius. When the deviation parameter is in the range of $$\epsilon \in (-1,\ 1)$$ ϵ ∈ ( - 1 , 1 ) , it can mimic the spin of a rotating Kerr black hole in the range $$a/M \in (0.0537, \ 0.3952)$$ a / M ∈ ( 0.0537 , 0.3952 ) for magnetic dipoles with values of the magnetic coupling parameter $$\beta \in [-0.25,\ 0.25]$$ β ∈ [ - 0.25 , 0.25 ] in corotating orbits.

Dynamics of charged test particles around quantum-corrected Schwarzschild black holes

“…The motion of charged particles around black holes is a useful tool to test modified gravity theories and plays an important role to get an insight into black holes physics (see Refs. [7,8,15,16,[124][125][126][127][128][129][130][131][132][133][134][135][136][137][138][139][140] and references therein). Particularly, in the presence of the external magnetic field, charged test particles' trajectories are affected not only by the gravitational field of the black hole, but also by the magnetic field surrounding the black hole.…”

“…When black holes are surrounded by an external magnetic field, the charged test particles' motions could be affected [104][105][106][107][108][109] and result in chaotic behaviors [110][111][112][113][114][115][116][117][118][119][120]. Motivated by exploring the nature of jets and winds coming from an active galactic nucleus [121][122][123], much attentions have been devoted to investigating the motion of a charged test particle and following its bound orbit around a black hole immersed in an external magnetic field in some modified gravity theories [124][125][126][127][128][129][130][131][132][133][134][135][136][137][138][139][140]. In fact, magnetic field strengths can be induced by different sources and the relevant properties have drawn much attention [141][142][143][144][145].…”

A critical assessment of black hole solutions with a linear term in their redshift function

“…In this section, we will present the physical relevance of the parameter β by claiming that its non-zero value can mimic the spin of a Kerr black hole in accounting for the size of the accretion disk of black holes. The idea that some parameters of static black hole solutions can be astrophysically indistinguishable from the spin of a rotating black hole in reference to this dataset has already been pioneered for nonsingular black holes in nonlinear electrodynamics [60], charged stringy black holes [61], deformed black holes [62], and black holes surrounded by dark matter [63]. In the case of our paper, we are in an even more extreme situation since we cannot provide an unambiguous physical interpretation to the parameter β because these analyses rely on the study of the geodesic motion which depends on the metric tensor and not the gravitational theory formulation.…”

Understanding Gravitational Entropy of Black Holes: A New Proposal via Curvature Invariants

“…The Cauchy, Killing and apparent horizon(s) [52] coincide and can still be found by solving f (r H ) = 0. This framework allows one to study post-Newtonian effects in astrophysical phenomena [53][54][55][56]. Replacing l a and n a in the null coframe (30) with…”