Magnetic fields around AGNs at large and small scales

Tyul’bashev, S. A.

doi:10.1051/0004-6361:20020440

Cited by 9 publications

(6 citation statements)

References 9 publications

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“…It is well known that there exist enormous magnetic fields around large astrophysical black holes, especially in the nucleus of galaxies [33][34][35][36]. These strong magnetic fields could be induced by currents in accretion disks near the supermassive galactic black holes.…”

Section: Introductionmentioning

confidence: 99%

Shadows of Bonnor black dihole by chaotic lensing

Wang,

Chen,

Jing

2017

Preprint

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We have studied numerically the shadows of Bonnor black dihole through the technique of backward ray-tracing. The presence of magnetic dipole yields non-integrable photon motion, which affects sharply the shadow of the compact object. Our results show that there exists a critical value for the shadow. As the magnetic dipole parameter is less than the critical value, the shadow is a black disk, but as the magnetic dipole parameter is larger than the critical one, the shadow becomes a concave disk with eyebrows possessing a self-similar fractal structure. These behavior are very similar to those of the equal-mass and non-spinning Majumdar-Papapetrou binary black holes. However, we find that the two larger shadows and the smaller eyebrow-like shadows are joined together by the middle black zone for the Bonnor black dihole, which is different from that in the Majumdar-Papapetrou binary black holes spacetime where they are disconnected. With the increase of magnetic dipole parameter, the middle black zone connecting the main shadows and the eyebrow-like shadows becomes narrow. Our result show that the spacetime properties arising from the magnetic dipole yields the interesting patterns for the shadow casted by Bonnor black dihole.

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Section: Introductionmentioning

confidence: 99%

Shadows of Bonnor black dihole by chaotic lensing

Wang,

Chen,

Jing

2017

Preprint

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“…The flux freezing is a characteristic of ideal magnetohydrodynamics (MHD). The typical magnetic field strengths for AGN have a wide range, from 10 4 G (Field & Rogers 1993) to 10 10 G (Kardashev 1995) (as cited by Tyul’bashev 2002). The magnetic fields observed in common envelopes are of the order of 10 7 –10 8 G (Sing 2005).…”

Section: Introductionmentioning

confidence: 99%

General relativistic magnetohydrodynamic Bondi-Hoyle accretion

Penner

2011

Monthly Notices of the Royal Astronomical Society

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In this paper, we present a fully relativistic study of axisymmetric magnetohydrodynamic (MHD) Bondi–Hoyle accretion on to a moving Kerr black hole. The equations of general relativistic MHD are solved using high‐resolution shock‐capturing methods. In this treatment, we consider the ideal MHD limit. The parameters of interest in this study are the adiabatic constant Γ, the asymptotic speed of sound c∞s and the plasma β parameter βP. We focus the investigation on the parameter regime in which the flow is supersonic or when v∞≥c∞s. In some cases, subsonic asymptotic flows are considered for comparison purposes. We study the accretion rates of the total energy and momenta, as well as the hydrodynamic energy and momentum accretion rates. The models presented in this study exhibit a matter density depletion in the downstream region of the black hole which tends to vacuum (ρ0= 0) in convergence tests. This feature is due to the presence of the magnetic field, more specifically the magnetic pressure, and is not seen in previous purely hydrodynamic studies.

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“…This effect is very well described when supposing existence of the super-strong magnetic field B ≈ 10 10 − 10 11 Gs [3]. In addition some other theories [5] imply existence of a strong magnetic field in the AGN. From these data for M and B at hand, by formula (2), one can easily see that for the heaviest galactic black holes, the magnetic field can be of order of fractions of a "unity" (1/M), thereby effecting the black hole metric itself.…”

Section: Introductionmentioning

confidence: 94%

Superradiant instability for black holes immersed in a magnetic field

Konoplya

2008

Physics Letters B

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Magnetic fields around AGNs at large and small scales

Cited by 9 publications

References 9 publications

Shadows of Bonnor black dihole by chaotic lensing

Shadows of Bonnor black dihole by chaotic lensing

General relativistic magnetohydrodynamic Bondi-Hoyle accretion

Superradiant instability for black holes immersed in a magnetic field

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