Magnetic Fields of Black Holes and the Variability Plane

Piotrovich, M. Yu.; Силантьев, Н. А.; Gnedin, Yu. N.; Natsvlishvili, T. M.

doi:10.48550/arxiv.1002.4948

Cited by 20 publications

(28 citation statements)

References 22 publications

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“…This possibility has been suggested and considered by several authors (e.g. Rees 1984;Punsly & Coroniti 1990;Blandford 1990) and, more recently, Piotrovich et al (2010). A characteristic value of 10 4 G, or B4 = 1, is generally adopted, and is used here; the results obtained here can easily be scaled to any other constant value of the field strength.…”

Section: The Methodsmentioning

confidence: 98%

Estimates of black hole spin properties of 55 sources

Daly

2011

Monthly Notices of the Royal Astronomical Society

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Studies of black hole spin and other parameters as a function of redshift provide information about the physical state and merger and accretion histories of the systems. One way that black hole spin may be estimated is through observations of extended radio sources. These sources, powered by outflows from an AGN, allow the beam power and total outflow energy to be studied. In a broad class of models, the beam power of the outflow is related to the spin of the black hole. This relationship is used to estimate black hole spins for 55 radio sources. The samples studied include 7 FR II quasars and 19 FR II radio galaxies with redshifts between 0.056 and 1.79, and 29 radio sources associated with CD galaxies with redshifts between 0.0035 and 0.291. The FR II sources studied have estimated spin values of between about 0.2 and 1; there is a range of values at a given redshift, and the values tend to increase with increasing redshift. Results obtained for FR II quasars are very similar to those obtained for FR II galaxies. A broader range of spin values are obtained for the sample of radio sources associated with CD galaxies studied. The fraction of the spin energy extracted per outflow event is estimated and ranges from about 0.03 to 0.5 for FR II sources and 0.002 to about 1 for radio sources associated with CD galaxies; the data are consistent with this fraction being independent of redshift though the uncertainties are large. The results obtained are consistent with those predicted by numerical simulations that track the merger and accretion history of AGN, supporting the idea that, for AGN with powerful large‐scale outflows, beam power is directly related to black hole spin.

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Section: The Methodsmentioning

confidence: 98%

Estimates of black hole spin properties of 55 sources

Daly

2011

Monthly Notices of the Royal Astronomical Society

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“…When thinking about astrophysical black holes, the external magnetic field may be due to the accretion disc around the black hole itself [86] or to the existence of nearby neutron stars [84,87,88,89]. The analysis of magnetic field strengths induced by different sources has been done in [90,91,92,93,94]. In the paper we also consider the simple case of a test magnetic field which does not modify the background geometry.…”

Section: Introductionmentioning

confidence: 99%

Charged particle and epicyclic motions around $4D$ Einstein-Gauss-Bonnet black hole immersed in an external magnetic field

Shaymatov,

Vrba,

Malafarina

et al. 2020

Preprint

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We investigate particle motion in the vicinity of a 4D Einstein-Gauss-Bonnet (EGB) black hole immersed in external asymptotically uniform magnetic field.It is well known that magnetic fields can strongly affect charged particle motion in the black hole vicinity due to the Lorenz force. We find that the presence of the Gauss-Bonnet (GB) coupling gives rise to a similar effect, reducing the radius of the innermost stable circular orbit (ISCO) with respect to the purely relativistic Schwarzschild black hole. Further, we consider particle collisions in the black hole vicinity to determine the center of mass energy and show that this energy increases with respect to the Schwarzschild case due to the effect of the GB term. Finally, we consider epicyclic motion and its frequencies and resonance as a mean to test the predictions of the model against astrophysical observations. In particular we test which values of the parameters of the theory best fit the 3:2 resonance of high-frequency quasi-periodic oscillations in three

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“…Magnetic field is one of the most important constituents of the cosmic space and one of the main sources of the dynamics of interacting matter in the Universe. Weak magnetic fields of about a few µG exist in galaxies and clusters of galaxies, while very strong magnetic fields of up to 10 4 − 10 8 G are supposed to exit near supermassive black holes in the active galactic nuclei and even around stellar mass black holes [1][2][3]. Magnetic field near a black hole leads to a number of processes, such as extraction of rotational energy from a black hole, known as the Blandford-Znajek effect [4], the charging of a black hole due to accretion of charged matter [5], the formation of an induced electric field on the black hole surface [6], negative absorption (masers) of electrons [7], and so on.…”

Section: Introductionmentioning

confidence: 99%

“…In [19,20], the black hole was described by the Ernst-Schwarzschild solution which contains a magnetic field as a parameter because the magnetic field is implied to be strong enough in order to deform the black hole geometry significantly. However, such strong geometrydeforming magnetic fields have little probability of exist-ing in nature [3].…”

Section: Introductionmentioning

confidence: 99%

Quasinormal modes, scattering, and Hawking radiation of Kerr-Newman black holes in a magnetic field

2011

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We perform a comprehensive analysis of the spectrum of proper oscillations (quasinormal modes), transmission/reflection coefficients and Hawking radiation for a massive charged scalar field in the background of the Kerr-Newman black hole immersed in an asymptotically homogeneous magnetic field. There are two main effects: the Zeeman shift of the particle energy in the magnetic field and the difference of values of an electromagnetic potential between the horizon and infinity, i.e. the Faraday induction. We have shown that "turning on" the magnetic field induces a stronger energy-emission rate and leads to "recharging" of the black hole. Thus, a black hole immersed in a magnetic field evaporates much quicker, achieving thereby an extremal state in a shorter period of time. Quasinormal modes are moderately affected by the presence of a magnetic field which is assumed to be relatively small compared to the gravitational field of the black hole.

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Magnetic Fields of Black Holes and the Variability Plane

Cited by 20 publications

References 22 publications

Estimates of black hole spin properties of 55 sources

Estimates of black hole spin properties of 55 sources

Charged particle and epicyclic motions around $4D$ Einstein-Gauss-Bonnet black hole immersed in an external magnetic field

Quasinormal modes, scattering, and Hawking radiation of Kerr-Newman black holes in a magnetic field

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