Reconciling the magnetic field structures seen in variable active galactic nuclei with the unified scheme

Nature ◽  
1993 ◽  
Vol 363 (6425) ◽  
pp. 142-144 ◽  
Author(s):  
Gopal-Krishna ◽  
Paul J. Wiita
Keyword(s):  
Magnetic Field ◽  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
The Magnetic Field

scholarly journals Magnetized black hole as an accelerator of charged particle

2021 ◽  
Author(s):  
Bobur Turimov
Keyword(s):  
Magnetic Field ◽  
Black Hole ◽  
Charged Particle ◽  
Active Galactic Nuclei ◽  
Zeeman Effect ◽  
Galactic Nuclei ◽  
X Ray ◽  
Fundamental Frequencies ◽  
The Magnetic Field ◽  
Relativistic Particles

Astrophysical accretion processes near the black hole candidates, such as active galactic nuclei (AGN), X-ray binary (XRB), and other astrophysical sources, are associated with high-energetic emission of radiation of relativistic particles and outflows (winds and/or jets). It is widely believed that the magnetic field plays a very important role to explain such high energetic processes in the vicinity of those astrophysical sources. In the present research note, we propose that the black hole is embedded in an asymptotically uniform magnetic field. We investigate the dynamical motion of charged particles in the vicinity of a weakly magnetized black hole. We show that in the presence of the magnetic field, the radius of the innermost stable circular orbits (ISCO) for a charged particle is located close to the black hole’s horizon. The fundamental frequencies, such as Keplerian and epicyclic frequencies of the charged particle are split into two parts due to the magnetic field, as an analog of the Zeeman effect. The orbital velocity of the charged particle measured by a local observer has been computed in the presence of the external magnetic field. We also present an analytical expression for the four-acceleration of the charged particle orbiting around black holes. Finally, we determine the intensity of the radiating charged accelerating relativistic particle orbiting around the magnetized black hole.

scholarly journals The revived Penrose process can power the central engine in active galactic nuclei

1986 ◽  
Vol 119 ◽  
pp. 395-398
Author(s):  
Sanjay M. Wagh ◽  
N. Dadhich
Keyword(s):  
Magnetic Field ◽  
Active Galactic Nuclei ◽  
Extraction Efficiency ◽  
Galactic Nuclei ◽  
High Energy ◽  
Energy Extraction ◽  
Central Engine ◽  
Penrose Process ◽  
The Magnetic Field ◽  
Very High

Using the fact that the efficiency of the revived (Wagh et al 1985) Penrose process of energy extraction from black holes immersed in electromagnetic fields can be very high (Parthasarathy et al, 1986) we show that this process can comfortably power the ‘central engine’ in Active Galactic Nuclei. The microphysical Penrose process energized particles will be ultrarelativistic in the asymptotic frame. Hence the kinematical analysis of escaping photons by Piran and Shaham (1977) will be a good approximation to the kinematics of these particles. From this analysis one expects the energized particles to emerge within an angle∼ 40° above and below the equatorial plane. These energetic particles, which are collimated in the funnel of an accretion disk and further on by the magnetic field, then, form supersonic, relativistic, bilateral jets. The relativistic Y factor for such jets can be expected to be ∼ 2 since these ultrarelativistic particles will effectively mimick radiation in ‘dragging’ the matter already injected inside the funnel. Various implications of high energy extraction efficiency are illustrated.

THE PARSEC-SCALE CIRCULAR POLARIZATION OF ACTIVE GALACTIC NUCLEI AT 22 AND 15 GHZ

2008 ◽  
Vol 17 (09) ◽  
pp. 1531-1535 ◽  
Author(s):  
V. M. VITRISHCHAK ◽  
D. C. GABUZDA
Keyword(s):  
Magnetic Field ◽  
Active Galactic Nuclei ◽  
Circular Polarization ◽  
Galactic Nuclei ◽  
Core Region ◽  
Field Orientation ◽  
Magnetic Field Orientation ◽  
Long Baseline ◽  
Very Long Baseline Array ◽  
The Magnetic Field

We present the results of parsec-scale circular polarization measurements based on Very Long Baseline Array data for a number of radio-bright, core-dominated active galactic nuclei obtained simultaneously at 22 and 15 GHz. The degrees of circular polarization mc for the VLBI core region at 15 GHz are similar to values reported earlier at this wavelength, with typical values of a few tenths of a percent. The origin of this polarization is almost certainly the conversion of linear to circular polarization during the propagation of the radiation through a magnetised plasma. We find that mc is as often higher as lower at the higher frequency, for reasons that are not clear. Our results confirm the earlier finding that the sign of the circular polarization at a given observing frequency is generally consistent across epochs separated by several years or more, suggesting stability of the magnetic field orientation in the innermost jets.

scholarly journals VLBA Imaging of a Large Sample of Blazars

1998 ◽  
Vol 164 ◽  
pp. 159-160
Author(s):  
J. M. Attridge ◽  
D. H. Roberts ◽  
J. F.C. Wardle
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Active Galactic Nuclei ◽  
Ambient Medium ◽  
Surrounding Medium ◽  
Galactic Nuclei ◽  
Large Sample ◽  
Field Lines ◽  
5 Ghz ◽  
The Magnetic Field

AbstractAs part of our continuing study of parsec-scale magnetic fields in active galactic nuclei we have obtained deep polarization-sensitive images of the blazar 1055+018 with the VLBA at 5 GHz. These dramatic images reveal a magnetized layer of material on the outer surfaces of the jet, distinct from the bulk of the jet. This morphology suggests interaction of the jet with the surrounding medium, the resulting shear stretching the magnetic field lines in the direction of the flow. Further multi-frequency polarization-sensitive observations of 1055+018 offer the opportunity to study radio jet-ambient medium interactions in detail.

scholarly journals Determination of magnetic field strength on the event horizon of supermassive black holes in active galactic nuclei

2020 ◽  
Vol 495 (1) ◽  
pp. 614-620
Author(s):  
M Yu Piotrovich ◽  
A G Mikhailov ◽  
S D Buliga ◽  
T M Natsvlishvili
Keyword(s):  
Magnetic Field ◽  
Black Holes ◽  
Field Strength ◽  
Active Galactic Nuclei ◽  
Magnetic Field Strength ◽  
Event Horizon ◽  
Galactic Nuclei ◽  
Supermassive Black Holes ◽  
Mean Values ◽  
The Magnetic Field

ABSTRACT We estimated the magnetic field strength at the event horizon for a sample of supermassive black holes (SMBHs) in active galactic nuclei (AGNs). Our estimates were made using the values of the inclination angles of the accretion disc to the line of sight, which we obtained previously from spectropolarimetric observations in the visible spectrum. We also used published values of full width at half-maximum of spectral line Hβ from broad-line region, masses of SMBHs, and luminosity of AGNs at 5100 $\mathring{\rm A}$. In addition, we used the literature data on the spins of SMBHs obtained from their X-ray spectra. Our estimates showed that the magnetic field strength at the event horizon of the majority of SMBHs in AGNs range from several to tens of kG and have mean values of about 104 G. At the same time, for individual objects, the fields are significantly larger – of the order of hundreds kG or even 1 MG.

scholarly journals Magnetically Driven Jets from Accretion Disks: Comparison Between 2.5D Nonsteady Simulations and 1.5D Nonsteady/Steady Solutions

1997 ◽  
Vol 163 ◽  
pp. 753-753 ◽  
Author(s):  
T. Kudoh ◽  
R. Matsumoto ◽  
K. Shibata
Keyword(s):  
Magnetic Field ◽  
Active Galactic Nuclei ◽  
Accretion Disks ◽  
Galactic Nuclei ◽  
Astrophysical Jets ◽  
Initial Value ◽  
Mhd Simulations ◽  
Current Belief ◽  
Steady Solutions ◽  
The Magnetic Field

We have performed 1D(1.5D) and 2D(2.5D) nonsteady MHD numerical simulations of astrophysical jets which are magnetically driven from Keplerian disks, in order to clarify the origin and structure of jets ejected from protostars and active galactic nuclei. The initial and boundary conditions are similar to those of 2D(2.5D) nonsteady MHD simulations of Shibata and Uchida (1986) and Matsumoto et al. (1996); there is initially a Keplerian disk with a nonrotating corona outside, both of which are penetrated by vertical magnetic fields. The subsequent interaction between the disk/corona and the vertical fields are studied as an initial value problem. Against the current belief that this kind of simulations show simply a transient jet caused by nonsteady interaction between the disk/corona and the magnetic field, we have found that the jets ejected from the disk in this way have the same properties of the steady magnetically driven jets that were investigated by using ID steady wind solution (Kudoh & Shibata 1995), even if the jets are not exactly in steady state.

scholarly journals EXACT RELATIVISTIC MODELS OF THIN DISKS AROUND STATIC BLACK HOLES IN A MAGNETIC FIELD

2014 ◽  
Vol 23 (01) ◽  
pp. 1450010 ◽  
Author(s):  
ANTONIO C. GUTIÉRREZ-PIÑERES ◽  
GONZALO GARCÍA-REYES ◽  
GUILLERMO A. GONZÁLEZ
Keyword(s):  
Magnetic Field ◽  
Black Hole ◽  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Thin Disk ◽  
Rayleigh Criterion ◽  
Static Black Hole ◽  
The Stability ◽  
Thin Disks ◽  
The Magnetic Field

The exact superposition of a central static black hole with surrounding thin disk in presence of a magnetic field is investigated. We consider two models of disk, one of infinite extension based on a Kuzmin–Chazy–Curzon metric and other finite based on the first Morgan–Morgan disk. We also analyze a simple model of active galactic nuclei (AGN) consisting of black hole, a Kuzmin–Chazy–Curzon disk and two rods representing jets, in presence of magnetic field. To explain the stability of the disks, we consider the matter of the disk made of two pressureless streams of counter-rotating charged particles (counter-rotating model) moving along electrogeodesic. Using the Rayleigh criterion, we derivate for circular orbits the stability conditions of the particles of the streams. The influence of the magnetic field on the matter properties of the disk and on its stability are also analyzed.

scholarly journals ON THE ROLE OF THE CURVATURE DRIFT INSTABILITY IN THE DYNAMICS OF ELECTRONS IN ACTIVE GALACTIC NUCLEI

2013 ◽  
Vol 22 (13) ◽  
pp. 1350081 ◽  
Author(s):  
ZAZA OSMANOV
Keyword(s):  
Magnetic Field ◽  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Rotational Energy ◽  
Relativistic Electrons ◽  
Field Lines ◽  
Drift Instability ◽  
The Magnetic Field ◽  
Relativistic Particles

We study the influence of the centrifugally driven curvature drift instability (CDI) on the dynamics of relativistic electrons in the magnetospheres of active galactic nuclei (AGN). We generalize in our previous paper by considering relativistic particles with different initial phases. Considering the Euler continuity and induction equations, by taking into account the resonant conditions, we derive the growth rate of the CDI. We show that due to the centrifugal effects, the rotational energy is efficiently pumped directly into the drift modes, that leads to the generation of a toroidal component of the magnetic field. As a result, the magnetic field lines transform into such a configuration when particles do not experience any forces and since the instability is centrifugally driven, at this stage the CDI is suspended.

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