scholarly journals Discovery of Helical Magnetic Fields in AGN, and CME and Ejection of Large-Scale Magnetic Fields from AGN

2003 ◽  
Vol 214 ◽  
pp. 303-308
Author(s):  
Han-Shu Chu ◽  
L. B. Baath ◽  
Fu-Jun Zhang ◽  
R. E. Spencer
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Active Galactic Nuclei ◽  
Large Scale ◽  
Direct Detection ◽  
Galactic Nuclei ◽  
Crucial Importance ◽  
Important Ingredient ◽  
Celestial Bodies ◽  
Helical Magnetic Field

Magnetic Fields are the crucial and most important ingredient involved in the processes of various violent activities in Active Galactic Nuclei and other celestial bodies. The generally accepted 2-sided symmetric-jets model of active galactic nuclei (AGN) does not include the magnetic fields. We present here the first direct detection of helical magnetic field in AGN, and the first direct detection of ejection of large scale magnetic fields from AGN. (CME) 2. The annular (helical) magnetic field is responsible for the collimation of the jet (through Pinch Effect) and may be of crucial importance for extraction of black hole rotational energy. 3. The CMEs are responsible for sporadic ejection of jet components in AGN, while the general accepted 2-sided jets pertain to the quiescent Jets. 4. Observations show that the CME with Asymmetric Jets can explain many phenomena and much of the morphological diversities in AGN.

scholarly journals A Helical Magnetic Field Model of the Jets

1987 ◽  
Vol 115 ◽  
pp. 381-383
Author(s):  
T. Maruyama ◽  
M. Fujimoto
Keyword(s):  
Magnetic Field ◽  
Active Galactic Nuclei ◽  
Lorentz Force ◽  
Field Model ◽  
Galactic Nuclei ◽  
Molecular Gas ◽  
Magnetic Field Model ◽  
Helical Magnetic Field ◽  
Jet Axis

A hydromagnetic model is presented for the bipolar flow of molecular gas from newborn stars and for the radio jet emerging out of active galactic nuclei. We assume a tightly-twisted helical magnetic field in the jet, which can collimate and accelerate the gas along the jet axis. The Lorentz force is also shown to rotate the gas around it.

scholarly journals Magnetism in the Early Universe

2018 ◽  
Vol 14 (A30) ◽  
pp. 295-298
Author(s):  
Tina Kahniashvili ◽  
Axel Brandenburg ◽  
Arthur Kosowsky ◽  
Sayan Mandal ◽  
Alberto Roper Pol
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Gravitational Waves ◽  
Early Universe ◽  
Large Scale ◽  
Direct Detection ◽  
Correlation Lengths ◽  
Cosmological Scenario ◽  
Expansion Of The Universe ◽  
The Universe

AbstractBlazar observations point toward the possible presence of magnetic fields over intergalactic scales of the order of up to ∼1 Mpc, with strengths of at least ∼10−16 G. Understanding the origin of these large-scale magnetic fields is a challenge for modern astrophysics. Here we discuss the cosmological scenario, focussing on the following questions: (i) How and when was this magnetic field generated? (ii) How does it evolve during the expansion of the universe? (iii) Are the amplitude and statistical properties of this field such that they can explain the strengths and correlation lengths of observed magnetic fields? We also discuss the possibility of observing primordial turbulence through direct detection of stochastic gravitational waves in the mHz range accessible to LISA.

scholarly journals Connecting turbulent velocities and magnetic fields in galaxy cluster simulations with active galactic nuclei jets

2021 ◽  
Vol 503 (1) ◽  
pp. 1327-1344
Author(s):  
K Ehlert ◽  
R Weinberger ◽  
C Pfrommer ◽  
V Springel
Keyword(s):  
Magnetic Fields ◽  
Active Galactic Nuclei ◽  
Large Scale ◽  
Velocity Dispersion ◽  
Velocity Structure ◽  
Galaxy Cluster ◽  
Galactic Nuclei ◽  
Cosmic Ray ◽  
Low Velocity ◽  
Active Galactic Nuclei Jets

ABSTRACT The study of velocity fields of the hot gas in galaxy clusters can help to unravel details of microphysics on small scales and to decipher the nature of feedback by active galactic nuclei (AGN). Likewise, magnetic fields as traced by Faraday rotation measurements (RMs) inform about their impact on gas dynamics as well as on cosmic ray production and transport. We investigate the inherent relationship between large-scale gas kinematics and magnetic fields through non-radiative magnetohydrodynamical simulations of the creation, evolution, and disruption of AGN jet-inflated lobes in an isolated Perseus-like galaxy cluster, with and without pre-existing turbulence. In particular, we connect cluster velocity measurements with mock RM maps to highlight their underlying physical connection, which opens up the possibility of comparing turbulence levels in two different observables. For single-jet outbursts, we find only a local impact on the velocity field, i.e. the associated increase in velocity dispersion is not volume-filling. Furthermore, in a setup with pre-existing turbulence, this increase in velocity dispersion is largely hidden. We use mock X-ray observations to show that at arcmin resolution, the velocity dispersion is therefore dominated by existing large-scale turbulence and is only minimally altered by the presence of a jet. For the velocity structure of central gas uplifted by buoyantly rising lobes, we find fast, coherent outflows with low velocity dispersion. Our results highlight that projected velocity distributions show complex structures, which pose challenges for the interpretation of observations.

scholarly journals Large-scale dynamo of accretion disks around supermassive nonrotating black holes

2006 ◽  
pp. 49-55
Author(s):  
A.L. Poplavsky ◽  
O.P. Kuznechik ◽  
N.I. Stetyukevich
Keyword(s):  
Magnetic Field ◽  
Black Holes ◽  
Active Galactic Nuclei ◽  
Accretion Disks ◽  
Large Scale ◽  
Temporal Distribution ◽  
Galactic Nuclei ◽  
Dynamo Action ◽  
Stable Circular Orbit ◽  
General Relativistic

In this paper one presents an analytical model of accretion disk magnetosphere dynamics around supermassive nonrotating black holes in the centers of active galactic nuclei. Based on general relativistic equations of magneto hydrodynamics, the nonstationary solutions for time-dependent dynamo action in the accretion disks, spatial and temporal distribution of magnetic field are found. It is shown that there are two distinct stages of dynamo process: the transient and the steady-state regimes, the induction of magnetic field at t > 6:6665 x 1011GM/c3 s becomes stationary, magnetic field is located near the innermost stable circular orbit, and its value rises up to ~ 105 G. Applications of such systems with nonrotating black holes in real active galactic nuclei are discussed.

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 Sweeping-Magnetic-Twist Mechanism and Molecular Bipolar Flows

1987 ◽  
Vol 115 ◽  
pp. 385-387
Author(s):  
Kazunari SHIBATA ◽  
Yutaka UCHIDA
Keyword(s):  
Magnetic Field ◽  
Black Hole ◽  
Active Galactic Nuclei ◽  
Accretion Disks ◽  
Large Scale ◽  
Galactic Nuclei ◽  
Main Mechanism ◽  
Astrophysical Jets ◽  
Centrifugal Effect ◽  
Poloidal Magnetic Field

Uchida and Shibata have proposed the “sweeping-magnetic-twist” mechanism for the formation of astrophysical jets in relation to the accretion disks (disks around protostars, around black hole in the center of active galactic nuclei, and so on) in which a jet is accelerated by thejxBforce in the relaxing magnetic twist created in the winding-up of the poloidal magnetic field by the rotation of the contracting disk (Uchida and Shibata 1985a, b; Shibata and Uchida 1986a, b; Uchidaet al.1985). In this mechanism, a jet is collimated also by thejxBforce due to the large scale poloidal magnetic field whose footpoints are squeezed in the contracting disk. The main mechanism involved is different from that of centrifugal wind models (Blandford and Payne 1982, Pudritz and Norman 1983) and worked out indepentently, but the centrifugal effect itself is automatically built-in.

scholarly journals CHANG-ES: XVIII—The CHANG-ES Survey and Selected Results

Galaxies ◽  
2019 ◽  
Vol 7 (1) ◽  
pp. 42 ◽  
Author(s):  
Judith Irwin ◽  
Ancor Damas-Segovia ◽  
Marita Krause ◽  
Arpad Miskolczi ◽  
Jiangtao Li ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Radio Continuum ◽  
Continuum Emission ◽  
Polarization Data ◽  
Wide Range ◽  
Nearby Galaxies ◽  
Broad Scale

The CHANG-ES (Continuum Halos in Nearby Galaxies) survey of 35 nearby edge-on galaxies is revealing new and sometimes unexpected and startling results in their radio continuum emission. The observations were in wide bandwidths centred at 1.6 and 6.0 GHz. Unique to this survey is full polarization data showing magnetic field structures in unprecedented detail, resolution and sensitivity for such a large sample. A wide range of new results are reported here, some never before seen in any galaxy. We see circular polarization and variability in active galactic nuclei (AGNs), in-disk discrete features, disk-halo structures sometimes only seen in polarization, and broad-scale halos with reversing magnetic fields, among others. This paper summarizes some of the CHANG-ES results seen thus far.

scholarly journals Long-Lived Positronium and AGN Jets

2012 ◽  
Vol 2012 ◽  
pp. 1-6 ◽  
Author(s):  
John T. Giblin ◽  
Janine Shertzer
Keyword(s):  
Magnetic Field ◽  
Black Holes ◽  
Active Galactic Nuclei ◽  
Accretion Disks ◽  
Bound States ◽  
Galactic Nuclei ◽  
Stable States ◽  
Electrons And Positrons ◽  
Field Lines ◽  
Helical Magnetic Field

We suggest that stable states of positronium might exist in the jets of active galactic nuclei (AGN). Electrons and positrons are created near the accretion disks of supermassive black holes at the centers of AGN and are accelerated along magnetic field lines while within the Alfvèn radius. The conditions in this region are ideal for the creation of bound states of positronium which are stable against annihilation. Traveling at relativistic speeds along the jet, the helical magnetic field enables the atoms to survive for great distances.

scholarly journals CME and Ejection of Large Scale Magnetic Fields, Helical Magnetic Fields, and Intrinsically Asymmetric Jets - New Findings in AGN

1998 ◽  
Vol 164 ◽  
pp. 121-122
Author(s):  
H. S. Chu ◽  
F. J. Zhang ◽  
R. E. Spencer
Keyword(s):  
Magnetic Fields ◽  
Active Galactic Nuclei ◽  
Large Scale ◽  
Direct Evidence ◽  
Galactic Nuclei ◽  
Relativistic Beaming ◽  
New Findings ◽  
Mass Ejection ◽  
Jet Structure ◽  
New Evidence

AbstractThe orthodox model of active galactic nuclei (AGN), as is generally accepted, is that of Rees. We have found an AGN (3C 147) which has a counter-jet much longer than the main jet. It also has an unusual sideways ejection from the nuclear region. Both of these and the 3-jet structure per se do not seem to conform with the general accepted model, and are also not explained by relativistic beaming effects. We speculate that this is due to coronal mass ejection (CME) in the accretion disk corona. Recently, we have found convincing new evidence that this is true. We have also found direct evidence of helical magnetic fields in the core region of 3C 147. These results may be of importance to the understanding of AGN.

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