scholarly journals Making Faranoff-Riley I radio sources III. The effects of the magnetic field on relativistic jets' propagation and source morphologies

2021 ◽  
Author(s):  
S. Massaglia ◽  
G. Bodo ◽  
P. Rossi ◽  
S. Capetti ◽  
A. Mignone
Keyword(s):  
Magnetic Field ◽  
Radio Sources ◽  
Relativistic Jets ◽  
The Magnetic Field

Magnetic-field configurations in compact extragalactic jets

1986 ◽  
Vol 64 (4) ◽  
pp. 463-465 ◽  
Author(s):  
T. W. Jones
Keyword(s):  
Magnetic Field ◽  
Very Long Baseline Interferometry ◽  
Radio Sources ◽  
Relativistic Jets ◽  
Detailed Model ◽  
Model Calculations ◽  
Long Baseline ◽  
Kolmogorov Turbulence ◽  
Extragalactic Jets ◽  
The Magnetic Field

Multifrequency and multitime polarimetry of active, compact radio sources strongly suggest that the magnetic-field structures in these sources are largely disordered or turbulent. Some initial, detailed model calculations of relativistic jets with turbulent fields have been performed in an effort to better understand the relationships between the observed polarization properties and physical structures of sources. Simulations are described involving nearly steady, isothermal, constant velocity jets with magnetic fields having approximately a Kolmogorov turbulence spectrum that is carried along the jet. They produce structures similar to those actually observed, including a core-jet appearance with superluminal knots. Likewise, the polarization has a behavior in frequency and time that is at least qualitatively similar to that observed. In addition, although individual portions of the model sources are highly polarized, as also seen with very long baseline interferometry, the integrated polarizations are relatively small, as observed.

Why only a small fraction of quasars are radio loud?

2018 ◽  
Vol 14 (S342) ◽  
pp. 201-204
Author(s):  
Xinwu Cao
Keyword(s):  
Magnetic Field ◽  
Black Hole ◽  
Angular Momentum ◽  
Angular Velocity ◽  
Strong Magnetic Field ◽  
Weak Magnetic Field ◽  
Thin Disk ◽  
Relativistic Jets ◽  
Jet Formation ◽  
The Magnetic Field

AbstractIt is still a mystery why only a small fraction of quasars contain relativistic jets. A strong magnetic field is a necessary ingredient for jet formation. Gas falls from the Bondi radius RB nearly freely to the circularization radius Rc, and a thin accretion disk is formed within Rc We suggest that the external weak magnetic field threading interstellar medium is substantially enhanced in this region, and the magnetic field at Rc can be sufficiently strong to drive outflows from the disk if the angular velocity of the gas is low at RB. In this case, the magnetic field is efficiently dragged in the disk, because most angular momentum of the disk is removed by the outflows that lead to a significantly high radial velocity. The strong magnetic field formed in this way may accelerate jets in the region near the black hole, either by the Blandford-Payne or/and Blandford-Znajek mechanisms. If the angular velocity of the circumnuclear gas is low, the field advection in the thin disk is inefficient, and it will appear as a radio-quiet (RQ) quasar.

scholarly journals Magnetic Field Configuration in 4C 39.25

1998 ◽  
Vol 164 ◽  
pp. 115-116 ◽  
Author(s):  
A. Alberdi ◽  
L. Lara ◽  
J.L. Gómez ◽  
J.M. Marcaide ◽  
M.A. Pérez-Torres ◽  
...  
Keyword(s):  
Magnetic Field ◽  
High Resolution ◽  
Radio Emission ◽  
Field Configuration ◽  
Radio Sources ◽  
Magnetic Field Configuration ◽  
Relativistic Jet ◽  
Scale Structures ◽  
The Magnetic Field

AbstractWe have performed simultaneous multi-frequency polarization VLBA observations of the compact radio sources 3C 395 and 4C 39.25 which show both stationary and superluminal components in their parsec-scale structures. Those of 3C 395 have been reported elsewhere. Here we report on high resolution maps of the total intensity and polarized radio emission of 4C 39.25, trace the magnetic field configuration along the jet, and explore different possibilities for the nature of the components within the framework of the bent shocked relativistic jet model.

scholarly journals The Two Component Magnetic Field of the Galaxy

1990 ◽  
Vol 140 ◽  
pp. 54-54
Author(s):  
R.R. Andreassian ◽  
A.N. Makarov
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Field Configuration ◽  
Radio Sources ◽  
Magnetic Field Configuration ◽  
Spiral Arms ◽  
Two Component ◽  
The Galaxy ◽  
The Magnetic Field ◽  
Spiral Arm

The present paper is devoted to a study of the magnetic field configuration of our Galaxy based on Faraday rotation measures (RM) of 185 pulsars and 802 extragalactic radio sources. RM data of pulsars located near the plane of the Galaxy are used for the study of magnetic fields in neighbouring spiral arms. For the distribution of spiral arms the well-known model of Georgelin and Georgelin (1976) is used. The calculations show (for details see Andreassian and Makarov, 1987, 1989) that in the Perseus spiral arm and the local Orion arm the magnetic fields have approximately the same directions (lo;bo) ≈ (80°;0°), while in the Sagittarius-Carina arm the magnetic field has an opposite direction.

scholarly journals CONSTRAINTS ON X-RAY POLARIZATION OF SYNCHROTRON JETS FROM STELLAR-MASS BLACK HOLES

2012 ◽  
Vol 08 ◽  
pp. 102-107
Author(s):  
D. M. RUSSELL
Keyword(s):  
Magnetic Field ◽  
Black Holes ◽  
Black Hole ◽  
Synchrotron Emission ◽  
Relativistic Jets ◽  
X Ray ◽  
Linearly Polarized ◽  
Hard State ◽  
X Ray Binaries ◽  
The Magnetic Field

For most black hole X-ray binaries, the fraction of X-ray flux originating in the synchrotron jets is generally thought to be low in the hard state. However in one intriguing case, the infrared – X-ray correlations, evolution of broadband spectra and timing signatures suggest that synchrotron emission from a jet likely dominated both the infrared and X-ray flux on the hard state decline of an outburst of XTE J1550–564 at a luminosity of ~ (2 × 10-4 – 2 × 10-3) L Edd . Synchrotron emission from the relativistic jets launched close to black holes can be highly linearly polarized, depending on the configuration of the magnetic field. It has recently been shown that the polarimetric signature of their jets is detected in the infrared and is highly variable. This reveals the magnetic geometry in a region of the compact jet near its base, close to the black hole. From these results, it is predicted that in some cases, high (possibly up to 10%), variable levels of X-ray polarization from synchrotron emission originating in jets will be detected from accreting black holes by future spaceborne X-ray polarimeters.

scholarly journals Constraining magnetic fields in galaxy clusters

2018 ◽  
Vol 14 (A30) ◽  
pp. 299-302
Author(s):  
Annalisa Bonafede ◽  
Chiara Stuardi ◽  
Federica Savini ◽  
Franco Vazza ◽  
Marcus Brüggen
Keyword(s):  
Magnetic Field ◽  
Particle Acceleration ◽  
Magnetic Fields ◽  
Galaxy Clusters ◽  
Faraday Rotation ◽  
Small Scale ◽  
Radio Sources ◽  
Synchrotron Emission ◽  
Combined Approach ◽  
The Magnetic Field

AbstractMagnetic fields originate small-scale instabilities in the plasma of the intra-cluster medium, and may have a key role to understand particle acceleration mechanisms. Recent observations at low radio frequencies have revealed that synchrotron emission from galaxy clusters is more various and complicated than previously thought, and new types of radio sources have been observed. In the last decade, big steps forward have been done to constrain the magnetic field properties in clusters thanks to a combined approach of polarisation observations and numerical simulations that aim to reproduce Faraday Rotation measures of sources observed through the intra-cluster medium. In this contribution, I will review the results on magnetic fields reached in the last years, and I will discuss the assumptions that have been done so far in light of new results obtained from cosmological simulations. I will also discuss how the next generation of radio instruments, as the SKA, will help improving our knowledge of the magnetic field in the intra-cluster medium.

scholarly journals Filaments Evolution in Extended Radio Sources

1990 ◽  
Vol 140 ◽  
pp. 457-458
Author(s):  
G. Bodo ◽  
A. Ferrari ◽  
S. Massaglia ◽  
E. Trussoni
Keyword(s):  
Magnetic Field ◽  
Time Scale ◽  
Field Direction ◽  
Cooling Time ◽  
Mhd Waves ◽  
Radio Sources ◽  
Magnetic Field Direction ◽  
Cygnus A ◽  
Extended Radio ◽  
The Magnetic Field

It has been recently shown (Bodo et al 1989) that filamentary structures observed in some extended radio sources (e.g. Cygnus A and M 87) can be related with thermal instabilities arising in the gas with a synchrotron radiating relativistic component. In particular is has been shown that, with the typical parameters of radio sources, two kind of unstable modes can develop on time scale comparable with the synchrotron cooling time: condensation stationary modes and travelling slow MHD waves. Both these kind of perturbations should lead to the formation of structures basically parallel to the magnetic field direction, as observed, however their general evolution, in particular if they will lead to the formation of dark or bright structures, cannot be extrapolated from the linear perturbative analysis.

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