scholarly journals A strong magnetic field in the jet base of a supermassive black hole

Science ◽  
2015 ◽  
Vol 348 (6232) ◽  
pp. 311-314 ◽  
Author(s):  
I. Marti-Vidal ◽  
S. Muller ◽  
W. Vlemmings ◽  
C. Horellou ◽  
S. Aalto
Keyword(s):  
Magnetic Field ◽  
Black Hole ◽  
Strong Magnetic Field ◽  
Supermassive Black Hole

scholarly journals A strong magnetic field around the supermassive black hole at the centre of the Galaxy

Nature ◽  
2013 ◽  
Vol 501 (7467) ◽  
pp. 391-394 ◽  
Author(s):  
R. P. Eatough ◽  
H. Falcke ◽  
R. Karuppusamy ◽  
K. J. Lee ◽  
D. J. Champion ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Black Hole ◽  
Strong Magnetic Field ◽  
Supermassive Black Hole ◽  
The Galaxy

Rotating black hole in a strong magnetic field

1980 ◽  
Vol 23 (3) ◽  
pp. 179-183 ◽  
Author(s):  
A. N. Aliev ◽  
D. V. Gal'tsov ◽  
A. A. Sokolov
Keyword(s):  
Magnetic Field ◽  
Black Hole ◽  
Strong Magnetic Field ◽  
Rotating Black Hole

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 Ultrahigh energy particle collisions near the black hole horizon in the strong magnetic field

2014 ◽  
Vol 29 (21) ◽  
pp. 1450112 ◽  
Author(s):  
O. B. Zaslavskii
Keyword(s):  
Magnetic Field ◽  
Black Hole ◽  
Strong Magnetic Field ◽  
Center Of Mass ◽  
Black Hole Horizon ◽  
Ultrahigh Energy ◽  
Particle Collisions ◽  
Energy Particle ◽  
Neutral Particles ◽  
Mass Frame

We consider collision between two charged (or charged and neutral) particles near the black hole horizon in the strong magnetic field B. It is shown that there exists a strip near the horizon within which collision of any two such particles leads to ultrahigh energy in the center-of-mass frame (CM frame). The results apply to generic (not necessarily vacuum) black holes.

scholarly journals Observational signatures of magnetic field structure in relativistic AGN jets

2019 ◽  
Vol 622 ◽  
pp. A122 ◽  
Author(s):  
Christopher Prior ◽  
Konstantinos N. Gourgouliatos
Keyword(s):  
Magnetic Field ◽  
Black Hole ◽  
Magnetic Fields ◽  
Radio Emission ◽  
Faraday Rotation ◽  
Large Scale ◽  
Field Structure ◽  
Synchrotron Emission ◽  
Supermassive Black Hole ◽  
Rotation Measure

Context. Active galactic nuclei (AGN) launch highly energetic jets sometimes outshining their host galaxy. These jets are collimated outflows that have been accelerated near a supermassive black hole located at the centre of the galaxy. Their, virtually indispensable, energy reservoir is either due to gravitational energy released from accretion or due to the extraction of kinetic energy from the rotating supermassive black hole itself. In order to channel part of this energy to the jet, though, the presence of magnetic fields is necessary. The extent to which these magnetic fields survive in the jet further from the launching region is under debate. Nevertheless, observations of polarised emission and Faraday rotation measure confirm the existence of large scale magnetic fields in jets. Aims. Various models describing the origin of the magnetic fields in AGN jets lead to different predictions about the large scale structure of the magnetic field. In this paper we study the observational signatures of different magnetic field configurations that may exist in AGN jets in order to asses what kind of information regarding the field structure can be obtained from radio emission, and what would be missed. Methods. We explore three families of magnetic field configurations. First, a force-free helical magnetic field corresponding to a dynamically relaxed field in the rest frame of the jet. Second, a magnetic field with a co-axial cable structure arising from the Biermann-battery effect at the accretion disk. Third, a braided magnetic field that could be generated by turbulent motion at the accretion disk. We evaluate the intensity of synchrotron emission, the intrinsic polarization profile and the Faraday rotation measure arising from these fields. We assume that the jet consists of a relativistic spine where the radiation originates from and a sheath containing thermalised electrons responsible for the Faraday screening. We evaluate these values for a range of viewing angles and Lorentz factors. We account for Gaussian beaming that smooths the observed profile. Results. Radio emission distributions from the jets with dominant large-scale helical fields show asymmetry across their width. The Faraday rotation asymmetry is the same for fields with opposing chirality (handedness). For jets which are tilted towards the observer the synchrotron emission and fractional polarization can distinguish the field’s chirality. When viewed either side-on or at a Blazar type angle only the fractional polarization can make this distinction. Further this distinction can only be made if the direction of the jet propagation velocity is known, along with the location of the jet’s origin. The complex structure of the braided field is found not to be observable due to a combination of line of sight integration and limited resolution of observation. This raises the possibility that, even if asymmetric radio emission signatures are present, the true structure of the field may still be obscure.

scholarly journals M87 black hole mass and spin estimate through the position of the jet boundary shape break

2019 ◽  
Vol 489 (1) ◽  
pp. 1197-1205 ◽  
Author(s):  
E E Nokhrina ◽  
L I Gurvits ◽  
V S Beskin ◽  
M Nakamura ◽  
K Asada ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Black Hole ◽  
Central Area ◽  
Active Galaxy ◽  
Test Case ◽  
Black Hole Mass ◽  
Boundary Shape ◽  
Supermassive Black Hole ◽  
Bulk Motion ◽  
Energy Equipartition

Abstract We propose a new method of estimating the mass of a supermassive black hole residing in the centre of an active galaxy. The active galaxy M87 offers a convenient test case for the method due to the existence of a large amount of observational data on the jet and ambient environment properties in the central area of the object. We suggest that the observed transition of a jet boundary shape from a parabolic to a conical form is associated with the flow transiting from the magnetically dominated regime to the energy equipartition between plasma bulk motion and magnetic field. By coupling the unique set of observations available for the jet kinematics, environment and boundary profile with our MHD modelling under assumption on the presence of a dynamically important magnetic field in the M87 jet, we estimate the central black hole mass and spin. The method leads us to believe that the M87 supermassive black hole has a mass somewhat larger than typically accepted so far.

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