Relativistic Jet Formation from Black Hole Magnetized Accretion Disks: Method, Tests, and Applications of a General RelativisticMagnetohydrodynamic Numerical Code

1999 ◽  
Vol 522 (2) ◽  
pp. 727-752 ◽  
Author(s):  
Shinji Koide ◽  
Kazunari Shibata ◽  
Takahiro Kudoh
1997 ◽  
Vol 163 ◽  
pp. 667-671
Author(s):  
Shinji Koide ◽  
Kazunari Shibata ◽  
Takahiro Kudoh

AbstractRecently, superluminal motions are observed not only from active galactic nuclei but also in our Galaxy. These phenomena are explained as relativistic jets propagating almost toward us with Lorentz factor more than 2. For the formation of such a relativistic jet, magnetically driven mechanism around a black hole is most promising. We have extended the 2.5D Newtonian MHD jet model (Shibata & Uchida 1986) to general relativistic regime. For this purpose, we have developed a general relativistic magnetohydrodynamic (GRMHD) numerical code and applied it to the simulation of the magnetized accretion disk around a black hole. We have found the formation of magnetically driven jets with 86 percent of light velocity (i.e. Lorentz factor ~ 2.0).


1997 ◽  
Vol 159 ◽  
pp. 56-63
Author(s):  
E. Rokak

AbstractIrradiated accretion disks around massive black holes are expected to produce part of the line spectrum of AGN, but most of the disk emission must be thermal, observed at UV wavelengths. The two emission components, lines and continuum, are fitted by a unique accretion-disk model that gives the mass of the black hole and the inclination of the disk. The distribution of the disk inclination in a complete sample of Seyfert 1 galaxies suggests that their nuclei are orientation-selected, affected by strong absorption at low disk latitudes. The black-hole masses in the same sample confirm the long-standing non-linearity between M and L for AGN and the non-causal relationship between nearby Seyfert 1 galaxies and distant quasars (i.e., pure luminosity evolution is ruled out).Irradiated accretion disks are also combined with the relativistic jet model in order to constrain the orientation and the Lorentz factor of 14 superluminal radio sources. At least for a few objects, the line and the radio data are inconsistent with both models, unless a new parameter (jet bending, a second emission-line component, etc.), is also involved. Despite this inconsistency and the ambiguous evidence for combined disk and jet fits in the remaining superluminal sources, a successful merger of these two models might address questions about the nature of AGN and also constrain the Hubble constant.


1998 ◽  
Vol 188 ◽  
pp. 415-416 ◽  
Author(s):  
Shinji Koide ◽  
Kazunari Shibata ◽  
Takahiro Kudoh

The radio jets ejected from active galactic nuclei (AGNs) sometimes show proper motions with apparent velocity exceeding the speed of light. This phenomenon, called superluminal motion, is explained as relativistic jets propagating in a direction almost toward us, and has been thought to be ejected from the close vicinity of hypothetical supermassive black holes powering AGNs (Rees 1996). The magnetic mechanism has been proposed not only for AGN jets (Lovelace 1976; Blandford & Payne 1983) but also for protostellar jets (Pudritz & Norman 1986; Uchida & Shibata 1985; Shibata & Uchida 1986), although no one has yet performed nonsteady general relativistic magnetohydrodynamic (GRMHD) numerical simulations on the formation of jets from the accretion disk around a black hole.


2012 ◽  
Vol 08 ◽  
pp. 253-258
Author(s):  
DIMITRIOS GIANNIOS ◽  
BRIAN D. METZGER

The tidal disruption of a star by a supermassive black hole provides us with unique information for otherwise dormant galactic nuclei. It has long been predicted that the disruption will be accompanied by a thermal 'flare', powered by the accretion of stellar debris. Recently, we proposed that a modest fraction of the accretion power can be channeled into a relativistic jet. We showed that, even if the jet is not pointing at our direction, the interactions of the jet with the interstellar medium can power a bright radio-IR transient. Recent transients discovered by Swift have all the expected characteristics of a new-born jet powered by the tidal disruption of a star. The evidence is strong that we are witnessing a most direct verification of the our proposal with the transient jet pointing directly at us. Upcoming radio transient surveys can independently discover numerous disruptions, complimenting searches at other wavelengths. Tidal disruptions can probe the physics of jet formation under relatively clean conditions, in which the flow parameters are independently constrained.


1997 ◽  
Vol 488 (1) ◽  
pp. 109-118 ◽  
Author(s):  
Christopher S. Reynolds ◽  
Mitchell C. Begelman

1997 ◽  
Vol 163 ◽  
pp. 620-625 ◽  
Author(s):  
H. Ford ◽  
Z. Tsvetanov ◽  
L. Ferrarese ◽  
G. Kriss ◽  
W. Jaffe ◽  
...  

AbstractHST images have led to the discovery that small (r ~ 1″ r ~ 100 – 200 pc), well-defined, gaseous disks are common in the nuclei of elliptical galaxies. Measurements of rotational velocities in the disks provide a means to measure the central mass and search for massive black holes in the parent galaxies. The minor axes of these disks are closely aligned with the directions of the large–scale radio jets, suggesting that it is angular momentum of the disk rather than that of the black hole that determines the direction of the radio jets. Because the disks are directly observable, we can study the disks themselves, and investigate important questions which cannot be directly addressed with observations of the smaller and unresolved central accretion disks. In this paper we summarize what has been learned to date in this rapidly unfolding new field.


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