scholarly journals The Black Hole Grazer

1998 ◽  
Vol 188 ◽  
pp. 449-450
Author(s):  
Y. Taniguchi ◽  
O. Kaburaki
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Binary System ◽  
Galactic Center ◽  
Center Of Mass ◽  
Galactic Nuclei ◽  
Orbital Plane ◽  
Roche Lobe ◽  
Surface Charges ◽  
Massive Black Holes

We propose an alternative model for the powering of active galactic nuclei (AGN), based on the assumption that all AGN have experienced mergers. In our model (Kaburaki and Taniguchi 1996; Taniguchi and Kaburaki 1996), a close pair of super-massive black holes (the black hole grazer) orbit one another in a plane roughly perpendicular to the galactic center magnetic field. The orbital motion induces surface charges on the black holes which produce an electric field. This field is strong enough to cause pair creation so that the Roche lobe of the binary system is filled with pair plasmas. Rigid-body rotation of the Roche-lobe magnetosphere drives electrodynamically a powerful synchrotron jet emanating from the center of mass of the binary. Furthermore, a pair of equatorial jets flow from the outer Lagrangian points of the binary system. Although these jets are not so collimated, they interact with the accreting gas ring formed around the orbital plane of the binary, causing broad line regions or H2O maser emission regions (Taniguchi et al. 1996). In addition to the primary jet, two secondary jets are also driven by local accretion disks around the two black holes. The interaction among the primary and the secondary jets may explain detailed jet morphology observed by VLBI facilities.

scholarly journals 11.3. The black hole grazer

1998 ◽  
Vol 184 ◽  
pp. 461-462
Author(s):  
Y. Taniguchi ◽  
O. Kaburaki
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Binary System ◽  
Galactic Center ◽  
Center Of Mass ◽  
Galactic Nuclei ◽  
Orbital Plane ◽  
Roche Lobe ◽  
Surface Charges ◽  
Massive Black Holes

We propose an alternative model for the powering of active galactic nuclei (AGN), based on the assumption that all AGN have experienced mergers. In our model (Kaburaki and Taniguchi 1996; Taniguchi and Kaburaki 1996), a close pair of super-massive black holes (the black hole grazer) orbit one another in a plane roughly perpendicular to the galactic center magnetic field. The orbital motion induces surface charges on the black holes which produce an electric field. This field is strong enough to cause pair creation so that the Roche lobe of the binary system is filled with pair plasmas. Rigid-body rotation of the Roche-lobe magnetosphere drives electrodynamically a powerful synchrotron jet emanating from the center of mass of the binary. Furthermore, a pair of equatorial jets flow from the outer Lagrangian points of the binary system. Although these jets are not so collimated, they interact with the accreting gas ring formed around the orbital plane of the binary, causing broad line regions or H2O maser emission regions (Taniguchi et al. 1996). In addition to the primary jet, two secondary jets are also driven by local accretion disks around the two black holes. The interaction among the primary and the secondary jets may explain detailed jet morphology observed by VLBI facilities.

scholarly journals Study of the Galactic Center with a High Resolution Gamma Ray Telescope

1989 ◽  
Vol 136 ◽  
pp. 639-643
Author(s):  
Ervin J. Fenyves ◽  
Stephen N. Balog ◽  
David B. Cline ◽  
M. Atac
Keyword(s):  
Black Holes ◽  
Active Galactic Nuclei ◽  
Gamma Ray ◽  
Galactic Center ◽  
Galactic Nuclei ◽  
Seyfert Galaxies ◽  
Hole Formation ◽  
Massive Black Holes ◽  
General Outcome ◽  
Enormous Amount

It is generally accepted that massive black holes are the most likely source for the energy radiated from active galactic nuclei, and may explain the enormous amount of energy emitted by quasars, radio galaxies, Seyfert galaxies, and BL Lacertid objects. Although the detailed mechanisms of the black hole formation in galactic nuclei are not clear at present, it seems to be quite possible that the formation of massive black holes is a general outcome of the evolution of galactic nuclei.

THE GALACTIC CENTER IS ALIVE

2011 ◽  
Vol 20 (10) ◽  
pp. 1937-1940
Author(s):  
PASCAL CHARDONNET ◽  
ANNA CHIAPPINELLI
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Dark Matter ◽  
Event Horizon ◽  
Galactic Center ◽  
Direct Proof ◽  
Massive Black Holes ◽  
Central Object ◽  
Evolution Of Galaxies ◽  
Formation And Evolution

The center of our Galaxy provides a uniquely accessible laboratory. It is a rich environment of extreme density, velocity and tidal fields of stars. It is the closest example of a galactic nucleus and could give the opportunity to understand the role that massive black-holes play in the formation and evolution of galaxies. It could be used to test the effects of relativity and dark matter in the Galactic Center. If the central object is a black-hole such observation would be a milstone: the first direct proof that an event horizon, and therefore a black-hole exists. The next decade will be decisive in new discoveries.

The Role of Gas in the Merging of Massive Black Holes in Galactic Nuclei. II. Black Hole Merging in a Nuclear Gas Disk

2005 ◽  
Vol 630 (1) ◽  
pp. 152-166 ◽  
Author(s):  
Andres Escala ◽  
Richard B. Larson ◽  
Paolo S. Coppi ◽  
Diego Mardones
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Galactic Nuclei ◽  
Massive Black Holes

scholarly journals Spectroscopy of the Stellar Wind in the Cygnus X-1 System

10.14311/1332 ◽  
2011 ◽  
Vol 51 (1) ◽  
Author(s):  
I. Miškovičová ◽  
M. Hanke ◽  
J. Wilms ◽  
M. A. Nowak ◽  
K. Pottschmidt ◽  
...  
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Binary System ◽  
Stellar Wind ◽  
Roche Lobe ◽  
High Mass ◽  
Lagrange Point ◽  
Companion Star ◽  
X Ray ◽  
Accretion Flow

The X-ray luminosity of black holes is produced through the accretion of material from their companion stars. Depending on the mass of the donor star, accretion of the material falling onto the black hole through the inner Lagrange point of the system or accretion by the strong stellar wind can occur. Cygnus X-1 is a high mass X-ray binary system, where the black hole is powered by accretion of the stellar wind of its supergiant companion star HDE226868. As the companion is close to filling its Roche lobe, the wind is not symmetric, but strongly focused towards the black hole. Chandra-HETGS observations allow for an investigation of this focused stellar wind, which is essential to understand the physics of the accretion flow. We compare observations at the distinct orbital phases of 0.0, 0.2, 0.5 and 0.75. These correspond to different lines of sight towards the source, allowing us to probe the structure and the dynamics of the wind.

Is there a massive black hole at the galactic center?

1979 ◽  
Vol 84 ◽  
pp. 395-400
Author(s):  
L. M. Ozernoy
Keyword(s):  
Black Hole ◽  
Galactic Center ◽  
Dynamical Evolution ◽  
Galactic Nuclei ◽  
Black Hole Mass ◽  
Massive Black Hole ◽  
Massive Black Holes ◽  
Infrared Observations ◽  
The Galaxy ◽  
Remote Past

During the past 10 years an hypothesis about the presence of a massive black hole at the center of our Galaxy (Lynden-Bell, 1969) has been an object of many exciting speculations. This hypothesis is based, firstly, on attempts to explain the nature of the “point radio source” at the galactic center (as well as a presumed much more powerful activity of the galactic nucleus in the remote past), and, secondly, on the opinion that the conditions in the course of dynamical evolution of galactic nuclei are favorable for the formation of massive black holes. However, both these approaches did not succeed in predicting with any confidence the black hole mass at the center of the Galaxy. The estimates available are based on indirect arguments and range from 107-1011 M⊙ (Novikov and Thorne, 1973) to 104 M⊙ (Shklovskii, 1976). A recent dynamical approach using NeII infrared observations of the galactic center (Wollman et al., 1977) has indicated that the black hole mass does not exceed 5×106 M⊙ (Oort, 1977), although this value may well be due to a very dense star cluster whose brightest members only are seen in the infrared.

BLACK HOLES IN GAMMA RAY BURSTS AND GALACTIC NUCLEI

2013 ◽  
Vol 22 (11) ◽  
pp. 1360008 ◽  
Author(s):  
REMO RUFFINI ◽  
C. R. ARGÜELLES ◽  
B. M. O. FRAGA ◽  
A. GERALICO ◽  
H. QUEVEDO ◽  
...  
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Active Galactic Nuclei ◽  
Gamma Ray ◽  
Galactic Nuclei ◽  
Future Research ◽  
Galactic Halos ◽  
Unified Approach ◽  
Massive Black Holes ◽  
The Moment

Current research marks a clear success in identifying the moment of formation of a Black Hole of ~ 10M⊙, with the emission of a Gamma Ray Burst. This explains in terms of the 'Blackholic Energy' the source of the energy of these astrophysical systems. Their energetics up to 1054 erg, make them detectable all over our Universe. Concurrently a new problematic has been arising related to: (a) The evidence of Dark Matter in galactic halos; (b) The origin of the Super Massive Black Holes in active galactic nuclei and Quasars and (c) The purported existence of a Black Hole in the Center of our Galaxy. These three aspects of this new problematic have been traditionally approached independently. We propose an unified approach to all three of them based on a system of massive self-gravitating neutrinos in General Relativity. Perspectives of future research are presented.

A TWO-STEP MECHANISM FOR PARTICLE ACCELERATION IN THE MAGNETOSPHERE OF ACCRETING BLACK HOLES

2008 ◽  
Vol 17 (09) ◽  
pp. 1585-1590
Author(s):  
YA. ISTOMIN ◽  
H. SOL
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Active Galactic Nuclei ◽  
Accretion Disks ◽  
Gamma Rays ◽  
Galactic Nuclei ◽  
Massive Black Holes ◽  
Relativistic Beaming ◽  
Ejection Process ◽  
Step Mechanism

Fast variability now observed in VHE gamma-rays from active galactic nuclei (PKS 2155–304, M87, Mkn 501) seems to require very small TeV emitting zones, even in the presence of a significant relativistic beaming. We explore the possibility to accelerate particles up to VHE energies in such small compact regions around massive black holes, taking into account the two places in the black hole surroundings where efficient acceleration can be expected during the accretion-ejection process, namely turbulent low-luminosity accretion disks and rotating magnetospheres.

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