scholarly journals What Physics Drives the Unified Model?

1999 ◽  
Vol 194 ◽  
pp. 199-207
Author(s):  
Michael A. Dopita
Keyword(s):  
Black Hole ◽  
Active Galactic Nucleus ◽  
Accretion Rate ◽  
Unified Model ◽  
Grand Unification ◽  
Evolutionary Status ◽  
Central Black Hole ◽  
Nuclear Regions

The Unified Model holds that the aspect-dependent effects primarily determine the apperance of the active galactic nucleus that we observe. However, additional parameters will be needed to fully unify the different tribes of AGN. Three parameters; aspect, accretion rate into the nuclear regions, and the evolutionary status of the central black hole probably hold the key to “grand” unification schemes.

scholarly journals Towards a Truly Unified Model of AGN: Aspect, Accretion and Evolution

1997 ◽  
Vol 14 (3) ◽  
pp. 230-245 ◽  
Author(s):  
Michael A. Dopita
Keyword(s):  
Black Holes ◽  
Dominant Role ◽  
Unified Model ◽  
Evolutionary Status ◽  
Massive Black Holes ◽  
Radio Jets ◽  
Line Region ◽  
Nuclear Regions ◽  
Diagnostic Capabilities ◽  
The Universe

AbstractThe Unified Model holds that the aspect-dependent effects primarily determine the nature of the active galactic nucleus that we observe. In this paper, I argue that three parameters; aspect, accretion rate into the nuclear regions, and the evolutionary status of the central black hole hold the key to unification. The mystery of why the epoch of quasar formation occurred so early in the evolution of the Universe, why radio-loud QSOs represent only a small fraction of the general population of QSOs, and why ellipticals are invariably the hosts of radio-loud active galaxies could be explained if (a) the most rapid growth of black holes occurred in galactic merger events, and if (b) an excess in the rate of nuclear feeding was able to choke off the radio jets, producing radio quiet QSOs. In this paper, I develop the idea that rate of nuclear feeding plays a dominant role and that feeding at super-Eddington rates into the broad-line region (BLR) during merger events is the means whereby massive black holes are grown. In particular, I develop a toy model for the radio-loud, radio-quiet dichotomy based on the rate of nuclear feeding, suggest an electron scattering model for the ‘big blue bump’ and its relation to the BLR, and emphasise the important diagnostic capabilities offered by analyses of the narrow line regions based on shock excitation models.

scholarly journals Hard X-Ray Irradiation Potentially Drives Negative AGN Feedback by Altering Molecular Gas Properties

2021 ◽  
Vol 257 (2) ◽  
pp. 64
Author(s):  
Taiki Kawamuro ◽  
Claudio Ricci ◽  
Takuma Izumi ◽  
Masatoshi Imanishi ◽  
Shunsuke Baba ◽  
...  
Keyword(s):  
Star Formation ◽  
Interstellar Medium ◽  
Active Galactic Nucleus ◽  
Accretion Rate ◽  
Spatial Separation ◽  
Molecular Gas ◽  
X Ray ◽  
Mass Accretion Rate ◽  
Nuclear Regions

Abstract To investigate the role of active galactic nucleus (AGN) X-ray irradiation on the interstellar medium (ISM), we systematically analyzed Chandra and Atacama Large Millimeter/submillimeter Array CO (J = 2–1) data for 26 hard X-ray (>10 keV) selected AGNs at redshifts below 0.05. While Chandra unveils the distribution of X-ray-irradiated gas via Fe-Kα emission, the CO (J = 2–1) observations reveal that of cold molecular gas. At high resolutions ≲1″, we derive Fe-Kα and CO (J = 2–1) maps for the nuclear 2″ region and for the external annular region of 2″–4″, where 2″ is ∼100–600 pc for most of our AGNs. First, focusing on the external regions, we find the Fe-Kα emission for six AGNs above 2σ. Their large equivalent widths (≳1 keV) suggest a fluorescent process as their origin. Moreover, by comparing the 6–7 keV/3–6 keV ratio, as a proxy of Fe-Kα, and CO (J = 2–1) images for three AGNs with the highest significant Fe-Kα detections, we find a possible spatial separation. These suggest the presence of X-ray-irradiated ISM and the change in the ISM properties. Next, examining the nuclear regions, we find that (1) the 20–50 keV luminosity increases with the CO (J = 2–1) luminosity; (2) the ratio of CO (J = 2–1)/HCN (J = 1–0) luminosities increases with 20–50 keV luminosity, suggesting a decrease in the dense gas fraction with X-ray luminosity; and (3) the Fe-Kα-to-X-ray continuum luminosity ratio decreases with the molecular gas mass. This may be explained by a negative AGN feedback scenario: the mass accretion rate increases with gas mass, and simultaneously, the AGN evaporates a portion of the gas, which possibly affects star formation.

scholarly journals The gravitational redshift in the broad line region of the active galactic nucleus Mrk 110

2006 ◽  
Vol 2 (S238) ◽  
pp. 369-370
Author(s):  
N. Gavrilović ◽  
L.Č Popović ◽  
W. Kollatschny
Keyword(s):  
Black Hole ◽  
Gravitational Field ◽  
Active Galactic Nucleus ◽  
Broad Line ◽  
Line Profiles ◽  
Central Black Hole ◽  
Broad Line Region ◽  
Line Region ◽  
Field Influence

AbstractWe used the long term spectroscopic observations of Mrk 110 (Hα and Hβ lines) to investigate the gravitational field influence on spectral line profiles. We found that effects of gravitational field can be measured and that the lines are more intense where the emission is originating close to the central black hole of Mrk 110.

scholarly journals Generation and Transport of Magnetic Flux in Accretion–Ejection Flows

Galaxies ◽  
2019 ◽  
Vol 7 (1) ◽  
pp. 12
Author(s):  
Ioannis Contopoulos
Keyword(s):  
Magnetic Field ◽  
Black Hole ◽  
Magnetic Flux ◽  
Electric Current ◽  
Large Scale ◽  
Accretion Rate ◽  
Quiescent State ◽  
Central Black Hole ◽  
Outward Diffusion ◽  
Astrophysical Mechanism

Astrophysical accretion flows are associated with energetic emission of radiation and outflows (winds and jets). Extensive observations of these two processes in X-ray binary outbursts are available. A convincing understanding of their dynamics remains, however, elusive. The main agent that controls the dynamics is believed to be a large scale magnetic field that threads the system. We propose that during the quiescent state, the field is held in place by a delicate balance between inward advection and outward diffusion through the accreting matter. We also propose that the source of the field is a growing toroidal electric current generated by the aberrated radiation pressure on the innermost plasma electrons in orbit around the central black hole. This is the astrophysical mechanism of the Cosmic Battery. When the return magnetic field outside the toroidal electric current diffuses through the surrounding disk, the disk magnetic field and its associated accretion rate gradually increase, thus leading the system to an outburst. After the central accretion flow approaches equipartition with radiation, it is disrupted, and the Cosmic Battery ceases to operate. The outward field diffusion is then reversed, magnetic flux reconnects with the flux accumulated around the central black hole and disappears. The magnetic field and the associated accretion rate slowly decrease, and the system is gradually driven back to quiescence. We conclude that the action (or inaction) of the Cosmic Battery may be the missing key that will allow us to understand the long-term evolution of astrophysical accretion–ejection flows.

The Double Nucleus and Central Black Hole of M31

1999 ◽  
Vol 522 (2) ◽  
pp. 772-792 ◽  
Author(s):  
John Kormendy ◽  
Ralf Bender
Keyword(s):  
Black Hole ◽  
Central Black Hole ◽  
Double Nucleus

scholarly journals Wandering of the central black hole in a galactic nucleus and correlation of the black hole mass with the bulge mass

2021 ◽  
Author(s):  
Hajime Inoue
Keyword(s):  
Black Hole ◽  
Loss Rate ◽  
Energy Gain ◽  
Stellar Disk ◽  
Black Hole Mass ◽  
Central Black Hole ◽  
Massive Black Hole ◽  
Stellar Cluster ◽  
Upper Limit ◽  
Simple Parameter

Abstract We investigate a mechanism for a super-massive black hole at the center of a galaxy to wander in the nucleus region. A situation is supposed in which the central black hole tends to move by the gravitational attractions from the nearby molecular clouds in a nuclear bulge but is braked via the dynamical frictions from the ambient stars there. We estimate the approximate kinetic energy of the black hole in an equilibrium between the energy gain rate through the gravitational attractions and the energy loss rate through the dynamical frictions in a nuclear bulge composed of a nuclear stellar disk and a nuclear stellar cluster as observed from our Galaxy. The wandering distance of the black hole in the gravitational potential of the nuclear bulge is evaluated to get as large as several 10 pc, when the black hole mass is relatively small. The distance, however, shrinks as the black hole mass increases, and the equilibrium solution between the energy gain and loss disappears when the black hole mass exceeds an upper limit. As a result, we can expect the following scenario for the evolution of the black hole mass: When the black hole mass is smaller than the upper limit, mass accretion of the interstellar matter in the circumnuclear region, causing the AGN activities, makes the black hole mass larger. However, when the mass gets to the upper limit, the black hole loses the balancing force against the dynamical friction and starts spiraling downward to the gravity center. From simple parameter scaling, the upper mass limit of the black hole is found to be proportional to the bulge mass, and this could explain the observed correlation of the black hole mass with the bulge mass.

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