scholarly journals Determination of the Central Mass in Active Galactic Nuclei Using Cross‐Correlation Lags and Velocity Dispersions

2000 ◽  
Vol 533 (1) ◽  
pp. 172-175 ◽  
Author(s):  
Michael J. Fromerth ◽  
Fulvio Melia
Keyword(s):  
Active Galactic Nuclei ◽  
Cross Correlation ◽  
Galactic Nuclei ◽  
Central Mass ◽  
Velocity Dispersions

scholarly journals Steps toward Determination of the Size and Structure of the Broad‐Line Region in Active Galactic Nuclei. X. Variability of Fairall 9 from Optical Data

1997 ◽  
Vol 112 (2) ◽  
pp. 271-283 ◽  
Author(s):  
M. Santos‐Lleo ◽  
E. Chatzichristou ◽  
C. Mendes de Oliveira ◽  
C. Winge ◽  
D. Alloin ◽  
...  
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Optical Data ◽  
Broad Line ◽  
Broad Line Region ◽  
Line Region ◽  
Size And Structure

scholarly journals 3.25. Radiative avalanche driven by a circumnuclear starburst torus

1998 ◽  
Vol 184 ◽  
pp. 139-140
Author(s):  
Ken Ohsuga ◽  
Masayuki Umemura
Keyword(s):  
Angular Momentum ◽  
Active Galactic Nuclei ◽  
Drag Force ◽  
Compact Star ◽  
Star Clusters ◽  
Galactic Nuclei ◽  
Curvature Radius ◽  
Thin Ring ◽  
Velocity Dispersions ◽  
Half Thickness

Recently, a novel mechanism for fueling active galactic nuclei (AGNs) has been proposed by Umemura et al. (1997a, b). That is a radiative avalanche, in which a rotating gas disk sheds angular momentum due to the radiation drag force exerted by starlight from circumnuclear starbursts, so that the mass accretion onto nuclei is driven. Originally, a thin ring of a starburst region has been assumed for simplicity. However, recent observations have revealed that circumnuclear starburst rings have radial extension of ∼ 10pc up to kpc, and they often consist of compact star clusters of < 10pc Thus, the ratio of the half thickness to curvature radius of the ring can be minimally less than one tenth when all the star clusters are aligned on a plane of an inner gas disk, while the ratio could be larger if the distributions of star clusters are extended due to some velocity dispersions.

Radiative wind from a luminous star cluster

2020 ◽  
Vol 72 (6) ◽  
Author(s):  
Jun Fukue
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Center ◽  
Star Clusters ◽  
Galactic Nuclei ◽  
Source Distribution ◽  
Radiative Force ◽  
Mass Reduction ◽  
Central Mass ◽  
Point Analysis ◽  
Thermally Driven

Abstract We reexamine the steady spherical wind from distributed sources, such as star clusters and a galactic center, taking into account the radiative force from distributed sources and mass reduction via orbital motions. We consider a cold dusty wind, an isothermal gaseous flow, and a nonisothermal general one without/with a central mass and a stagnation radius for various powers of source distributions. We perform singular point analysis for each case, and obtain a transonic solution, if one exists. We find that thermally driven outflows can emerge in limited situations, such that the source distribution is rather steep in the isothermal flow. On the other hand, under the appropriate conditions radiatively driven winds can easily be produced. Radiative cluster winds without a central mass could emerge from newly born star clusters or neutron star clusters, whereas those with a central mass could appear from active galactic nuclei. Radiative cluster winds would also operate in first star clusters.

Determination of supermassive black hole spins in active galactic nuclei

2020 ◽  
Vol 35 (02n03) ◽  
pp. 2040054
Author(s):  
M. Yu. Piotrovich ◽  
V. L. Afanasiev ◽  
S. D. Buliga ◽  
T. M. Natsvlishvili
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Active Galactic Nuclei ◽  
Accretion Disk ◽  
Galactic Nuclei ◽  
Supermassive Black Holes ◽  
Disk Model ◽  
Supermassive Black Hole

Based on spectropolarimetry for a number of active galactic nuclei in Seyfert 1 type galaxies observed with the 6-m BTA telescope, we have estimated the spins of the supermassive black holes at the centers of these galaxies. We have determined the spins based on the standard Shakura-Sunyaev accretion disk model. More than 70% of the investigated active galactic nuclei are shown to have Kerr supermassive black holes with a dimensionless spin greater than 0.9.

scholarly journals On Uncertainties in Cross‐Correlation Lags and the Reality of Wavelength‐dependent Continuum Lags in Active Galactic Nuclei

1998 ◽  
Vol 110 (748) ◽  
pp. 660-670 ◽  
Author(s):  
Bradley M.  Peterson ◽  
Ignaz  Wanders ◽  
Keith  Horne ◽  
Stefan  Collier ◽  
Tal  Alexander ◽  
...  
Keyword(s):  
Active Galactic Nuclei ◽  
Cross Correlation ◽  
Galactic Nuclei
Sign in / Sign up

Export Citation Format

Share Document