scholarly journals The role of failed accretion disk winds in active galactic nuclei

2019 ◽  
Vol 15 (S356) ◽  
pp. 82-86 ◽  
Author(s):  
Margherita Giustini ◽  
Daniel Proga
Keyword(s):  
Active Galactic Nuclei ◽  
Accretion Disks ◽  
Galactic Nuclei ◽  
Broad Line ◽  
X Ray ◽  
Broad Line Region ◽  
Line Region ◽  
Gravitational Pull ◽  
Theoretical Evidence

AbstractBoth observational and theoretical evidence point at outflows originating from accretion disks as fundamental ingredients of active galactic nuclei (AGN). These outflows can have more than one component, for example an unbound supersonic wind and a failed wind (FW). The latter is a prediction of the simulations of radiation-driven disk outflows which show that the former is accompanied by an inner failed component, where the flow struggles to escape from the strong gravitational pull of the supermassive black hole. This FW component could provide a physical framework to interpret various phenomenological components of AGN. Here we briefly discuss a few of them: the broad line region, the X-ray obscurer, and the X-ray corona.

scholarly journals FeII, FeI Emission Lines from Accretion Disks: An Explanation for “FeII Problem” in AGNs?

1994 ◽  
Vol 159 ◽  
pp. 463-463
Author(s):  
Chunyan Wei ◽  
Fuzhen Cheng ◽  
Junhan You
Keyword(s):  
Active Galactic Nuclei ◽  
Accretion Disk ◽  
Accretion Disks ◽  
Galactic Nuclei ◽  
Emission Lines ◽  
Broad Line ◽  
Broad Line Region ◽  
Line Region

For the solution of the puzzling “FeII problem” in active galactic nuclei(AGNs) (Netzer et al. 1983; Wills et al. 1985), we pay our attention to optical band and suggest: (1)the observed so-called “FeII emission lines” features may be blending of FeII multiples and FeI multiples. Our previous work(Wei et al. 1993) has showed that there are many FeI emission lines whose wavelength lie around the observed “FeII emission lines” features. In fact, FeI emission lines have been observed in the spectrum of PHL 1092(Bergeron et al. 1980; Cheng et al. 1993). (2)the emission lines from accretion disk must be considered besides the emission from broad line region.

scholarly journals Supernova Fragments and the Origin of the Rapid X-ray Variability

1994 ◽  
Vol 159 ◽  
pp. 371-371
Author(s):  
R. Cid Fernandes ◽  
R. Terlevich ◽  
G. Tenorio-Tagle ◽  
J. Franco ◽  
M. Rozyczka
Keyword(s):  
Active Galactic Nuclei ◽  
Luminosity Function ◽  
Galactic Nuclei ◽  
Seyfert Galaxies ◽  
Broad Line ◽  
X Ray ◽  
Broad Line Region ◽  
Line Region

The Starburst model for Radio Quiet Active Galactic Nuclei proved able to explain the origin of the broad line region, the variability characteristics of line and continuum in Seyfert galaxies, X-ray spectra, the luminosity function of QSOs and etc. But can we understand the rapid X-ray variability observed in several AGN with supernovae?

scholarly journals Pumping of H2O Megamasers

1998 ◽  
Vol 11 (2) ◽  
pp. 960-963
Author(s):  
Moshe Elitzur
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Broad Line ◽  
X Ray ◽  
Star Forming ◽  
Broad Line Region ◽  
Star Forming Regions ◽  
Disk Rotation ◽  
Line Region ◽  
Pump Mechanism

AbstractStrong H2O maser emission is detected from active galactic nuclei (AGN) as well as Galactic objects such as star-forming regions and late-type stars. In spite of the widely different luminosities of the different masers, a common pump mechanism seems adequate: neutral collisions at densities of ˜ 108-1010 cm-3 and temperatures of ˜ 250-500 K. The different properties of the various masers can be attributed to geometry. Although disk rotation controls the AGN maser geometry it does not directly determine the dimensions. X-ray radiation and spiral shocks have been suggested as the heating sources of H2O megamasers. Both are capable of explaining the observations, and the radiative scenario seems best understood in terms of chance alignment of standard broad-line-region clouds. It is not yet clear whether these different proposals produce distinct maser signatures.

scholarly journals Soft X-ray Variability and the Covering Fraction of Active Galactic Nuclei

1989 ◽  
Vol 134 ◽  
pp. 118-119
Author(s):  
Michael A. Strauss ◽  
Kenneth W. Wachter ◽  
Alexei V. Filippenko
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Line Of Sight ◽  
X Rays ◽  
Broad Line ◽  
X Ray ◽  
Broad Line Region ◽  
Line Region ◽  
Partial Covering

The variability of soft X-rays (0.2 – 2 keV) in some low-luminosity type 1 Seyferts may partly be due to an extrinsic mechanism: dense clouds of gas in the broad-line region, opaque to soft X-rays, move across our line of sight to the X-ray emitting portions of the accretion disk (Reichert, Mushotzky, and Holt 1986; Lawrence and Elvis 1982; Halpern 1984). As the clouds move, the covering fraction changes stochastically. Evidence for partial covering of the X-ray source in low-luminosity AGNs has been seen in soft X-ray spectra by Holt et al. (1980) and Reichert et al. (1985).

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 Spectral Variability in Seyfert Galaxies

1987 ◽  
Vol 121 ◽  
pp. 161-167
Author(s):  
B.M. Peterson
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Seyfert Galaxies ◽  
Broad Line ◽  
Spectral Variability ◽  
Broad Line Region ◽  
Broad Emission ◽  
Line Region ◽  
Order Of Magnitude ◽  
Optical Continuum

Recent observations of spectral variability in active galactic nuclei have established the connection between the broad emission-line and optical continuum flux changes. The inferred size of the broad-line region is at least an order of magnitude smaller than conventional estimates based on photoionization models, which leads to new conclusions about the nature of the broad-line region.

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