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.

scholarly journals Broad-line region structure and line profile variations in the changing look AGN HE 1136-2304

2018 ◽  
Vol 619 ◽  
pp. A168 ◽  
Author(s):  
W. Kollatschny ◽  
M. W. Ochmann ◽  
M. Zetzl ◽  
M. Haas ◽  
D. Chelouche ◽  
...  
Keyword(s):  
Seyfert Galaxies ◽  
Spectroscopic Properties ◽  
Emission Lines ◽  
Broad Line ◽  
Spectral Variability ◽  
Continuum Source ◽  
Line Intensities ◽  
Broad Line Region ◽  
Line Region ◽  
Optical Continuum

Aims. A strong X-ray outburst was detected in HE 1136-2304 in 2014. Accompanying optical spectra revealed that the spectral type has changed from a nearly Seyfert 2 type (1.95), classified by spectra taken 10 and 20 years ago, to a Seyfert 1.5 in our most recent observations. We seek to investigate a detailed spectroscopic campaign on the spectroscopic properties and spectral variability behavior of this changing look AGN and compare this to other variable Seyfert galaxies. Methods. We carried out a detailed spectroscopic variability campaign of HE 1136-2304 with the 10 m Southern African Large Telescope (SALT) between 2014 December and 2015 July. Results. The broad-line region (BLR) of HE 1136-2304 is stratified with respect to the distance of the line-emitting regions. The integrated emission line intensities of Hα, Hβ, He I λ5876, and He II λ4686 originate at distances of 15.0−3.8+4.2, 7.5−5.7+4.6, 7.3−4.4+2.8, and 3.0−3.7+5.3 light days with respect to the optical continuum at 4570 Å. The variability amplitudes of the integrated emission lines are a function of distance to the ionizing continuum source as well. We derived a central black hole mass of 3.8 ± 3.1 × 107 M⊙ based on the linewidths and distances of the BLR. The outer line wings of all BLR lines respond much faster to continuum variations indicating a Keplerian disk component for the BLR. The response in the outer wings is about two light days shorter than the response of the adjacent continuum flux with respect to the ionizing continuum flux. The vertical BLR structure in HE 1136-2304 confirms a general trend that the emission lines of narrow line active galactic nuclei (AGNs) originate at larger distances from the midplane in comparison to AGNs showing broader emission lines. Otherwise, the variability behavior of this changing look AGN is similar to that of other AGN.

scholarly journals Accretion in the broad line region of active galactic nuclei

2006 ◽  
Vol 2 (S238) ◽  
pp. 329-330
Author(s):  
E. Bon ◽  
L. Č. Popović ◽  
D. Ilić
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Emission Lines ◽  
Broad Line ◽  
Line Profiles ◽  
Spherical Region ◽  
Broad Line Region ◽  
Broad Emission ◽  
Line Region ◽  
Two Component

AbstractWe modeled the single-peaked Broad Emission Lines (BELs) with two-component model (accretion disk, with surrounding spherical region), comparing it with observational line profiles for a number of Active Galactic Nuclei (AGN). We find that the accretion in the Broad Line Region (BLR) can be present even if the profiles of BELs are single-peaked.

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 Broad Emission Lines in Active Galactic Nuclei

1997 ◽  
Vol 159 ◽  
pp. 80-95 ◽  
Author(s):  
J. A. Baldwin
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Emission Lines ◽  
Broad Line ◽  
Broad Line Region ◽  
Broad Emission ◽  
Line Region

AbstractThis paper assesses what we have learned about the structure of AGN broad-line region (BLR), with emphasis on the work other than reverberation studies in order to complement other recent reviews. Basic photoionization models are briefly described. Current models of the BLR and some of the observations that might distinguish among them are discussed.

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
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