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 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 A Possible Mechanism to Explain the Narrow Line Variability of Seyfert Galaxies on Timescales of Months

1987 ◽  
Vol 121 ◽  
pp. 223-226
Author(s):  
Nikolay G. Bochkarev
Keyword(s):  
Phase Transfer ◽  
Seyfert Galaxies ◽  
Broad Line ◽  
Line Flux ◽  
Gas Emission ◽  
X Ray ◽  
Line Intensities ◽  
Broad Line Region ◽  
Line Region ◽  
Narrow Emission

Gas in the shadow of clouds in the outer parts of the broad line region can radiate a considerable fraction (dozens of percent) of the narrow emission line flux. The variability of the X-ray luminosity of the central source should result in significant variations of the gas emission on a timescale of months. Particularly strong changes of line intensities and column densities of gas in the shadow (~ 1023 cm−2) can be produced by phase transfer between two thermally stable fluids with temperatures 10–20×103 K and 40–100×103 K, which can exist in the shadow of clouds.

LOCATING THE BLAZAR EMISSION SITE WITH FERMI VARIABILITY

2012 ◽  
Vol 08 ◽  
pp. 37-42
Author(s):  
MARKOS GEORGANOPOULOS ◽  
AMANDA DOTSON ◽  
DEMOSTHENES KAZANAS ◽  
ERIC PERLMAN
Keyword(s):  
Energy Dissipation ◽  
Broad Line ◽  
Jet Formation ◽  
Spectral Variability ◽  
Ongoing Debate ◽  
Broad Line Region ◽  
Photon Field ◽  
First Case ◽  
Line Region

This work presents a method for settling the following ongoing debate: is the GeV emission of powerful blazars produced inside the sub-pc size broad line region (BLR) or further out at scales of ~ 10 pc where the IR photon field of the dusty molecular torus dominates over that the UV field of the BLR? In the first case the GeV emission is most probably external Compton (EC) scattering of the ~ 10 eV BLR photons21, while in the second the seed photons for the EC GeV emission are the ~ 0.1 eV photons of the dust9 in the molecular torus8. The issue of the energy dissipation location is connected to the jet formation and collimation process25 and, as we argue here, can be resolved with Fermi spectral variability observations.

scholarly journals The broad line region of AGN: Kinematics and physics

2006 ◽  
pp. 1-11 ◽  
Author(s):  
L.C. Popovic
Keyword(s):  
Electron Temperature ◽  
Accretion Disk ◽  
Emission Lines ◽  
Physical Parameters ◽  
Broad Line ◽  
Physical Conditions ◽  
Broad Line Region ◽  
Broad Emission ◽  
Line Region

In this paper a discussion of kinematics and physics of the Broad Line Region (BLR) is given. The possible physical conditions in the BLR and problems in determination of the physical parameters (electron temperature and density) are considered. Moreover, one analyses the geometry of the BLR and the probability that (at least) a fraction of the radiation in the Broad Emission Lines (BELs) originates from a relativistic accretion disk.

scholarly journals Influence of the Gravitational Field on the Shape of Spectral Lines in Spectra of Seyfert Galaxies and Quasars

1994 ◽  
Vol 159 ◽  
pp. 456-456
Author(s):  
L. Č. Popović ◽  
I. Vince ◽  
A. Kubičela
Keyword(s):  
Gravitational Field ◽  
Seyfert Galaxies ◽  
Important Influence ◽  
Spectral Lines ◽  
Line Of Sight ◽  
Broad Line ◽  
Broad Line Region ◽  
Preliminary Examination ◽  
Line Region ◽  
Ngc 7469

On the basis of preliminary examination of the model of Seyfert galaxies and quasars we have concluded that their gravitational field may have an important influence on the shape of spectral lines when the emission cloud is in gravitational field of massive nuclei (mass about 107–108 M⊙ for Seyfert galaxies, see e.g. Padovani et al. 1990), and the emission cloud is large enough (for example about 1014–1015 m for Broad Line Region (BLR) of NGC 7469 (Bonatto & Pastoriza 1990) or about 1021 m for quasar 3C 257 (Forbes et al. 1990)), so that the emitters are in very different gravitational field along the line of sight.

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