scholarly journals 5.9. Gas dynamics in the central part of the Sy 1 galaxies: III Zw 2 and Mrk 817

1998 ◽  
Vol 184 ◽  
pp. 227-228
Author(s):  
L. Č. Popović ◽  
I. Vince ◽  
A. Kubičela ◽  
S. Salim
Keyword(s):  
Active Galactic Nuclei ◽  
Gas Dynamics ◽  
Galactic Nuclei ◽  
Active Galaxies ◽  
Line Shapes

Spectra of Active Galactic Nuclei (AGN) indicate that in their central parts a composite motion of emission gas exists. An analysis of broad as well as narrow lines of active galaxies can give information about gas dynamics in central part of these objects (see e.g. Netzer 1990, Osterbrock 1990). Here we present the investigation of the Hβ and O III[4959,5007] line shapes of the two Sy 1 galaxis: Mrk 817 and III Zw2.

AGN evolution as seen in spectral lines: The case of narrow-line Seyfert 1s

2019 ◽  
Vol 15 (S356) ◽  
pp. 94-94
Author(s):  
Marco Berton
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Spectroscopic Studies ◽  
Spectral Lines ◽  
Narrow Line ◽  
Line Profiles ◽  
Line Shapes ◽  
Fundamental Information ◽  
Line Region ◽  
Gaussian Samples

AbstractLine profiles can provide fundamental information on the physics of active galactic nuclei (AGN). In the case of narrow-line Seyfert 1 galaxies (NLS1s) this is of particular importance since past studies revealed how their permitted line profiles are well reproduced by a Lorentzian function instead of a Gaussian. This has been explained with different properties of the broad-line region (BLR), which may present more pronounced turbulent motions in NLS1s with respect to other AGN. We investigated the line profiles in a recent large NLS1 sample classified using SDSS, and we divided the sources into two subsamples according to their line shapes, Gaussian or Lorentzian. The line profiles seem to separate all the properties of NLS1s. Black hole mass, Eddington ratio, [OIII] luminosity, and Fe II strength are all very different in the Lorentzian and Gaussian samples, as well as their position on the quasar main sequence. We interpret this in terms of evolution within the class of NLS1s. The Lorentzian sources may be the youngest objects, while Gaussian profiles may be typically associated to more evolved objects. Further detailed spectroscopic studies are needed to fully confirm our hypothesis.

scholarly journals Quasar Evolution and the Growth of Black Holes in the Nuclei of Active Galaxies

1989 ◽  
Vol 134 ◽  
pp. 233-239
Author(s):  
R. D. Blandford
Keyword(s):  
Black Holes ◽  
Active Galactic Nuclei ◽  
Radiation Pressure ◽  
High Redshift ◽  
Galactic Nuclei ◽  
Rapid Decrease ◽  
Active Galaxies ◽  
Host Galaxy ◽  
Nearby Galaxies ◽  
The Mean

The observed evolutionary behavior of active galactic nuclei is compatible with a model in which black holes form in the nuclei of new-born galaxies and then grow at a rate limited by both radiation pressure and the supply of gas. Individual sources become more luminous with time as long as they are being fueled. However, the rapid decrease in the mean rate of supply of gas causes a strong decline in the space density of active objects. Nearby galaxies should harbor modest size (∼ 106 – 108 M⊙) black holes. It is suggested that the gas that fuels high redshift quasars is mostly derived from the host galaxy.

scholarly journals Infrared Line Shapes in Active Galactic Nuclei

1994 ◽  
Vol 159 ◽  
pp. 462-462
Author(s):  
Rodger I. Thompson
Keyword(s):  
Active Galactic Nuclei ◽  
Electron Density ◽  
Galactic Nuclei ◽  
Complete Spectrum ◽  
Line Shapes ◽  
Ngc 4151

This paper presents the complete spectrum of NGC 4151 from 0.87 to 2.5 μm as well as detail of the Paschen α profile in 3C273 at a resolution of about 5000. Analysis of the several observed Fe II lines yields a most probable electron density of 104 and a most likely temperature of 104. The Fe II to H ratio is 2+/− 1 × 10−6 which is 5–7% of the available iron if the Fe/H ratio is solar.

MEASUREMENTS OF COSMIC RAYS AT THE HIGHEST ENERGIES WITH THE PIERRE AUGER OBSERVATORY

2011 ◽  
Vol 20 (05) ◽  
pp. 685-696
Author(s):  
◽  
DIEGO HARARI
Keyword(s):  
Cosmic Rays ◽  
Cosmic Microwave Background ◽  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Active Galaxies ◽  
Pierre Auger Observatory ◽  
Matter Distribution ◽  
Microwave Background ◽  
Independent Evidence ◽  
Arrival Directions

Measurements with the Pierre Auger Observatory indicate with unprecedented statistics that the flux of cosmic rays is strongly suppressed above 4 × 1019 eV. The suppression is consistent with the prediction that cosmic rays with larger energies can only arrive from nearby sources due to their interaction with the cosmic microwave background, but could also be related to the efficiency of the acceleration processes at the sources. The Observatory has found independent evidence of the nearby extragalactic origin of cosmic rays with energy above ~6×1019 eV with a measurement of the fraction of arrival directions that correlate with the positions of active galactic nuclei within ~100 Mpc. This correlation does not identify active galaxies as the sites of origin, since their distribution traces the overall local matter distribution. We review recent measurements made with the Pierre Auger Observatory of the flux, anisotropy and composition of CRs.

scholarly journals Surveys for active galaxies: discovery and studies

2020 ◽  
pp. 149-158
Author(s):  
A. M. Mickaelian ◽  
H. V. Abrahamyan ◽  
G. M. Paronyan ◽  
G. A. Mikayelyan ◽  
M. V. Gyulzadyan
Keyword(s):  
Active Galactic Nuclei ◽  
Classification Scheme ◽  
Galactic Nuclei ◽  
Active Galaxies ◽  
Research Subjects ◽  
Byurakan Survey ◽  
Byurakan Astrophysical Observatory ◽  
X Ray ◽  
Main Research ◽  
Astronomical Surveys

We present surveys and related studies of active galaxies carried out at the Byurakan Astrophysical Observatory (BAO). This was one of the main research subjects at BAO during many years, since mid-1950s, when Viktor Ambartsumian suggested the hypothesis of the activity of the galactic nuclei. A number of surveys and searches for Active Galactic Nuclei (AGN) and other active galaxies were accomplished during 1960s-1980s. Since mid-1990s, our research group carried out new surveys and studies of active galaxies based on the First Byurakan Survey (FBS or Markarian Survey) and then a number of others. Here we also present the recent results of studies on active galaxies (both AGN and Starbursts) by the Extragalactic group of the Byurakan Astrophysical Observatory (BAO) Research Department “Astronomical Surveys”. These studies are characterized by multiwavelength approach to statistical analysis of large amount of data obtained in different wavelengths; from X-ray to radio. A fine classification scheme for active galaxies has also been suggested.

scholarly journals Gamma-Ray Emission from Extragalactic Radio Sources: EGRET Observations of Active Galactic Nuclei

1996 ◽  
Vol 175 ◽  
pp. 277-280
Author(s):  
Peter F. Michelson
Keyword(s):  
Active Galactic Nuclei ◽  
Gamma Ray ◽  
Galactic Nuclei ◽  
High Energy ◽  
Radio Spectrum ◽  
Active Galaxies ◽  
Emission Characteristics ◽  
Radio Sources ◽  
Emission Models ◽  
Gamma Ray Emission

The Energetic Gamma-Ray Experiment Telescope (EGRET) on the Compton Gamma-Ray Observatory is an imaging high-energy telescope with sensitivity from approximately 20 MeV to 30 GeV. EGRET has observed more than 129 sources during more than 4 years of operation. Among these sources, 51 have been identified with active galaxies. A common characteristic of the AGN sources is that they are all radio-loud, flat radio spectrum sources. Many of them are seen as superluminal radio sources as well. The gamma-ray emission characteristics of these sources are reviewed and some of the proposed emission models are discussed.

Influence of Black Hole Spin on the Shape of the Fe Kα Spectral Line: The Case of 3C 405

2011 ◽  
Vol 20 (3) ◽  
Author(s):  
P. Jovanović ◽  
V. Borka Jovanović ◽  
D. Borka
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Active Galactic Nuclei ◽  
Accretion Disks ◽  
Galactic Nuclei ◽  
Kerr Metric ◽  
Line Shapes ◽  
Cygnus A ◽  
Angular Momenta ◽  
Innermost Region

AbstractHere we analyze how the angular momenta (spins) of black holes in the centers of Active Galactic Nuclei (AGN) affect the shape of the FeK line emitted from their accretion disks. For that purpose, we compared the observed line profile in the case of radio galaxy 3C 405 (Cygnus A) with its profiles, obtained by numerical simulations based on ray-tracing method in the Kerr metric. Our results show that the spins of rotating central black holes of AGN have significant influence on their FeKα line shapes. Also, we found that in the case of Cygnus A the observed line is probably emitted from the innermost region of its slightly inclined accretion disk around very slowly rotating or even stationary central black hole.

scholarly journals 5.13. High-density-and-temperature circumnuclear molecular torus in M51

1998 ◽  
Vol 184 ◽  
pp. 237-238
Author(s):  
S. Matsushita ◽  
K. Kohno ◽  
B. Vila-Vilaro ◽  
R. Kawabe ◽  
T. Tosaki
Keyword(s):  
Active Galactic Nuclei ◽  
Molecular Clouds ◽  
Galactic Nuclei ◽  
Active Galaxies ◽  
High Density ◽  
Molecular Gas ◽  
Physical Conditions

It is very important to know the physical conditions of circumnuclear molecular gas in order to understand the nature of Active Galactic Nuclei (AGN), since the circumnuclear molecular gas in active galaxies might be directly affected by or is affecting the activity of nucleus. To investigate the physical conditions of the molecular clouds in detail, multi-line observations with millimeter arrays are essential.

Supermassive Black Holes in Active Galactic Nuclei. I. The Consistency of Black Hole Masses in Quiescent and Active Galaxies

2001 ◽  
Vol 555 (2) ◽  
pp. L79-L82 ◽  
Author(s):  
Laura Ferrarese ◽  
Richard W. Pogge ◽  
Bradley M. Peterson ◽  
David Merritt ◽  
Amri Wandel ◽  
...  
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Supermassive Black Holes ◽  
Active Galaxies ◽  
Black Hole Masses
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