On the Unification of Active Galactic Nuclei

@article{Elitzur2012OnTU,
  title={On the Unification of Active Galactic Nuclei},
  author={Moshe Elitzur},
  journal={The Astrophysical Journal},
  year={2012},
  volume={747},
  pages={1}
}
  • M. Elitzur
  • Published 8 February 2012
  • Physics
  • The Astrophysical Journal
The inevitable spread in properties of the toroidal obscuration of active galactic nuclei (AGNs) invalidates the widespread notion that type 1 and 2 AGNs are intrinsically the same objects, drawn randomly from the distribution of torus covering factors. Instead, AGNs are drawn preferentially from the distribution; type 2 are more likely drawn from the distribution higher end, type 1 from its lower end. Type 2 AGNs have a higher IR luminosity, lower narrow-line luminosity, and a higher fraction… 

Figures from this paper

Revisiting the Unified Model of Active Galactic Nuclei
This review describes recent developments related to the unified model of active galactic nuclei (AGNs). It focuses on new ideas about the origin and properties of the central obscurer (torus) and
Nuclear obscuration in active galactic nuclei
The material surrounding accreting supermassive black holes connects the active galactic nucleus with its host galaxy and, besides being responsible for feeding the black hole, provides important
Luminosity-dependent unification of active galactic nuclei and the X-ray Baldwin effect
The existence of an anti-correlation between the equivalent width (EW) of the narrow core of the iron Kline and the luminosity of the continuum (i.e. the X-ray Baldwin effect) in type-I active
AGN and Megamasers
  • A. Tarchi
  • Physics
    Proceedings of the International Astronomical Union
  • 2012
Abstract Luminous extragalactic masers are traditionally referred to as the ‘megamasers’. Those produced by water molecules are associated with accretion disks, radio jets, or outflows in the nuclear
The narrow Fe Kα line and the molecular torus in active galactic nuclei: an IR/X-ray view
The narrow component of the iron K alpha is an almost ubiquitous feature in the X-ray spectra of active galactic nuclei (AGN) and is believed to originate in neutral material, possibly located in the
Double-Peaked Profiles: Ubiquitous Signatures of Disks in the Broad Emission Lines of Active Galactic Nuclei
Broad (~10,000 km/s), double-peaked emission-line profiles of Balmer lines emitted by active galactic nuclei (AGN) are thought to originate in the outer parts of an accretion disk surrounding a
X-RAY ABSORPTION, NUCLEAR INFRARED EMISSION, AND DUST COVERING FACTORS OF AGNs: TESTING UNIFICATION SCHEMES
We present the distributions of the geometrical covering factors of the dusty tori (f2) of active galactic nuclei (AGNs) using an X-ray selected complete sample of 227 AGNs drawn from the Bright
Mildly obscured active galaxies and the cosmic X-ray background
The diffuse cosmic X-ray background (CXB) is the sum of the emission of discrete sources, mostly massive black-holes accreting matter in active galactic nuclei (AGN). The CXB spectrum differs from
Galaxy and Mass Assembly (GAMA): active galactic nuclei in pairs of galaxies
There exist conflicting observations on whether or not the environment of broad and narrow line AGN differ and this consequently questions the validity of the AGN unification model. The high
Probing the active galactic nucleus unified model torus properties in Seyfert galaxies
We studied the physical parameters of a sample comprising of all Spitzer/IRS public spectra of Seyfert galaxies in the mid-infrared (5.2-38$\mu$m range) under the active galactic nuclei (AGN) unified
...
1
2
3
4
5
...

References

SHOWING 1-10 OF 37 REFERENCES
Unified models for active galactic nuclei and quasars
Because the critical central regions of Active Galactic Nuclei (AGN) and quasars are strongly nonspherical but spatially unresolved, orientation effects have been the source of much confusion. In
THE DISTRIBUTION OF ABSORBING COLUMN DENSITIES AMONG SEYFERT 2 GALAXIES
We use hard X-ray data for an "optimal" sample of Seyfert 2 galaxies to derive the distribution of the gaseous absorbing column densities among obscured active nuclei in the local universe. Of all
The Space Density of Compton-Thick Active Galactic Nucleus and the X-Ray Background
We constrain the number density and evolution of Compton-thick (CT) active galactic nuclei (AGNs). In the local universe, we use the wide-area surveys from the Swift and INTEGRAL satellites, while
TORUS AND ACTIVE GALACTIC NUCLEUS PROPERTIES OF NEARBY SEYFERT GALAXIES: RESULTS FROM FITTING INFRARED SPECTRAL ENERGY DISTRIBUTIONS AND SPECTROSCOPY
We used the CLUMPY torus models and a Bayesian approach to fit the infrared spectral energy distributions and ground-based high angular resolution mid-infrared spectroscopy of 13 nearby Seyfert
The toroidal obscuration of active galactic nuclei
The relative frequency of broad-lined and narrow-lined active galactic nuclei: implications for unified schemes
I discuss evidence concerning the relative occurrence of narrow-lined and broad-lined active galactic nuclei (AGN), in optical, IR, X-ray, and radio-selected samples. Both narrow-lined AGN and
Testing the Unification Model for Active Galactic Nuclei in the Infrared: Are the Obscuring Tori of Type 1 and 2 Seyferts Different?
We present new mid-infrared (MIR) imaging data for three Type-1 Seyfert galaxies obtained with T-ReCS on the Gemini-South Telescope at subarcsecond resolution. Our aim is to enlarge the sample
Molecular tori in Seyfert galaxies - Feeding the monster and hiding it
The principal properties of the tori of gas which surround Seyfert nuclei are discussed. The internal state of the clouds and their size distribution function are examined, and it is shown that the
On the 10-micron silicate feature in Active Galactic Nuclei
The 10μm silicate feature observed with Spitzer in active galactic nuclei (AGN) reveals some puzzling behavior. It (1) has been detected in emission in type 2 sources, (2) shows broad, flat-topped
Unified Schemes for Radio-Loud Active Galactic Nuclei
The appearance of active galactic nuclei (AGN) depends so strongly on orientation that our current classification schemes are dominated by random pointing directions instead of more interesting
...
1
2
3
4
...