ON THE UNIFICATION OF ACTIVE GALACTIC NUCLEI

By M. Elitzur. 2012

136 citations recorded by the source corpus.

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 of Compton thick X-ray obscuration than type 1. Meaningful studies of unification statistics cannot be conducted without first determining the intrinsic distribution function of torus covering factors.

Subfields: Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/6666dccd0fc2ee7fc61f0c042e165e3447ba8000

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Citations in the corpus

• Determining Inclinations of Active Galactic Nuclei Via Their Narrow-Line Region Kinematics (2012, background): “…at the AGN center is covered by obscuring material, and has a clumpy composition that does not create a hard cut-off between observing a Type 1 or Type 2 AGN, but instead only reduces the probability to directly view the AGN as our line of sight strays further from the torus axis (Elitzur 2012).”
• Explaining changing-look AGN with state transition triggered by rapid mass accretion rate drop (2018, background): “…effects, such as obscuration events, where material from the clumpy molecular torus moves into or out of the c© 2015 The Authors line of sight (e.g., Elitzur 2012; Gardner & Done 2017), or microlensing (e.g., Lawrence et al. 2016), but clearly there is an intrinsic change in luminosity in systems…”
• The subarcsecond mid-infrared view of local active galactic nuclei – II. The mid-infrared–X-ray correlation (2015, background): “Third, higher obscured objects could have on average higher covering factors (Ramos Almeida et al. 2011; Elitzur 2012), which could mitigate differences.”
• REVERBERATION MEASUREMENTS OF THE INNER RADIUS OF THE DUST TORUS IN 17 SEYFERT GALAXIES (2014, background): “…of scatter in the relationship between the Seyfert type and viewing angle was expected from a realistic clumpy dust torus model, which consists of dusty clouds stochastically distributed following the probability distribution as a function of the angle from the equatorial plane (Elitzur 2012).”
• THE DISCOVERY OF THE FIRST “CHANGING LOOK” QUASAR: NEW INSIGHTS INTO THE PHYSICS AND PHENOMENOLOGY OF ACTIVE GALACTIC NUCLEI (2014, background): “These types of changes might also be explained via variable absorption: in models where the obscuring material has a patchy distribution (e.g., Elitzur 2012), the dynamical movement of dust clouds could, in principle, result in a change of classification.”
• Discovery of 21 New Changing-look AGNs in the Northern Sky (2017, background): “…of obscuring material, in a scenario that the dusty toroidal structure obscuring the BLR has a patchy distribution (e.g., Nenkova et al. 2008a,b; Elitzur 2012) or an accelerating outflow (e.g., Shapovalova et al. 2010); (2) variable accretion rate, in an evolutionary paradigm that AGN follows…”
• A systematic search for changing-look quasars in SDSS (2015, background): “Another possibility is that the entire UV/continuum emitting region and BLR is obscured; this might be expected if the distribution of dust lying at the outskirts of the BLR is patchy (e.g., Nenkova et al. 2008a,b; Elitzur 2012).”
• Radio galaxies and feedback from AGN jets (2020, background): “…picture remains similar to that of e.g., Urry and Padovani (1995) but with some important differences in detail; in principle accretion rate, black hole mass, jet power, obscuration covering fraction as in Elitzur (2012) and angle to the line of sight are all independent parameters of a system.”
• Revisiting the Unified Model of Active Galactic Nuclei (2015, background): “The realization of a significant spread in fC at a given luminosity, suggests that the covering factor is a second unification parameter (Elitzur 2012).”