Spectral components of NGC 4151

Rieke, G. H.; Lebofsky, M. J.

doi:10.1086/159350

Cited by 68 publications

(85 citation statements)

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“…To reassure ourselves of the credibility of the energy balance arguments above, we have examined the behavior of NGC 4151, since (1) its UV continuum has been derived in detail (Alexander et al 1999), (2) its flux variations have been exceptionally well monitored (e.g., Lyuty & Doroshenko 1999; Doroshenko et al 2001), and (3) its infrared SED is very well determined (e.g., Rieke & Lebofsky 1981;McAlary et al 1983;Deo et al 2009;García-González et al 2016). The energy balance test on this archetypal type-1 AGN seems to fail at very first glance: even if we take the UV continuum toward the upper range as derived by Alexander et al (1999), the infrared luminosity is too large to be consistent with energy balance by 20% or more if we analyze the comparison for the simple case of isotropic emission.…”

Section: Analysis and Resultsmentioning

confidence: 99%

“…This basic hypothesis for the source emission was first suggested by SEDs (Rieke 1978), then by detailed decomposition into spectral components demonstrating a reduction in the amplitude of the variability as one goes further into the infrared (Rieke & Lebofsky 1981;Cutri et al 1985;Neugebauer et al 1989;Neugebauer & Matthews 1999). It has been firmly established through reverberation mapping, which shows time lags in the infrared response to variations in the optical-ultraviolet output by roughly the time expected if the reradiating dust is at the distance from the nucleus where it is heated close to its sublimation temperature (e.g., Koshida et al 2014;Gandhi et al 2015;Lira et al 2015;Pozo Nuñez et al 2015;Schnülle et al 2015).…”

Section: Rationalementioning

confidence: 97%

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The Intrinsic Far-infrared Continua of Type-1 Quasars

Lyu

Rieke

2017

ApJ

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The range of currently proposed active galactic nucleus (AGN) far-infrared templates results in uncertainties in retrieving host galaxy information from infrared observations and also undermines constraints on the outer part of the AGN torus. We discuss how to test and reconcile these templates. Physically, the fraction of the intrinsic AGN IR-processed luminosity compared with that from the central engine should be consistent with the dust-covering factor. In addition, besides reproducing the composite spectral energy distributions (SEDs) of quasars, a correct AGN IR template combined with an accurate library of star-forming galaxy templates should be able to reproduce the IR properties of the host galaxies, such as the luminosity-dependent SED shapes and aromatic feature strengths. We develop tests based on these expected behaviors and find that the shape of the AGN intrinsic far-IR emission drops off rapidly starting at ∼20μm and can be matched by an Elvis et al.-like template with aminor modification. Despite the variations in the near-to mid-IR bands, AGNs in quasars and Seyfert galaxies have remarkably similar intrinsic far-IR SEDs at λ ∼ 20-100μm, suggesting a similar emission character of the outermost region of the circumnuclear torus. The variations of the intrinsic AGN IR SEDs among the type-1 quasar population can be explained by the changing relative strengths of four major dust components with similar characteristic temperatures, and there is evidence for compact AGN-heated dusty structures at sub-kiloparsec scales in the far-IR.

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Section: Analysis and Resultsmentioning

confidence: 99%

Section: Rationalementioning

confidence: 97%

The Intrinsic Far-infrared Continua of Type-1 Quasars

Lyu

Rieke

2017

ApJ

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“…We assume that the AGN part of the SED is always a red power-law (see Elvis et al 1994), being a combination of (thermal) emission from the heated dust of the circumnuclear torus and (non-thermal) nuclear emission (Rieke & Lebofsky 1981). Its IRAC colours would reside in the wedge independent of its obscuration for the vast majority of our AGN.…”

Section: Agn-host Contributionmentioning

confidence: 99%

Optical and infrared properties of active galactic nuclei in the Lockman Hole

Rovilos

Fotopoulou

Salvato

et al. 2011

A&A

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We present the observed-frame optical, near-, and mid-infrared properties of X-ray-selected active galactic nuclei (AGN) in the Lockman Hole. Using a likelihood ratio method on optical, near-infrared or mid-infrared catalogues, we assigned counterparts to 401 out of the 409 X-ray sources of the XMM-Newton catalogue. Accurate photometry was collected for all the sources from U to 24 μm. We used X-ray and optical criteria to remove any normal galaxies, galactic stars, or X-ray clusters among them and studied the multiwavelength properties of the remaining 377 AGN. We used a mid-IR colour-colour selection to understand the AGN contribution to the optical and infrared emission. Using this selection, we identified different behaviours of AGN-dominated and host-dominated sources in X-ray-optical-infrared colour-colour diagrams. More specifically, the AGN-dominated sources show a clear trend in the f x / f R C vs. R C − K and f 24 μm / f R C vs. R C − K diagrams, while the hosts follow the behaviour of non X-ray detected galaxies. In the optical-near-infrared colour-magnitude diagram we see that the known trend of redder objects to be more obscured in X-rays is stronger for AGN-dominated than for host-dominated systems. This is an indication that the trend is more related to the AGN, which contaminate the overall colours, than to any evolutionary effects. Finally, we find that a significant fraction (∼30%) of the reddest AGN are not obscured in X-rays.

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“…Dust at such temperatures is destroyed by sputtering, while the presence of dust in the torus is supported by abundant observational evidence. Emission from warm dust manifests itself in a broad hump in the spectral energy distribution (SED) in the ∼ 1 − 10µ wavelength band (Rieke & Lebofsky 1981;Barvainis 1987;Sanders et al 1989;Pier & Krolik 1993). Interferometric observations provide direct evidence of warm, multi-temperature dust at parsec scales in a growing sample of nearby type II and type I AGNs, including NGC 1068 (Poncelet et al 2006;Raban et al 2009;Wittkowski et al 2004;Jaffe et al 2004) the Circinus galaxy (Tristram et al 2007(Tristram et al , 2014 and others (Kishimoto et al 2013;Hönig et al 2012;Meisenheimer et al 2007;Beckert et al 2008).…”

Section: Introductionmentioning

confidence: 99%

Parsec-scale Obscuring Accretion Disk with Large-Scale Magnetic Field in AGNs

Dorodnitsyn

Kallman

2017

ApJ

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Magnetic field dragged from the galactic disk along with inflowing gas can provide vertical support to the geometrically and optically thick pc-scale torus in AGN. Using the Soloviev solution initially developed for Tokamaks we derive an analytical model for a rotating torus supported and confined by magnetic field. We further perform three-dimensional magneto-hydrodynamics simulations of X-ray irradiated pc-scale magnetized tori. We follow the time evolution and compare models which adopt initial conditions derived from our analytic model with simulations in which the initial magnetic flux is entirely contained within the gas torus. Numerical simulations demonstrate that the initial conditions based on the analytic solution produce a longer-lived torus and one which produces obscuration which is generally consistent with observed constraints.

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Spectral components of NGC 4151

Cited by 68 publications

References 0 publications

The Intrinsic Far-infrared Continua of Type-1 Quasars

The Intrinsic Far-infrared Continua of Type-1 Quasars

Optical and infrared properties of active galactic nuclei in the Lockman Hole

Parsec-scale Obscuring Accretion Disk with Large-Scale Magnetic Field in AGNs

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