The correlation of narrow line emission and X-ray luminosity   in active galactic nuclei

Netzer, H.; Mainieri, V.; Rosati, P.; Trakhtenbrot, Benny

doi:10.1051/0004-6361:20054203

Cited by 112 publications

(166 citation statements)

References 46 publications

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“…10 we also plot the results from Best et al (2005) corresponding to AGN with L([OIII]) luminosity larger than 10 8.0 and 10 8.5 L , as labeled. Using the relation between the observed L(OIII) and the X-ray luminosity given by Netzer et al (2006, Eq. (1)), these L([OIII]) luminosities represent a fiducial range for local objects with X-ray luminosities similar to those in our sample (L X > 10 43 erg s −1 ) when an average extinction E(B−V) = 0.4 ± 0.2 is taken into account (see discussion in Netzer et al 2006).…”

Section: Agn Fractionsupporting

confidence: 71%

Black hole growth and starburst activity atz= 0.6–4 in the Chandra Deep Field South

Brusa¹,

Fiore

Santini

et al. 2009

A&A

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106

113

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Aims. The co-evolution of host galaxies and the active black holes which reside in their centre is one of the most important topics in modern observational cosmology. Here we present a study of the properties of obscured active galactic nuclei (AGN) detected in the CDFS 1 Ms observation and their host galaxies. Methods. We limited the analysis to the MUSIC area, for which deep K-band observations obtained with ISAAC@VLT are available, ensuring accurate identifications of the counterparts of the X-ray sources as well as reliable determination of photometric redshifts and galaxy parameters, such as stellar masses and star formation rates. In particular, we: 1) refined the X-ray/infrared/optical association of 179 sources in the MUSIC area detected in the Chandra observation; 2) studied the host galaxies observed and rest frame colors and properties. Results. We found that X-ray selected (L X > ∼ 10 42 erg s −1 ) AGN show Spitzer colors consistent with both AGN and starburst dominated infrared continuum; the latter would not have been selected as AGN from infrared diagnostics. The host galaxies of X-ray selected obscured AGN are all massive (M * > 10 10 M ) and, in 50% of the cases, are also actively forming stars (1/SSFR < t Hubble ) in dusty environments. The median L/L Edd value of the active nucleus is between 2% and 10% depending on the assumed M BH /M * ratio. Finally, we found that the X-ray selected AGN fraction increases with the stellar mass up to a value of ∼30% at z > 1 and M * > 3 × 10 11 M , a fraction significantly higher than in the local Universe for AGN of similar luminosities.

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Section: Agn Fractionsupporting

confidence: 71%

Black hole growth and starburst activity atz= 0.6–4 in the Chandra Deep Field South

Brusa¹,

Fiore

Santini

et al. 2009

A&A

Self Cite

106

113

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“…Moreover, if line extinction is stronger in type 2 than in type 1 sources, then the type 2 quasar fraction would also be underestimated. Several independent measurements have suggested that this is indeed the case (Netzer et al 2006, and references therein). Reddening estimates from Balmer decrements suggest that the narrow-line regions of type 2 sources are more heavily reddened than those of type 1 sources (De Zotti & Gaskell 1985;Dahari & De Robertis 1988).…”

Section: Reddening and Extinctionmentioning

confidence: 86%

“…Recent IR observations strongly indicate that the narrow-line regions of type 2 quasars are significantly more obscured than those of type 1 quasars, by up to a factor of 10 (Haas et al 2005). Netzer et al (2006) suggest that [O iii]5007 luminosity is a factor of ∼2 larger in type 1 than in type 2 quasars for the same 2 -10 keV X-ray luminosity, as would be the case if type 2 sources are more reddened than type 1 sources. Finally, such a trend is also hinted at by our analysis of radio properties of type 1 and type 2 sources (Section 5.3).…”

Section: Reddening and Extinctionmentioning

confidence: 98%

Space Density of Optically Selected Type 2 Quasars

Reyes¹,

Zakamska²,

Strauss³

et al. 2008

The Astronomical Journal

275

167

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Type 2 quasars are luminous active galactic nuclei whose central regions are obscured by large amounts of gas and dust. In this paper, we present a catalog of type 2 quasars from the Sloan Digital Sky Survey, selected based on their optical emission lines. The catalog contains 887 objects with redshifts z < 0.83; this is 6 times larger than the previous version and is by far the largest sample of type 2 quasars in the literature. We derive the [O iii]5007 luminosity function (LF) for 10 8.3 L < L [O iii] < 10 10 L (corresponding to intrinsic luminosities up to M[2500 Å] −28 mag or bolometric luminosities up to 4 × 10 47 erg s −1 ). This LF provides robust lower limits to the actual space density of obscured quasars due to our selection criteria, the details of the spectroscopic target selection, and other effects. We derive the equivalent LF for the complete sample of type 1 (unobscured) quasars and determine the ratio of type 2 to type 1 quasar number densities. Our data constrain this ratio to be at least ∼ 1.5:1 for 10 8.3 L < L [O iii] < 10 9.5 L at z < 0.3, and at least ∼ 1.2:1 for L [O iii] ∼ 10 10 L at 0.3 < z < 0.83. Type 2 quasars are at least as abundant as type 1 quasars in the relatively nearby universe (z 0.8) for the highest luminosities.

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“…One such possibility is the commonly used [O iii](λ5007 Å) luminosity, although some degree of anisotropy has been reported (e.g. Netzer et al 2006). In Fig.…”

Section: Mid-ir Continuum Emission and Its Relation To Agn Luminositymentioning

confidence: 99%

The dusty heart of nearby active galaxies

Hoenig

Kishimoto

Gandhi

et al. 2010

A&A

154

135

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In a series of papers, we aim at stepping towards characterizing physical properties of the AGN dust torus by combining IR highspatial resolution observations with 3D clumpy torus models. In this first paper, we present mid-IR imaging and 8−13 μm lowresolution spectroscopy of nine type 1 and ten type 2 AGN. The observations were carried out with the VLT/VISIR mid-IR imager and spectrograph and can be considered the largest currently available mid-infrared spectro-photometric data set of AGN at spatial resolution < ∼ 100 pc. These data resolve scales at which the emission from the dust torus dominates the overall flux, and emission from the host galaxy (e.g. star-formation) is resolved out in most cases. The silicate absorption features are moderately deep and emission features, if seen at all, are shallow. The strongest silicate emission feature in our sample shows some notable shift of the central wavelength from the expected 9.7 μm (based on ISM extinction curves) to ∼10.5 μm. We compare the observed mid-IR luminosities of our objects to AGN luminosity tracers (X-ray, optical and [O iii] luminosities) and find that the mid-IR radiation is emitted quite isotropically. In two cases, IC 5063 and MCG-3-34-64, we find evidence for extended dust emission in the narrow-line region. We confirm the correlation between observed silicate feature strength and Hydrogen column density, which was recently found in Spitzer data at lower spatial resolution. In a further step, our 3D clumpy torus model has been used to interpret the data. We show that the strength of the silicate feature and the mid-IR spectral index α can be used to get reasonable constraints on the radial dust distribution of the torus and the average number of clouds N 0 along an equatorial line-of-sight in clumpy torus models. The mid-IR spectral index α is almost exclusively determined by the radial dust distribution power-law index a, while the silicate feature depth mostly depends on N 0 and the torus inclination. A comparison of model predictions to our type 1 and type 2 AGN reveals that average parameters of a = −1.0 ± 0.5 and N 0 = 5 − 8 are typically seen in the presented sample, which means that the radial dust distribution is rather shallow. As a proof-of-concept of this method, we compared the model parameters derived from α and the silicate feature strength to more detailed studies of full IR SEDs and interferometry and found that the constraints on a and N 0 are consistent. Finally, we may have found evidence that the radial structure of the torus changes from low to high AGN luminosities towards steeper dust distributions, and we discuss implications for the IR size-luminosity relation.

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The correlation of narrow line emission and X-ray luminosity in active galactic nuclei

Cited by 112 publications

References 46 publications

Black hole growth and starburst activity atz= 0.6–4 in the Chandra Deep Field South

Black hole growth and starburst activity atz= 0.6–4 in the Chandra Deep Field South

Space Density of Optically Selected Type 2 Quasars

The dusty heart of nearby active galaxies

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