The Optical-Ultraviolet Continuum of a Sample of QSO[CLC]s[/CLC]

Natali, Fábio; Giallongo, E.; Cristiani, S.; Franca, F. La

doi:10.1086/300211

Cited by 46 publications

(57 citation statements)

References 23 publications

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“…This value is also similar to the best value found for image B. This value is in good agreement with the mean power law index α = −0.33 ± 0.59 found by Natali et al (1998) in the range 1200-5500 Å or with the power law index of the composite SDSS quasar spectra measured in the range 1300-5000 Å (i.e. α = −0.44; Vanden Berk et al 2001).…”

Section: Application To A-b-c Spectrasupporting

confidence: 90%

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Multi-wavelength study of the gravitational lens system RXS J1131-1231

Sluse

Claeskens

Hutsemékers

et al. 2007

A&A

108

114

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Aims. We discuss and characterize micro-lensing among the 3 brightest lensed images (A-B-C) of the gravitational lens system RXS J1131-1231 (a quadruply imaged AGN) by means of long slit optical and NIR spectroscopy. Qualitative constraints on the size of different emission regions are derived. We also perform a spectroscopic study of two field galaxies located within 1.6 arcmin radius from the lens. Methods. We decompose the spectra into their individual emission components using a multi-component fitting approach. A complementary decomposition of the spectra enables us to isolate the macro-lensed fraction of the spectra independently of any spectral modelling.Results. 1. The data support micro-lensing de-amplification of images A and C. Not only is the continuum emission microlensed in those images but also a fraction of the Broad Line emitting Region (BLR).2. Micro-lensing of a very broad component of Mg ii emission line suggests that the corresponding emission occurs in a region more compact than the other components of the emission line.3. We find evidence that a large fraction of the Fe ii emission arises in the outer parts of the BLR. We also find a very compact emitting region in the ranges 3080-3540 Å and 4630-4800 Å that is likely associated with Fe ii. 4. The [O iii] narrow emission line regions are partly spatially resolved. This enables us to put a lower limit of ∼110h −1 pc on their intrinsic size.5. Analysis of Mg ii absorption found in the spectra indicates that the absorbing medium is intrinsic to the quasar, has a covering factor of 20%, and is constituted of small clouds homogeneously distributed in front of the continuum and BLRs. 6. Two neighbour galaxies are detected at redshifts z = 0.10 and z = 0.289. These galaxies are possible members of galaxy groups reported at those redshifts.

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Section: Application To A-b-c Spectrasupporting

confidence: 90%

“…First we fitted components (1), (2) and (4) in three rest-frame windows nearly free of Fe ii emission, namely λλ2600-2700 Å, 2950-3100 Å and 5400-5500 Å (Natali et al 1998). Secondly, we imposed a null weight to the emission line regions and fitted components (1) to (4) using the previous results as initial conditions.…”

Section: Overview Of the Methodsmentioning

confidence: 99%

Multi-wavelength study of the gravitational lens system RXS J1131-1231

Sluse

Claeskens

Hutsemékers

et al. 2007

A&A

108

114

View full text Add to dashboard Cite

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“…This composite SED agrees very well with spectroscopic observations of type-1 sources performed by ISO in the mid-IR (Clavel et al 2000;Spoon et al 2002), showing a strong power-like continuum, very weak or no PAH emission bands and no evidence of the 10 µm silicate absorption feature. Optical luminosities for type-1 AGN were computed using the R-band k-correction by Natali et al (1998), which takes into account the large effect of broad lines entering and leaving the passband.…”

Section: The Methodsmentioning

confidence: 99%

Active Galactic Nuclei in the Mid-Ir. Evolution and Contribution to the Cosmic Infrared Background

Franca¹,

Matute

2004

Multiwavelength AGN Surveys

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Aims. We study the evolution of the luminosity function (LF) of type-1 and type-2 Active Galactic Nuclei (AGN) in the mid-infrared, and then derive the contribution of the AGN to the Cosmic InfraRed Background (CIRB) and the expected source counts to be observed by Spitzer at 24 µm. Methods. We used a sample of type-1 and type-2 AGN selected at 15 µm (ISO) and 12 µm (IRAS), and classified on the basis of their optical spectra. Local spectral templates of type-1 and type-2 AGN have been used to derive the intrinsic 15 µm luminosities. We adopted an evolving smooth two-power law shape of the LF, whose parameters have been derived using an un-binned maximum likelihood method. Results. We find that the LF of type-1 AGN is compatible with a pure luminosity evolution. A small flattening of the faint (L 15 < L * 15 ) slope of the LF with increasing redshift is favoured by the data. A similar evolutionary scenario is found for the type-2 population with a rate k L ranging from ∼1.8 to 2.6, depending significantly on the adopted mid-infrared spectral energy distribution. Also for type-2 AGN a flattening of the LF with increasing redshift is suggested by the data, possibly caused by the loss of a fraction of type-2 AGN hidden within the optically classified starburst and normal galaxies. The type-1 AGN contribution to the CIRB at 15 µm is (4.2-12.1)× 10 −11 Wm −2 sr −1 , while the type-2 AGN contribution is (5.5-11.0)× 10 −11 W m −2 sr −1 . We expect that Spitzer will observe, down to a flux limit of S 24 µm =0.01 mJy, a density of ∼1200 deg −2 type-1 and ∼1000 deg −2 type-2 optically classified AGN. Conclusions. AGN evolve in the mid-infrared with a rate similar to the ones found in the optical and X-rays bands. The derived total contribution of the AGN to the CIRB (4-10%) and Spitzer counts should be considered as lower limits, because of a possible loss of type-2 sources caused by the optical classification.

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“…In Tables 2 and 3 we also include the individual host galaxy magnitude errors (combining Poisson errors, subtraction method uncertainties, and the systematical oversubtraction error). Nuclear K-corrections were taken from Natali et al (1998). In Appendix B we present notes on selected individual objects, where our host magnitudes are compared to those of the few previous studies of the same objects.…”

Section: Host Galaxy Magnitudesmentioning

confidence: 99%