<i>ISO</i>observations and models of galaxies with hidden broad line regions

Efstathiou, A.; Siebenmorgen, R.

doi:10.1051/0004-6361:20041958

Cited by 16 publications

(18 citation statements)

References 60 publications

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“…This paper uses the AGN tapered disc models of Efstathiou & Rowan‐Robinson (). The tapered disc models, in combination with the starburst models of Efstathiou, Rowan‐Robinson & Siebenmorgen (), have been successful in fitting the SEDs of ULIRGs (Farrah et al ), hyperluminous infrared galaxies (Farrah et al ; Verma et al ; Efstathiou ), submillimetre galaxies (Efstathiou & Siebenmorgen ) and active galaxies (Alexander et al ; Ruiz et al ; Efstathiou & Siebenmorgen ; Farrah et al ). The torus is modelled as a disc, whose thickness increases with distance from the central source but tapers off in the outer regions of the torus.…”

Section: Radiative Transfer Modelsmentioning

confidence: 99%

Principal component analysis and radiative transfer modelling ofSpitzerInfrared Spectrograph spectra of ultraluminous infrared galaxies

Hurley

Oliver

Farrah

et al. 2012

Monthly Notices of the Royal Astronomical Society

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The mid-infrared spectra of ultraluminous infrared galaxies (ULIRGs) contain a variety of spectral features that can be used as diagnostics to characterise the spectra. However, such diagnostics are biased by our prior prejudices on the origin of the features. Moreover, by using only part of the spectrum they do not utilise the full information content of the spectra. Blind statistical techniques such as principal component analysis (PCA) consider the whole spectrum, find correlated features and separate them out into distinct components.We further investigate the principal components (PCs) of ULIRGs derived in Wang et al. (2011). We quantitatively show that five PCs is optimal for describing the IRS spectra. These five components (PC1-PC5) and the mean spectrum provide a template basis set that reproduces spectra of all z < 0.35 ULIRGs within the noise. For comparison, the spectra are also modelled with a combination of radiative transfer models of both starbursts and the dusty torus surrounding active galactic nuclei. The five PCs typically provide better fits than the models. We argue that the radiative transfer models require a colder dust component and have difficulty in modelling strong PAH features.Aided by the models we also interpret the physical processes that the principal components represent. The third principal component is shown to indicate the nature of the dominant power source, while PC1 is related to the inclination of the AGN torus.Finally, we use the 5 PCs to define a new classification scheme using 5D Gaussian mixtures modelling and trained on widely used optical classifications. The five PCs, average spectra for the four classifications and the code to classify objects are made available at: http://www.phys.susx.ac.uk/~pdh21/PCA/.

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Section: Radiative Transfer Modelsmentioning

confidence: 99%

Principal component analysis and radiative transfer modelling ofSpitzerInfrared Spectrograph spectra of ultraluminous infrared galaxies

Hurley

Oliver

Farrah

et al. 2012

Monthly Notices of the Royal Astronomical Society

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“…and Dopita et al (2005). For this study the models of Efstathiou et al (2000) which were extended to higher optical depths by Efstathiou & Siebenmorgen (2005) will be used. The models incorporate the stellar population synthesis models of Bruzual & Charlot (1993), a simple model for the evolution of the molecular clouds that constitute the starburst and detailed radiative transfer that includes the effect of transiently heated particles/PAHs (Siebenmorgen & Krügel 1992).…”

Section: Starburst Modelsmentioning

confidence: 99%

A model for the infrared emission of FSC 10214+4724

Efstathiou

2006

Monthly Notices of the Royal Astronomical Society: Letters

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A model for the infrared emission of the high redshift ultraluminous infrared galaxy FSC 10214+4724 is presented. The model assumes three components of emission: a dusty torus viewed edge-on, clouds that are associated with the narrow-line region and a highly obscured starburst. It is demonstrated that the presence of clouds in the narrow-line region, with a covering factor of 17%, can explain why the mid-infrared spectrum of FSC 10214+4724 shows a silicate feature in emission despite the fact that its torus is viewed edge-on. It is also shown that the same model, but with the torus viewed face-on, predicts a spectrum with silicate emission features that is characteristic of the spectra of quasars recently observed with Spitzer.Comment: 5 pages, 4 figures, accepted for publication as a MNRAS Lette

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“…In this case, one might expect that the distribution of the Mid InfraRed (MIR) luminosity differs between "dusty" and "non dusty" Seyferts. The MIR Spectral Energy Distribution of obscured AGN is dominated by "torus" reprocessing of the high-energy continuum (Alonso-Herrero et al 2001;Efstathiou & Siebenmorgen 2005). In Fig.…”

Section: Correlation Between X-ray Absorption and Nuclear Dust Contentmentioning

confidence: 99%

X-ray obscuration and obscured AGN in the local universe

Guainazzi¹,

Matt

Perola

2005

A&A

264

276

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We discuss the X-ray properties of 49 local (z < 0.035) Seyfert 2 galaxies with HST/WFC2 high-resolution optical coverage. It includes the results of 26 still unpublished Chandra and XMM-Newton observations, which yield 25 (22) new X-ray detections in the 0.5-2 keV (2-10 keV) energy band. Our sample covers a range in the 2-10 keV observed flux, F 2−10 , from 3 × 10 −11 to 6 × 10 −15 erg cm −2 s −1 . The percentage of objects that are likely obscured by Compton-thick matter (column density, N H ≥ σ −1 t 1.6 × 10 24 cm −2 ) is 50%, and reaches 80% for log (F 2−10 ) < 12.3. Hence, K α fluorescent iron lines with large Equivalent Width (EW > 0.6 keV) are common in our sample (6 new detections at a confidence level ≥2σ). They are explained as due to reflection off the illuminated side of optically thick material. We confirm a correlation between the presence of a ∼100-pc scale nuclear dust in the WFC2 images and Compton-thin obscuration. We interpret this correlation as due to the large covering fraction of gas associated with the dust lanes. The X-ray spectra of highly obscured AGN invariably present a prominent soft excess emission above the extrapolation of the hard X-ray component. This soft component can account for a very large fraction of the overall X-ray energy budget. As this component is generally unobscured -and therefore likely produced in extended gas structures -it may lead to a severe underestimation of the nuclear obscuration in z ∼ 1 absorbed AGN, if standard X-ray colors are used to classify them. As a by-product of our study, we report the discovery of a soft X-ray, luminous ( 7 × 10 40 erg s −1 ) halo embedding the interacting galaxy pair Mkn 266.

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ISOobservations and models of galaxies with hidden broad line regions

Cited by 16 publications

References 60 publications

Principal component analysis and radiative transfer modelling ofSpitzerInfrared Spectrograph spectra of ultraluminous infrared galaxies

Principal component analysis and radiative transfer modelling ofSpitzerInfrared Spectrograph spectra of ultraluminous infrared galaxies

A model for the infrared emission of FSC 10214+4724

X-ray obscuration and obscured AGN in the local universe

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