A Grid of Composite Models for the Simulation of the Emission‐Line Spectra from the Narrow‐Line Regions of Active Galaxies

Contini, M.; Viegas, S. M.

doi:10.1086/318956

Cited by 53 publications

(61 citation statements)

References 8 publications

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“…Up to now, it is not clear what the physical mechanisms involved in the production of these features are, but three possible scenarios have been suggested: (i) collisional ionization of gas with temperatures of T e ∼ 10 6 K (Oliva et al 1994); (ii) photoionization by the central non-thermal continuum (Ferguson et al 1997); and (iii) a combination of shocks and photoionization (Viegas-Aldrovandi & Contini 1989;Contini & Viegas 2001). Although these lines are common in most AGN, NLS1 appear as suitable candidates to investigate their origin because they are not severely blended with nearby broad features as in classical Seyfert 1 or diluted by stellar absorption features as in Seyfert 2.…”

Section: Agn (M Bhmentioning

confidence: 99%

“…With this in mind, we have run a grid of models with parameters in the range suitable to the NLR of AGN and selected the models that best matches at least some of the observed line ratios. The grid was based on Contini & Viegas (2001). The results are obtained by the SUMA code (Viegas & Contini 1994) which, besides the line and continuum spectra emitted by the gas, also calculates re-radiation by dust.…”

Section: Modeling the Spectramentioning

confidence: 99%

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The narrow line region of Ark 564

Contini

Rodríguez-Ardila

Viegas³

2003

A&A

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Abstract. The continuum and emission-line spectrum of the narrow-line Seyfert 1 galaxy Ark 564 is used to investigate, for the first time, the physical conditions and structure of its narrow line region (NLR). For this purpose, composite models, accounting for the coupled effect of photoionization and shocks, are employed. The emission-line spectrum of Ark 564, which ranges from the ultraviolet to the near-infrared, shows a rich forbidden line spectrum. Strong emphasis is given to the study of the coronal line region. The diversity of physical conditions deduced from the observations requires multi-cloud models to reproduce the observed lines and continuum. We find that a combination of high velocity (V s = 1500 km s −1 ) shock-dominated clouds as well as low velocity (V s = 150 km s −1 ) radiation-dominated clouds explains the coronal lines, while the optical low-ionization lines are mainly explained by shock-dominated clouds. The results for Ark 564 are compared with those obtained for other Seyfert galaxies previously analyzed such as NGC 5252, Circinus, NGC 4051 and NGC 4151. The model results for the ultraviolet and optical permitted lines suggest that the broad line region may contribute up to 80%, depending on the emission-line, being of about 30% for Hβ. The consistency of the multi-cloud model is checked by comparing the predicted and observed continuum, from radio to X-ray, and indicate that the dust-to-gas ratio in the clouds varies from 10 −15 to 10 −12 .

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Section: Agn (M Bhmentioning

confidence: 99%

Section: Modeling the Spectramentioning

confidence: 99%

The narrow line region of Ark 564

Contini

Rodríguez-Ardila

Viegas³

2003

A&A

Self Cite

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“…; StorchiBergmann et al 1996), which are signatures of shock-excited gas (Contini & Viegas 2001;Viegas & Contini 1989). This, together with the observed lack of star formation in the central spiral, favors the idea that this spiral is a shock with strong shear.…”

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confidence: 99%

Feeding the Monster: The Nucleus of NGC 1097 at Subarcsecond Scales in the Infrared with the Very Large Telescope

2005

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Near-IR images of the prototype LINER /Seyfert type 1 galaxy NGC 1097 observed with the Very Large Telescope using adaptive optics disclose with unprecedented detail a complex central network of filamentary structure spiraling down to the center of the galaxy. The structure, consisting of several spiral arms, some almost completing a revolution about the center, is most prominent within a radius of about 300 pc. Gas and dust may be channelled to the center of NGC 1097 along this central spiral. Some filaments can be traced farther out, where they seem to connect with the nuclear star-forming ring at a 0.7 kpc radius. Straight principal shocks running along the primary large-scale bar of NGC 1097, seen in the optical images as prominent dust lanes, curve into this ring, but radio polarization vectors cross the nuclear ring at a rather large angle. Here we attempt to explain this morphology in terms of three-dimensional gas flow in a barred galaxy. In our scenario, parts of the principal shock that propagate in the off-plane gas can cross the nuclear star-forming ring and excite waves inward from it. If the dispersion relation of the excited waves allows for their propagation, they will naturally take the shape of the observed central spiral. The nuclear region of NGC 1097 remains unresolved at subarcsecond scales in the near-IR, with an upper size limit of <10 pc FWHM. Thus, any putative central dusty torus or gaseous disk envisaged by the active galactic nucleus (AGN ) unified schemes has to be smaller than 10 pc in diameter at near-IR wavelengths. The extinction in the region between the nuclear star-forming ring and the nucleus increases very moderately, reaching A v $ 1 at the immediate surroundings of the nucleus. Thus, if the nuclear filaments are tracing cold dust, they contribute to a very low extinction in the line of sight and are likely to be distributed in a rather thin disk.

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“…Viegas-Aldrovandi & Contini 1989;Murayama & Taniguchi 1998;Allen et al 1998;Evans et al 1999;Contini & Viegas 2001;Collins et al 2009). Groves et al (2004) use a conventional range of powerlaw indices of α = −2.0 to α = −1.2, for a single powerlaw covering 0.005 to 1 keV.…”

Section: Introductionmentioning

confidence: 99%

A Physically Based Model of the Ionizing Radiation From Active Galaxies for Photoionization Modeling

Childress

Groves

Sutherland

et al. 2016

ApJ

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We present a simplified model of Active Galactic Nucleus (AGN) continuum emission designed for photoionization modeling. The new model oxaf reproduces the diversity of spectral shapes that arise in physically-based models. We identify and explain degeneracies in the effects of AGN parameters on model spectral shapes, with a focus on the complete degeneracy between the black hole mass and AGN luminosity. Our re-parametrized model oxaf removes these degeneracies and accepts three parameters which directly describe the output spectral shape: the energy of the peak of the accretion disk emission E peak , the photon power-law index of the non-thermal emission Γ, and the proportion of the total flux which is emitted in the non-thermal component p NT . The parameter E peak is presented as a function of the black hole mass, AGN luminosity, and 'coronal radius' of the optxagnf model upon which oxaf is based. We show that the soft X-ray excess does not significantly affect photoionization modeling predictions of strong emission lines in Seyfert narrow-line regions. Despite its simplicity, oxaf accounts for opacity effects where the accretion disk is ionized because it inherits the 'color correction' of optxagnf. We use a grid of mappings photoionization models with oxaf ionizing spectra to demonstrate how predicted emission-line ratios on standard optical diagnostic diagrams are sensitive to each of the three oxaf parameters. The oxaf code is publicly available in the Astrophysics Source Code Library.

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A Grid of Composite Models for the Simulation of the Emission‐Line Spectra from the Narrow‐Line Regions of Active Galaxies

Cited by 53 publications

References 8 publications

The narrow line region of Ark 564

The narrow line region of Ark 564

Feeding the Monster: The Nucleus of NGC 1097 at Subarcsecond Scales in the Infrared with the Very Large Telescope

A Physically Based Model of the Ionizing Radiation From Active Galaxies for Photoionization Modeling

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