A Multicloud Warm‐Absorber Model for NGC 4051

Contini, M.; Viegas, S. M.

doi:10.1086/307727

Cited by 12 publications

(10 citation statements)

References 23 publications

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“…Veilleux (1991) reported blue wings in the forbidden optical emission lines and proposed a model with outflow and obscuring dust. The mid‐ and far‐infrared fluxes have been explained by Rodriguez Espinosa et al (1996) and Contini & Viegas (1999) as due to hot dust emission. In X‐rays Lawrence et al (1985) found variability on time‐scales of hundreds of seconds and Salvati et al (1993) reported a flux change by a factor of 2 at 2.2 μm in 6 months.…”

Section: Samplementioning

confidence: 80%

Gemini/GMOS Integral Field Unit stellar kinematics of the nuclear region of six nearby active galaxies

Barbosa

Storchi‐Bergmann

Fernandes

et al. 2006

Monthly Notices of the Royal Astronomical Society

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We present 2D mapping of the stellar velocity field within the inner 5 arcsec of six nearby active galaxies, using spectra obtained with the Integral Field Unit (IFU) of the Gemini Multi‐Object Spectrograph instrument at the Gemini North telescope. The sampling of the observations is 0.2 arcsec, corresponding at the galaxies to spatial extents ranging from 10 to 30 pc. The spatial resolution range from 20 to about 180 pc, and the observed field of view covers a few hundred parsecs around the nuclei. The Ca ii triplet absorption features at ≈8500 Å were used to measure the stellar radial velocities and velocity dispersions. The radial velocity fields are dominated by rotation in all galaxies. A simple kinematical model assuming a purely rotating system with circular orbits in a plane was fitted to the radial velocity data. The turnover of the rotation curve is at only ≈50 pc for NGC 4051 and between 200 and 700 pc for the other five galaxies. The velocity dispersion (σ) maps show the largest values (100 ≥σ≥ 150 km s−1) at the centre. In the cases of NGC 2273 and 3227, there is a decrease to σ≈ 70–80 km s−1 at ≈200–300 pc from the nucleus, delineating partial rings of low‐σ values. A similar broken ring seems to be present at ≈400 pc from the nucleus also in NGC 4593. We interpret these low‐σ rings as traces of recently formed stars that partially keep the cold kinematics of the original gas from which they have formed. In NGC 3516 there is a decrease of σ outwards with the steepest gradient observed along the direction of the galaxy major axis, where σ reaches ≈80–90 km s−1 at ≈400 pc from the nucleus. The main novelty of the present work is the unprecedented spatial resolution reached by a 2D study of stellar kinematics of Seyfert galaxies using an IFU. The few similar IFU studies available in the literature for Seyfert galaxies have a much poorer spatial resolution and/or are restricted to the study of emission‐line kinematics.

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Section: Samplementioning

confidence: 80%

Gemini/GMOS Integral Field Unit stellar kinematics of the nuclear region of six nearby active galaxies

Barbosa

Storchi‐Bergmann

Fernandes

et al. 2006

Monthly Notices of the Royal Astronomical Society

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“…However, there may be other models which explain the observed line ratios of NGC 4051. Recently, Contini & Viegas (1999) proposed a multi-cloud model in which the existence of shocks is introduced for NGC 4051. Their model explains the optical line ratios and the continuum SED, although they did not mention the spatial extension of ionized regions.…”

Section: Resultsmentioning

confidence: 99%

Extended High-Ionization Nuclear Emission-Line Region in the Seyfert Galaxy NGC 4051

Nagao

Murayama

Taniguchi

et al. 2000

The Astronomical Journal

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We present an optical spectroscopic analysis of the well-known Seyfert galaxy NGC 4051. The highionization nuclear emission-line region (HINER) traced by [Fe X] λ6374 is found to be spatially extended to a radius of 3 ′′ (≈ 150 pc) west and southwest from the nucleus; NGC 4051 is the third example which has an extended HINER.The nuclear spectrum shows that the flux of [Fe X] λ6374 is stronger than that of [Fe VII] λ6087 in our observation. This property cannot be interpreted in terms of a simple one-zone photoionization model.In order to understand what happens in the nuclear region in NGC 4051, we investigate the physical condition of the nuclear emission-line region in detail using new photoionization models in which the following three emission-line components are taken into account; (1) optically thick, ionization-bounded clouds; (2) optically thin, matter-bounded clouds; and (3) a contamination component which emits Hα and Hβ lines. Here the observed extended HINER is considered to be associated with the low-density, matter-bounded clouds. Candidates of the contamination component are either the broad-line region (BLR) or nuclear star forming regions or both. The complexity of the excitation condition found in NGC 4051 can be consistently understood if we take account of these contamination components.

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“…The data at ν ≤ 10 15 Hz show that contribution from the old stellar population is present in Ark 564 (dash-dot line), as is found for most AGN. In the radio band, only one measurement in one frequency is available, so we cannot decide whether there is also some contribution from synchrotron emission created by Fermi mechanism at the shock front (dashed line, see Contini & Viegas 1999). …”

Section: The Sed Of the Continuummentioning

confidence: 99%

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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A Multicloud Warm‐Absorber Model for NGC 4051

Cited by 12 publications

References 23 publications

Gemini/GMOS Integral Field Unit stellar kinematics of the nuclear region of six nearby active galaxies

Gemini/GMOS Integral Field Unit stellar kinematics of the nuclear region of six nearby active galaxies

Extended High-Ionization Nuclear Emission-Line Region in the Seyfert Galaxy NGC 4051

The narrow line region of Ark 564

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