High-resolution near-infrared spectra of NGC 4151: Line and continuum analysis

Thompson, Rodger I.

doi:10.1086/175732

Cited by 24 publications

(31 citation statements)

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“…3), and Ton S 180. That line has only been reported before in NGC 4151 (Thompson 1995) and NGC 1068 (Oliva et al 2001). …”

Section: Resultssupporting

confidence: 69%

“…That result had reinforced the use of [Si vi] 1.962 lm as a diagnostic of AGN activity and had allowed the detection of hidden AGNs, mostly in ULIRG samples (Veilleux, Sanders, & Kim 1999;Murphy et al 2000). Thompson (1995) Rieke, & Rieke (1995) studied a sample of six Seyfert 1 galaxies (one of them NGC 4151) in the 2 lm region and detected [Si vi] 1.963 lm in all the galaxies and [Ca viii] 2.321 lm in two of them.…”

Section: Introductionmentioning

confidence: 89%

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Near‐Infrared Coronal Lines in Narrow‐Line Seyfert 1 Galaxies

Rodríguez-Ardila

Viegas

Pastoriza

et al. 2002

ApJ

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We report spectroscopic observations in the wavelength region 0.8-2.4 lm aimed at detecting near-infrared coronal lines in a sample of five narrow-line and one broad-line Seyfert 1 galaxies. Our measurements show that [Si vi] 1.963 lm, [S ix] 1.252 lm, and [S viii] 0.991 lm are present in most of the objects and are useful tracers of nuclear activity. Line ratios between coronal and low-ionization forbidden lines are larger in narrow-line Seyfert 1 galaxies. A positive correlation between FHWM and ionization potential of the forbidden lines is observed. Some coronal lines have widths similar to those of lines emitted in the broad-line region (BLR), indicating that part of their flux originates in gas close to the outer portions of the BLR. Most coronal lines are blueshifted relative to the systemic velocity of the galaxy, and this shift increases with the increase in line width. Asymmetries toward the blue are observed in the profiles of high-ionization Fe lines, suggesting that the emitting gas is related to winds or outflows, most probably originating in material that is being evaporated from the torus. This scenario is supported by models that combine the effects of shock ionization and photoionization by a central continuum source in the gas clouds. The agreement between the coronal line emission predicted by the models and the observations is satisfactory; the models reproduced the whole range of coronal line intensities observed. We also report the detection of [Fe xiii] 1.074, 1.079 lm in three of our objects and the first detection of [P ii] 1.188 lm and [Ni ii] 1.191 lm in a Seyfert 1 galaxy, Ark 564. Using the ratio [P ii]/[Fe ii], we deduced that most Fe present in the outer narrow-line region of Ark 564 is locked up in grains and that the influence of shocks is negligible.

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“…3), and Ton S 180. That line has only been reported before in NGC 4151 (Thompson 1995) and NGC 1068 (Oliva et al 2001). …”

Section: Resultssupporting

confidence: 69%

Section: Introductionmentioning

confidence: 89%

Near‐Infrared Coronal Lines in Narrow‐Line Seyfert 1 Galaxies

Rodríguez-Ardila

Viegas

Pastoriza

et al. 2002

ApJ

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“…Later works reported a similar trend in other active galaxies with either optical or NIR lines (Osterbrock 1981;Pelat et al 1981;Penston et al 1984;Thompson 1995). Conversely, Giannuzzo et al (1995) found that CLs show an ample variety of FWHMs, leading to the conclusion that the CLR occupies different regions in different galaxies.…”

Section: Kinematics Of the Coronal Line Regionmentioning

confidence: 70%

The Near-Infrared Coronal Line Spectrum of 54 Nearby Active Galactic Nuclei

Rodríguez-Ardila

Prieto

Portilla

et al. 2011

ApJ

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The relationship between the emission of coronal lines (CLs) and nuclear activity in 36 Type 1 and 18 Type 2 active galactic nuclei (AGNs) is analyzed, for the first time, based on near-infrared (0.8-2.4 μm) spectra. The eight CLs studied, of Si, S, Fe, Al, and Ca elements and corresponding to ionization potentials (IPs) in the range 125-450 eV, are detected (3σ ) . We found that the non-detection is largely associated with either loss of spatial resolution or increasing object distance: CLs are essentially nuclear and easily lose contrast in the continuum stellar light for nearby sources or get diluted by the strong AGN continuum as the redshift increases. Yet, there are AGNs where the lack of coronal emission, i.e., lines with IP 100 eV, may be genuine. The absence of these lines reflects a non-standard AGN ionizing continuum, namely, a very hard spectrum lacking photons below a few Kev. The analysis of the line profiles points out a trend of increasing FWHM with increasing IPs up to energies around 300 eV, where a maximum in the FWHM is reached. For higher IP lines, the FWHM remains nearly constant or decreases with increasing IPs. We ascribe this effect to an increasing density environment as we approach the innermost regions of these AGNs, where densities above the critical density of the CLs with IPs larger than 300 eV are reached. This sets a strict range limit for the density in the boundary region between the narrow and the broad region of 10 8 -10 9 cm −3 . A relationship between the luminosity of the CLs and that of the soft and hard X-ray emission and the soft X-ray photon index is observed: the coronal emission becomes stronger with both increasing X-ray emission (soft and hard) and steeper X-ray photon index, i.e., softer X-ray spectra. Thus, photoionization appears as the dominant excitation mechanism. These trends hold when considering Type 1 sources only; they get weaker or vanish when including Type 2 sources, very likely because the X-ray emission measured in the latter is not the intrinsic ionizing continuum.

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“…However, no systematic study of the continuum characteristics in a representative sample of AGN have been made yet by means of spectroscopy. Previous works, concentrated on individual or on a small sample of objects, report a continuum described well by a broken power-law, with a flattening of the continuum slope at ∼1.1 µm (Thompson 1995(Thompson , 1996Rudy et al 2000Rudy et al , 2001Rodríguez-Ardila et al 2002a). It means that there would be a minimum in the continuum emission around 1.1 µm, probably associated to the red end of the optical power-law distribution associated to the central engine and the onset of the emission due to reprocessed nuclear radiation by dust (Barvainis 1987;Rudy et al 2000).…”

Section: The Continuum Spectramentioning

confidence: 99%

“…It is motivated by the fact that for a large fraction of objects (44/51), no previous NIR spectra covering the JHK bands simultaneously are available in the literature. In fact, only NGC 4151 (Thompson 1995 -Mrk 334. This Seyfert galaxy from the CfA catalog, classified as 1.8, is located in an interacting system in an advanced stage of merger.…”

Section: Notes On Individual Objectsmentioning

confidence: 99%

A 0.8–2.4μm spectral atlas of active galactic nuclei

Riffel

Rodríguez-Ardila²,

Pastoriza

2006

A&A

197

286

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Aims. We present a near-infrared spectral atlas of 47 active galactic nuclei (AGN) of all degrees of activity in the wavelength interval of 0.8-2.4 µm, including the fluxes of the observed emission lines. We analyze the spectroscopic properties of the continuum and emission line spectra of the sources. Methods. In order to exclude aperture and seeing effects we used near-infrared spectroscopy in the short cross-dispersed mode (SXD, 0.8-2.4 µm), taking the JHK-bands spectra simultaneously.Results. We present the most extensive NIR spectral atlas of AGN to date. This atlas offers a suitable database for studying the continuum and line emission properties of these objects in a region full of interesting features. The shape of the continuum of QSOs and Sy 1's are similar, being essentially flat in the H and K bands, while a strong variation is found in the J band. In Seyfert 2 galaxies, the continuum in the Fλ × λ space smoothly decreases in flux from 1.2 µm redwards in almost all sources. In J, it smoothly rises bluewards in some sources, while in others a small decrease in flux is observed. The spectra are dominated by strong emission

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High-resolution near-infrared spectra of NGC 4151: Line and continuum analysis

Cited by 24 publications

References 0 publications

Near‐Infrared Coronal Lines in Narrow‐Line Seyfert 1 Galaxies

Near‐Infrared Coronal Lines in Narrow‐Line Seyfert 1 Galaxies

The Near-Infrared Coronal Line Spectrum of 54 Nearby Active Galactic Nuclei

A 0.8–2.4μm spectral atlas of active galactic nuclei

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