High-resolution radio observations of Seyfert galaxies in the extended 12- m sample -- I. The observations

Thean, Andrew; Pedlar, A.; Kukula, M. J.; Baum, Stefi A.; O’Dea, C. P.

doi:10.1046/j.1365-8711.2000.03401.x

Cited by 127 publications

(191 citation statements)

References 57 publications

(95 reference statements)

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“…The CfA and 12 m surveys were chosen because of the existing database of high-resolution VLA, MERLIN, and Very Long Baseline Array ( VLBA) observations already available for comparison (Kukula et al 1995;Murray et al 1999;Thean et al 2000Thean et al , 2001b. At cz $ 5000 km s À1 , the present observations provide a linear resolution of $5 kpc.…”

Section: Sample Selectionmentioning

confidence: 99%

“…The nucleus also contains a linear, jetlike radio source 1B6 (370 pc) in extent ( Ulvestad & Wilson 1984b;Gallimore et al 1999;Thean et al 2000). The AGN is marked by a $7 mas (1.6 pc) VLBI-scale radio jet ( Hummel et al 1982;Wilson et al 1998) that aligns with the arcsecond-scale jet.…”

Section: Ngc 2639mentioning

confidence: 99%

“…Radio imaging surveys of statistically well-defined samples of Seyfert galaxies have mainly employed long interferometric baselines (i.e., Very Large Array [ VLA] A configuration or MERLIN ) that filter out low surface brightness emission distributed over larger angular scales ( Ulvestad & Wilson 1984a, 1984bKukula et al 1995;Thean et al 2000Thean et al , 2001b. These surveys may have therefore artificially suppressed the detection of larger scale outflows.…”

Section: Introductionmentioning

confidence: 99%

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A Survey of Kiloparsec-Scale Radio Outflows in Radio-Quiet Active Galactic Nuclei

et al. 2006

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Seyfert galaxies commonly host compact jets spanning 10-100 pc scales, but larger structures are resolved out in long-baseline aperture synthesis surveys. Previous, targeted studies showed that kiloparsec-scale radio structures ( KSRs) may be a common feature of Seyfert and LINER galaxies, and the origin of KSRs may be starbursts or active galactic nuclei (AGNs). We report a new Very Large Array survey of a complete sample of Seyfert and LINER galaxies. Out of all of the surveyed radio-quiet sources, we find that 44% (19 out of 43) show extended radio structures at least 1 kpc in total extent that do not match the morphology of the disk or its associated star-forming regions. The detection rate is a lower limit owing to the combined effects of projection and resolution. The infrared colors of the KSR host galaxies are unremarkable compared to other Seyfert galaxies, and the large-scale outflows orient randomly with respect to the host galaxy axes. The KSR Seyfert galaxies instead stand out by deviating significantly from the far-infrared-radio correlation for star-forming galaxies, with tendency toward radio excess, and they are more likely to have a relatively luminous, compact radio source in the nucleus; these results argue that KSRs are powered by the AGNs rather than starbursts. The high detection rate indicates that Seyfert galaxies generate radio outflows over a significant fraction of their lifetime, which is much longer than the dynamical timescale of an AGNpowered jet but is comparable instead to the buoyancy timescale. The likely explanation is that the KSRs originate from jet plasma that has been decelerated by interaction with the nuclear interstellar medium ( ISM ). Based on a simple ram pressure argument, the kinetic power of the jet on kiloparsec scales is about 3 orders of magnitude weaker than the power of the jet on 10-100 pc scales. This result is consistent with the interaction model, in which case virtually all of the jet power must be lost to the ISM within the inner kiloparsec.

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Section: Sample Selectionmentioning

confidence: 99%

Section: Ngc 2639mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A Survey of Kiloparsec-Scale Radio Outflows in Radio-Quiet Active Galactic Nuclei

et al. 2006

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“…From our data, the inclination of the torus structure cannot be assumed. Thean et al (2000) observed NGC 7172 as part of a sample of 87 mid-infrared selected AGN from Rush et al (1993) at 8.4-GHz with the VLA A-configuration. The radio map shows, as in our NIR observation, an elongation to the south-west.…”

Section: Discussionmentioning

confidence: 99%

“…Therefore, Imanishi (2001) concludes that NGC 7172 is powered by a highly obscured AGN and is not contaminated by the nuclear starburst. Thean et al (2000) present a radio contour map of NGC 7172, which may detect an outflow to the south-west. Although the beam is elongated, the shape is comparable to the 12 μm map of Roche et al (2007).…”

Section: Ngc 7172mentioning

confidence: 99%

Unveiling the nucleus of NGC 7172

Smajić

Fischer

Zuther

et al. 2012

A&A

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Aims. We present the results of near-infrared (NIR) H + K European Southern Observatory SINFONI integral field spectroscopy (IFS) of the Seyfert 2 galaxy NGC 7172. We investigate the central 800 pc, concentrating on excitation conditions, morphology, and stellar content. NGC 7172 was selected from a sample of the ten nearest Seyfert 2 galaxies from the Veron-Cetty & Veron catalogue. All objects were chosen as test cases for adaptive optics (AO) assisted observations that allow a detailed study (at high spatial and spectral resolution) of the nuclear and host environments. NGC 7172 has a prominent dustlane crossing the central galaxy region from east to west, which makes it an ideal candidate to investigate the effect of obscuration by strong galactic extinction on (active) galaxies and their classification. Methods. The NIR is less influenced by dust extinction than optical light and is sensitive to the mass-dominating stellar populations. SINFONI integral field spectroscopy combines NIR imaging and spectroscopy and provides us with the opportunity to analyze several emission and absorption lines to investigate the stellar populations and ionization mechanisms over the 4 × 4 field of view (FOV). is predominantly inhabited by gas, dust, and an old K-M type giant stellar population. The gaseous, molecular, and stellar velocity maps show a related disturbed disk structure and similar velocities. Conclusions. We find evidence of nuclear activity located behind the prominent dustlane crossing the central region of the galaxy. The nucleus of NGC 7172, which is optically classified as a Seyfert 2 nucleus without any trace of broad emission lines, is a Seyfert 1 nucleus either surrounded by a molecular dust torus or hidden behind the strong galactic extinction. Our observation provides support for the unified model scheme. However, an evolutionary scenario cannot be ruled out by our observation.

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Recent Star Formation in Galaxies

Bressan

2002

New Quests in Stellar Astrophysics: The Link Between Stars and Cosmology

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High-resolution radio observations of Seyfert galaxies in the extended 12- m sample -- I. The observations

Cited by 127 publications

References 57 publications

A Survey of Kiloparsec-Scale Radio Outflows in Radio-Quiet Active Galactic Nuclei

A Survey of Kiloparsec-Scale Radio Outflows in Radio-Quiet Active Galactic Nuclei

Unveiling the nucleus of NGC 7172

Recent Star Formation in Galaxies

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