The NICMOS Snapshot Survey of Nearby Galaxies

Böker, Torsten; Calzetti, Daniela; Sparks, W. B.; Axon, D. J.; Bergeron, Louis; Bushouse, H.; Colina, L.; Daou, D.; Gilmore, Diane; Holfeltz, S. T.; MacKenty, John; Mazzuca, Lisa M.; Monroe, Bruce M.; Najita, J.; Noll, K. S.; Nota, A.; Ritchie, C.; Schultz, A.; Sosey, M.; Storrs, A. D.; Suchkov, A. A.

doi:10.1086/313253

Cited by 96 publications

(84 citation statements)

References 18 publications

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“…The brightness profile in the range of radius of 2 −12 derived from the NICMOS/HST data is well-fitted by a de Vaucouleurs' formula indicating a classical bulge. But in the same range of radius the ionized gas spirals are seen -mainly to the west of the nucleus (Boker et al 1999); therefore for some reason the prominent bulge is not able to stabilize the inner disk. Could the bulge be non-axisymmetric?…”

Section: Discussionmentioning

confidence: 99%

“…The galaxy was exposed on June 4, 1998, during 192 s through a F 160W (H-continuum) filter and during 512 s through a F 187N (Paα) filter. The results of these observations are reported in detail by Boker et al (1999); we use them to estimate morphological parameters of isophotes. To extend our photometric analysis to the outer parts of the global galactic disk, we also took recourse to ground-based photometry; we used the public data of Frei et al (1996), obtained at the Palomar 1.5 m telescope through Thuan & Gunn's gri-filters: though of medium resolution (seeing of 2.…”

Section: Observations and Data Reductionmentioning

confidence: 99%

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A lopsided chemically distinct nucleus in NGC 5055

Afanasiev

Сильченко

2002

A&A

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Abstract. Kinematics and stellar population properties in the center of nearby Sbc galaxy NGC 5055 are studied with the Multi-Pupil Spectrograph of the 6 m telescope of the Special Astrophysical Observatory of Russian Academy of Sciences (SAO RAS). We confirm the rotation and stellar velocity dispersion asymmetries along the major axis reported earlier by other authors. We have found a resolved chemically distinct core in NGC 5055, with the magnesium-enhanced region shifted by 2. 5 (100 pc) to the south-west from a photometric center, toward a kinematically identified circumnuclear stellar disk. Mean ages of stellar populations in the true nucleus, defined as the photometric center, and in the magnesium-enhanced substructure are coincident and equal to 3-4 Gyr being younger by several Gyr with respect to the bulge stellar population. A possible origin of the asymmetries in the center of NGC 5055 is discussed.

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Section: Discussionmentioning

confidence: 99%

Section: Observations and Data Reductionmentioning

confidence: 99%

A lopsided chemically distinct nucleus in NGC 5055

Afanasiev

Сильченко

2002

A&A

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“…4 toward south. It is part of a survey of 94 nearby galaxies from the Revised Shapley Ames Catalog (Böker et al 1999).…”

Section: Other Images Of Ngc 3627mentioning

confidence: 99%

Molecular Gas in NUclei of GAlaxies (NUGA)

Casasola

Hunt

Combes

et al. 2011

A&A

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We present 12 CO(1-0) and 12 CO(2-1) maps of the interacting barred LINER/Seyfert 2 galaxy NGC 3627 obtained with the IRAM interferometer at resolutions of 2. 1 × 1. 3 and 0. 9 × 0. 6, respectively. We also present single-dish IRAM 30 m 12 CO(1-0) and 12 CO(2-1) observations used to compute short spacings and complete interferometric measurements. These observations are complemented by IRAM 30 m measurements of HCN(1-0) emission detected in the center of NGC 3627. The molecular gas emission shows a nuclear peak, an elongated bar-like structure of ∼18 (∼900 pc) diameter in both 12 CO maps and, in 12 CO(1-0), a two-arm spiral feature from r ∼ 9 (∼450 pc) to r ∼ 16 (∼800 pc). The inner ∼18 bar-like structure, with a north/south orientation (PA = 14 • ), forms two peaks at the extremes of this elongated emission region. The kinematics of the inner molecular gas shows signatures of non-circular motions associated both with the 18 bar-like structure and the spiral feature detected beyond it. The 1.6 μm H-band 2MASS image of NGC 3627 shows a stellar bar with a PA = −21 • , different from the PA (= 14 • ) of the 12 CO bar-like structure, indicating that the gas is leading the stellar bar. The far-infrared Spitzer-MIPS 70 and 160 μm images of NGC 3627 show that the dust emission is intensified at the nucleus and at the ansae at the ends of the bar, coinciding with the 12 CO peaks. The GALEX far-ultraviolet (FUV) morphology of NGC 3627 displays an inner elongated (north/south) ring delimiting a hole around the nucleus, and the 12 CO bar-like structure is contained in the hole observed in the FUV. The torques computed with the HST-NICMOS F160W image and our PdBI maps are negative down to the resolution limit of our images, ∼60 pc in 12 CO(2-1). If the bar ends at ∼3 kpc, coincident with corotation (CR), the torques are negative between the CR of the bar and the nucleus, down to the resolution limit of our observations. This scenario is compatible with a recently-formed rapidly rotating bar which has had insufficient time to slow down because of secular evolution, and thus has not yet formed an inner Lindblad resonance (ILR). The presence of molecular gas inside the CR of the primary bar, where we expect that the ILR will form, makes NGC 3627 a potential smoking gun of inner gas inflow. The gas is fueling the central region, and in a second step could fuel directly the active nucleus.

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“…The NICMOS images were re-reduced with the STSDAS task calnica using the best reference files, and the images were calibrated in the standard way. The "pedestal" effect (see Böker et al 1999) was removed with the van der Marel algorithm 2 . Sky values were assumed to be zero since the galaxy filled the WFPC2/NICMOS frames, an assumption which makes an error of ∼ 0.1 mag at most, in the corner of the images.…”

Section: Near-infrared and Optical Observationsmentioning

confidence: 99%

Molecular gas in NUclei of GAlaxies (NUGA)

García‐Burillo¹,

Combes²,

Schinnerer³

et al. 2005

A&A

173

242

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We discuss the efficiency of stellar gravity torques as a mechanism to account for the feeding of the central engines of four low luminosity Active Galactic Nuclei (AGN): NGC 4321 (HII nucleus/LINER), NGC 4826 (HII nucleus/LINER), NGC 4579 (LINER 1.9/Seyfert 1.9) and NGC 6951 (Seyfert 2). These galaxies have been observed as part of the NUclei of GAlaxies-(NUGA) CO project, aimed at the study of AGN fueling mechanisms. Our calculations allow us to derive the characteristic time-scales for gas flows and discuss whether torques from the stellar potentials are efficient enough to drain the gas angular momentum in the inner 1 kpc of these galaxies. The stellar potentials are derived using high-resolution near infrared (NIR) images and the averaged effective torques on the gas are estimated using the high-resolution (∼0.5 -2 ) CO maps of the galaxies. Results indicate paradoxically that feeding should be thwarted close to the AGNs: in the four cases analyzed, gravity torques are mostly positive inside r ∼ 200 pc, resulting in no inflow on these scales. As a possible solution for the paradox, we speculate that the agent responsible for driving inflow to still smaller radii is transient and thus presently absent in the stellar potential. Alternatively, the gravity torque barrier associated with the Inner Lindblad Resonance of the bars in these galaxies could be overcome by other mechanisms that become competitive in due time against gravity torques. In particular, we estimate on a case-by-case basis the efficiency of viscosity versus gravity torques to drive AGN fueling. We find that viscosity can counteract moderate-to-low gravity torques on the gas if it acts on a nuclear ring of high gas surface density contrast and ∼a few 100 pc size. We propose an evolutionary scenario in which gravity torques and viscosity act in concert to produce recurrent episodes of activity during the typical lifetime of any galaxy. In this scenario the recurrence of activity in galaxies is indirectly related to that of the bar instabilities although the active phases are not necessarily coincident with the maximum strength of a single bar episode. The general implications of these results for the current understanding of fueling of low-luminosity AGN are discussed.

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The NICMOS Snapshot Survey of Nearby Galaxies

Cited by 96 publications

References 18 publications

A lopsided chemically distinct nucleus in NGC 5055

A lopsided chemically distinct nucleus in NGC 5055

Molecular Gas in NUclei of GAlaxies (NUGA)

Molecular gas in NUclei of GAlaxies (NUGA)

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