Disc galaxies with multiple triaxial structures.
II. JHK surface photometry and numerical simulations

Friedli, D.; Wozniak, H.; Rieke, M. J.; Martinet, L.; Bratschi, P.

doi:10.1051/aas:1996212

Cited by 115 publications

(173 citation statements)

References 24 publications

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“…Our value of PA 0 differs slightly (by 10 • ) from the measurements of Friedli et al (1996). The radial dependences of the isophotal PA and , in all observed bands, coincide with those of Wozniak et al (1995) and Friedli et al (1996).…”

Section: Ngc 2950supporting

confidence: 84%

“…However, the parameters from Table 7 allow us to obtain a more smooth well-ordered spiral of the maximum of the m = 2 harmonic. In the circumnuclear region, PA of the SED755 isophotes matches the NIR data of Friedli et al (1996), but it deviates by more than 25 • from the measurements in the V and R c bands. This can be related to the dust extinction, which is more significant in the optical bands.…”

Section: Ngc 470mentioning

confidence: 56%

“…The first systematic observational study of this phenomenon was made by Buta & Crocker (1993), who published a list of 13 galaxies, where the secondary (inner) bar was arbitrarily oriented with respect to the primary (outer) one. In the following years the isophotal analysis technique made it possible to detect secondary bars in optical (Wozniak et al 1995;Erwin & Sparke 1999;Erwin & Sparke 2003) and NIR images of barred galaxies (Friedli et al 1996;Jungwiert et al 1997;Laine et al 2002). Up to now, we have found 71 candidate double-barred galaxies in the literature (see references in Moiseev 2001b).…”

Section: Introductionmentioning

confidence: 91%

“…It varies from PA 0 = 50 • (Friedli et al 1996) to 130−140 • (Erwin & Sparke 1999. The outer Vband isophotes (Fig.…”

Section: Ngc 2681mentioning

confidence: 99%

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Structure and kinematics of candidate double-barred galaxies

Моисеев

Valdés

Chavushyan

2004

A&A

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Abstract.Results of optical and NIR spectral and photometric observations of a sample of candidate double-barred galaxies are presented. Velocity fields and velocity dispersion maps of stars and ionized gas, continuum and emission-line images were constructed from integral-field spectroscopy observations carried out at the 6 m telescope (BTA) of SAO RAS, with the MPFS spectrograph and the scanning Fabry-Perot Interferometer. NGC 2681 was also observed with the long-slit spectrograph of the BTA. Optical and NIR images were obtained at the BTA and at the 2.1 m telescope (OAN, México). High-resolution images were retrieved from the HST data archive. Morphological and kinematic features of all 13 sample objects are described in detail. Attention is focused on the interpretation of observed non-circular motions of gas and stars in circumnuclear (one kiloparsec-scale) regions. We have shown first of all that these motions are caused by the gravitational potential of a large-scale bar. NGC 3368 and NGC 3786 have nuclear bars only, their isophotal twist at larger radii being connected with the bright spiral arms. Three cases of inner polar disks in our sample (NGC 2681, NGC 3368 and NGC 5850) are considered. We found ionized-gas counter-rotation in the central kiloparsec of the lenticular galaxy NGC 3945. Seven galaxies (NGC 470, NGC 2273, NGC 2681, NGC 3945, NGC 5566, NGC 5905, and NGC 6951) have inner mini-disks nested in large-scale bars. Minispiral structures occur often in these nuclear disks. It is interesting that the majority of the observed, morphological and kinematical, features in the sample galaxies can be explained without the secondary bar hypothesis. Thus we suggest that a dynamically independent secondary bar is a rarer phenomenon than follows from isophotal analysis of the images only.

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Section: Ngc 2950supporting

confidence: 84%

Section: Ngc 470mentioning

confidence: 56%

Section: Introductionmentioning

confidence: 91%

“…It varies from PA 0 = 50 • (Friedli et al 1996) to 130−140 • (Erwin & Sparke 1999. The outer Vband isophotes (Fig.…”

Section: Ngc 2681mentioning

confidence: 99%

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Structure and kinematics of candidate double-barred galaxies

Моисеев

Valdés

Chavushyan

2004

A&A

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“…However, while the presence of three nested bars or triaxial features have been reported in a handful of active galaxies (e.g., Friedli et al 1996;Laine et al 2002), the current limited spatial resolution of NIR surveys and molecular gas surveys does not yet allow systematic observational tests of this scenario.…”

Section: From Hundred Pc To Sub-pc Scalesmentioning

confidence: 99%

The Fueling and Evolution of AGN: Internal and External Triggers

Jogee

Lecture Notes in Physics

120

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In this chapter, I review the fueling and evolution of active galactic nuclei (AGN) under the influence of internal and external triggers, namely intrinsic properties of host galaxies (morphological or Hubble type, color, presence of bars and other non-axisymmetric features, etc) and external factors such as environment and interactions. The most daunting challenge in fueling AGN is arguably the angular momentum problem as even matter located at a radius of a few hundred pc must lose more than 99.99 % of its specific angular momentum before it is fit for consumption by a BH. I review mass accretion rates, angular momentum requirements, the effectiveness of different fueling mechanisms, and the growth and mass density of black BHs at different epochs. I discuss connections between the nuclear and larger-scale properties of AGN, both locally and at intermediate redshifts, outlining some recent results from the GEMS and GOODS HST surveys.Comment: Invited Review Chapter to appear in LNP Volume on "AGN Physics on All Scales", Chapter 6, in press. 40 pages, 12 figures. Typo in Eq 5 correcte

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BV photometry of five shell galaxies

Pierfederici¹,

Rampazzo

2004

Astron Nachr

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Abstract. Current views consider shell structures as bona fide signatures of a recent minor/major merging event though also weak interaction models (WIM) could produce long lasting shells on host galaxies possessing a stellar thick disc. We present a B V band photometric study of a sample of 5 shell galaxies belonging to the Malin & Carter (1983) compilation. The structural properties and colors of the galaxies, as well as the colors of their shells are examined in detail. We did not find signatures of the presence of double nuclei. NGC 7585 is the only E galaxy in the sample and has a moderately boxy structure. The other galaxies have either a discy structure or are mixed E/S0 type galaxies. NGC 474 is a true lenticular. NGC 6776 shows a diffuse asymmetric outer structure and a system of tails of the the same color of the galaxy body; but not clear shells. In general, the color of the shells in our sample is similar or slightly redder than that of the host galaxy, whose color, in turn, is typical of the early-type morphological class. One of the outer shells of NGC 474 is significantly bluer than the body of the galaxy. Since NGC 474 appears to be interacting with NGC 470, the color of this one shell could be explained as result of a recent acquisition of material through tidal interaction. The WIM hypothesis could explain both the red and the blue shells of NGC 474, this latter acquired from the fly-by of the nearby companion NGC 470, but the lack of the constancy of shell surface brightness as a ratio of the underlying galaxy brightness argues against WIM. We speculate about evidence, which also comes from different observations, that suggests a merging/accretion origin of the shells.

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Disc galaxies with multiple triaxial structures. II. JHK surface photometry and numerical simulations

Cited by 115 publications

References 24 publications

Structure and kinematics of candidate double-barred galaxies

Structure and kinematics of candidate double-barred galaxies

The Fueling and Evolution of AGN: Internal and External Triggers

BV photometry of five shell galaxies

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