The Ringed Spiral Galaxy NGC 4622. I. Photometry, Kinematics, and the Case for Two Strong Leading Outer Spiral Arms

Buta, Ronald J.; Byrd, G. G.; Freeman, T.

doi:10.1086/345821

Cited by 32 publications

(28 citation statements)

References 70 publications

(77 reference statements)

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“…However, if we assume that the inner arm trails, the outer arms lead, and the galaxy rotates clockwise, as was recently demonstrated in Buta et al (2003), then there is a strong Fig. 10.-Left: Phase shift versus radius for the SA(r)a galaxy NGC 4622.…”

Section: Leading Arms In a Grand-design Spiral Galaxymentioning

confidence: 80%

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The Potential-Density Phase-Shift Method for Determining the Corotation Radii in Spiral and Barred Galaxies

Zhang¹,

Buta²

2007

Astron J

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We have developed a new method for determining the corotation radii of density waves in disk galaxies, which makes use of the calculated radial distribution of an azimuthal phase shift between the potential and density wave patterns. The approach originated from improved theoretical understandings of the relation between the morphology and kinematics of galaxies, and on the dynamical interaction between density waves and the basic-state disk stars which results in the secular evolution of disk galaxies. In this paper, we present the rationales behind the method, and the first application of it to several representative barred and grand-design spiral galaxies, using near-infrared images to trace the mass distributions, as well as to calculate the potential distributions used in the phase shift calculations. We compare our results with those from other existing methods for locating the corotations, and show that the new method both confirms the previously-established trends of bar-length dependence on galaxy morphological types, as well as provides new insights into the possible extent of bars in disk galaxies. The method also facilitates the estimation of mass accretion/excretion rates due to bar and spiral density waves, providing an alternative way of quantifying the importance of these features in disk galaxies. A preliminary analysis of a larger sample shows that the phase shift method is likely to be a generally-applicable, accurate, and essentially model-independent method for determining the pattern speeds and corotation radii of single or nested density wave patterns in galaxies. Other implications of the results of this work include that most of the nearby bright disk galaxies appear to possess quasi-stationary spiral modes; that these density wave modes as well as the associated basic-states of the galactic disks slowly transform over the time span of a Hubble time due to a collective dissipation process directly related to the presence of the phase shift between the potential and density patterns; and that self-consistent N-particle systems contain physics not revealed by the passive orbit analysis approaches.

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Section: Leading Arms In a Grand-design Spiral Galaxymentioning

confidence: 80%

“…′′ 8, and the green circle which marks the major negative-to-positive crossing where the inner trailing pattern and the outer leading pattern decouple. This image has not been corrected for the small inclination (19 • ) derived by Buta et al (2003). positive/negative crossing at 35.…”

Section: Leading Arms In a Grand-design Spiral Galaxymentioning

confidence: 99%

The Potential-Density Phase-Shift Method for Determining the Corotation Radii in Spiral and Barred Galaxies

Zhang¹,

Buta²

2007

Astron J

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“…Fourier decomposition can reveal surprising cases of counterwinding spiral structure (KIG 652/NGC 5768). Only a few other similar cases are known in literature: NGC 4622 (Buta, Byrd & Freeman 2003a), ESO 297−27 (Grouchy et al 2008), NGC 3124 (Purcell 1998; Buta 1999) and IRAS 18293−3413 (Väisänen et al 2008).…”

Section: Discussionmentioning

confidence: 99%

Fourier photometric analysis of isolated galaxies in the context of the AMIGA project

Durbala¹,

Buta²,

Sulentic³

et al. 2009

Monthly Notices of the Royal Astronomical Society

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We present here the results of a Fourier photometric decomposition of a representative sample of ∼100 isolated CIG galaxies (Catalog of Isolated Galaxies) in the morphological range Sb–Sc. This study is an integral part of the AMIGA (Analysis of the Interstellar Medium of Isolated Galaxies) project. It complements the photometric analysis presented in our previous paper for the same sample of disc galaxies by allowing a description of the spiral structure morphology. We also estimate dynamical measures like torque strength for bar and spiral, and also the total non‐axisymmetric torque by assuming a constant mass‐to‐light ratio, and explore the interplay between the spiral and bar components of galaxies. Both the length (lbar) and the contrast (e.g. A2b) of the Fourier bars decrease along the morphological sequence Sb–Sbc–Sc, with bars in earlier types being longer and showing higher contrast. The bars of Sb galaxies are ∼three times longer than the bars in Sc types, consistent with our previous study. We find that the longer bars are not necessarily stronger (as quantified by the torque Qb measure), but longer bars show a higher contrast A2b, in very good agreement with theoretical predictions. Our data suggest that bar and spiral components are rather independent in the sense that the torque strengths of the two components are not correlated. The total strength Qg is a very reliable tracer of the bar strength measure Qb, the two quantities showing a very tight linear correlation. Comparison with a similar sample of disc galaxies (same morphological range) extracted from the OSUBGS (Ohio State University Bright Galaxy Survey) indicates that the isolated CIG/AMIGA galaxies host significantly longer Fourier bars and possibly show a different distribution of spiral torque Qs. The Fourier analysis also revealed a potential case of counterwinding spiral structure (KIG 652/NGC 5768), which deserves further kinematic study. We find that m= 2 (i.e. dominating two‐armed pattern) is the most common spiral arm multiplicity among the sample of Sb–Sc CIG/AMIGA galaxies (∼40 per cent), m= 2 and 3 and m= 1 and 2 are found in ∼28 and ∼13 per cent of isolated galaxies, respectively.

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“…In ESO 297-27, the inner single arm leads while an outer three arms are trailing (Grouchy et al 2008). There is also the reverse case when the outer two-armed pattern leads while the inner one-arm trails as in NGC 4622 (Buta et al 2003). Thus while there is some evidence for lopsidedness being leading in the inner parts, it needs to be confirmed whether it is leading or trailing in the outer parts.…”

Section: Introductionmentioning

confidence: 96%

Angular momentum transport and evolution of lopsided galaxies

Saha¹,

Jog²

2014

Monthly Notices of the Royal Astronomical Society

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The surface brightness distribution in the majority of stellar galactic discs falls off exponentially. Often what lies beyond such a stellar disc is the neutral hydrogen gas whose distribution also follows a nearly exponential profile at least for a number of nearby disc galaxies. Both the stars and gas are commonly known to host lopsided asymmetry especially in the outer parts of a galaxy. The role of such asymmetry in the dynamical evolution of a galaxy has not been explored so far.Following Lindblad's original idea of kinematic density waves, we show that the outer part of an exponential disc is ideally suitable for hosting lopsided asymmetry. Further, we compute the transport of angular momentum in the combined stars and gas disc embedded in a dark matter halo. We show that in a pure star and gas disc, there is a transition point where the free precession frequency of a lopsided mode, Ω − κ, changes from retrograde to prograde and this in turn reverses the direction of angular momentum flow in the disc leading to an unphysical behaviour. We show that this problem is overcome in the presence of a dark matter halo, which sets the angular momentum flow outwards as required for disc evolution, provided the lopsidedness is leading in nature. This, plus the well-known angular momentum transport in the inner parts due to spiral arms, can facilitate an inflow of gas from outside perhaps through the cosmic filaments.

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The Ringed Spiral Galaxy NGC 4622. I. Photometry, Kinematics, and the Case for Two Strong Leading Outer Spiral Arms

Cited by 32 publications

References 70 publications

The Potential-Density Phase-Shift Method for Determining the Corotation Radii in Spiral and Barred Galaxies

The Potential-Density Phase-Shift Method for Determining the Corotation Radii in Spiral and Barred Galaxies

Fourier photometric analysis of isolated galaxies in the context of the AMIGA project

Angular momentum transport and evolution of lopsided galaxies

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