Circumnuclear regions in barred spiral galaxies — I. Near-infrared imaging

Pérez-Ramírez, D.; Knapen, Johan H.; Peletier, Reynier F.; Laine, Seppo; Doyon, René; Nadeau, Daniel

doi:10.1046/j.1365-8711.2000.03521.x

Cited by 48 publications

(62 citation statements)

References 54 publications

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“…Using the BC criterion we find corotation for the inner bar and the main bar as peaks 1 and 4, respectively. The inner bar length is the mean of those of Erwin (2004) and Perez-Ramirez et al (2000), while the outer bar length is the value of Erwin (2004). Koda & Sofue (2006) apply a cloud-orbit model finding a corotation radius of 38.5 arcsec for the main bar, almost compatible with our value (Table 1).…”

Section: Ngc 4303 (M61)supporting

confidence: 85%

The ratio of pattern speeds in double-barred galaxies

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Beckman

Zaragoza-Cardiel

et al. 2014

Monthly Notices of the Royal Astronomical Society: Letters

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We have obtained two-dimensional velocity fields in the ionized gas of a set of 8 double-barred galaxies, at high spatial and spectral resolution, using their Hα emission fields measured with a scanning Fabry-Perot spectrometer. Using the technique by which phase reversals in the non-circular motion indicate a radius of corotation, taking advantage of the high angular and velocity resolution we have obtained the corotation radii and the pattern speeds of both the major bar and the small central bar in each of the galaxies; there are few such measurements in the literature. Our results show that the inner bar rotates more rapidly than the outer bar by a factor between 3.3 and 3.6.

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Section: Ngc 4303 (M61)supporting

confidence: 85%

The ratio of pattern speeds in double-barred galaxies

Font

Beckman

Zaragoza-Cardiel

et al. 2014

Monthly Notices of the Royal Astronomical Society: Letters

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“…The gas flow along the bar and its deviation into circumnuclear orbits can be followed via the presence of dust lanes which indicate compressed and shocked gas. These dust lanes in the central disk of NGC 1530 were imaged by Pérez-Ramírez et al (2000;their Fig. 2b) in the near IR, at subarcsec resolution, and are especially well seen in their J-K colour image, which we reproduce here in Fig.…”

Section: The Inner Kinematic Structure: a Spiralling Inflow Patternsupporting

confidence: 69%

“…As a test of this prediction we have produced a simple kinematic model showing how these flows would appear in projected velocity. We have assumed for simplicity that the intrinsic velocity vector has a constant amplitude, equal to 60 km s −1 , and projected it into the line of sight to the observer, using the inclination and position angle of the galaxy, and assuming that the dust lanes in the observations from Pérez-Ramírez et al (2000) denote the lines of flow, and that the spiral arms are trailing (this implies that the western part of the galaxy is closer to the observer than the eastern part). The resultant pattern of projected velocities is shown in Fig.…”

Section: The Inner Kinematic Structure: a Spiralling Inflow Patternmentioning

confidence: 99%

Ionized gas kinematics and massive star formation in NGC 1530

Zurita¹,

Relaño²,

Beckman³

et al. 2003

A&A

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Abstract. We present emission line mapping of the strongly barred galaxy NGC 1530 obtained using Fabry-Pérot interferometry in Hα, at significantly enhanced angular resolution compared with previously published studies. The main point of the work is to examine in detail the non-circular components of the velocity field of the gas, presumably induced by the strongly non-axisymmetric gravitational potential of the bar. To do this we first derive a model rotation curve making minimum assumptions about kinematic symmetry, and go on to measure the non-circular component of the full radial velocity field. This clearly reveals the streaming motions associated with the spiral density wave producing the arms, and the quasi-elliptical motions with speeds of order 100 km s −1 aligned with the bar. It also shows in some detail how these flows swing in towards and around the nucleus as they cross a circumnuclear resonance, from the dominant "x 1 orbits" outside the resonance to "x 2 orbits" within it.Comparing cross-sections of this residual velocity map along and across the bar with the surface brightness map in Hα indicates a systematic offset between regions of high non-circular velocity and massive star formation. To investigate further we produce maps of velocity gradient along and across the bar. These illustrate very nicely the shear compression of the gas, revealed by the location of the dust lanes along loci of maximum velocity gradient perpendicular to the bar. They also show clearly how shear, seen in our data as velocity gradient perpendicular to the flow, acts to inhibit massive star formation, whereas shocks, seen as strong velocity gradients along the flow vector, act to enhance it. Although the inhibiting effect of gas shear flow on star formation has long been predicted, this is the clearest observational illustration so far of the effect, thanks to the strong shock-induced counterflow system in the bar. It is also the clearest evidence that dust picks out shock-induced inflow along bars. These observations should be of considerable interest to those modelling massive star formation in general.

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“…As predicted by simulations, there is plenty of fuel -the central concentration of molecular gas is higher in barred than in unbarred galaxies (Sakamoto et al 1999). Additional examples of nuclear star formation rings -and multiple discussions of the best cases -can be found in van der Kruit (1974Kruit ( , 1976; Rubin, Ford, & Peterson (1975); Sandage & Brucato (1979); ;Gerin, Nakai, & Combes (1988); Benedict et al (1992Benedict et al ( , 1993Benedict et al ( , 1996Benedict et al ( , 2002; Buta (1986aButa ( , b, 1988Buta ( , 1995; Pogge (1989); García-Barreto et al (1991); ; ; Pogge & Eskridge (1993: NGC 1819; Forbes et al (1994a, b); Quillen et al (1995); Phillips et al (1996); Buta & Combes (1996); Maoz et al (1996); Regan et al (1996); Elmegreen et al (1997); Colina et al (1997); Contini et al (1997);Vega Beltrán et al (1998); Buta & Purcell (1998) ;Buta, Crocker, & Byrd (1999); Martini & Pogge (1999); ; Pérez-Ramírez et al (2000, 2001; Wong & Blitz (2000, 2001; Waller et al (2001); Lourenso et al (2001); Alonso-Herrero, ; Díaz et al (2002); …”

Section: Figurementioning

confidence: 99%

Secular Evolution and the Formation of Pseudobulges in Disk Galaxies

Kormendy¹,

Kennicutt

2004

Annu. Rev. Astron. Astrophys.

1,761

107

2,359

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The Universe is in transition. At early times, galactic evolution was dominated by hierarchical clustering and merging, processes that are violent and rapid. In the far future, evolution will mostly be secular: the slow rearrangement of energy and mass that results from interactions involving collective phenomena such as bars, oval disks, spiral structure, and triaxial dark halos. Both processes are important now. This paper reviews internal secular evolution, concentrating on one important consequence, the buildup of dense central components in disk galaxies that look like classical, merger-built bulges but that were made slowly out of disk gas. We call these pseudobulges.We begin with an "existence proof" -a review of how bars rearrange disk gas into outer rings, inner rings, and stuff dumped onto the center. Simulation results correspond closely to the morphology of barred galaxies. In the simulations, gas transported to small radii reaches high densities that plausibly feed star formation. In the observations, many SB and oval galaxies have dense central concentrations of gas and star formation. Optical colors and spectra often imply young stellar populations. So the formation of pseudobulges is well supported by theory and observations. It is embedded in a broader evolution picture that accounts for much of the richness observed in galaxy structure.If secular processes built dense central components that masquerade as bulges, how can we distinguish them from merger-built bulges? Observations show that pseudobulges retain a memory of their disky origin. 2That is, they have one or more characteristics of disks: (1) flatter shapes than those of classical bulges, (2) correspondingly large ratios of ordered to random velocities indicative of disk dynamics, (3) small velocity dispersions σ with respect to the Faber-Jackson correlation between σ and bulge luminosity, (4) spiral structure or nuclear bars in the "bulge" part of the light profile, (5) nearly exponential brightness profiles, and (6) starbursts. These structures occur preferentially in barred and oval galaxies in which secular evolution should be most rapid. So the cleanest examples of pseudobulges are recognizable.Are their formation timescales plausible? We use measurements of central gas densities and star formation rates to show that pseudobulges of the observed densities form on reasonable timescales of a few billion years.Thus a large variety of observational and theoretical results contribute to a new picture of galaxy evolution that complements hierarchical clustering and merging. Secular evolution consists of more than the aging of stellar populations. Every galaxy is dynamically evolving.

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Circumnuclear regions in barred spiral galaxies — I. Near-infrared imaging

Cited by 48 publications

References 54 publications

The ratio of pattern speeds in double-barred galaxies

The ratio of pattern speeds in double-barred galaxies

Ionized gas kinematics and massive star formation in NGC 1530

Secular Evolution and the Formation of Pseudobulges in Disk Galaxies

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