Pattern speed domains in ringed disk galaxies from observational and simulational databases

Byrd, G. G.; Rautiainen, P.; Salo, H.; Buta, Ronald J.; Crocher, D. A.

doi:10.1086/117085

Cited by 100 publications

(111 citation statements)

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“…In our simulations, after the bar perturbation is introduced but before a clear periodic orbit inner ring forms, we see no temporary round rings but instead distorted spiral features with elongated shapes resembling the long and short dimensions of the final inner ring, whose elongation is a function of the strength of the bar perturbation. This is consistent with the more extensive simulation survey of Byrd et al (1994), who find that ''As the bar is weakened, the inner ring becomes more circular.'' This was confirmed by Salo et al (1999).…”

Section: Isophote Methods Proposed By Contopoulos and The Shapes Of Resupporting

confidence: 89%

“…The rings strongly resemble the periodic orbits that would exist in a weak bar potential near specific orbit resonances, based on both analytic (Contopoulos 1979; and numerical studies (Schwarz 1981(Schwarz , 1984Byrd et al 1994;Rautiainen & Salo 2000;Buta & Combes 1996Regan & Teuben 2004). Paper I argued that these characteristics imply that NGC 3081 has been evolving in a relatively undisturbed manner for much of a Hubble time.…”

Section: Introductionmentioning

confidence: 91%

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The Inner Resonance Ring of NGC 3081. II. Star Formation, Bar Strength, Disk Surface Mass Density, and Mass-to-Light Ratio

Byrd¹,

Freeman²,

Buta³

2006

Astron J

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We complement our Hubble Space Telescope (HST ) observations of the inner ring of the galaxy NGC 3081 using an analytical approach and n-body simulations. We find that a gas cloud inner (r) ring forms under a rotating bar perturbation with very strong azimuthal cloud crowding where the ring crosses the bar major axis. Thus, star formation results near to and ''downstream'' of the major axis. From the dust distribution and radial velocities, the disk rotates counterclockwise (CCW ) on the sky like the bar pattern speed. We explain the observed CCW color asymmetry crossing the major axis as due to the increasing age of stellar associations inside the r ring major axis. These move faster than the pattern speed. The exterior point of the r ring at the bar major axis has an orbital rate equal to the pattern speed. We show how the perturbation strength can be estimated from the ring shapes and relative spacing over the inner through outer ring regions. The bar strength (maximum tangential/radial force) appears to be constant from 6 to 15 kpc. We derive how the perturbation, the fractional long wavelength m ¼ 2 intensity, and the rotation curve can be used to calculate the disk surface mass density versus radius. The disk surface density at 7 kpc is 13 M pc À2 rising to 19 at 13 kpc. The latter is insufficient by a factor of seven to generate the observed rotation curve, implying halo domination. The surface density may have been reduced at 7 kpc due to inner ring gas cloud scattering. The surface density plus the observed surface brightness gives a disk mass-to-light (M/L) ratio which increases from 7 kpc through 13 kpc, contradicting the usual assumption in bar strength calculations. The simulation ring lifetime of several billion years is consistent with our $400 Myr HST estimates. With a sufficiently high gas cloud surface mass density, our simulations form gas cloud ''associations'' near the ends of the bar as observed. Too high a density destroys the ring.

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Section: Isophote Methods Proposed By Contopoulos and The Shapes Of Resupporting

confidence: 89%

Section: Introductionmentioning

confidence: 91%

The Inner Resonance Ring of NGC 3081. II. Star Formation, Bar Strength, Disk Surface Mass Density, and Mass-to-Light Ratio

Byrd¹,

Freeman²,

Buta³

2006

Astron J

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“…Models of gas dynamics in galaxies come in two main categories: ballistic models in which the gas is represented by colliding clouds on ballistic orbits (Combes & Gerin 1985;Byrd et al 1994), and hydrodynamic models in which the gas is assumed to be a continuous dissipative medium (Athanassoula 1992;Piner et al 1995;Wada & Habe 1995;Friedli & Benz 1993). Comparisons of the two approaches are discussed in Lindblad & Lindblad (1994), Wada (1994), and Regan et al (1999).…”

Section: Discussionmentioning

confidence: 99%

Molecular gas in NUclei of GAlaxies (NUGA)

Boone

Baker

Schinnerer

et al. 2007

A&A

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“…(e. g., Schwarz 1984;Combes & Gerin 1985;Byrd et al 1994;Englmaier & Gerhard 1997;Salo et al 1999;Weiner, Sellwood, & Williams 2001a). Well motivated hints of these results came much earlier (Freeman 1970b).…”

Section: Bar-driven Radial Transport Of Gas: the Formation Of Ringsmentioning

confidence: 92%

Secular Evolution and the Formation of Pseudobulges in Disk Galaxies

Kormendy¹,

Kennicutt

2004

Annu. Rev. Astron. Astrophys.

1,738

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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Pattern speed domains in ringed disk galaxies from observational and simulational databases

Cited by 100 publications

References 0 publications

The Inner Resonance Ring of NGC 3081. II. Star Formation, Bar Strength, Disk Surface Mass Density, and Mass-to-Light Ratio

The Inner Resonance Ring of NGC 3081. II. Star Formation, Bar Strength, Disk Surface Mass Density, and Mass-to-Light Ratio

Molecular gas in NUclei of GAlaxies (NUGA)

Secular Evolution and the Formation of Pseudobulges in Disk Galaxies

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