What determines the strength and the slowdown rate of bars?

Athanassoula, E.

doi:10.1046/j.1365-8711.2003.06473.x

Cited by 532 publications

(837 citation statements)

References 38 publications

(67 reference statements)

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“…2). This behavior of bar evolution is well known and is likely due to angular momentum loss to the inner halo (Athanassoula 2003). Note, however, that some of the bar angular momentum is also transferred to the outer disc, resulting in the extended disc profiles seen in Fig.…”

Section: The Bars In Our Simulationsmentioning

confidence: 51%

Evolution of galactic discs: multiple patterns, radial migration, and disc outskirts

Minchev

Famaey

Quillen

et al. 2012

A&A

186

208

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We investigate the evolution of galactic discs in N-body tree-SPH simulations. We find that discs, initially truncated at three scalelengths, can triple their radial extent, solely driven by secular evolution. At the same time, the initial radial metallicity gradients are flattened and even reversed in the outer discs. Both Type I (single exponential) and Type II (down-turning) observed disc surfacebrightness profiles can be explained by our findings. We show that profiles with breaks beyond the bar's outer Lindblad resonance, at present only explained as the effect of star-formation threshold, can occur even if no star formation is considered. We explain these results with the strong angular momentum outward transfer, resulting from torques and radial migration associated with multiple patterns, such as central bars and spiral waves of different multiplicity. We find that even for stars ending up on cold orbits, the changes in angular momentum exhibit complex structure as a function of radius, unlike the expected effect of transient spirals alone. We show that the bars in all of our simulations are the most effective drivers of radial migration through their corotation resonance, throughout the 3 Gyr of evolution studied. Focussing on one of our models, we find evidence for non-linear coupling among m = 1, 2, 3 and 4 density waves, where m is the pattern multiplicity. In this way the waves involved conspire to carry the energy and angular momentum extracted by the first mode from the inner parts of the disc much farther out than a single mode could. We suggest that the naturally occurring larger resonance widths at galactic radii beyond four scale-lengths may have profound consequences on the formation and location of breaks in disc density profiles, provided spirals are present at such large distances. We also consider the effect of gas inflow and show that when in-plane smooth gas accretion of ∼5 M /yr is included, the outer discs become more unstable, leading to a strong increase in the stellar velocity dispersion. This, in turn, causes the formation of a Type III (up-turning) profile in the old stellar population. We propose that observations of Type III surface brightness profiles, combined with an up-turn in the stellar velocity dispersions beyond the disc break, could be a signature of ongoing gas-accretion. The results of this study suggest that disc outskirts comprised of stars migrated from the inner disc would have relatively large radial velocity dispersions (>30 km s −1 at 6 scale-lengths for Milky Way-size systems), and significant thickness when seen edge-on.

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Section: The Bars In Our Simulationsmentioning

confidence: 51%

Evolution of galactic discs: multiple patterns, radial migration, and disc outskirts

Minchev

Famaey

Quillen

et al. 2012

A&A

186

208

View full text Add to dashboard Cite

show abstract

“…A bar is a common phenomenon in the universe; about 65% of nearby spiral galaxies have bars, among which over 30% have strong bars (Eskridge et al 2000), and the percentage of bars remains high out to a redshift of z ∼ 1 (Elmegreen et al 2004;Jogee et al 2004). Bars can provide intense nonaxisymmetry in the gravitational potential, which causes gas to lose angular momentum and then fall to the inner region of galaxies (Athanassoula 2003;Kormendy & Fisher 2005). Sheth et al (2005) compared the molecular gas distribution in a sample of nearby galaxies from BIMA-SONG CO (J = 1-0) and found that more molecular gas is concentrated in the central kiloparsecs of barred spirals than that in other Hubble-type galaxies, which is consistent with radial inflow driven by a bar.…”

Section: Introductionmentioning

confidence: 80%

Star Formation Properties in Barred Galaxies (Sfb). I. Ultraviolet to Infrared Imaging and Spectroscopic Studies of NGC 7479

Zhang

Cao

Meng

et al. 2011

The Astronomical Journal

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Large-scale bars and minor mergers are important drivers for the secular evolution of galaxies. Based on ground-based optical images and spectra as well as ultraviolet data from the Galaxy Evolution Explorer and infrared data from the Spitzer Space Telescope, we present a multi-wavelength study of star formation properties in the barred galaxy NGC 7479, which also has obvious features of a minor merger. Using various tracers of star formation, we find that under the effects of both a stellar bar and a minor merger, star formation activity mainly takes place along the galactic bar and arms, while the star formation rate changes from the bar to the disk. With the help of spectral synthesis, we find that strong star formation took place in the bar region about 100 Myr ago, and the stellar bar might have been ∼10 Gyr old. By comparing our results with the secular evolutionary scenario from Jogee et al., we suggest that NGC 7479 is possibly in a transitional stage of secular evolution at present, and it may eventually become an earlier type galaxy or a luminous infrared galaxy. We also note that the probable minor merger event happened recently in NGC 7479, and we find two candidates for minor merger remnants.

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“…Particles in a possible dark matter bar (Colín et al 2006), dark disk (Bruch et al 2008;Read et al 2008) and even in the dark matter halo (Athanassoula 2005) are trapped/scattered in the same resonances as stars are. It has been shown that different bar-induced resonances can be populated by disk-like and halo particles (Athanassoula 2002(Athanassoula , 2003Ceverino & Klypin 2007).…”

Section: Local Dark Matter Kinematicsmentioning

confidence: 99%

Stellar Kinematic Constraints on Galactic Structure Models Revisited: Bar and Spiral Arm Resonances

Antoja

Valenzuela

Pichardo

et al. 2009

ApJ

111

127

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We study the phase space available to the local stellar distribution using a Galactic potential consistent with several recent observational constraints. We find that the induced phase space structure has several observable consequences. The spiral arm contribution to the kinematic structure in the solar neighborhood may be as important as the one produced by the Galactic bar. We suggest that some of the stellar kinematic groups in the solar neighborhood, like the Hercules structure and the kinematic branches, can be created by the dynamical resonances of self-gravitating spiral arms and not exclusively by the Galactic bar. A structure coincident with the Arcturus kinematic group is developed when a hot stellar disk population is considered, which introduces a new perspective on the interpretation of its extragalactic origin. A bar-related resonant mechanism can modify this kinematic structure. We show that particles in the dark matter disk-like structure predicted by recent LCDM galaxy formation experiments, with similar kinematics to the thick disk, are affected by the same resonances, developing phase space structures or dark kinematic groups that are independent of the Galaxy assembly history and substructure abundance. We discuss the possibility of using the stellar phase space groups as constraints to non-axisymmetric models of the Milky Way structure.

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What determines the strength and the slowdown rate of bars?

Cited by 532 publications

References 38 publications

Evolution of galactic discs: multiple patterns, radial migration, and disc outskirts

Evolution of galactic discs: multiple patterns, radial migration, and disc outskirts

Star Formation Properties in Barred Galaxies (Sfb). I. Ultraviolet to Infrared Imaging and Spectroscopic Studies of NGC 7479

Stellar Kinematic Constraints on Galactic Structure Models Revisited: Bar and Spiral Arm Resonances

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