What determines the strength and the slowdown rate of bars

By E. Athanassoula. 2003

421 citations recorded by the source corpus.

Isolated barred galaxies evolve by redistributing their angular momentum, which, emitted by material in the inner disc at resonance with the bar, can be absorbed by resonant material in the outer disc, or in the halo. The amount of angular momentum that can be emitted/absorbed at a given resonance depends on the distribution function of the emitting/absorbing material. It thus depends not only on the amount of material on resonant orbits, but also on the velocity dispersion of that material. As it loses angular momentum, the bar becomes stronger and it also rotates slower. Thus the strength of the bar and the decrease of its pattern speed with time are set by the amount of angular momentum exchanged within the galaxy, which, in turn, is regulated by the mass distribution and the velocity dispersion of the material in the disc and spheroidal components. Correlations between the pattern speed of the bar, its strength and the angular momentum absorbed by the spheroid (halo plus bulge) argue strongly that it is the amount of angular momentum exchanged that determines the strength and the slowdown rate of the bar. The decrease of the bar pattern speed with time should not be used to set constraints on the halo-to-disc mass ratio, since it depends also on the velocity dispersion of the halo and disc material.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/98293fe6c74b9ae2c6f1c204d80ff1d824daf105

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Citations in the corpus

An analytic model of angular momentum transport by gravitational torques: from galaxies to massive black holes (2010, background): “Goldreich & Tremaine (1978, 1979) and Athanassoula (1992a, 2003) derive this result rigorously.”
Physical properties and environments of nearby galaxies (2009, background): “The formation of the bars themselves and the role of their interaction with the surrounding density field is a matter of debate (Sellwood 2000; Athanassoula 2003; Gadotti & de Souza 2005).”
Galaxy Masses: A Review (2013, background): “Indeed, Athanassoula (2003) and Athanassoula et al. (2013) have argued that the decrease in the pattern speed does not depend only on the mass of the dark matter halo, but also also on other galaxy properties such as gas fraction, or halo shape.”
Secular Evolution and the Formation of Pseudobulges in Disk Galaxies (2004, background): “The Combes & Sanders (1981) results have been confirmed and extended by many authors (e. g., Combes et al. 1990; Pfenniger & Friedli 1991; Berentzen et al. 1998; Athanassoula &Misiriotis 2002; Athanassoula 2003).”
Bars in Disk-dominated and Bulge-dominated Galaxies at z ~ 0: New Insights from ~3600 SDSS Galaxies (2007, background): “Work with live halos has showed that there is resonant transfer of angular momentum between the bar, the DM halo, and the outer disk (e.g., Debattista & Sellwood 1998, 2000; Athanassoula 2002, 2003): the angular momentum absorbed by the DM halo makes an existing bar grow and slow down.”
How Large Are the Bars in Barred Galaxies (2005, background): “It would be fruitful to examine more carefully why some simulations produce larger bars than others (see, for example, the discussions in Athanassoula 2003; Valenzuela & Klypin 2003), and whether there are any parameters (e.g., relative halo mass, halo structure and kinematics, and in particular…”
Double-Barred Galaxies I. A Catalog of Barred Galaxies with Stellar Secondary Bars and Inner Disks (2003, background): “As Athanassoula (2003) notes, “Although the notion of bar strength is clear to everyone, and it is very often easy, when comparing two bars, to say which one is strongest, a precise definition is not trivial.””
Bar Diagnostics in Edge-On Spiral Galaxies. III. N-Body Simulations of Disks (2004, methodology): “Athanassoula & Misiriotis (2002) and Athanassoula (2002, 2003a) also clearly showed that, even for highly concentrated and/or dominant halos, luminous matter can dominate the inner parts of the models at late times.”
HOW DO DISKS SURVIVE MERGERS? (2008, background): “…friction limit, following Weinberg (1985) (for more detailed solutions, which ultimately give similar results, see Hernquist & Weinberg 1992b; Athanassoula 2003; Weinberg & Katz 2007): dj/dt = −4παG2Mbar,gasρ(Rd)v−2bar, whereρ(Rd) is the background density andα ∼ 1 is a numerical constant…”
Image decomposition of barred galaxies and AGN hosts (2007, background): “Athanassoula (2002, 2003) presents theoretical work which shows that bars get longer with age by capturing disc stars, which is in agreement with the observational findings in Gadotti & de Souza (2005) and GdS06, although more observational evidences are needed to settle this point.”
Secular bar formation in galaxies with a significant amount of dark matter (2002, methodology): “This non-linear interaction is clearly important for the long-term evolution of the bar (Athanassoula 2003).”
BUDDA: A New Two-dimensional Bulge/Disk Decomposition Code for Detailed Structural Analysis of Galaxies (2004, background): “This galaxy apparently has a very strong bar that could have destroyed the preexisting disk within the bar length, and it may be another case as those (NGC 4608 andNGC5701) discovered by Gadotti & de Souza (2003; see also Athanassoula 2003).”
Multicomponent decompositions for a sample of S0 galaxies (2005, background): “In this process an initially weak bar grows stronger and the bar may also consume material that originally belonged to the disc (Athanassoula 2003).”
Properties of Bars and Bulges in the Hubble Sequence (2007, methodology): “One of the most important discoveries has been that bars evolve due to angular momentum transfer between bars and dark matter halos, so that bars become longer and more massive when evolved over time (Athanassoula 2003).”
The population of barred galaxies in the local universe - I. Detection and characterisation of bars (2009, background): “…rotations because of large-scale violent bending instabilities and settle with an increased thickness and vertical velocity dispersion (e.g., Combes & Sanders 1981; Combes et al. 1990; Raha et al. 1991; Athanassoula 2003; Debattista et al. 2004; Athanassoula 2005; Martinez-Valpuesta et al. 2006).”
Bar formation and evolution in disc galaxies with gas and a triaxial halo: morphology, bar strength and halo properties (2012, background): “…accompanied by a considerable effort with N-body simulations (e.g. Debattista & Sellwood 2000; Athanassoula 2002; Athanassoula & Misiriotis 2002; Athanassoula 2003, hereafter A03; O’Neill & Dubinski 2003; Valenzuela & Klypin 2003; Holley-Bockelmann, Weinberg & Katz 2005; Martinez-Valpuesta,…”
Evolution of galactic discs: multiple patterns, radial migration, and disc outskirts (2012, background): “This behavior of bar evolution is well known and is likely due to angular momentum loss to the inner halo (Athanassoula, 2003).”
The Formation of a Realistic Disk Galaxy in Λ-dominated Cosmologies (2002, background): “In the ΛCDM galaxy a "fat" bar or oval distortion typical of early-type galaxies (Athanassoula 2003) is first seen atz = 0.6 and then is progressively thickened by tidal heating from infalling satellites as well as by numerical heating, becoming progressively harder to distinguish.”