Gas-driven evolution of stellar orbits in barred galaxies

Berentzen, I.; Heller, Clayton; Shlosman, Isaac; Fricke, K. J.

doi:10.1046/j.1365-8711.1998.01836.x

Cited by 126 publications

(187 citation statements)

References 24 publications

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“…Second is the inflow of gas towards the galaxy center which results in the transfer of angular momentum to the bar wave which then weakens the bar itself (Bournaud, Combes & Semelin 2005). The buckling instability is an important bar thickening mechanism that results in a boxy/peanut bulge which can temporarily weaken a bar (Raha et al 1991;Berentzen et al 1998;Athanassoula & Misiriotis 2002;Martinez-Valpuesta, Shlosman & Heller 2006;Debattista et al 2006). All these effects result in a more massive and dynamically hotter central component and a weaker bar.…”

Section: Discussionmentioning

confidence: 99%

Variation of bar strength with central velocity dispersion in spiral galaxies

Das

Laurikainen

Salo

et al. 2008

Astrophys Space Sci

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We investigate the variation of bar strength with central velocity dispersion in a sample of barred spiral galaxies. The bar strength is characterized by Q g , the maximal tangential perturbation associated with the bar, normalized by the mean axisymmetric force. It is derived from the galaxy potentials which are obtained using near-infrared images of the galaxies. However, Q g is sensitive to bulge mass. Hence we also estimated bar strengths from the relative Fourier intensity amplitude (A 2 ) of bars in near-infrared images. The central velocity dispersions were obtained from integral field spectroscopy observations of the velocity fields in the centers of these galaxies; it was normalized by the rotation curve amplitude obtained from HI line width for each galaxy. We found a correlation between bar strengths (both Q g and A 2 ) and the normalized central velocity dispersions in our sample. This suggests that bars weaken as their central components become kinematically hotter. This may have important implications for the secular evolution of barred galaxies.

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Section: Discussionmentioning

confidence: 99%

Variation of bar strength with central velocity dispersion in spiral galaxies

Das

Laurikainen

Salo

et al. 2008

Astrophys Space Sci

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“…This suggests that the relationship between bulge morphology and bar viewing angle is not as straightforward as the N-body simulations suggest (e.g., Combes et al 1990;Raha et al 1991), or that the pure N-body kinematics is too idealized, particularly for gas-rich galaxies. The structure and dynamics of (thick) bars may be strongly influenced by the presence of a gas disk, as has been advocated by Berentzen et al (1998). While they argued that the bar and buckling instabilities (and thus the boxiness of the bulges) are weakened by gas, which does not seem to be the case here (there are plenty of gas-rich but strong B/ PS bulges), it would be interesting to see if the kinematic bar signatures are strongly affected.…”

Section: B/ps Bulges and Barsmentioning

confidence: 92%

“…Studying the stars directly is nevertheless essential as B/ PS bulges are stellar structures and, when compared with N-body simulations, stellar kinematics largely bypass issues such as the selection of an optimal gaseous tracer (H , CO, H i, etc. ), star formation, and (for gas-poor objects) the response of the orbital structure to a massive gas disk (e.g., Berentzen et al 1998).…”

Section: Introductionmentioning

confidence: 99%

Stellar Kinematics of Boxy Bulges: Large-Scale Bars and Inner Disks

2004

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Long-slit stellar kinematic observations were obtained along the major axis of 30 edge-on spiral galaxies, 24 with a boxy or peanut-shaped (B/PS) bulge and six with other bulge types for comparison. Such B/ PS bulges are identified in at least 45% of highly inclined systems, and a growing body of theoretical and observational work suggests that they are the edge-on projection of thickened bars. Profiles of the mean stellar velocity V, the velocity dispersion , as well as the asymmetric (h 3 ) and symmetric (h 4 ) deviations from a pure Gaussian are presented for all objects. Comparing these profiles with stellar kinematic bar diagnostics developed from N-body simulations, we find bar signatures in 24 of our sample galaxies (80%). Galaxies with a B/ PS bulge typically show a double-humped rotation curve with an intermediate dip or plateau. They also frequently show a rather flat central velocity dispersion profile accompanied by a secondary peak or plateau, and numerous galaxies have a local central minimum (k40%). The h 3 profiles display up to three slope reversals. Most importantly, h 3 is normally correlated with V over the presumed bar length, contrary to expectations from axisymmetric disks. These characteristic bar signatures strengthen the case for a close relationship between B/ PS bulges and bars and leave little room for other explanations of the bulges' shape. We also find that h 3 is anticorrelated with V in the very center of most galaxies (k60%), indicating that these objects additionally harbor cold and dense decoupled (quasi-) axisymmetric central stellar disks, which may be related to the central light peaks. These central disks coincide with previously identified star-forming ionized-gas disks (nuclear spirals) in gas-rich systems, and we argue that they formed out of gas accumulated by the bar at its center through inflow. As suggested by N-body models, the asymmetry of the velocity profile (h 3 ) appears to be a reliable tracer of asymmetries in disks, allowing us to discriminate between axisymmetric and barred disks seen in projection. B/ PS bulges (and thus a large fraction of all bulges) appear to be made up mostly of disk material, which has acquired a large vertical extent through bar-driven vertical instabilities. Their formation is thus probably dominated by secular evolution processes rather than merging.

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“…The gas loss of angular momentum is sufficient to destroy the bar completely, and this occurs even before a CMC is built. The presence of a CMC of only 1% is not enough to destroy the bar, but 1-2% of gas infall is enough, which explains the result of previous simulations (Berentzen et al 1998.…”

Section: Role Of Gas In Bar Destructionmentioning

confidence: 66%

“…This was shown both by Nbody simulations, and orbit computations in fixed potentials (Hasan et al 1990, Combes 1994, Norman et al 1996, Berentzen et al 1998. Bars are destroyed by 1-5% mass concentrations within 1kpc (percentage with respect to the disk mass).…”

Section: Destruction Of Barsmentioning

confidence: 73%

The role of bars

Combes¹

2004

Proc. IAU

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Abstract. Secular evolution and fueling is driven by bars in spiral galaxies, and the related dynamical processes are reviewed. It is shown that gravity torques dominate over viscous torques, and produce gas infall to the center. In this infall, the bar wave accepts the angular momentum, which produces its destruction. In the end, a central mass concentration is built, which also contributes to this destruction. While gas can be stalled at ILR for a while, secondary bars then take over the fueling. In a galaxy life-time, several bar episodes can successively develop. Through external gas accretion, disks are replenished by intermittence, between two bar phases. While the general trend for a galaxy is to evolve towards early-types, its morphology can oscillate, and turn back transiently to later-types.

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Gas-driven evolution of stellar orbits in barred galaxies

Cited by 126 publications

References 24 publications

Variation of bar strength with central velocity dispersion in spiral galaxies

Variation of bar strength with central velocity dispersion in spiral galaxies

Stellar Kinematics of Boxy Bulges: Large-Scale Bars and Inner Disks

The role of bars

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