Stellar kinematics in double-barred galaxies: the sigma-hollows

Abstract

We present SAURON integral-field stellar velocity and velocity dispersion maps for four double-barred early-type galaxies: NGC2859, NGC3941, NGC4725 and NGC5850. The presence of the inner bar does not produce major changes in the line-of-sight velocity, but it appears to have an important effect in the stellar velocity dispersion maps: we find two sigma-hollows of amplitudes between 10 and 40 km/s on either side of the center, at the ends of the inner bars. We have performed numerical simulations to explain these features. Ruling out other possibilities, we conclude that the sigma-hollows are an effect of the contrast between two kinematically different components: the high velocity dispersion of the bulge and the more ordered motion (low velocity dispersion) of the inner bar.

5 pages, 2 figures. Accepted for publication in ApJ Letters

References in corpus (3)

• The SAURON project - VII. Integral-field absorption and emission-line kinematics of 24 spiral galaxy bulges
• Long-Lived Double-Barred Galaxies From Pseudo-Bulges
• Induced Nested Galactic Bars Inside Assembling Dark Matter Halos

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• Composite Bulges: The Coexistence of Classical Bulges and Disky Pseudobulges in S0 and Spiral Galaxies
• Secular- and merger-built bulges in barred galaxies
• Forming Double-barred Galaxies From Dynamically Cool Inner Disks
• Kinematic properties of double-barred galaxies: simulations vs. integral-field observations
• Orthogonal vertical velocity dispersion distributions produced by bars