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Kinematic Clues to Bar Evolution for Galaxies in the Local Universe: Why the Fastest Rotating Bars are Rotating Most Slowly

Font, J and Beckman, JE and Martínez-Valpuesta, I and Borlaff, AS and James, PA and Díaz-García, S and García-Lorenzo, B and Camps-Fariña, A and Gutiérrez, L and Amram, P (2017) Kinematic Clues to Bar Evolution for Galaxies in the Local Universe: Why the Fastest Rotating Bars are Rotating Most Slowly. The Astrophysical Journal, 835 (2). ISSN 1538-4357

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Abstract

We have used Spitzer images of a sample of 68 barred spiral galaxies in the local universe to make systematic measurements of bar length and bar strength. We combine these with precise determinations of the corotation radii associated with the bars, taken from our previous study, which used the phase change from radial inflow to radial outflow of gas at corotation, based on high-resolution two-dimensional velocity fields in Hα taken with a Fabry-Pérot spectrometer. After presenting the histograms of the derived bar parameters, we study their dependence on the galaxy morphological type and on the total stellar mass of the host galaxy, and then produce a set of parametric plots. These include the bar pattern speed versus bar length, the pattern speed normalized with the characteristic pattern speed of the outer disk versus the bar strength, and the normalized pattern speed versus R, the ratio of corotation radius to bar length. To provide guidelines for our interpretation, we used recently published simulations, including disk and dark matter halo components. Our most striking conclusion is that bars with values of R < 1.4, previously considered dynamically fast rotators, can be among the slowest rotators both in absolute terms and when their pattern speeds are normalized. The simulations confirm that this is because as the bars are braked, they can grow longer more quickly than the outward drift of the corotation radius. We conclude that dark matter halos have indeed slowed down the rotation of bars on Gyr timescales. © 2017. The American Astronomical Society. All rights reserved..

Item Type: Article
Uncontrolled Keywords: 0201 Astronomical And Space Sciences, 0305 Organic Chemistry, 0306 Physical Chemistry (Incl. Structural)
Subjects: Q Science > QB Astronomy
Q Science > QC Physics
Q Science > QD Chemistry
Divisions: Astrophysics Research Institute
Publisher: American Astronomical Society
Date Deposited: 06 Mar 2017 11:49
Last Modified: 08 Sep 2017 20:23
DOI or Identification number: 10.3847/1538-4357/835/2/279
URI: http://researchonline.ljmu.ac.uk/id/eprint/5766

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