The incidence of bar-like kinematic flows in CALIFA galaxies
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2015
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Wiley
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Abstract
We carry out a direct search for bar-like non-circular flows in intermediate-inclination, gas-rich disc galaxies with a range of morphological types and photometric bar classifications from the first data release (DR1) of the Calar Alto Legacy Integral Field Spectroscopy Area (CALIFA) survey. We use the diskfit algorithm to apply rotation only and bisymmetric flow models to Hα velocity fields for 49/100 CALIFA DR1 systems that meet our selection criteria. We find satisfactory fits for a final sample of 37 systems. diskfit is sensitive to the radial or tangential components of a bar-like flow with amplitudes greater than 15 km s^-1 across at least two independent radial bins in the fit, or ∼2.25 kpc at the characteristic final sample distance of ∼75 Mpc. The velocity fields of 25/37 (67.6^+6.6_-8.5) per cent) galaxies are best characterized by pure rotation, although only 17/25 (68.0^+7.7_-10.4 per cent) of them have sufficient Hα emission near the galaxy centre to afford a search for non-circular flows. We detect non-circular flows in the remaining 12/37 (32.4(-6.6)(+8.5) per cent) galaxies. We conclude that the non-circular flows detected in 11/12 (91.7^+2.8_-14.9) per cent) systems stem from bars. Galaxies with intermediate (AB) bars are largely undetected, and our detection thresholds therefore represent upper limits to the amplitude of the non-circular flows therein. We find 2/23 (8.7^+9.6_-2.9) per cent) galaxies that show non-circular motions consistent with a bar-like flow, yet no photometric bar is evident. This suggests that in ∼10 per cent of galaxies either the existence of a bar may be missed completely in photometry or other processes may drive bar-like flows and thus secular galaxy evolution.
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© 2015 RAS. KS acknowledges support from the Natural Sciences and Engineering Research Council of Canada. CJW acknowledges support through the Marie Curie Career Integration Grant 303912. RAM is funded by the Spanish program of International Campus of Excellence Moncloa (CET). JIMA acknowledges support from the European Research Council Starting Grant (SEDmorph; P.I. V. Wild).Funding for the SDSS and SDSS-II has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, the National Science Foundation, the U.S. Department of Energy, the National Aeronautics and Space Administration, the Japanese Monbukagakusho, the Max Planck Society, and the Higher Education Funding Council for England. The SDSS Web Site is http://www.sdss.org/.The SDSS is managed by the Astrophysical Research Consortium for the Participating Institutions. The Participating Institutions are the American Museum of Natural History, Astrophysical Institute Potsdam, University of Basel, University of Cambridge, Case Western Reserve University, University of Chicago, Drexel University, Fermilab, the Institute for Advanced Study, the Japan Participation Group, Johns Hopkins University, the Joint Institute for Nuclear Astrophysics, the Kavli Institute for Particle Astrophysics and Cosmology, the Korean Scientist Group, the Chinese Academy of Sciences (LAMOST), Los Alamos National Laboratory, the Max-Planck-Institute for Astronomy (MPIA), the Max-Planck-Institute for Astrophysics (MPA), New Mexico State University, Ohio State University, University of Pittsburgh, University of Portsmouth, Princeton University, the United States Naval Observatory and the University of Washington.