Kinematic alignment of non-interacting CALIFA galaxies^⋆

Quantifying the impact of bars on stellar and ionised gas velocity field orientations

¹ Instituto de Astrofísica de Canarias, Calle vía Lactéa s/n, 38205, Spain
e-mail: jkbb@iac.es
² Departamento de Astrofísica, Universidad de La Laguna (ULL), 38200 La Laguna, Tenerife, Spain
³ Max-Planck Institute for Astronomy, Königstul 17, 69117 Heidelberg, Germany
⁴ School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, KY16 9SS, UK
⁵ Department of Physics, Royal Military Collage of Canada, PO Box 17000, Station Forces, Kingston, Ontario, K7K7B4, Canada
⁶ Instituto de Astrofísica de Andalucía (CSIC), Glorieta de la Astronomía S/N, 18008 Granada, Spain
⁷ Instituto de Astronomía, Universidad Nacional Autonóma de Mexico, A.P. 70-264, 04510 México, D.F., Mexico
⁸ Centro Astronómico Hispano Alemán de Calar Alto (CSIC-MPG), C/ Jesús Durbán Remón 2-2, 4004 Almería, Spain
⁹ European Southern Observatory, ESO Headquarters, Karl-Schwarzschild-Str. 2, 85748 Garching b. München, Germany
¹⁰ Leibniz-Institut für Astrophysik Potsdam (AIP), An der Sternwarte 16, 14482 Potsdam, Germany
¹¹ CEI Campus Moncloa, UCM-UPM, Departamento de Astrofísica y CC. de la Atmósfera, Facultad de CC. Físicas, Universidad Complutense de Madrid, Avda. Complutense S/N, 28040 Madrid, Spain
¹² University of Vienna, Department of Astrophysics, Türkenschanzstr. 17, 1180 Vienna, Austria
¹³ Department of Physics & Astronomy, University of Missouri-Kansas City, 5110 Rockhill Road, Kansas City, MO, USA
¹⁴ Sydney Institute for Astronomy, School of Physics A28, University of Sydney, NSW 2006 Sydney, Australia

Received: 22 January 2014
Accepted: 20 May 2014

Abstract

We present 80 stellar and ionised gas velocity maps from the Calar Alto Legacy Integral Field Area (CALIFA) survey in order to characterise the kinematic orientation of non-interacting galaxies. The study of galaxies in isolation is a key step towards understanding how fast-external processes, such as major mergers, affect kinematic properties in galaxies. We derived the global and individual (projected approaching and receding sides) kinematic position angles (PAs) for both the stellar and ionised gas line-of-sight velocity distributions. When compared to the photometric PA, we find that morpho-kinematic differences are smaller than 22 degrees in 90% of the sample for both stellar and nebular components and that internal kinematic misalignments are generally smaller than 16 degrees. We find a tight relation between the global stellar and ionised gas kinematic PA consistent with circular-flow pattern motions in both components (~90% of the sample has differences smaller than 16 degrees). This relation also holds, generally in barred galaxies across the bar and galaxy disc scales. Our findings suggest that even in the presence of strong bars, both the stellar and the gaseous components tend to follow the gravitational potential of the disc. As a result, kinematic orientation can be used to assess the degree of external distortions in interacting galaxies.