Bar pattern speeds in CALIFA galaxies I. Fast bars across the Hubble sequence

Astronomy and Astrophysics 576 (2015): A102 reproduced with permission from Astronomy & Astrophysics, © ESO
Context. The bar pattern speed (Ωb) is defined as the rotational frequency of the bar, and it determines the bar dynamics. Several methods have been proposed for measuring Ωb. The non-parametric method proposed by Tremaine & Weinberg (1984, ApJ, 282, L5; TW) and based on stellar kinematics is the most accurate. This method has been applied so far to 17 galaxies, most of them SB0 and SBa types. Aims. We have applied the TW method to a new sample of 15 strong and bright barred galaxies, spanning a wide range of morphological types from SB0 to SBbc. Combining our analysis with previous studies, we investigate 32 barred galaxies with their pattern speed measured by the TW method. The resulting total sample of barred galaxies allows us to study the dependence of Ωb on galaxy properties, such as the Hubble type. Methods. We measured Ωb using the TW method on the stellar velocity maps provided by the integral-field spectroscopy data from the CALIFA survey. Integral-field data solve the problems that long-slit data present when applying the TW method, resulting in the determination of more accurate Ωb. In addition, we have also derived the ratio R of the corotation radius to the bar length of the galaxies. According to this parameter, bars can be classified as fast (R < 1.4) and slow (R > 1.4). Results. For all the galaxies, R is compatible within the errors with fast bars. We cannot rule out (at 95% level) the fast bar solution for any galaxy. We have not observed any significant trend between R and the galaxy morphological type. Conclusions. Our results indicate that independent of the Hubble type, bars have been formed and then evolve as fast rotators. This observational result will constrain the scenarios of formation and evolution of bars proposed by numerical simulations
J.A.L.A. have been partly funded by the Spanish Ministry for Science, project AYA2013-43188-P. J.M.A. acknowledges support from the European Research Council Starting Grant (SEDmorph; P.I. V. Wild). R. A. Marino is funded by the Spanish program of International Campus of Excellence Moncloa (CEI). I.M. acknowledges the financial support from the Spanish grant AYA2010-15169 and from the Junta de Andalucia through TIC-114 and the Excellence Project P08-TIC-03531. R.G.D. and E.P. have been partly funded by Spanish grant AYA2010-1581. J.I.P. acknowledges financial support from MINECO AYA2010-21887-C04-01 grant and from Junta de Andalucía Excellence Project PEX2011-FQM7058. S.F.S. acknowledges support from CONACyT grant 180125. This study makes uses of the data provided by the Calar Alto Legacy Integral Field Area (CALIFA) survey (http://www.califa.caha.es). Based on observations collected at the Centro Astronómico Hispano Alemán (CAHA) at Calar Alto, operated jointly by the Max-PlanckInstitut fur Astronomie and the Instituto de Astrofísica de Andalucía (CSIC). CALIFA is the first legacy survey being performed at Calar Alto.The CALIFA collaboration would like to thank the IAA-CSIC and MPIA-MPG as major partners of the observatory, and CAHA itself, for the unique access to telescope time and support in manpower and infrastructures. The CALIFA collaboration thanks also the CAHA staff for the dedication to this project. R.G.D., E.P., R.G.B., and C.C.F. wants to thanks finalcial support from AYA2010-15081. J.F.-B. acknowledgessupport from grant AYA2013-48226-C3-1-P from MINECO