Bar pattern speeds in CALIFA galaxies: I. Fast bars across the Hubble
  sequence
  The bar pattern speed ($\Omega_{\rm b}$) is defined as the rotational
frequency of the bar, and it determines the bar dynamics. Several methods have
been proposed for measuring $\Omega_{\rm b}$. The non-parametric method
proposed by Tremaine \& Weinberg (1984; 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. 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
$\Omega_{\rm b}$ on galaxy properties, such as the Hubble type. We measured
$\Omega_{\rm b}$ 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 $\Omega_{\rm b}$. In
addition, we have also derived the ratio $\cal{R}$ of the corotation radius to
the bar length of the galaxies. According to this parameter, bars can be
classified as fast ($\cal{R}$ $< 1.4$) and slow ($\cal{R}$>1.4). For all the
galaxies, $\cal{R}$ 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 $\cal{R}$ and the galaxy morphological
type. 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.
