SDSS-IV MaNGA: pattern speeds of barred galaxies
  The MaNGA project has obtained IFU data for several thousand nearby galaxies,
including barred galaxies. With the two dimensional spectral and kinematic
information provided by IFUs, we can measure the pattern speed of a barred
galaxy, which determines the bar dynamics. We apply the non-parametric method
proposed by Tremaine \& Weinberg to estimate the bar pattern speed for 53
barred galaxies, making this the largest sample studied so far in this way. Our
sample is selected from the MaNGA first public data release as part of SDSS
Data Release 13 according mainly to the axis ratio and position angle
difference between the bar and disc, while kinematic data is from the later
SDSS Data Release 14. We have used both the photometric position angle from the
photometric image and the kinematic position angle from the stellar velocity
map to derive the pattern speed. Combining three independent bar length
measurements and the circular velocity from Jeans Anisotropic modelling (JAM),
we also determine the dimensionless ratio $\cal{R}$ of the corotation radius to
the bar length. We find that the galaxy's position angle is the main
uncertainty in determining the bar pattern speed. The kinematic position angle
leads to fewer ultrafast bars than the photometric position angle, and this
could be due to the method of measuring the kinematic position angle. We study
the dependence of $\cal{R}$ values on galaxy properties such as the dark matter
fraction from JAM modelling and the stellar age and metallicity from stellar
population synthesis (SPS). A positive correlation between the bar length and
bar strength is found: the longer the bar, the stronger the bar. However, no
other significant correlations are found. This may result from errors in
deriving the $\cal{R}$ values or from the complex formation and slowdown
processes of galactic bars.
