Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA;Sterrewacht Leiden, PO Box 9513, 2300 RA Leiden, the Netherlands;School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD
Abstract:
The pattern speed is one of the fundamental parameters that determines the structure of barred galaxies. This quantity is usually derived from indirect methods or by employing model assumptions. The number of bar pattern speeds derived using the model-independent Tremaine & Weinberg technique is still very limited. We present the results of model-independent measurements of the bar pattern speed in four galaxies ranging in Hubble type from SB0 to SBbc. Three of the four galaxies in our sample are consistent with bars being fast rotators. The lack of slow bars is consistent with previous observations and suggests that barred galaxies do not have centrally concentrated dark matter haloes. This contradicts simulations of cosmological structure formation and observations of the central mass concentration in nonbarred galaxies.