[Previous] | [Session 13] | [Next]

[13.18] Model independent measurements of bar pattern speeds

J. Gerssen (STScI), K. Kuijken (Sterrewacht Leiden), M. R. Merrifield (University of Nottingham)

The pattern speed in 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. The results for all four galaxies are consistent with bars being fast rotators. The lack of slow bars suggests that barred galaxies do not have centrally concentrated dark matter halos. This contradicts simulations of cosmological structure formation and observations of the central mass concentration in nonbarred galaxies.

[Previous] | [Session 13] | [Next]

Bulletin of the American Astronomical Society, 34, #4
© 2002. The American Astronomical Soceity.