Central Rotation Curves of Galaxies.pdf

arXiv:astro-ph/0010595v1 30 Oct 2000 Central Rotation Curves of Galaxies Yoshiaki SOFUE Institute of Astronomy, University of Tokyo, Mitaka, Tokyo181-0015, Japan: ******@-toky February 5, 2008 Abstract We emphasize the use of high-resolution CO line observations to derive central rotation curves of galaxies. We present an example for high-resolution interferometer observations of NGC 3079,and discuss the PV diagram and derived rotation curve. The CO central rotation curves bined with the outer curves from Hαand HI-line obser- vations to obtain total RC. We show that well resolved RCs formassive galaxies generally start from non-zero velocities at the nucleus. 1 Introduction The CO molecular lines are useful to derive accurate rotation curves in the central regions of spiral galaxies, because of the high concentration in the center as well as for negligible extinction (Sofue 1996, Sofue et al 1997, 1998, 1999). Recent high-dynamic-D spectroscopy in optical lines also make it possible to obtain high accuracy rotation curves in the central regions (Rubin et al 1997; Bertola et al 1998). However, in general, optical lines su?er from signi?cant extinction by the central dustydisks, which is particularly sign?cant for highly-inclined and edge-ongalaxies. Hence, the CO lines will be the most appropriate tool to investigatethe central kinematics of spiral galaxies, if the ang