Minor axis kinematics of 19 S0-Sbc bulges^*

¹ School of Physics & Astronomy, University of Nottingham, Nottingham NG7 2RD, UK e-mail: Reynier.Peletier@nottingham.ac.uk
² Instituto de Astrofísica de Canarias, 38200 La Laguna, Tenerife, Spain e-mail: balcells@ll.iac.es; vazdekis@ll.iac.es
³ CRAL, Observatoire de Lyon, 69561 St-Genis Laval cedex, France

Corresponding author: J. Falcón-Barroso, ppxjf2@nottingham.ac.uk

Received: 15 November 2002
Accepted: 18 March 2003

Abstract

We present minor axis kinematic profiles for a well-studied sample of 19 early- to intermediate-type disk galaxies. We introduce, for the first time, the use of single-burst stellar population (SSP) models to obtain stellar velocities, velocity dispersions and higher order Gauss-Hermite moments (h₃, h₄) from galaxy spectra in the near-infrared Ca ii triplet region. SSP models, which employs the synthetic spectra of [CITE], provide a means to address the template-mismatch problem, and are shown to provide as good or better fits as traditional stellar templates. We anticipate the technique to be of particular use for high-redshift galaxy kinematics. We give the measurement of a recently defined CaT^* index [CITE], and describe the global properties of the bulge kinematics as derived from the kinematic profiles. We detect small-amplitude minor-axis rotation, generally due to inner isophotal twists as a result of slightly triaxial bulges or misaligned inner disks; such inner features do not show peculiar colors or distinct CaT^* index values. Velocity dispersion profiles, which extend well into the disk region, show a wide range of slopes. Flattened bulges tend to have shallower velocity dispersion profiles. The inferred similarity of bulge and disk radial velocity dispersions supports the interpretation of these bulges as thickened disks.