Integral Field Spectroscopy of 23 Spiral Bulges

Abstract

We have obtained integral-field spectroscopy for 23 spiral bulges using INTEGRAL on the William Herschel Telescope and SPIRAL on the Anglo-Australian Telescope. This is the first two-dimensional survey directed solely at the bulges of spiral galaxies. Eleven galaxies of the sample do not have previous measurements of the stellar velocity dispersion (σ_*). These data are designed to complement our Space Telescope Imaging Spectrograph program for estimating black hole masses in the range 10⁶-10⁸ M_solar using gas kinematics from nucleated disks. These observations will serve to derive the stellar dynamical bulge properties using the traditional Mg b and Ca II triplets. We use both cross-correlation and maximum penalized likelihood to determine projected σ_* in these systems and present radial velocity fields, major axis rotation curves, curves of growth, and σ_* fields. Using cross-correlation to extract the low-order two-dimensional stellar dynamics we generally see coherent radial rotation and irregular velocity dispersion fields suggesting that σ_* is a nontrivial parameter to estimate.