Kinematics in the Central Kiloparsec of Spiral Galaxies

Results from kinematic observations of the central regions of spiral galaxies are reviewed, with particular emphasis on starburst and AGN hosts. While morphological studies lead to important insight, a more complete understanding of the physical processes that drive the evolution of the central regions can be achieved with measurements of the kinematics of gas and stars. Here, a variety of observational techniques at different wavelengths is critically discussed, and specific areas of interest are highlighted, such as inflow in barred galaxies and the origin of nuclear spiral arms. A brief discussion of a number of case studies is presented to illustrate recent progress.Comment: Invited review, to appear in The Central kpc of Starbursts and AGN: the La Palma Connection, eds. J. H. Knapen, J. E. Beckman, I. Shlosman, and T. J. Mahoney (ASP: San Francisco), Vol. 249. 18 pages latex, includes 9 postscript figures. Uses newpasp.sty (included

High-resolution UKIRT observations of circumnuclear star formation in M100

We present high-resolution, near-infrared imaging of the circumnuclear region of the barred spiral galaxy M100 (=NGC 4321), accompanied by near-infrared spectroscopy. We identify a total of 43 distinct regions in the K-band image, and determine magnitudes and colours for 41 of them. By comparison with other near-infrared maps we also derive colour excesses and K-band extinctions for the knots. Combining the imaging and spectroscopic results, we conclude that the knots are the result of bursts of star formation within the last 15-25 Myr. We discuss the implications of these new results for our dynamical and evolutionary understanding of this galaxy.Comment: 10 pages, 4 figures, uses mn-1.4.sty. Accepted for publication in Monthly Notices of the Royal Astronomical Societ

Deficiency of `Thin' Stellar Bars in Seyfert Host Galaxies

Using all available major samples of Seyfert galaxies and their corresponding control samples of closely matched non-active galaxies, we find that the bar ellipticities (or axial ratios) in Seyfert galaxies are systematically different from those in non-active galaxies. Overall, there is a deficiency of bars with large ellipticities (i.e., `fat' or `weak' bars) in Seyferts, compared to non-active galaxies. Accompanied with a large dispersion due to small number statistics, this effect is strictly speaking at the `2sigma' level. To obtain this result, the active galaxy samples of near-infrared surface photometry were matched to those of normal galaxies in type, host galaxy ellipticity, absolute magnitude, and, to some extent, in redshift. We discuss possible theoretical explanations of this phenomenon within the framework of galactic evolution, and, in particular, of radial gas redistribution in barred galaxies. Our conclusions provide further evidence that Seyfert hosts differ systematically from their non-active counterparts on scales of a few kpc.Comment: Astrophysical Journal Letters, in press. Latex, 2 postscript figure