Yoshiaki Sofue

Rotation Curves of Spiral Galaxies

▪ Abstract Rotation curves of spiral galaxies are the major tool for determining the distribution of mass in spiral galaxies. They provide fundamental information for understanding the dynamics, ev...

CENTRAL ROTATION CURVES OF SPIRAL GALAXIES

We present high-resolution central-to-outer rotation curves for Sb, SBb, Sc, and SBc galaxies. We discuss their general characteristics, particularly their central behavior, as well as dependencies on morphological types, activity, and peculiarity. The rotation curves generally show a steep nuclear rise and high-velocity central rotation, followed by a broad maximum in the disk and then a flat rotation due to the massive halo. Since the central high velocity and steep rise are common to all massive galaxies, they cannot be due to noncircular motions. Disk rotation curves of barred galaxies show larger dispersion than those of normal galaxies, probably because of noncircular motions. Interacting galaxies often show perturbed outer rotation curves, while their central rotation shows no particular peculiarity. In addition, central activities, such as starbursts and active galactic nuclei, appear to show no particular correlation with the property of rotation curves. This would suggest that the central activities are triggered by a more local effect than the global dynamical property.

The Most Completely Sampled Rotation Curves for Galaxies

We have compiled high-resolution position-velocity diagrams observed along the major axes of nearby spiral galaxies in the CO-line emission, and derived rotation curves for the inner regions of the galaxies. We have combined the inner rotation curves with the outer HI and optical rotation curves to obtain the total rotation curves. The inner rotation curves are characterized by a steep increase within a few hundred pc radius, indicating a compact massive concentration near the nucleus. We fit the obtained rotation curves for individual galaxies by a modified Miyamoto-Nagais potential by assuming existence of four mass components; a nuclear mass component with a scale radius of 100-150 pc and a mass of

Unified Rotation Curve of the Galaxy — Decomposition into de Vaucouleurs Bulge, Disk, Dark Halo, and the 9-kpc Rotation Dip —

\sim 3-5\times 10^{9}Msun

Three-Dimensional Distribution of the ISM in the Milky Way Galaxy : II. The Molecular Gas Disk

; a central bulge of 0.5 to 1 kpc radius of a mass

Three-Dimensional Distribution of the ISM in the Milky Way Galaxy: I. The H I Disk

\sim 10^{10}Msun

Bipolar Hypershell Galactic Center Starburst Model: Further Evidence from ROSAT Data and New Radio and X-Ray Simulations

; a disk with scale radius 5 to 7 kpc and thickness 0.5 kpc of a mass

A bisymmetric spiral magnetic field and the spiral arms in our Galaxy

\sim 1-2 Mgal

A Grand Rotation Curve and Dark Matter Halo in the Milky Way Galaxy

; and a massive halo of scale radius 15 to 20 kpc with a mass

Nuclear-to-Outer Rotation Curves of Galaxies in the CO and HI Lines

\sim 2-3 Mgal