H6 - rotation of other galaxies

• the supporting mechanism avoids collapse to the centre

spirals

• for spirals, rotation is the supporting mechanism arising naturally from the angular momentum of matter balances gravity

• naturally, disk-like structures emerge with low velocity dispersion

• thus, spirals show bulk motion with large velocities in the outskirts

• a broadened line profile is formed from the combination of all radial velocity

• the width is set by the maximum and minimum velocities

• the FWHM is used as proxy as the extreme values are hard to measure

• the shape depends on the redshift-blueshift balance of materials, and the disk-bulge balance

  • flared disk (double peaked) when spiral arms are dominant
  • core-dominated disk with a clear maximum intensity at low radial velocities