Relative rotation and velocity dispersion of the Nuclear Stellar Disk

Determine whether the Milky Way Nuclear Stellar Disk rotates faster and with lower velocity dispersion than the Galactic bulge immediately outside it.

Background

The Nuclear Stellar Disk (NSD) is expected to be a rapidly rotating, dynamically cold stellar component, but observational studies have produced discrepant estimates of its rotation and radial-velocity dispersion. Existing measurements are affected by small samples, contamination from foreground and background populations, and the convolution of intrinsic dispersion with measurement errors.

Resolving whether the NSD is dynamically distinct from the surrounding bulge is important for identifying its stellar population and formation history. The paper notes that current data do not yet establish whether the NSD has both a higher rotation velocity and a lower velocity dispersion than the nearby bulge.