Regularized 3D spectroscopy with CubeFit: method and application to the
  Galactic Center Circumnuclear disk
  The Galactic Center black hole and the nuclear star cluster are surrounded by
a clumpy ring of gas and dust (the circumnuclear disk, CND) that rotates about
them at a standoff distance of ~1.5 pc. The mass and density of individual
clumps in the CND are disputed. We seek to use H$_2$ to characterize the clump
size distribution and to investigate the morphology and dynamics of the
interface between the ionized interior layer of the CND and the molecular
reservoir lying further out (corresponding to the inner rim of the CND,
illuminated in ultraviolet light by the central star cluster). We have observed
two fields of approximately 20"x20" in the CND at near-infrared wavelengths
with the OSIRIS spectro-imager at the Keck Observatory. These two fields,
located at the approaching and receding nodes of the CND, best display this
interface. Our data cover two H$_2$ lines as well as the Br$\gamma$ line
(tracing H ii). We have developed the tool CubeFit, an original method to
extract maps of continuous physical parameters (such as velocity field and
velocity dispersion) from integral-field spectroscopy data, using
regularization to largely preserve spatial resolution in regions of low
signal-to-noise ratio. This original method enables us to isolate compact,
bright features in the interstellar medium of the CND. Several clumps in the
southwestern field assume the appearance of filaments, many of which are
parallel to each other. We conclude that these clumps cannot be
self-gravitating.
