  We examine an Infrared Dark Cloud (IRDC) at high spatial resolution as a
means to study rotation, outflow, and infall at the onset of massive star
formation. Submillimeter Array observations combined with IRAM 30 meter data in
12CO(2--1) reveal the outflow orientation in the IRDC 18223-3 region, and PdBI
3 mm observations confirm this orientation in other molecular species. The
implication of the outflow's presence is that an accretion disk is feeding it,
so using high density tracers such as C18O, N2H+, and CH3OH, we looked for
indications of a velocity gradient perpendicular to the outflow direction.
Surprisingly, this gradient turns out to be most apparent in CH3OH. The large
size (28,000 AU) of the flattened rotating object detected indicates that this
velocity gradient cannot be due solely to a disk, but rather from inward
spiraling gas within which a Keplerian disk likely exists. From the outflow
parameters, we derive properties of the source such as an outflow dynamical age
of ~37,000 years, outflow mass of ~13 M_sun, and outflow energy of ~1.7 x 10^46
erg. While the outflow mass and energy are clearly consistent with a high-mass
star forming region, the outflow dynamical age indicates a slightly more
evolved evolutionary stage than previous spectral energy distribution (SED)
modeling indicates. The calculated outflow properties reveal that this is truly
a massive star in the making. We also present a model of the observed methanol
velocity gradient. The rotational signatures can be modeled via rotationally
infalling gas. These data present evidence for one of the youngest known
outflow/infall/disk systems in massive star formation. A tentative evolutionary
picture for massive disks is discussed.
