The Circumnuclear Star Formation Environment of NGC 6946: Br-gamma and
  H2 Results from Keck Integral Field Spectroscopy
  We present a 3-dimensional data cube of the K band continuum and the
Br-gamma, H2 S(0) and S(1) lines within the central 18.5" x 13.8" (520 pc x 390
pc) region of NGC 6946. Data were obtained using OSIRIS, a near-infrared
Integral Field Unit at Keck Observatory, with Laser Guide Star Adaptive Optics.
The 0.3" resolution allows us to investigate the stellar bulge and the forming
star clusters in the nuclear region on 10 parsec scales. We detect giant HII
regions associated with massive young star clusters in the nuclear spiral/ring
(R ~ 30pc) and in the principal shocks along the nuclear bar. Comparisons of
the Br-gamma fluxes with Pa-alpha line emission and radio continuum indicate
A_K ~ 3, A_V ~ 25 for the nuclear star forming regions. The most luminous HII
regions are restricted to within 70pc of the center, despite the presence of
high gas columns at larger radii (R ~ 200pc). H2 emission is restricted to
clouds within R ~ 60pc of the center, and in this sense resembles the
distribution of the HCN line emission. We propose that gas-assisted migration
of the young star clusters is contributing to the buildup of the nuclear bar
and nuclear star cluster (R < 30pc) in this galaxy.
