Infall, outflow, and rotation in the G19.61-0.23 hot molecular core
  Aims: The main goal of this study is to perform a sub-arcsecond resolution
analysis of the high-mass star formation region G19.61-0.23, both in the
continuum and molecular line emission. While the centimeter continuum images
will be discussed in detail in a forthcoming paper, here we focus on the
(sub)mm emission, devoting special attention to the hot molecular core.
Results: Our observations resolve the HMC into three cores whose masses are on
the order of 10^1-10^3 Msun. No submm core presents detectable free-free
emission in the centimeter regime, but they appear to be associated with masers
and thermal line emission from complex organic molecules. Towards the most
massive core, SMA1, the CH3CN (18_K-17_K) lines reveal hints of rotation about
the axis of a jet/outflow traced by H2O maser and H13CO+ (1--0) line emission.
Inverse P-Cygni profiles of the 13CO (3--2) and C18O (3--2) lines seen towards
SMA1 indicate that the central high-mass (proto)star(s) is (are) still gaining
mass with an accretion rate $ge 3 ~10^{-3}$ Msun/yr. Due to the linear scales
and the large values of the accretion rate, we hypothesize that we are
observing an accretion flow towards a cluster in the making, rather than
towards a single massive star.
