Spitzer spectral line mapping of protostellar outflows: I. Basic data
  and outflow energetics
  We report the results of spectroscopic mapping observations carried out
toward protostellar outflows in the BHR71, L1157, L1448, NGC 2071, and VLA 1623
molecular regions using the Infrared Spectrograph (IRS) of the Spitzer Space
Telescope. These observations, covering the 5.2 - 37 micron spectral region,
provide detailed maps of the 8 lowest pure rotational lines of molecular
hydrogen and of the [SI] 25.25 micron and [FeII] 26.0 micron fine structure
lines. The molecular hydrogen lines, believed to account for a large fraction
of the radiative cooling from warm molecular gas that has been heated by a
non-dissociative shock, allow the energetics of the outflows to be elucidated.
Within the regions mapped towards these 5 outflow sources, total H2
luminosities ranging from 0.02 to 0.75 L(solar) were inferred for the sum of
the 8 lowest pure rotational transitions. By contrast, the much weaker [FeII]
26.0 micron fine structure transition traces faster, dissociative shocks; here,
only a small fraction of the fast shock luminosity emerges as line radiation
that can be detected with Spitzer/IRS.
