Herschel spectroscopy of Massive Young Stellar Objects in the Magellanic
  Clouds
  We present Herschel Space Observatory Photodetector Array Camera and
Spectrometer (PACS) and Spectral and Photometric Imaging Receiver Fourier
Transform Spectrometer (SPIRE FTS) spectroscopy of a sample of twenty massive
Young Stellar Objects (YSOs) in the Large and Small Magellanic Clouds (LMC and
SMC). We analyse the brightest far infrared (far-IR) emission lines, that
diagnose the conditions of the heated gas in the YSO envelope and pinpoint
their physical origin.We compare the properties of massive Magellanic and
Galactic YSOs.We find that [OI] and [CII] emission, that originates from the
photodissociation region associated with the YSOs, is enhanced with respect to
the dust continuum in the Magellanic sample. Furthermore the photoelectric
heating efficiency is systematically higher for Magellanic YSOs, consistent
with reduced grain charge in low metallicity environments. The observed CO
emission is likely due to multiple shock components. The gas temperatures,
derived from the analysis of CO rotational diagrams, are similar to Galactic
estimates. This suggests a common origin to the observed CO excitation, from
low-luminosity to massive YSOs, both in the Galaxy and the Magellanic Clouds.
Bright far-IR line emission provides a mechanism to cool the YSO environment.
We find that, even though [OI], CO and [CII] are the main line coolants, there
is an indication that CO becomes less important at low metallicity, especially
for the SMC sources. This is consistent with a reduction in CO abundance in
environments where the dust is warmer due to reduced ultraviolet-shielding.
Weak H$_2$O and OH emission is detected, consistent with a modest role in the
energy balance of wider massive YSO environments.
