ATLASGAL --- towards a complete sample of massive star forming clumps
  By matching infrared-selected, massive young stellar objects (MYSOs) and
compact HII regions in the RMS survey to massive clumps found in the
submillimetre ATLASGAL survey, we have identified ~1000 embedded young massive
stars between 280\degr < $\ell$ < 350\degr and 10degr < $\ell$ < 60\degr with
|b|<1.5degr. Combined with an existing sample of radio-selected methanol masers
and compact HII regions, the result is a catalogue of ~1700 massive stars
embedded within ~1300 clumps located across the inner Galaxy, containing three
observationally distinct subsamples, methanol-maser, MYSO and HII-region
associations, covering the most important tracers of massive star formation,
thought to represent key stages of evolution. We find that massive star
formation is strongly correlated with the regions of highest column density in
spherical, centrally condensed clumps. We find no significant differences
between the three samples in clump structure or the relative location of the
embedded stars, which suggests that the structure of a clump is set before the
onset of star formation, and changes little as the embedded object evolves
towards the main sequence. There is a strong linear correlation between clump
mass and bolometric luminosity, with the most massive stars forming in the most
massive clumps. We find that the MYSO and HII-region subsamples are likely to
cover a similar range of evolutionary stages and that the majority are near the
end of their main accretion phase. We find few infrared-bright MYSOs associated
with the most massive clumps, probably due to very short pre-main sequence
lifetimes in the most luminous sources.
