The G305 star-forming complex: Embedded Massive Star Formation
  Discovered by Herschel Hi-GAL
  We present a Herschel far-infrared study towards the rich massive star-
forming complex G305, utilising PACS 70, 160 {\mu}m and SPIRE 250, 350, and 500
{\mu}m observations from the Hi-GAL survey of the Galactic plane. The focus of
this study is to identify the embedded massive star-forming population within
G305, by combining far-infrared data with radio continuum, H2O maser, methanol
maser, MIPS, and Red MSX Source survey data available from previous studies. By
applying a frequentist technique we are able to identify a sample of the most
likely associations within our multi-wavelength dataset, that can then be
identified from the derived properties obtained from fitted spectral energy
distributions (SEDs). By SED modelling using both a simple modified blackbody
and fitting to a comprehensive grid of model SEDs, some 16 candidate
associations are identified as embedded massive star-forming regions. We derive
a two-selection colour criterion from this sample of log(F70/F500)\geq 1 and
log(F160/F350)\geq 1.6 to identify an additional 31 embedded massive star
candidates with no associated star-formation tracers. Using this result we can
build a picture of the present day star-formation of the complex, and by
extrapolating an initial mass function, suggest a current population of \approx
2 \times 10^4 young stellar objects (YSOs) present, corresponding to a star
formation rate (SFR) of 0.01-0.02 M\odot yr^-1. Comparing this resolved star
formation rate, to extragalactic star formation rate tracers (based on the
Kennicutt-Schmidt relation), we find the star formation activity is
underestimated by a factor of \geq 2 in comparison to the SFR derived from the
YSO population.
