The Red MSX Source survey: critical tests of accretion models for the formation of massive stars
B Davies, M Hoare, S Lumsden, T Hosokawa, R Oudmaijer, J Urquhart, J Mottram, J Stead
We use several prescriptions of protostellar accretion and a description of the Galactic gas distribution to simulate the luminosities and spatial distribution of the massive protostellar population of the Galaxy. Comparing the results to data from the Red MSX Source (RMS) survey, we find that the observations are best matched by accretion rates which increase as the protostar grows, as predicted by turbulent core and competitive accretion models. Although we cannot distinguish between these accelerating accretion models, we can rule out constant or falling accretion rates. To simultaneously match the low- and high-luminosity young stellar objects (YSO) distribution requires the inclusion of a swollen pre-main-sequence phase, lasting approximately a Kelvin-Helmholz time. The YSO phase lifetime is ~105 yr, while the compact HII region phase lasts between ~2 and 4×105 yr, depending on the final stellar mass. The absolute numbers of YSOs are best matched by a global star-formation rate of 1.5−2 M¤ yr−1.