With the aim of understanding the role of massive outflows in high-mass star formation , we mapped in the ^ { 12 } CO J = 2 - 1 transition 26 high-mass star-forming regions at very early stages of their evolution .
At a spatial resolution of 11 ^ { \prime \prime } bipolar molecular outflows were found in 21 of them .
The other five sources show confusing morphology but strong line wings .
This high detection rate of bipolar structure proves that outflows common in low-mass sources are also ubiquitous phenomena in the formation process of massive stars .
The flows are large , very massive and energetic , and the data indicate stronger collimation than previously thought .
The dynamical timescales of the flows correspond well to the free-fall timescales of the associated cores .
Comparing with correlations known for low-mass flows , we find continuity up to the high-mass regime suggesting similar flow-formation scenarios for all masses and luminosities .
Accretion rate estimates in the 10 ^ { 4 } L _ { \odot } range are around 10 ^ { -4 } M _ { \odot } yr ^ { -1 } , higher than required for low-mass star formation , but consistent with high-mass star formation scenarios .
Additionally , we find a tight correlation between the outflow mass and the core mass over many orders of magnitude .
The strong correlation between those two quantities implies that the product of the accretion efficiency f _ { acc } = \dot { M } _ { acc } / ( M _ { core } / t _ { ff } ) and f _ { r } ( the ratio between jet mass loss rate and accretion rate ) , which equals the ratio between jet and core mass ( f _ { acc } f _ { r } = M _ { jet } / M _ { core } ) , is roughly constant for all core masses .
This again indicates that the flow-formation processes are similar over a large range of masses .
Additionally , we estimate median f _ { r } and f _ { acc } values of approximately 0.2 and 0.01 , respectively , which is consistent with current jet-entrainment models . To summarize , the analysis of the bipolar outflow data strongly supports theories which explain massive star formation by scaled up , but otherwise similar physical processes – mainly accretion – to their low-mass counterparts .