Protostellar Outflows at the EarliesT Stages (POETS). X. Preliminary statistics of 6.7,GHz masers near POETS sources

So far, the POETS survey has focused on studying the properties of 22.2,GHz H2O masers and the radio continuum emission near young stellar objects at high angular resolution. Now, we wish to add the information from another star formation tracer, the Class II 6.7,GHz CH3OH (methanol) maser, towards the same POETS targets. We seek to probe the existence of 6.7,GHz maser emission near POETS sources with high-sensitivity observations and study their kinematic properties with respect to local radio continuum and 22.2,GHz maser emission at high angular and spectral resolutions. Within the POETS survey, we used the Very Large Array in the A configuration, operating at high spectral resolution (0.1,̨ms) and achieving a sensitivity of a few mJy,beam per channel map, in order to (i) probe the emission from methanol gas in the 6.7,GHz maser transition and (ii) trace its absolute spatial distribution and local standard of rest velocity. Karl G. Jansky -1 We present a preliminary analysis of 6.7,GHz CH3OH maser emission towards a subsample of the POETS survey (including the 22 fields observed so far), 60% of which show a detection above a brightness temperature threshold of 1 (5σ). Five sources in this subsample are new detections. We draw a 6.7,GHz maser brightness function by studying the distribution of the intrinsic luminosity of the maser population and predict that more than 30% of the whole population is undetected at typical interferometric sensitivities of a few 10,mJy,beam . We confirm that 6.7,GHz masers arise close to the young star with which they are associated and quantify that 90% of them are distributed within radii of only 3000,au on average. Furthermore, we find a tight correlation between the 6.7,GHz maser luminosity from a given source and the local free-free emission, suggesting that the radio continuum provides the dominant source of seed photons amplified by the methanol gas. -1