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arXiv · 2610.36096

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

A. Aberfelds·A. Sanna·L. Moscadelli·C. Goddi·T. R. Hunter·C. L. Brogan
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Abstract

So far, the POETS survey has focused on studying at high angular resolution the properties of both 22.2 GHz H2O masers and the radio continuum emission near young stellar objects (YSOs). Now, we want to add the information coming 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 (VLA) in the A configuration, operating at high spectral resolution (0.1 km/s) 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. We present a preliminary analysis of 6.7 GHz CH3OH maser emission toward a subsample of the POETS survey (22 fields observed so far), 60 % of which show detection above a brightness temperature threshold of 10^7 K. Five sources among 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 they are associated with and quantify that, on average, 90 % of them are distributed within radii of 3000 au only. Furthermore, we find a tight correlation between the 6.7 GHz maser luminosity coming 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.

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A. Aberfelds, A. Sanna, L. Moscadelli, C. Goddi, T. R. Hunter, C. L. Brogan. 2026-10-26. Protostellar Outflows at the EarliesT Stages (POETS) X. Preliminary statistics of 6.7 GHz masers near POETS sources. https://arxiv.org/abs/2610.36096

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