Connecting Galactic and extragalactic outflows: From the Cygnus-X cluster to active galaxies

Niels Bohr Institute & Centre for Star and Planet Formation, Copenhagen University, ∅ster Voldgade 5–7, 1350 Copenhagen K, Denmark
e-mail: iaskret@gmail.com; lars.kristensen@nbi.ku.dk

Received: 3 August 2021
Accepted: 30 January 2022

Abstract

Context. Molecular outflows are commonly detected originating from both protostellar and extragalactic sources. Separate studies of low-mass, isolated high-mass, and extragalactic sources reveal scaling relations connecting the force carried by an outflow and the properties of the source that drives it, as for example the mass and luminosity.

Aims. The aim of this work is twofold: first, to examine the effects, if any, of clustered star formation on the protostellar outflows and their scaling relations and, second, to explore the possibility that outflows varying in scale and energetics by many orders of magnitude are consistent with being launched by the same physical processes.

Methods. To that end, high-angular resolution CO J = 3–2 observations were used of ten high-mass protostars in the Cygnus-X molecular cloud, obtained at the SubMilliMeter Array as part of the Protostellar Interferometric Line Survey of Cygnus-X (PILS-Cygnus). From these data, the outflow force, that is the momentum ejection rate, was measured. In addition, an extended sample of protostellar and extragalactic outflow-force measurements was assembled from existing literature to allow for a direct comparison of the scaling relations of the two types of outflows.

Results. Molecular outflows were detected originating from all ten sources of the PILS-Cygnus survey, and their outflow forces are found to be in close agreement with measurements from the literature. In addition, the comparison of the protostellar and extragalactic sources reveals, with 95% confidence, that Class 0 protostars and extragalactic sources follow the same outflow force–bolometric luminosity correlation.

Conclusions. The close agreement between the Cygnus-X sources and sources of similar envelope mass and bolometric luminosity suggests that clustered star formation has no significant effect on protostellar outflows. We find a strong indication that protostellar and extragalactic outflows are consistent with having a similar launch mechanism. The existence of such a mechanism would enable the development of a single universal outflow launch model, although more observations are required in order to verify this connection.