SQUALO II: Probing Accretion Through CO Molecular Outflows in Massive Star-forming Clumps
Abstract
Molecular outflows probe protostellar accretion and mass transfer from clump scales to forming stars. We present an ALMA study of CO (J=2-1) outflows toward 13 massive clumps from the SQUALO sample, spanning a broad evolutionary range and exhibiting clump-scale infall. We identify 51 high-velocity CO lobes associated with 31 outflow systems and derive their physical and dynamical properties assuming local thermodynamic equilibrium. Outflow inferred accretion rates are typically 10^{-5}-10^{-3} Msun/yr, consistent with active massive star formation. The maximum outflow velocity shows little dependence on candidate driving-core mass, indicating that it is not a reliable tracer of protostellar mass in clustered environments. Outflow momentum flux correlates positively with clump surface density, whereas accretion rate shows a tentative, statistically nonsignificant decrease with increasing virial parameter. Total outflow inferred accretion rate shows a tentative positive relation with clump-scale infall rate but remains systematically lower, suggesting that the detected outflows represent only part of the large-scale mass flux. The clump L/M ratio moderately anticorrelates with projected outflow length, although projection, observational limitations, and the embedded source population prevent a unique evolutionary interpretation. Together with the continuum derived fragmentation properties, our results show that compact cores embedded within infalling clumps drive the outflows. The tentative relation between clump-scale infall and protostellar accretion suggests a possible connection across these scales, although our observations do not directly trace mass transfer from filaments to individual protostars.
Versions
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BibTeX
@misc{mercimek2026squalo,
title = {{SQUALO II: Probing Accretion Through CO Molecular Outflows in Massive Star-forming Clumps}},
author = {S. Mercimek and G. A. Fuller and A. Traficante and T. Pillai and A. Nucara and W. -A. Chen and D. Walker and L. Testi and M. Benedettini},
howpublished = {arXiv},
year = {2026},
month = nov,
doi = {10.48550/arxiv.2611.09588},
eprint = {2611.09588},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2611.09588},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - SQUALO II: Probing Accretion Through CO Molecular Outflows in Massive Star-forming Clumps
AU - S. Mercimek
AU - G. A. Fuller
AU - A. Traficante
AU - T. Pillai
AU - A. Nucara
AU - W. -A. Chen
AU - D. Walker
AU - L. Testi
AU - M. Benedettini
PY - 2026
DA - 2026/11/06
PB - arXiv
DO - 10.48550/arxiv.2611.09588
UR - https://arxiv.org/abs/2611.09588
AB - Molecular outflows probe protostellar accretion and mass transfer from clump scales to forming stars. We present an ALMA study of CO (J=2-1) outflows toward 13 massive clumps from the SQUALO sample, spanning a broad evolutionary range and exhibiting clump-scale infall. We identify 51 high-velocity CO lobes associated with 31 outflow systems and derive their physical and dynamical properties assuming local thermodynamic equilibrium. Outflow inferred accretion rates are typically 10^{-5}-10^{-3} Msun/yr, consistent with active massive star formation. The maximum outflow velocity shows little dependence on candidate driving-core mass, indicating that it is not a reliable tracer of protostellar mass in clustered environments. Outflow momentum flux correlates positively with clump surface density, whereas accretion rate shows a tentative, statistically nonsignificant decrease with increasing virial parameter. Total outflow inferred accretion rate shows a tentative positive relation with clump-scale infall rate but remains systematically lower, suggesting that the detected outflows represent only part of the large-scale mass flux. The clump L/M ratio moderately anticorrelates with projected outflow length, although projection, observational limitations, and the embedded source population prevent a unique evolutionary interpretation. Together with the continuum derived fragmentation properties, our results show that compact cores embedded within infalling clumps drive the outflows. The tentative relation between clump-scale infall and protostellar accretion suggests a possible connection across these scales, although our observations do not directly trace mass transfer from filaments to individual protostars.
ER -