Trace the Self-Gravitating Gas Using CO Isotopologues
Abstract
Recent studies have shown that the star formation rate (SFR) correlates tightly and linearly with the mass of gravitationally bound gas, which can be delineated from the power-law tail of the column-density probability distribution function (N-PDF) derived from dust emission observations. This relationship holds across four orders of magnitude within the Milky Way--spanning low-mass to high-mass star-forming regions and encompassing the extreme environment of the Central Molecular Zone. Building on this framework, we present a new approach for estimating the mass of gravitationally bound gas in molecular clouds using multi-line CO isotopologue observations. Our sample includes 16 molecular clouds with robust detections in 12CO, 13CO, and C18O J = 1-0, spanning both massive inner Galaxy clouds and nearby star-forming regions. We find that the N-PDFs derived from combined CO isotopologue data recover the characteristic log-normal plus power-law profiles seen in dust-based studies. The mass and spatial distribution of the self-gravitating structures estimated from both dust-based and CO-based methods agree well throughout the sample. This indicates that the CO isotopologue combination can robustly trace the self-gravitating component via the N-PDF method and provides a reliable, scalable, and velocity-resolved alternative to dust emission for identifying the star-forming gas in molecular clouds.
Versions
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BibTeX
@misc{feng2026trace,
title = {{Trace the Self-Gravitating Gas Using CO Isotopologues}},
author = {Linjing Feng and Jingwen Wu and Sihan Jiao and Zhi-Yu Zhang and Junzhi Wang and Chao-Wei Tsai and Di Li and Hauyu Baobab Liu and Yan Sun and Neal J. Evans II and Yuxin Lin and Hao Ruan and Fangyuan Deng and Yuanzhen Xiong and Ruofei Zhang},
howpublished = {arXiv},
year = {2026},
month = aug,
doi = {10.48550/arxiv.2608.12473},
eprint = {2608.12473},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2608.12473},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Trace the Self-Gravitating Gas Using CO Isotopologues
AU - Linjing Feng
AU - Jingwen Wu
AU - Sihan Jiao
AU - Zhi-Yu Zhang
AU - Junzhi Wang
AU - Chao-Wei Tsai
AU - Di Li
AU - Hauyu Baobab Liu
AU - Yan Sun
AU - Neal J. Evans II
AU - Yuxin Lin
AU - Hao Ruan
AU - Fangyuan Deng
AU - Yuanzhen Xiong
AU - Ruofei Zhang
PY - 2026
DA - 2026/08/12
PB - arXiv
DO - 10.48550/arxiv.2608.12473
UR - https://arxiv.org/abs/2608.12473
AB - Recent studies have shown that the star formation rate (SFR) correlates tightly and linearly with the mass of gravitationally bound gas, which can be delineated from the power-law tail of the column-density probability distribution function (N-PDF) derived from dust emission observations. This relationship holds across four orders of magnitude within the Milky Way--spanning low-mass to high-mass star-forming regions and encompassing the extreme environment of the Central Molecular Zone. Building on this framework, we present a new approach for estimating the mass of gravitationally bound gas in molecular clouds using multi-line CO isotopologue observations. Our sample includes 16 molecular clouds with robust detections in ^12CO, ^13CO, and C^18O J = 1-0, spanning both massive inner Galaxy clouds and nearby star-forming regions. We find that the N-PDFs derived from combined CO isotopologue data recover the characteristic log-normal plus power-law profiles seen in dust-based studies. The mass and spatial distribution of the self-gravitating structures estimated from both dust-based and CO-based methods agree well throughout the sample. This indicates that the CO isotopologue combination can robustly trace the self-gravitating component via the N-PDF method and provides a reliable, scalable, and velocity-resolved alternative to dust emission for identifying the star-forming gas in molecular clouds.
ER -