Molecule-dependent abundance behavior of oxygen-bearing complex organics in high-mass star-forming regions: A uniform 50-source survey

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Abstract
We present a uniform IRAM-30 m survey analysis of four oxygen-bearing complex organic molecules (COMs) – methanol (CH 3 OH), acetaldehyde (CH 3 CHO), methyl formate (CH 3 OCHO), and dimethyl ether (CH 3 OCH 3 ) – toward 50 high-mass star-forming regions (HMSFRs) associated with 6.7 GHz methanol masers. Column densities were derived through a homogeneous rotation-diagram approach, with CH 3 CN used as a proxy excitation-temperature reference when needed. In the CH 3 OH-normalized abundance-ratio space, CH 3 OCHO/CH 3 OH and CH 3 OCH 3 /CH 3 OH show the strongest pairwise correlation, whereas the correlations involving CH 3 CHO are weaker. No clear monotonic trends are found with galactocentric distance or beam-averaged H 2 column density. Comparison with previous observations places the CH 3 OCHO–CH 3 OCH 3 behavior within the range of earlier abundance-ratio measurements, while CH 3 CHO shows larger inter-study variation. A representative warm-up chemical model was used only for qualitative comparison with the observed abundance ranges, which are most closely matched during the decline from the post-desorption abundance peaks in the model. These results provide homogeneous beam-averaged abundance-ratio constraints for common O-bearing COMs in HMS-FRs and show that their source-to-source behavior is molecule-dependent rather than fully described by a single common abundance pattern.
Funding Information
  • National SKA Program of China (2025SKA0120100)
  • National Natural Science Foundation of China (W2512014)
  • National Natural Science Foundation of China (12573065)
  • Fundamental Research Funds for the Central Universities (2025CDJ-IAISYB-060)
  • Postdoctoral Fellows Excellence Support Program (2404013554893087)
  • Natural Science Foundation of Top Talent of SZTU (GDRC202402)

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