The ALMA-QUARKS survey: Extensive detection of acetamide in multiple high-mass star-forming regions

Abstract

Acetamide (CH${}_3$CONH${}_2$), a key interstellar amide and a methyl derivative of formamide (NH${}_2$CHO), has been sparsely detected, limiting insights into its prebiotic relevance. We present the first systematic survey for acetamide toward 52 hot molecular cores using ALMA Band 6 data. Acetamide has been detected in 10 cores, markedly expanding the inventory of known emitters. The derived column densities of acetamide range from $(2.5\pm 0.9)\times 10^{14}$ to $(1.5\pm 0.6)\times 10^{16}$ cm${}^{-2}$, compared to formamide's $(1.1\pm 0.1)\times 10^{15}$ to $(6.9\pm 0.4)\times 10^{16}$ cm${}^{-2}$. The nearly constant abundance ratios (~3-9) and strong abundance correlation between the two amides across sources suggest a chemically linked formation pathway, likely on grain surfaces. The presence of peptide-like molecules in these regions implies that complex organic species can survive star formation processes, offering a potential pathway toward prebiotic chemistry. These findings constrain the dominant grain surface formation routes of acetamide, confirm its broader prevalence in highmass star-forming regions, and underscore the importance of targeted amide surveys in tracing the chemical evolution toward prebiotic complexity.

10 pages, 8 figures, 3 tables, Published in A&A

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