The family of amide molecules toward NGC 6334I

Abstract: Amide molecules produced in space could play a key role in the formation of biomolecules on a young planetary object. However, the formation and chemical network of amide molecules in space is not well understood. In this work, ALMA observations are used to study a number of amide(-like) molecules toward the high-mass star-forming region NGC 6334I. The first detections of cyanamide (NH${2}$CN), acetamide (CH${3}$C(O)NH${2}$) and N-methylformamide (CH${3}$NHCHO) are presented for this source. These are combined with analyses of isocyanic acid (HNCO) and formamide (NH${2}$CHO) and a tentative detection of urea (carbamide; NH${2}$C(O)NH${2}$). Abundance correlations show that most amides are likely formed in related reactions occurring in ices on interstellar dust grains in NGC 6334I. However, in an expanded sample of sources, large abundance variations are seen for NH${2}$CN that seem to depend on the source type, which suggests that the physical conditions within the source heavily influence the production of this species. The rich amide inventory of NGC 6334I strengthens the case that interstellar molecules can contribute to the emergence of biomolecules on planets.