The ALMA-PILS survey: Stringent limits on small amines and nitrogen-oxides towards IRAS 16293–2422B.

Context. Hydroxylamine (NH₂OH) and methylamine (CH₃NH₂) have both been suggested as precursors to the formation of amino acids and are therefore, of interest to prebiotic chemistry. Their presence in interstellar space and formation mechanisms, however, are not well established. Aims. We aim to detect both amines and their potential precursor molecules NO, N₂O, and CH₂NH towards the low-mass protostellar binary IRAS 16293–2422, in order to investigate their presence and constrain their interstellar formation mechanisms around a young Sun-like protostar. Methods. ALMA observations from the unbiased, high-angular resolution and sensitivity Protostellar Interferometric Line Survey (PILS) are used. Spectral transitions of the molecules under investigation are searched for with the CASSIS line analysis software. Results. CH₂NH and N₂O are detected for the first time, towards a low-mass source, the latter molecule through confirmation with the single-dish TIMASSS survey. NO is also detected. CH₃NH₂ and NH₂OH are not detected and stringent upper limit column densities are determined. Conclusions. The non-detection of CH₃NH₂ and NH₂OH limits the importance of formation routes to amino acids involving these species. The detection of CH₂NH makes amino acid formation routes starting from this molecule plausible. The low abundances of CH₂NH and CH₃NH₂ compared to Sgr B2 indicate that different physical conditions influence their formation in low- and high-mass sources. [ABSTRACT FROM AUTHOR]