Processing of hydroxylamine, NH2OH, an important prebiotic precursor, on interstellar ices

14 pags., 15 figs., 6 tabs.Hydroxylamine, NH2OH, is one of the already detected interstellar molecules with the highest prebiotic potential. Yet, the abundance of this molecule found by astronomical observations is rather low for a relatively simple molecule, ∼10-10 relative to H2. This seemingly low abundance can be rationalized by destruction routes operating on interstellar dust grains. In this work, we tested the viability of this hypothesis under several prisms, finding that the origin of a lower abundance of NH2OH can be explained by two chemical processes, one operating at low temperature (10 K) and the other at intermediate temperature (20 K). At low temperatures, enabling the hydrogen abstraction reaction HNO + H → NO + H2, even in small amounts, partially inhibits the formation of NH2OH through successive hydrogenation of NO, and reduces its abundance on the grains. We found that enabling a 15-30 per cent of binding sites for this reaction results in reductions of NH2OH abundance of approximately one to two orders of magnitude. At warmer temperatures (20 K, in our study), the reaction NH2OH + H → HNOH + H2, which was found to be fast (k ∼106 s-1) in this work, followed by further abstractions by adsorbates that are immobile at 10 K (O, N) are the main route of NH2OH destruction. Our results shed light on the abundance of hydroxylamine in space and pave the way to constraining the subsequent chemistry experienced by this molecule and its derivatives in the interstellar prebiotic chemistry canvas.GM thanks the Japan Society for the Promotion of Science (Grant P22013) and the Alexander von Humboldt Foundation for their support. Some calculations of this work were performed with the support of the state of Baden-Wwrttemberg ¨ through bwHPC and the German Research Foundation (DFG) through grant no. INST 40/575-1 FUGG (JUSTUS 2 cluster). VMR has received support from the project RYC2020-029387-I (COOL: Cosmic Origins Of Life) funded by MCIN/AEI /10.13039/501100011033. BM thanks Spain MIC grant PID2020-113084GB-I00. KF acknowledges support from JSPS KAKENHI grants 20H05847 and 21K13967. YA acknowledges support by Grant-in-Aid for Scientific Research (S) 18H05222, and Grant-in-Aid for Transformative Research Areas(A) grant no. 20H05847