Hydroxylamine in Astrophysical Ices: IR Spectra and Cosmic Ray-Induced Radiolytic Chemistry

Gas-phase hydroxylamine (NH₂OH) has recently been detected within dense clouds in the interstellar medium. However, it is also likely present within interstellar ices, as well as on the icy surfaces of outer Solar System bodies, where it may react to form more complex prebiotic molecules such as amino acids.

In this work, we aimed to provide IR spectra of NH₂OH in astrophysical ice analogues that will help in the search for this molecule in various astrophysical environments. Furthermore, we aimed to provide quantitative information on the stability of NH₂OH upon exposure to ionizing radiation analogous to cosmic rays, as well as on the ensuing chemistry and potential formation of complex prebiotic molecules. Ices composed of NH₂OH, H2O, and CO were prepared by vapor deposition and IR spectra were acquired between 4000−500~cm−1 (2.5−20μm) prior and during irradiation using 15 keV protons.

In interstellar ice analogues, the most prominent IR absorption band of NH₂OH is that at about 1188~cm⁻¹, which may be a good candidate to use in searches of this species in icy space environments. Calculated effective destruction cross-sections and G-values for the NH₂OH-rich ices studied show that NH₂OH is rapidly destroyed upon exposure to ionizing radiation (more rapidly than a number of previously studied organic molecules), and that this destruction is slightly enhanced when it is mixed with other icy species.

The irradiation of a NH₂OH:H₂O:CO ternary ice mixture leads to a rich chemistry that includes the formation of simple inorganic molecules such as NH₃, CO₂, OCN⁻, and H₂O₂, as well as ammonium salts and, possibly, complex organic molecules relevant to life such as formamide, formic acid, urea, and glycine.

Belén Maté, Ramón J. Peláez, Germán Molpeceres, Richárd Rácz, Duncan V. Mifsud, Juan Ortigoso, Víctor M. Rivilla, Gergő Lakatos, Béla Sulik, Péter Herczku, Sergio Ioppolo, Sándor Biri, Zoltán Juhász

Comments: Accepted for publication in A&A
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Cite as: arXiv:2501.17587 [astro-ph.GA] (or arXiv:2501.17587v1 [astro-ph.GA] for this version)
https://doi.org/10.48550/arXiv.2501.17587
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Submission history
From: German Molpeceres
[v1] Wed, 29 Jan 2025 11:41:15 UTC (1,062 KB)
https://arxiv.org/abs/2501.17587
Astrobiology,